The 6to4 tunnel documentation is provided by Eric de Thouars.
-
-
-
Warning: The 6to4 tunnel feature of Shorewall
-only facilitates IPv6 over IPv4 tunneling. It does not provide any IPv6 security
-measures.
-
-
6to4 tunneling with Shorewall can be used to connect your IPv6 network
-to another IPv6 network over an IPv4 infrastructure
-
+
+
+
Warning: The 6to4 tunnel feature of Shorewall
+ only facilitates IPv6 over IPv4 tunneling. It does not provide any IPv6
+security measures.
+
+
6to4 tunneling with Shorewall can be used to connect your IPv6 network
+ to another IPv6 network over an IPv4 infrastructure
+
More information on Linux and IPv6 can be found in the Linux IPv6 HOWTO. Details
-on how to setup a 6to4 tunnels are described in the section Setup
- of 6to4 tunnels.
-
+ href="http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO">Linux IPv6 HOWTO.
+Details on how to setup a 6to4 tunnels are described in the section Setup
+ of 6to4 tunnels.
+
Connecting two IPv6 Networks
-
+
Suppose that we have the following situation:
-
+
-
-
-
We want systems in the 2002:100:333::/64 subnetwork to be
-able to communicate with the systems in the 2002:488:999::/64 network. This
-is accomplished through use of the /etc/shorewall/tunnels file and the "ip"
-utility for network interface and routing configuration.
-
-
Unlike GRE and IPIP tunneling, the /etc/shorewall/policy,
-/etc/shorewall/interfaces and /etc/shorewall/zones files are not used. There
-is no need to declare a zone to represent the remote IPv6 network. This remote
-network is not visible on IPv4 interfaces and to iptables. All that is visible
-on the IPv4 level is an IPv4 stream which contains IPv6 traffic. Separate
-IPv6 interfaces and ip6tables rules need to be defined to handle this traffic.
-
-
+
+
+
We want systems in the 2002:100:333::/64 subnetwork to be
+ able to communicate with the systems in the 2002:488:999::/64 network. This
+ is accomplished through use of the /etc/shorewall/tunnels file and the "ip"
+ utility for network interface and routing configuration.
+
+
Unlike GRE and IPIP tunneling, the /etc/shorewall/policy,
+ /etc/shorewall/interfaces and /etc/shorewall/zones files are not used. There
+ is no need to declare a zone to represent the remote IPv6 network. This
+remote network is not visible on IPv4 interfaces and to iptables. All that
+is visible on the IPv4 level is an IPv4 stream which contains IPv6 traffic.
+ Separate IPv6 interfaces and ip6tables rules need to be defined to handle
+this traffic.
+
In /etc/shorewall/tunnels on system A, we need the following:
-
-
+
+
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
6to4
-
net
-
134.28.54.2
-
-
-
-
+
6to4
+
net
+
134.28.54.2
+
+
+
+
-
-
-
This entry in /etc/shorewall/tunnels, opens the firewall so that the IPv6
+
+
+
This entry in /etc/shorewall/tunnels, opens the firewall so that the IPv6
encapsulation protocol (41) will be accepted to/from the remote gateway.
-
+
Use the following commands to setup system A:
-
-
+
+
>ip tunnel add tun6to4 mode sit ttl 254 remote 134.28.54.2
- >ip link set dev tun6to4 up
- >ip addr add 3ffe:8280:0:2001::1/64 dev tun6to4
- >ip route add 2002:488:999::/64 via 3ffe:8280:0:2001::2
-
-
+ >ip link set dev tun6to4 up
+ >ip addr add 3ffe:8280:0:2001::1/64 dev tun6to4
+ >ip route add 2002:488:999::/64 via 3ffe:8280:0:2001::2
+
+
Similarly, in /etc/shorewall/tunnels on system B we have:
-
-
+
+
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
6to4
-
net
-
206.191.148.9
-
-
-
-
+
6to4
+
net
+
206.191.148.9
+
+
+
+
-
-
+
+
And use the following commands to setup system B:
-
-
+
+
>ip tunnel add tun6to4 mode sit ttl 254 remote 206.191.148.9
- >ip link set dev tun6to4 up
- >ip addr add 3ffe:8280:0:2001::2/64 dev tun6to4
- >ip route add 2002:100:333::/64 via 3ffe:8280:0:2001::1
-
-
-
On both systems, restart Shorewall and issue the configuration commands
-as listed above. The systems in both IPv6 subnetworks can now talk to each
-other using IPv6.
-
-
Updated 5/18/2003 - Tom Eastep
+ >ip link set dev tun6to4 up
+ >ip addr add 3ffe:8280:0:2001::2/64 dev tun6to4
+ >ip route add 2002:100:333::/64 via 3ffe:8280:0:2001::1
+
+
+
On both systems, restart Shorewall and issue the configuration commands
+ as listed above. The systems in both IPv6 subnetworks can now talk to each
+ other using IPv6.
This configuration is used on a corporate network that
+ has a Linux (RedHat 8.0) server with three interfaces, running Shorewall
+ 1.4.5 release,
+
Make sure you know what public IP addresses are currently
+being used and verify these before starting.
+
Verify you DNS settings before starting any
+Shorewall configuration especially if you have split DNS.
+
System names and Internet IP addresses have been changed
+to protect the innocent.
+
+
+
+
Warning: This configuration
+uses a combination of Static NAT and Proxy ARP. This is generally not
+ relevant to a simple configuration with a single public IP address.
+ If you have just a single public IP address, most of what you see
+here won't apply to your setup so beware of copying parts of this
+configuration and expecting them to work for you. What you copy may
+or may not work in your configuration.
+
+
+
+
I have a T1 with 64 static IP addresses (63.123.106.65-127/26). The
+ internet is connected to eth0. The local network is connected via eth1
+ (10.10.0.0/22) and the DMZ is connected to eth2 (192.168.21.0/24). I
+have an IPSec tunnel connecting our offices in Germany to our offices
+in the US. I host two Microsoft Exchange servers for two different companies
+behind the firewall hence, the two Exchange servers in the diagram below.
+
+
Summary:
+
+
+
+
SNAT for all systems connected to the LAN
+- Internal addresses 10.10.x.x to external address 63.123.106.127.
+
Static NAT for Polaris (Exchange Server
+ #2). Internal address 10.10.1.8 and external address 63.123.106.70.
+
Static NAT for Sims (Inventory Management server).
+ Internal address 10.10.1.56 and external address 63.123.106.75.
+
+
Static NAT for Project (Project Web
+ Server). Internal address 10.10.1.55 and external
+ address 63.123.106.84.
+
Static NAT for Fortress (Exchange
+Server). Internal address 10.10.1.252 and external
+address 63.123.106.93.
+
Static NAT for BBSRV (Blackberry Server).
+ Internal address 10.10.1.230 and external address
+ 63.123.106.97.
+
Static NAT for Intweb (Intranet Web
+ Server). Internal address 10.10.1.60 and external
+ address 63.123.106.115.
+
+
+
+
The firewall runs on a 2Gb, Dual PIV/2.8GHz, Intel motherboard with
+ RH8.0.
+
+
The Firewall is also a proxy server running Privoxy 3.0.
+
+
The single system in the DMZ (address 63.123.106.80) runs sendmail,
+ imap, pop3, DNS, a Web server (Apache) and an FTP server (vsFTPd 1.1.0).
+ That server is managed through Proxy ARP.
+
+
All administration and publishing is done using ssh/scp. I have X installed
+ on the firewall and the system in the DMZ. X applications tunnel
+ through SSH to Hummingbird Exceed running on a PC located in the LAN.
+ Access to the firewall using SSH is restricted to systems in the LAN, DMZ
+or the system Kaos which is on the Internet and managed by me.
+
+
+
+
+
+
+
The Ethernet 0 interface in the Server is configured with IP
+ address 63.123.106.68, netmask 255.255.255.192. The server's default
+ gateway is 63.123.106.65, the Router connected to my network and
+the ISP. This is the same default gateway used by the firewall
+ itself. On the firewall, Shorewall automatically
+ adds a host route to 63.123.106.80 through Ethernet
+ 2 (192.168.21.1) because of the entry in
+/etc/shorewall/proxyarp (see below). I modified the start, stop and
+init scripts to include the fixes suggested when having an IPSec tunnel.
+
+
Some Mistakes I Made:
+
+
Yes, believe it or not, I made some really basic mistakes when building
+ this firewall. Firstly, I had the new firewall setup in parallel with
+the old firewall so that there was no interruption of service to my users.
+ During my out-bound testing, I set up systems on the LAN to utilize the
+ firewall which worked fine. When testing my NAT connections, from the
+outside, these would fail and I could not understand why. Eventually,
+I changed the default route on the internal system I was trying to access,
+to point to the new firewall and "bingo", everything worked as expected.
+This oversight delayed my deployment by a couple of days not to mention
+level of frustration it produced.
+
+
Another problem that I encountered was in setting up the Proxyarp system
+ in the DMZ. Initially I forgot to remove the entry for the eth2 from
+the /etc/shorewall/masq file. Once my file settings were correct, I started
+ verifying that the ARP caches on the firewall, as well as the outside
+system "kaos", were showing the correct Ethernet MAC address. However,
+in testing remote access, I could access the system in the DMZ only from
+the firewall and LAN but not from the Internet. The message I received
+was "connection denied" on all protocols. What I did not realize was that
+a "helpful" administrator that had turned on an old system and assigned
+the same address as the one I was using for Proxyarp without notifying
+me. How did I work this out. I shutdown the system in the DMZ, rebooted
+the router and flushed the ARP cache on the firewall and kaos. Then, from
+kaos, I started pinging that IP address and checked the updated ARP cache
+and lo-and-behold a different MAC address showed up. High levels of frustration
+etc., etc. The administrator will not be doing that again! :-)
+
+
Lessons Learned:
+
+
+
Read the documentation.
+
Draw your network topology before starting.
+
Understand what services you are going to allow in and out of
+ the firewall, whether they are TCP or UDP packets and make a note
+of these port numbers.
+
Try to get quiet time to build the firewall - you need to focus
+ on the job at hand.
+
When asking for assistance, be honest and include as much detail
+ as requested. Don't try and hide IP addresses etc., you will probably
+ screw up the logs and make receiving assistance harder.
+
Read the documentation.
+
+
+
+
Futures:
+
+
This is by no means the final configuration. In the near future, I will
+ be moving more systems from the LAN to the DMZ. I will also be watching
+ the logs for port scan programs etc. but, this should be standard security
+ maintenance.
+
+
Here are copies of my files. I have removed most of the internal
+documentation for the purpose of this space however, my system still has
+the original files with all the comments and I highly recommend you do
+the same.
+
+
+
+
Shorewall.conf
+
+
+
############################################################################## # /etc/shorewall/shorewall.conf V1.4 - Change the following variables to # match your setup # # This program is under GPL [http://www.gnu.org/copyleft/gpl.htm] # # This file should be placed in /etc/shorewall # # (c) 1999,2000,2001,2002,2003 - Tom Eastep (teastep@shorewall.net) ############################################################################## # L O G G I N G ############################################################################## LOGFILE=/var/log/messages LOGFORMAT="Shorewall:%s:%s:" LOGRATE= LOGBURST= LOGUNCLEAN=info BLACKLIST_LOGLEVEL= LOGNEWNOTSYN= MACLIST_LOG_LEVEL=info TCP_FLAGS_LOG_LEVEL=debug RFC1918_LOG_LEVEL=debug PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:/usr/local/sbin SUBSYSLOCK=/var/lock/subsys/shorewall STATEDIR=/var/lib/shorewall MODULESDIR= FW=fw NAT_ENABLED=Yes MANGLE_ENABLED=Yes IP_FORWARDING=On ADD_IP_ALIASES=Yes ADD_SNAT_ALIASES=Yes TC_ENABLED=Yes CLEAR_TC=No MARK_IN_FORWARD_CHAIN=No CLAMPMSS=No ROUTE_FILTER=Yes NAT_BEFORE_RULES=No MULTIPORT=Yes DETECT_DNAT_IPADDRS=Yes MUTEX_TIMEOUT=60 NEWNOTSYN=Yes BLACKLIST_DISPOSITION=DROP MACLIST_DISPOSITION=REJECT TCP_FLAGS_DISPOSITION=DROP #LAST LINE -- DO NOT REMOVE
+
+
+
Zones File
+
+
+
# # Shorewall 1.4 -- Sample Zone File For Two Interfaces # /etc/shorewall/zones # # This file determines your network zones. Columns are: # # ZONE Short name of the zone # DISPLAY Display name of the zone # COMMENTS Comments about the zone # #ZONE DISPLAY COMMENTS net Net Internet loc Local Local Networks dmz DMZ Demilitarized Zone vpn1 VPN1 VPN to Germany #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
+
Interfaces File:
+
+
+
##############################################################################
+ #ZONE INTERFACE BROADCAST OPTIONS
+ net eth0 62.123.106.127 routefilter,norfc1918,blacklist,tcpflags
+ loc eth1 detect dhcp,routefilter
+ dmz eth2 detect
+ vpn1 ipsec0
+ #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
+
+
+
+
Routestopped File:
+
+
+
#INTERFACE HOST(S) eth1 - eth2 - #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
+
+
+
Policy File:
+
+
+
############################################################################### #SOURCE DEST POLICY LOG LEVEL LIMIT:BURST loc net ACCEPT loc fw ACCEPT loc dmz ACCEPT # If you want open access to the Internet from your Firewall # remove the comment from the following line. fw net ACCEPT fw loc ACCEPT fw dmz ACCEPT dmz fw ACCEPT dmz loc ACCEPT dmz net ACCEPT # # Adding VPN Access loc vpn1 ACCEPT dmz vpn1 ACCEPT fw vpn1 ACCEPT vpn1 loc ACCEPT vpn1 dmz ACCEPT vpn1 fw ACCEPT # net all DROP info all all REJECT info #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
+
Masq File:
+
+
+
#INTERFACE SUBNET ADDRESS eth0 eth1 163.123.106.126 # #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
+
NAT File:
+
+
+
#EXTERNAL INTERFACE INTERNAL ALL INTERFACES LOCAL # # Intranet Web Server 63.123.106.115 eth0:0 10.10.1.60 No No # # Project Web Server 63.123.106.84 eth0:1 10.10.1.55 No No # # Blackberry Server 63.123.106.97 eth0:2 10.10.1.55 No No # # Corporate Mail Server 63.123.106.93 eth0:3 10.10.1.252 No No # # Second Corp Mail Server 63.123.106.70 eth0:4 10.10.1.8 No No # # Sims Server 63.123.106.75 eth0:5 10.10.1.56 No No # #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
+
Proxy ARP File:
+
+
+
#ADDRESS INTERFACE EXTERNAL HAVEROUTE # # The Corporate email server in the DMZ 63.123.106.80 eth2 eth0 No # #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
+
+
+
Tunnels File:
+
+
+
# TYPE ZONE GATEWAY GATEWAY ZONE PORT ipsec net 134.147.129.82 #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
+
+
+
Rules File (The shell variables are set in /etc/shorewall/params):
+
+
+
############################################################################## #ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL # PORT PORT(S) DEST # # Accept DNS connections from the firewall to the network # ACCEPT fw net tcp 53 ACCEPT fw net udp 53 # # Accept SSH from internet interface from kaos only # ACCEPT net:63.123.106.98 fw tcp 22 # # Accept connections from the local network for administration # ACCEPT loc fw tcp 20:22 ACCEPT loc net tcp 22 ACCEPT loc fw tcp 53 ACCEPT loc fw udp 53 ACCEPT loc net tcp 53 ACCEPT loc net udp 53 # # Allow Ping To And From Firewall # ACCEPT loc fw icmp 8 ACCEPT loc dmz icmp 8 ACCEPT loc net icmp 8 ACCEPT dmz fw icmp 8 ACCEPT dmz loc icmp 8 ACCEPT dmz net icmp 8 DROP net fw icmp 8 DROP net loc icmp 8 DROP net dmz icmp 8 ACCEPT fw loc icmp 8 ACCEPT fw dmz icmp 8 DROP fw net icmp 8 # # Accept proxy web connections from the inside # ACCEPT loc fw tcp 8118 # # Forward PcAnywhere, Oracle and Web traffic from outside to the Demo systems # From a specific IP Address on the Internet. # # ACCEPT net:207.65.110.10 loc:10.10.3.151 tcp 1521,http # ACCEPT net:207.65.110.10 loc:10.10.2.32 tcp 5631:5632 # # Intranet web server ACCEPT net loc:10.10.1.60 tcp 443 ACCEPT dmz loc:10.10.1.60 tcp 443 # # Projects web server ACCEPT net loc:10.10.1.55 tcp 80 ACCEPT dmz loc:10.10.1.55 tcp 80 # # Blackberry Server ACCEPT net loc:10.10.1.230 tcp 3101 # # Corporate Email Server ACCEPT net loc:10.10.1.252 tcp 25,53,110,143,443 # # Corporate #2 Email Server ACCEPT net loc:10.10.1.8 tcp 25,80,110,443 # # Sims Server ACCEPT net loc:10.10.1.56 tcp 80,443 ACCEPT net loc:10.10.1.56 tcp 7001:7002 ACCEPT net:63.83.198.0/24 loc:10.10.1.56 tcp 5631:5632 # # Access to DMZ ACCEPT loc dmz udp 53,177 ACCEPT loc dmz tcp 80,25,53,22,143,443,993,20,110 - ACCEPT net dmz udp 53 ACCEPT net dmz tcp 25,53,22,21,123 ACCEPT dmz net tcp 25,53,80,123,443,21,22 ACCEPT dmz net udp 53 # #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
+
+
+
Start File:
+
+
+
############################################################################ # Shorewall 1.4 -- /etc/shorewall/start # # Add commands below that you want to be executed after shorewall has # been started or restarted. # qt service ipsec start
+
+
+
Stop File:
+
+
+
############################################################################ # Shorewall 1.4 -- /etc/shorewall/stop # # Add commands below that you want to be executed at the beginning of a # "shorewall stop" command. # qt service ipsec stop
+
+
+
Init File:
+
+
+
############################################################################ # Shorewall 1.4 -- /etc/shorewall/init # # Add commands below that you want to be executed at the beginning of # a "shorewall start" or "shorewall restart" command. # qt service ipsec stop
This documentation is intended primarily for reference.
- Step-by-step instructions for configuring
- Shorewall in common setups may be found in the
- QuickStart Guides.
-
-
Components
-
-
Shorewall consists of the following components:
-
-
-
params -- a parameter file installed
- in /etc/shorewall that can be used to establish the
- values of shell variables for use in other files.
-
shorewall.conf -- a parameter file
- installed in /etc/shorewall that is used to set several
- firewall parameters.
-
zones - a parameter file installed
- in /etc/shorewall that defines a network partitioning
- into "zones"
-
policy -- a parameter file installed
- in /etc/shorewall/ that establishes overall firewall
- policy.
-
rules -- a parameter file installed
- in /etc/shorewall and used to express firewall
- rules that are exceptions to the high-level policies
- established in /etc/shorewall/policy.
-
blacklist -- a parameter file
- installed in /etc/shorewall and used to list blacklisted
- IP/subnet/MAC addresses.
-
ecn -- a parameter
- file installed in /etc/shorewall and used to selectively disable
- Explicit Congestion Notification (ECN - RFC 3168).
-
-
functions
- -- a set of shell functions used by both the firewall
- and shorewall shell programs. Installed in /etc/shorewall
- prior to version 1.3.2, in /var/lib/shorewall in version
- s 1.3.2-1.3.8 and in /usr/lib/shorewall in later versions.
-
modules -- a parameter file installed
- in /etc/shorewall and that specifies kernel modules and
- their parameters. Shorewall will automatically load
- the modules specified in this file.
-
-
tos-- a parameter
- file installed in /etc/shorewall that is used to specify
- how the Type of Service (TOS) field in packets is to be set.
-
-
common.def -- a parameter file
- installed in in /etc/shorewall that defines firewall-wide
- rules that are applied before a DROP or REJECT policy
- is applied.
-
interfaces -- a parameter
- file installed in /etc/shorewall/ and used to describe the
- interfaces on the firewall system.
-
hosts-- a parameter file
- installed in /etc/shorewall/ and used to describe
- individual hosts or subnetworks in zones.
-
maclist-- a parameter file
- installed in /etc/shorewall and used to verify the MAC address
- (and possibly also the IP address(es)) of devices.
-
-
masq - This file also describes
- IP masquerading under Shorewall and is installed in
- /etc/shorewall.
-
firewall -- a shell
- program that reads the configuration files in /etc/shorewall
- and configures your firewall. This file is
- installed in your init.d directory (/etc/rc.d/init.d
- ) where it is renamed shorewall. /etc/shorewall/firewall
- (/var/lib/shorewall/firewall in versions 1.3.2-1.3.8
- and /usr/lib/shorewall/firewall in 1.3.9 and later) is
-a symbolic link to this program.
-
nat -- a parameter file in /etc/shorewall
- used to define static NAT .
routestopped -- a parameter
- file in /etc/shorewall used to define those hosts that can
- access the firewall when Shorewall is stopped.
-
tcrules-- a
-parameter file in /etc/shorewall used to define rules for classifying
- packets for Traffic Shaping/Control.
-
tunnels -- a parameter file in
-/etc/shorewall used to define IPSec tunnels.
-
shorewall -- a shell program
- (requiring a Bourne shell or derivative) used
- to control and monitor the firewall. This should be placed
- in /sbin or in /usr/sbin (the install.sh script and
- the rpm install this file in /sbin).
-
version
- -- a file created in /etc/shorewall/
-(/var/lib/shorewall in version 1.3.2-1.3.8 and /usr/lib/shorewall
- beginning in version 1.3.9) that describes the version
-of Shorewall installed on your system.
-
-
-
-
/etc/shorewall/params
-
-
You may use the file /etc/shorewall/params file to set shell variables
- that you can then use in some of the other configuration
- files.
-
-
It is suggested that variable names begin with an upper case letter to distinguish them from variables used internally
- within the Shorewall programs
The result will be the same as if the record had been written
-
-
net eth0 130.252.100.255 blacklist,norfc1918
-
-
Variables may be used anywhere in the other configuration
- files.
-
-
/etc/shorewall/zones
-
-
This file is used to define the network zones. There is one entry
- in /etc/shorewall/zones for each zone; Columns
- in an entry are:
-
-
-
ZONE
- - short name for the zone. The name should be 5 characters
- or less in length (4 characters or less if you are running Shorewall
- 1.4.4 or later) and consist of lower-case letters or numbers.
- Short names must begin with a letter and the name assigned
- to the firewall is reserved for use by Shorewall itself.
- Note that the output produced by iptables is much easier
- to read if you select short names that are three characters or
- less in length. The name "all" may not be used as a zone
- name nor may the zone name assigned to the firewall itself via the
- FW variable in /etc/shorewall/shorewall.conf.
-
DISPLAY
- - The name of the zone as displayed during Shorewall
- startup.
-
COMMENTS
- - Any comments that you want to make about the zone.
- Shorewall ignores these comments.
-
-
-
-
The /etc/shorewall/zones file released with Shorewall is as follows:
-
-
-
-
-
-
-ZONE
-
-DISPLAY
-
-COMMENTS
-
-
-
-
net
-
Net
-
Internet
-
-
-
loc
-
Local
-
Local
- networks
-
-
-
dmz
-
DMZ
-
Demilitarized
- zone
-
-
-
+
-
-
You may add, delete and modify entries in the /etc/shorewall/zones file
- as desired so long as you have at least one zone
- defined.
-
-
Warning 1: If you rename or delete a zone, you should perform "shorewall
- stop; shorewall start" to install the change
-rather than "shorewall restart".
-
-
Warning 2: The order of entries in the /etc/shorewall/zones file is
- significant in some cases.
-
-
/etc/shorewall/interfaces
-
-
This file is used to tell the firewall which of your firewall's network
- interfaces are connected to which zone. There
- will be one entry in /etc/shorewall/interfaces for each
- of your interfaces. Columns in an entry are:
-
+
+
This documentation is intended primarily for reference.
+ Step-by-step instructions for configuring
+ Shorewall in common setups may be found in
+the QuickStart Guides.
+
+
Components
+
+
Shorewall consists of the following components:
+
-
ZONE
- - A zone defined in the /etc/shorewall/zones
- file or "-". If you specify "-", you must
-use the /etc/shorewall/hosts
- file to define the zones accessed via this interface.
-
INTERFACE
- - the name of the interface (examples: eth0, ppp0,
- ipsec+). Each interface can be listed on only one record
- in this file. DO NOT INCLUDE
- THE LOOPBACK INTERFACE (lo) IN THIS FILE!!!
-
BROADCAST
- - the broadcast address(es) for the sub-network(s)
- attached to the interface. This should be left empty
- for P-T-P interfaces (ppp*, ippp*); if you need to specify
- options for such an interface, enter "-" in this column. If
- you supply the special value "detect" in this column, the firewall
- will automatically determine the broadcast address.
- In order to use "detect":
-
+
params -- a parameter file installed
+ in /etc/shorewall that can be used to establish the
+ values of shell variables for use in other files.
+
shorewall.conf -- a parameter file
+ installed in /etc/shorewall that is used to set several
+ firewall parameters.
+
zones - a parameter file installed
+ in /etc/shorewall that defines a network partitioning
+ into "zones"
+
policy -- a parameter file installed
+ in /etc/shorewall/ that establishes overall firewall
+ policy.
+
rules -- a parameter file installed
+ in /etc/shorewall and used to express firewall
+ rules that are exceptions to the high-level policies
+ established in /etc/shorewall/policy.
+
blacklist -- a parameter file
+ installed in /etc/shorewall and used to list blacklisted
+ IP/subnet/MAC addresses.
+
ecn -- a parameter
+ file installed in /etc/shorewall and used to selectively disable
+ Explicit Congestion Notification (ECN - RFC 3168).
+
+
functions
+ -- a set of shell functions used by both the firewall
+ and shorewall shell programs. Installed in /etc/shorewall
+ prior to version 1.3.2, in /var/lib/shorewall in version
+ s 1.3.2-1.3.8 and in /usr/lib/shorewall in later versions.
+
modules -- a parameter file installed
+ in /etc/shorewall and that specifies kernel modules and
+ their parameters. Shorewall will automatically load
+ the modules specified in this file.
+
+
tos-- a parameter
+ file installed in /etc/shorewall that is used to specify
+ how the Type of Service (TOS) field in packets is to be set.
+
+
common.def -- a parameter file
+ installed in in /etc/shorewall that defines firewall-wide
+ rules that are applied before a DROP or REJECT policy
+ is applied.
+
interfaces -- a parameter
+ file installed in /etc/shorewall/ and used to describe the
+interfaces on the firewall system.
+
hosts-- a parameter file
+ installed in /etc/shorewall/ and used to describe
+ individual hosts or subnetworks in zones.
+
maclist-- a parameter file
+installed in /etc/shorewall and used to verify the MAC address
+ (and possibly also the IP address(es)) of devices.
+
+
masq - This file also describes
+ IP masquerading under Shorewall and is installed in
+ /etc/shorewall.
+
firewall -- a shell
+ program that reads the configuration files in
+ /etc/shorewall and configures your firewall.
+This file is installed in your init.d directory
+(/etc/rc.d/init.d ) where it is renamed shorewall.
+ /etc/shorewall/firewall (/var/lib/shorewall/firewall
+ in versions 1.3.2-1.3.8 and /usr/lib/shorewall/firewall
+in 1.3.9 and later) is a symbolic link to this program.
+
nat -- a parameter file in /etc/shorewall
+ used to define static NAT .
routestopped -- a parameter
+ file in /etc/shorewall used to define those hosts that can
+ access the firewall when Shorewall is stopped.
+
tcrules-- a parameter
+ file in /etc/shorewall used to define rules for classifying
+ packets for Traffic Shaping/Control.
+
tunnels -- a parameter file in
+ /etc/shorewall used to define IPSec tunnels.
+
shorewall -- a shell program
+ (requiring a Bourne shell or derivative) used
+ to control and monitor the firewall. This should be placed
+ in /sbin or in /usr/sbin (the install.sh script and
+ the rpm install this file in /sbin).
+
version
+ -- a file created in /etc/shorewall/
+ (/var/lib/shorewall in version 1.3.2-1.3.8 and /usr/lib/shorewall
+ beginning in version 1.3.9) that describes the version
+ of Shorewall installed on your system.
+
+
+
+
/etc/shorewall/params
+
+
You may use the file /etc/shorewall/params file to set shell variables
+ that you can then use in some of the other
+configuration files.
+
+
It is suggested that variable names begin with an upper case letter to distinguish them from variables used internally
+ within the Shorewall programs
The result will be the same as if the record had been written
+
+
net eth0 130.252.100.255 blacklist,norfc1918
+
+
Variables may be used anywhere in the other configuration
+ files.
+
+
/etc/shorewall/zones
+
+
This file is used to define the network zones. There is one entry
+ in /etc/shorewall/zones for each zone; Columns
+ in an entry are:
+
+
+
ZONE
+ - short name for the zone. The name should be 5 characters
+ or less in length (4 characters or less if you are running Shorewall
+ 1.4.4 or later) and consist of lower-case letters or numbers.
+ Short names must begin with a letter and the name assigned
+ to the firewall is reserved for use by Shorewall itself.
+ Note that the output produced by iptables is much easier
+ to read if you select short names that are three characters
+or less in length. The name "all" may not be used as
+a zone name nor may the zone name assigned to the firewall itself
+ via the FW variable in /etc/shorewall/shorewall.conf.
+
DISPLAY
+ - The name of the zone as displayed during Shorewall
+ startup.
+
COMMENTS
+ - Any comments that you want to make about the zone.
+ Shorewall ignores these comments.
+
+
+
+
The /etc/shorewall/zones file released with Shorewall is as follows:
+
+
+
+
+
+
+ ZONE
+
+ DISPLAY
+
+ COMMENTS
+
+
+
+
net
+
Net
+
Internet
+
+
+
loc
+
Local
+
Local
+ networks
+
+
+
dmz
+
DMZ
+
Demilitarized
+ zone
+
+
+
+
+
+
+
You may add, delete and modify entries in the /etc/shorewall/zones file
+ as desired so long as you have at least one
+zone defined.
+
+
Warning 1: If you rename or delete a zone, you should perform "shorewall
+ stop; shorewall start" to install the change
+ rather than "shorewall restart".
+
+
Warning 2: The order of entries in the /etc/shorewall/zones file is
+ significant in some cases.
+
+
/etc/shorewall/interfaces
+
+
This file is used to tell the firewall which of your firewall's network
+ interfaces are connected to which zone. There
+ will be one entry in /etc/shorewall/interfaces for
+each of your interfaces. Columns in an entry are:
+
+
+
ZONE
+ - A zone defined in the /etc/shorewall/zones
+ file or "-". If you specify "-", you must
+ use the /etc/shorewall/hosts
+ file to define the zones accessed via this interface.
+
INTERFACE
+ - the name of the interface (examples: eth0, ppp0,
+ ipsec+). Each interface can be listed on only one record
+in this file. DO NOT INCLUDE
+THE LOOPBACK INTERFACE (lo) IN THIS FILE!!!
+
BROADCAST
+ - the broadcast address(es) for the sub-network(s)
+ attached to the interface. This should be left empty
+for P-T-P interfaces (ppp*, ippp*); if you need to specify
+ options for such an interface, enter "-" in this column. If
+ you supply the special value "detect" in this column, the firewall
+ will automatically determine the broadcast address.
+In order to use "detect":
+
-
the interface must be up before you start
-your firewall
-
the interface
- must only be attached to a single sub-network (i.e.,
+
the interface must be up before you start
+ your firewall
+
the interface
+ must only be attached to a single sub-network (i.e.,
there must have a single broadcast address).
-
+
-
-
OPTIONS
- - a comma-separated list of options. Possible options
+
+
OPTIONS
+ - a comma-separated list of options. Possible options
include:
-
- newnotsyn (Added in version 1.4.6) - This option
- overrides NEWNOTSYN=No for packets arriving on
- this interface. In other words, packets coming in on this interface are
- processed as if NEWNOTSYN=Yes had been specified in /etc/shorewall/shorewall.conf.
-
- routeback (Added in version 1.4.2) - This option causes Shorewall
- to set up handling for routing packets that arrive on this interface
- back out the same interface. If this option is specified, the ZONE column
- may not contain "-".
+
+ newnotsyn (Added in version 1.4.6) - This
+option overrides NEWNOTSYN=No for packets arriving
+on this interface. In other words, packets coming in on this interface
+are processed as if NEWNOTSYN=Yes had been specified in /etc/shorewall/shorewall.conf.
+
+ routeback (Added in version 1.4.2) - This option causes Shorewall
+ to set up handling for routing packets that arrive on this interface
+ back out the same interface. If this option is specified, the ZONE
+column may not contain "-".
-
-
tcpflags (added in version 1.3.11) - This option causes
-Shorewall to make sanity checks on the header flags in TCP packets arriving
-on this interface. Checks include Null flags, SYN+FIN, SYN+RST and FIN+URG+PSH;
-these flag combinations are typically used for "silent" port scans. Packets
- failing these checks are logged according to the TCP_FLAGS_LOG_LEVEL option
- in /etc/shorewall/shorewall.conf and are disposed of
-according to the TCP_FLAGS_DISPOSITION option.
-
- blacklist - This option
-causes incoming packets on this interface
-to be checked against the blacklist.
-
- dhcp - The interface
- is assigned an IP address via DHCP or is used
- by a DHCP server running on the firewall. The firewall
- will be configured to allow DHCP traffic to and from the
- interface even when the firewall is stopped. You may
- also wish to use this option if you have a static IP but you
-are on a LAN segment that has a lot of Laptops that use DHCP and
+
+
tcpflags (added in version 1.3.11) - This option causes Shorewall
+to make sanity checks on the header flags in TCP packets arriving on this
+interface. Checks include Null flags, SYN+FIN, SYN+RST and FIN+URG+PSH; these
+flag combinations are typically used for "silent" port scans. Packets failing
+these checks are logged according to the TCP_FLAGS_LOG_LEVEL option in /etc/shorewall/shorewall.conf and are disposed of according
+ to the TCP_FLAGS_DISPOSITION option.
+
+ blacklist - This option
+ causes incoming packets on this interface
+ to be checked against the blacklist.
+
+ dhcp - The interface
+ is assigned an IP address via DHCP or is used
+by a DHCP server running on the firewall. The firewall
+ will be configured to allow DHCP traffic to and from the
+ interface even when the firewall is stopped. You may
+also wish to use this option if you have a static IP but you
+are on a LAN segment that has a lot of Laptops that use DHCP and
you select the norfc1918 option (see below).
-
-
norfc1918 - Packets arriving on this interface and that
- have a source address that is reserved in RFC 1918 or in other
- RFCs will be dropped after being optionally logged.
- If packet mangling is enabled in /etc/shorewall/shorewall.conf
- , then packets arriving on this interface that
- have a destination address that is reserved by one of
-these RFCs will also be logged and dropped.
-
- Addresses blocked
-by the standard rfc1918 file
- include those addresses reserved by RFC1918 plus
- other ranges reserved by the IANA or by other RFCs.
+
+
norfc1918 - Packets arriving on this interface and that
+ have a source address that is reserved in RFC 1918 or in other
+ RFCs will be dropped after being optionally logged.
+ If packet mangling is enabled in /etc/shorewall/shorewall.conf
+ , then packets arriving on this interface
+that have a destination address that is reserved by
+one of these RFCs will also be logged and dropped.
+
+ Addresses blocked
+ by the standard rfc1918
+ file include those addresses reserved
+by RFC1918 plus other ranges reserved by the IANA or
+by other RFCs.
-
-
Beware that as IPv4 addresses become in increasingly short supply,
- ISPs are beginning to use RFC 1918 addresses
-within their own infrastructure. Also, many cable
-and DSL "modems" have an RFC 1918 address that can be used
-through a web browser for management and monitoring functions.
- If you want to specify norfc1918 on your external
- interface but need to allow access to certain addresses
- from the above list, see FAQ 14.
+
+
Beware that as IPv4 addresses become in increasingly short supply,
+ ISPs are beginning to use RFC 1918 addresses
+ within their own infrastructure. Also, many cable
+ and DSL "modems" have an RFC 1918 address that can be used
+ through a web browser for management and monitoring functions.
+ If you want to specify norfc1918 on your external
+ interface but need to allow access to certain addresses
+ from the above list, see FAQ 14.
-
-
routefilter - Invoke the Kernel's route filtering
- (anti-spoofing) facility on this interface. The
- kernel will reject any packets incoming on this interface
- that have a source address that would be routed outbound
- through another interface on the firewall.
- Warning: If you specify this
- option for an interface then the interface must be up prior
-to starting the firewall.
+
+
routefilter - Invoke the Kernel's route filtering
+ (anti-spoofing) facility on this interface. The
+ kernel will reject any packets incoming on this interface
+ that have a source address that would be routed
+outbound through another interface on the firewall.
+ Warning: If you specify
+this option for an interface then the interface must be up
+prior to starting the firewall.
-
-
dropunclean - Packets from this interface that
- are selected by the 'unclean' match target in iptables will
- be optionally logged and then dropped.
- Warning: This feature requires
- that UNCLEAN match support be configured in your
- kernel, either in the kernel itself or as a module. UNCLEAN
- support is broken in some versions of the kernel
- but appears to work ok in 2.4.17-rc1.
+
+
dropunclean - Packets from this interface that
+are selected by the 'unclean' match target in iptables will
+ be optionally logged and then dropped.
+ Warning: This feature requires
+ that UNCLEAN match support be configured in your
+ kernel, either in the kernel itself or as a module. UNCLEAN
+ support is broken in some versions of the kernel
+but appears to work ok in 2.4.17-rc1.
-
+
- Update 12/17/2001: The unclean match
+ Update 12/17/2001:
The unclean match
patch from 2.4.17-rc1 is available
- for download. I am currently
- running this patch applied to kernel
- 2.4.16.
+ href="ftp://ftp.shorewall.net/pub/shorewall/misc/unclean.patch">available
+ for download. I am currently
+ running this patch applied to
+kernel 2.4.16.
-
-
Update 12/20/2001: I've
- seen a number of tcp connection
- requests with OPT (020405B40000080A...)
- being dropped in the badpkt chain. This
- appears to be a bug in the remote TCP stack whereby
-it is 8-byte aligning a timestamp (TCP option
-8) but rather than padding with 0x01 it is padding
- with 0x00. It's a tough call whether to deny people
- access to your servers because of this rather minor
- bug in their networking software. If you wish to disable
-the check that causes these connections to be
-dropped, here's
- a kernel patch against 2.4.17-rc2.
+
+
Update 12/20/2001: I've
+ seen a number of tcp connection
+ requests with OPT (020405B40000080A...)
+ being dropped in the badpkt chain.
+This appears to be a bug in the remote TCP stack whereby
+ it is 8-byte aligning a timestamp (TCP option
+ 8) but rather than padding with 0x01 it is padding
+ with 0x00. It's a tough call whether to deny people
+ access to your servers because of this rather minor
+ bug in their networking software. If you wish to disable
+ the check that causes these connections to
+be dropped, here's
+ a kernel patch against 2.4.17-rc2.
-
-
logunclean - This option works like dropunclean
- with the exception that packets
- selected by the 'unclean' match
-target in iptables are logged but not dropped.
- The level at which the packets are logged
-is determined by the setting of LOGUNCLEAN and if LOGUNCLEAN
- has not been set, "info" is assumed.
+
+
logunclean - This option works like dropunclean
+ with the exception that packets
+ selected by the 'unclean' match
+ target in iptables are logged but not dropped.
+ The level at which the packets are logged
+ is determined by the setting of LOGUNCLEAN and if LOGUNCLEAN
+ has not been set, "info" is assumed.
-
-
proxyarp (Added in version 1.3.5) - This option causes
- Shorewall to set /proc/sys/net/ipv4/conf/<interface>/proxy_arp
- and is used when implementing
- Proxy ARP Sub-netting as described
- at
- http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/. Do
- not set this option if you are implementing
-Proxy ARP through entries in
- /etc/shorewall/proxyarp.
-
- maclist (Added
- in version 1.3.10) - If this option is specified, all
- connection requests from this interface are subject to
- MAC Verification. May only
-be specified for ethernet interfaces.
-
-
+
+
proxyarp (Added in version 1.3.5) - This option causes
+ Shorewall to set /proc/sys/net/ipv4/conf/<interface>/proxy_arp
+ and is used when implementing
+ Proxy ARP Sub-netting as described
+ at
+ http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/. Do
+ not set this option if you are implementing
+ Proxy ARP through entries in
+ /etc/shorewall/proxyarp.
+
+ maclist (Added
+ in version 1.3.10) - If this option is specified, all
+ connection requests from this interface are subject to
+ MAC Verification. May only be
+ specified for ethernet interfaces.
Don't use dropunclean
- -- It's broken in my opinion
-
Use logunclean
+
+
Don't use dropunclean
+ -- It's broken in my opinion
+
Use logunclean
only when you are trying to debug a problem
-
Use dhcp and proxyarp
- when needed.
-
-
+
Use dhcp and proxyarp
+ when needed.
+
+
-
+
-
-
Example 1: You have a conventional firewall setup in which eth0 connects
- to a Cable or DSL modem and eth1 connects to
-your local network and eth0 gets its IP address via
-DHCP. You want to check all packets entering from the internet
- against the black list. Your /etc/shorewall/interfaces
- file would be as follows:
-
-
-
+
+
Example 1: You have a conventional firewall setup in which eth0 connects
+ to a Cable or DSL modem and eth1 connects to
+ your local network and eth0 gets its IP address via
+ DHCP. You want to check all packets entering from the internet
+ against the black list. Your /etc/shorewall/interfaces
+ file would be as follows:
+
+
+
-
+
-
-
-ZONE
-
-INTERFACE
-
-BROADCAST
-
-OPTIONS
-
-
-
net
-
eth0
-
detect
-
dhcp,norfc1918,blacklist
-
-
-
loc
-
eth1
-
detect
-
-
-
+
+
+ ZONE
+
+ INTERFACE
+
+ BROADCAST
+
+ OPTIONS
+
+
+
net
+
eth0
+
detect
+
dhcp,norfc1918,blacklist
+
+
+
loc
+
eth1
+
detect
+
+
+
-
-
-
+
+
+
-
-
-
Example 2: You have a standalone dialup GNU/Linux System. Your /etc/shorewall/interfaces
- file would be:
-
-
-
+
+
+
Example 2: You have a standalone dialup GNU/Linux System. Your /etc/shorewall/interfaces
+ file would be:
+
+
+
-
+
-
-
-ZONE
-
-INTERFACE
-
-BROADCAST
-
-OPTIONS
-
-
-
net
-
ppp0
-
-
-
-
-
+
+
+ ZONE
+
+ INTERFACE
+
+ BROADCAST
+
+ OPTIONS
+
+
+
net
+
ppp0
+
+
+
+
+
-
-
-
+
+
+
-
-
-
Example 3: You have local interface eth1 with two IP addresses -
+
+
+
Example 3: You have local interface eth1 with two IP addresses -
192.168.1.1/24 and 192.168.12.1/24
-
-
-
+
+
+
-
-
-
-ZONE
-
-INTERFACE
-
-BROADCAST
-
-OPTIONS
-
-
-
loc
-
eth1
-
192.168.1.255,192.168.12.255
-
-
-
+
+
+
+ ZONE
+
+ INTERFACE
+
+ BROADCAST
+
+ OPTIONS
+
+
+
loc
+
eth1
+
192.168.1.255,192.168.12.255
+
+
+
-
-
-
+
+
+
-
+
+
+
/etc/shorewall/hosts
+ Configuration
+
+
For most applications, specifying zones entirely in terms of network
+ interfaces is sufficient. There may be times though where you need to
+define a zone to be a more general collection of hosts. This is the purpose
+of the /etc/shorewall/hosts file.
+
+
WARNING: The only times that you need
+entries in /etc/shorewall/hosts are:
+
-
/etc/shorewall/hosts
- Configuration
-
-
For most applications, specifying zones entirely in terms of network
- interfaces is sufficient. There may be times though where you need to define
-a zone to be a more general collection of hosts. This is the purpose of
-the /etc/shorewall/hosts file.
-
-
WARNING: The only times that you need entries
-in /etc/shorewall/hosts are:
-
-
-
You have more than one zone connecting through
+
You have more than one zone connecting through
a single interface; or
-
You have a zone that has multiple subnetworks
- that connect through a single interface and you want the Shorewall
- box to route traffic between those subnetworks.
-
-
+
You have a zone that has multiple subnetworks
+ that connect through a single interface and you want the Shorewall
+ box to route traffic between those subnetworks.
+
+
- IF YOU DON'T HAVE EITHER OF THOSE SITUATIONS THEN
-DON'T TOUCH THIS FILE!!
+ IF YOU DON'T HAVE EITHER OF THOSE SITUATIONS THEN
+ DON'T TOUCH THIS FILE!!
HOST(S)
- - The name of a network interface followed by a colon
+
HOST(S)
+ - The name of a network interface followed by a colon
(":") followed by a comma-separated list either:
-
+
-
-
-
+
+
+
-
An
- IP address (example - eth1:192.168.1.3)
-
A
- subnet in CIDR notation(example
- - eth2:192.168.2.0/24)
-
+
An IP address (example - eth1:192.168.1.3)
+
+
A subnet in CIDR notation
+ (example - eth2:192.168.2.0/24)
+
+
-
-
The interface name much match an entry in /etc/shorewall/interfaces.
-
-
Warning: If you are running a
-version of Shorewall earlier than 1.4.6, only a single host/subnet address
-may be specified in an entry in /etc/shorewall/hosts.
-
-
-
-
-
OPTIONS
- - A comma-separated list of option
-
-
-
-
-
-
routeback (Added in version 1.4.2) - This option causes Shorewall
- to set up handling for routing packets sent by this host group
-back back to the same group.
-
- maclist - Added in version 1.3.10. If specified,
- connection requests from the hosts specified in this entry
- are subject to MAC Verification.
- This option is only valid for ethernet interfaces.
-
-
-
-
If you don't define any hosts for a zone, the hosts in the zone default
- to i0:0.0.0.0/0 , i1:0.0.0.0/0, ... where i0,
- i1, ... are the interfaces to the zone.
-
-
Note: You probably DON'T
- want to specify any hosts for your internet zone since the
-hosts that you specify will be the only ones that you will be able
-to access without adding additional rules.
-
-
Example 1:
-
-
Your local interface is eth1 and you have two groups of local hosts that
- you want to make into separate zones:
-
-
-
192.168.1.0/25
-
-
192.168.1.128/
-
-
-
-
Your /etc/shorewall/interfaces file might look like:
-
-
-
-
-
-
-
-
-ZONE
-
-INTERFACE
-
-BROADCAST
-
-OPTIONS
-
-
-
net
-
eth0
-
detect
-
dhcp,norfc1918
-
-
-
-
-
eth1
-
192.168.1.127,192.168.1.255
-
-
-
-
-
-
-
-
-
-
-
-
The '-' in the ZONE column for eth1 tells Shorewall that eth1 interfaces
- to multiple zones.
-
-
Your /etc/shorewall/hosts file might look like:
-
-
-
-
-
-
-
-
-
-ZONE
-
-HOST(S)
-
-OPTIONS
-
-
-
loc1
-
eth1:192.168.1.0/25
-
-
-
-
-
loc2
-
eth1:192.168.1.128/25
-
-
-
-
-
-
-
-
-
-
-
Example 2:
-
-
Your local interface is eth1 and you have two groups of local hosts that
- you want to consider as one zone and you want Shorewall to route
- between them:
-
-
-
192.168.1.0/25
-
192.168.1.128/25
-
-
-
-
Your /etc/shorewall/interfaces file might look like:
-
-
-
-
-
-
-
-
-ZONE
-
-INTERFACE
-
-BROADCAST
-
-OPTIONS
-
-
-
net
-
eth0
-
detect
-
dhcp,norfc1918
-
-
-
loc
-
-
eth1
-
192.168.1.127,192.168.1.255
-
-
-
-
-
-
-
-
-
-
-
-
Your /etc/shorewall/hosts file might look like:
-
-
-
-
-
-
-
-
-
-ZONE
-
-HOST(S)
-
-OPTIONS
-
-
-
loc
-
eth1:192.168.1.0/25
-
-
-
-
-
loc
-
eth1:192.168.1.128/25
-
-
-
-
-
-
-
-
-
- If you are running Shorewall
-1.4.6 or later, your hosts file may look like:
-
-
-
-
-
-
-ZONE
-
-HOST(S)
-
-OPTIONS
-
-
-
loc
-
eth1:192.168.1.0/25,192.168.1.128/25
-
-
-
-
-
-
-
-
-
-
-
-
Nested and Overlapping Zones
-
-
The /etc/shorewall/interfaces and /etc/shorewall/hosts file allow
-you to define nested or overlapping zones. Such overlapping/nested zones
- are allowed and Shorewall processes zones in the order
-that they appear in the /etc/shorewall/zones file. So if
-you have nested zones, you want the sub-zone to appear before
-the super-zone and in the case of overlapping zones, the rules
- that will apply to hosts that belong to both zones is
- determined by which zone appears first in /etc/shorewall/zones.
-
-
Hosts that belong to more than one zone may be managed by the rules
- of all of those zones. This is done through use
- of the special CONTINUE policy described
- below.
-
-
/etc/shorewall/policy
- Configuration.
-
-
This file is used to describe the firewall policy regarding establishment
- of connections. Connection establishment is described
- in terms of clients who initiate connections
-and servers who receive those connection requests.
- Policies defined in /etc/shorewall/policy describe which
- zones are allowed to establish connections with other zones.
-
-
Policies established in /etc/shorewall/policy can be viewed as default
- policies. If no rule in /etc/shorewall/rules applies
- to a particular connection request then the policy
-from /etc/shorewall/policy is applied.
-
-
Four policies are defined:
-
-
-
ACCEPT
- - The connection is allowed.
-
DROP
- - The connection request is ignored.
-
REJECT
- - The connection request is rejected with an RST (TCP)
- or an ICMP destination-unreachable packet being returned
- to the client.
-
CONTINUE
- - The connection is neither ACCEPTed, DROPped
- nor REJECTed. CONTINUE may be used when one or both of
-the zones named in the entry are sub-zones of or intersect
-with another zone. For more information, see below.
-
NONE - (Added in version 1.4.1) - Shorewall
- should not set up any infrastructure for handling traffic from the
- SOURCE zone to the DEST zone. When this policy is specified, the LOG
- LEVEL and BURST:LIMIT columns must be left
- blank.
-
-
-
-
-
For each policy specified in /etc/shorewall/policy, you can indicate
- that you want a message sent to your system log
- each time that the policy is applied.
-
-
Entries in /etc/shorewall/policy have four columns as follows:
POLICY - The default policy
- for connection requests from the SOURCE zone to the DESTINATION
- zone.
-
-
LOG LEVEL - Optional. If left
- empty, no log message is generated when the policy is
-applied. Otherwise, this column should contain an integer
- or name indicating a syslog
-level.
-
-
LIMIT:BURST - Optional.
-If left empty, TCP connection requests from the SOURCE
- zone to the DEST zone will not be rate-limited.
- Otherwise, this column specifies the maximum rate at
- which TCP connection requests will be accepted followed by
-a colon (":") followed by the maximum burst size that will
-be tolerated. Example: 10/sec:40 specifies that
-the maximum rate of TCP connection requests allowed will be 10
- per second and a burst of 40 connections will be tolerated. Connection
- requests in excess of these limits will be dropped.
-
-
-
-
In the SOURCE and DEST columns, you can enter "all" to indicate all
- zones.
-
-
The policy file installed by default is as follows:
-
-
-
+
The interface name much match an entry in /etc/shorewall/interfaces.
+
+
+
Warning: If you are running a
+version of Shorewall earlier than 1.4.6, only a single host/subnet address
+may be specified in an entry in /etc/shorewall/hosts.
+
+
+
+
+
OPTIONS
+ - A comma-separated list of option
+
+
+
+
+
+
routeback (Added in version 1.4.2) - This option causes Shorewall
+ to set up handling for routing packets sent by this host group back
+ back to the same group.
+
+ maclist - Added in version 1.3.10. If specified,
+ connection requests from the hosts specified in this entry
+ are subject to MAC Verification.
+ This option is only valid for ethernet interfaces.
+
+
+
+
If you don't define any hosts for a zone, the hosts in the zone default
+ to i0:0.0.0.0/0 , i1:0.0.0.0/0, ... where i0,
+ i1, ... are the interfaces to the zone.
+
+
Note: You probably DON'T
+ want to specify any hosts for your internet zone since the
+ hosts that you specify will be the only ones that you will be
+able to access without adding additional rules.
+
+
Example 1:
+
+
Your local interface is eth1 and you have two groups of local hosts that
+ you want to make into separate zones:
+
+
+
192.168.1.0/25
+
+
192.168.1.128/
+
+
+
+
Your /etc/shorewall/interfaces file might look like:
+
+
+
-
+
-
-
SOURCE
-
DEST
-
-POLICY
-
-LOG LEVEL
-
LIMIT:BURST
-
-
-
loc
-
net
-
ACCEPT
-
-
-
-
-
+
+
+ ZONE
+
+ INTERFACE
+
+ BROADCAST
+
+ OPTIONS
+
+
+
net
+
eth0
+
detect
+
dhcp,norfc1918
+
+
+
-
+
eth1
+
192.168.1.127,192.168.1.255
+
+
+
+
+
+
+
+
+
+
+
+
The '-' in the ZONE column for eth1 tells Shorewall that eth1 interfaces
+ to multiple zones.
+
+
Your /etc/shorewall/hosts file might look like:
+
+
+
+
+
+
+
+
+
+ ZONE
+
+ HOST(S)
+
+ OPTIONS
+
+
+
loc1
+
eth1:192.168.1.0/25
+
+
+
-
net
-
all
-
DROP
-
info
-
-
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
-
-
-
-
-
-
-
This table may be interpreted as follows:
-
-
-
All connection
- requests from the local network to hosts on the
- internet are accepted.
-
All connection
- requests originating from the internet are ignored
-and logged at level KERNEL.INFO.
-
All other connection
- requests are rejected and logged.
-
-
-
-
WARNING:
-
-
The firewall script processes the
- /etc/shorewall/policy file from top to bottom and
- uses the first applicable policy that it finds.
- For example, in the following policy file, the policy
- for (loc, loc) connections would be ACCEPT as specified
- in the first entry even though the third entry in the file specifies
- REJECT.
-
-
-
-
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG
-LEVEL
-
LIMIT:BURST
-
-
-
loc
-
all
-
ACCEPT
-
-
-
-
-
-
-
net
-
all
-
DROP
-
info
-
-
-
-
-
loc
-
loc
-
REJECT
-
info
-
-
-
-
-
-
-
-
-
-
-
IntraZone Traffic
- Shorewall allows a zone to be associated with more than
- one interface or with multiple networks that interface through
-a single interface. Beginning with Shorewall 1.4.1, Shorewall will
-ACCEPT all traffic from a zone to itself provided that there is no
-explicit policy governing traffic from that zone to itself (an explicit
-policy does not specify "all" in either the SOURCE or DEST column)
-and that there are no rules concerning connections from that zone to
-itself. If there is an explicit policy or if there are one or more rules,
-then traffic within the zone is handled just like traffic between zones
-is.
-
-
Any time that you have multiple interfaces associated with a single zone,
- you should ask yourself if you really want traffic routed between
- those interfaces. Cases where you might not want that behavior are:
-
-
-
-
Multiple 'net' interfaces to different ISPs. You
- don't want to route traffic from one ISP to the other through your
- firewall.
-
Multiple VPN clients. You don't necessarily want
- them to all be able to communicate between themselves using your gateway/router.
-
-
-
-
-
The CONTINUE
- policy
-
-
Where zones are nested or overlapping , the
- CONTINUE policy allows hosts that are within multiple
- zones to be managed under the rules of all of these
-zones. Let's look at an example:
-
-
/etc/shorewall/zones:
-
-
-
-
-
-
-
-ZONE
-
-DISPLAY
-
-COMMENTS
-
-
-
sam
-
Sam
-
Sam's
- system at home
-
-
-
net
-
Internet
-
The Internet
-
-
-
loc
-
Loc
-
Local
- Network
-
-
-
-
-
-
-
-
-
/etc/shorewall/interfaces:
-
-
-
-
-
-
-
-ZONE
-
-INTERFACE
-
-BROADCAST
-
-OPTIONS
-
-
-
-
-
eth0
-
detect
-
dhcp,norfc1918
-
-
-
loc
-
eth1
-
detect
-
-
-
-
-
-
-
-
-
-
-
/etc/shorewall/hosts:
-
-
-
-
-
-
-
-ZONE
-
-HOST(S)
-
-OPTIONS
-
-
-
net
-
eth0:0.0.0.0/0
-
-
-
-
-
sam
-
eth0:206.191.149.197
-
-
-
-
-
-
-
-
-
-
-
Note that Sam's home system is a member of both the sam zone
- and the
- net zone and as described above
- , that means that sam must be listed before net
- in /etc/shorewall/zones.
-
-
/etc/shorewall/policy:
-
-
-
-
-
-
-
- SOURCE
-
- DEST
-
-POLICY
-
-LOG LEVEL
-
-
-
loc
-
net
-
ACCEPT
-
-
-
-
-
sam
-
all
-
CONTINUE
-
-
-
-
-
net
-
all
-
DROP
-
info
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
-
-
-
-
-
The second entry above says that when Sam is the client, connection
- requests should first be process under rules where
- the source zone is sam and if there is no match
- then the connection request should be treated under rules
- where the source zone is net. It is important that
-this policy be listed BEFORE the next policy (net to all).
-
-
Partial /etc/shorewall/rules:
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
-PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
...
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
DNAT
-
sam
-
loc:192.168.1.3
-
tcp
-
ssh
-
-
-
-
-
-
-
DNAT
-
net
-
loc:192.168.1.5
-
tcp
-
www
-
-
-
-
-
-
-
...
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Given these two rules, Sam can connect to the firewall's internet interface
- with ssh and the connection request will be forwarded
- to 192.168.1.3. Like all hosts in the net zone,
- Sam can connect to the firewall's internet interface
- on TCP port 80 and the connection request will be forwarded
- to 192.168.1.5. The order of the rules is not significant.
-
-
Sometimes it is necessary to suppress port forwarding
- for a sub-zone. For example, suppose that all
- hosts can SSH to the firewall and be forwarded to 192.168.1.5
- EXCEPT Sam. When Sam connects to the firewall's external
- IP, he should be connected to the firewall itself. Because
- of the way that Netfilter is constructed, this requires two
- rules as follows:
-
-
-
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
-PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
...
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
DNAT
-
sam
-
fw
-
tcp
-
ssh
-
-
-
-
-
-
-
DNAT
-
net!sam
-
loc:192.168.1.3
-
tcp
-
ssh
-
-
-
-
-
-
-
...
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
The first rule allows Sam SSH access to the firewall. The second
- rule says that any clients from the net zone
- with the exception of those in the
-'sam' zone should have their
- connection port forwarded to
- 192.168.1.3. If you need to exclude
- more than one zone in this way, you
- can list the zones separated
- by commas (e.g., net!sam,joe,fred).
- This technique also may be used when
- the ACTION is REDIRECT.
-
-
/etc/shorewall/rules
-
-
The /etc/shorewall/rules file defines exceptions to the policies established
- in the /etc/shorewall/policy file. There is one
- entry in /etc/shorewall/rules for each of these rules.
-
-
-
-
Shorewall automatically enables firewall->firewall traffic over the
- loopback interface (lo) -- that traffic cannot be regulated
- using rules and any rule that tries to regulate such traffic
- will generate a warning and will be ignored.
-
-
-
Entries in the file have the following columns:
-
-
-
ACTION
-
-
-
-
ACCEPT, DROP,
- REJECT, CONTINUE. These have the same meaning here as
- in the policy file above.
-
DNAT -- Causes
- the connection request to be forwarded to the system
- specified in the DEST column (port forwarding). "DNAT"
- stands for "Destination Network
- Address Translation"
-
DNAT- -- The above ACTION
- (DNAT) generates two iptables rules: 1) and header-rewriting
- rule in the Netfilter 'nat' table and; 2) an ACCEPT rule
-in the Netfilter 'filter' table. DNAT- works like DNAT but only
-generates the header-rewriting rule.
-
-
REDIRECT --
- Causes the connection request to be redirected to
-a port on the local (firewall) system.
-
REDIRECT- -- The above ACTION (REDIRECT) generates
- two iptables rules: 1) and header-rewriting rule in the Netfilter
- 'nat' table and; 2) an ACCEPT rule in the Netfilter 'filter'
- table. REDIRECT- works like REDIRECT but only generates the header-rewriting
- rule.
-
-
LOG - Log the packet -- requires a syslog
- level (see below).
-
-
-
-
-
-
The ACTION may optionally be followed by ":" and a syslog level (example: REJECT:info). This
-causes the packet to be logged at the specified level prior to being
-processed according to the specified ACTION. Note: if the ACTION
-is LOG then you MUST specify a syslog level.
-
- The use of DNAT
-or REDIRECT requires that you have NAT enabled.
-
-
-
SOURCE
-- Describes the source hosts to which the rule applies..
- The contents of this field must begin with the
-name of a zone defined in /etc/shorewall/zones, $FW or "all".
- If the ACTION is DNAT or REDIRECT, sub-zones may be excluded
- from the rule by following the initial zone name with "!'
- and a comma-separated list of those sub-zones to be excluded.
- There is an example above.
-
- If the source is
-not 'all' then the source may be further restricted by
-adding a colon (":") followed by a comma-separated list
-of qualifiers. Qualifiers are may include:
-
-
-
-
An interface
- name - refers to any connection requests arriving on
- the specified interface (example loc:eth4). Beginning
- with Shorwall 1.3.9, the interface name may optionally be followed
- by a colon (":") and an IP address or subnet (examples: loc:eth4:192.168.4.22,
- net:eth0:192.0.2.0/24).
-
An IP address
- - refers to a connection request from the host with
- the specified address (example net:155.186.235.151).
- If the ACTION is DNAT, this must not be a DNS name.
A subnet -
-refers to a connection request from any host in the
- specified subnet (example net:155.186.235.0/24).
-
-
-
-
-
DEST
-- Describes the destination host(s) to which the rule
- applies. May take most of the forms described above for
- SOURCE plus the following two additional forms:
-
-
-
-
An IP address
- followed by a colon and the port number
- that the server is listening on (service names from
-/etc/services are not allowed - example loc:192.168.1.3:80).
-
-
-
A single port
- number (again, service names are not allowed) --
- this form is only allowed if the ACTION is REDIRECT and refers
- to a server running on the firewall itself and listening
- on the specified port.
-
-
-
- Restrictions:
-
-
-
-
MAC addresses may not be specified.
-
In DNAT rules, only IP addresses may be
-given -- DNS names are not permitted.
-
You may not specify both an IP address and
- an interface name in the DEST column.
-
-
-
- Unlike in the SOURCE column, a range of IP addresses may be specified
- in the DEST column as <first address>-<last address>.
- When the ACTION is DNAT or DNAT-, connections will be assigned
-to the addresses in the range in a round-robin fashion (load-balancing).
-
-
PROTO
- - Protocol. Must be a protocol name from /etc/protocols,
- a number or "all". Specifies the protocol of the connection
- request.
-
DEST
- PORT(S) - Port or port range (<low port>:<high
- port>) being connected to. May only be specified
- if the protocol is tcp, udp or icmp. For icmp, this
-column's contents are interpreted as an icmp type. If you
- don't want to specify DEST PORT(S) but need to include information
- in one of the columns to the right, enter "-" in this column.
- You may give a list of ports and/or port ranges separated by
-commas. Port numbers may be either integers or service names from
-/etc/services.
-
SOURCE
- PORTS(S) - May be used to restrict the
- rule to a particular client port or port range (a port
-range is specified as <low port number>:<high
- port number>). If you don't want to restrict client ports but
- want to specify something in the next column, enter "-" in
-this column. If you wish to specify a list of port number
- or ranges, separate the list elements with commas (with
-no embedded white space). Port numbers may be either integers
- or service names from /etc/services.
-
ORIGINAL
-DEST - This column may only be non-empty if the
- ACTION is DNAT or REDIRECT.
-
- If DNAT or REDIRECT
- is the ACTION and the ORIGINAL DEST column is left
-empty, any connection request arriving at the firewall
- from the SOURCE that matches the rule will be forwarded
- or redirected. This works fine for connection requests
-arriving from the internet where the firewall has only a
-single external IP address. When the firewall has multiple
- external IP addresses or when the SOURCE is other than the
-internet, there will usually be a desire for the rule to only
-apply to those connection requests directed to particular
- IP addresses (see Example 2 below for another usage). Those IP
-addresses are specified in the ORIGINAL DEST column as a comma-separated
-list.
-
- The IP address(es)
- may be optionally followed by ":" and a second IP
- address. This latter address, if present, is used as the
- source address for packets forwarded to the server (This
-is called "Source NAT" or SNAT.
-
- If this list begins with "!" then the rule will only apply if the
- original destination address matches none of the addresses listed.
-
- Note:
- When using SNAT, it is a good idea to qualify the source with
- an IP address or subnet. Otherwise, it is likely that SNAT will
- occur on connections other than those described in the rule.
- The reason for this is that SNAT occurs in the Netfilter POSTROUTING
- hook where it is not possible to restrict the scope of a rule
- by incoming interface.
-
- Example:
- DNAT loc:192.168.1.0/24 loc:192.168.1.3
- tcp www - 206.124.146.179:192.168.1.3
-
- If SNAT
- is not used (no ":" and second IP address), the
- original source address is used. If you want any destination
- address to match the rule but want to specify SNAT,
- simply use a colon followed by the SNAT address.
-
-
-
-
Example 1. You wish to forward all
- ssh connection requests from the internet to
-local system 192.168.1.3.
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
-PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
DNAT
-
net
-
loc:192.168.1.3
-
tcp
-
ssh
-
-
-
-
-
-
-
-
-
-
-
-
-
Example 2. You want to redirect all local www connection requests
- EXCEPT
- those to your own http server (206.124.146.177)
- to a Squid transparent proxy
- running on the firewall and listening on port 3128. Squid will
- of course require access to remote web servers. This example
- shows yet another use for the ORIGINAL
- DEST column; here, connection
- requests that were NOT
- (notice the
-"!") originally destined to 206.124.146.177 are
- redirected to local port 3128.
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
-PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
REDIRECT
-
loc
-
3128
-
tcp
-
www
-
-
-
-
!206.124.146.177
-
-
-
ACCEPT
-
fw
-
net
-
tcp
-
www
-
-
-
-
-
-
-
-
-
-
-
-
-
Example 3. You want to run a web server at 155.186.235.222 in your
- DMZ and have it accessible remotely and locally. the DMZ is managed
- by Proxy ARP or by classical sub-netting.
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
-PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
ACCEPT
-
net
-
dmz:155.186.235.222
-
tcp
-
www
-
-
-
-
-
-
-
ACCEPT
-
loc
-
dmz:155.186.235.222
-
tcp
-
www
-
-
-
-
-
-
-
-
-
-
-
-
-
Example 4. You want to run wu-ftpd on 192.168.2.2 in your masqueraded
- DMZ. Your internet interface address is 155.186.235.151
- and you want the FTP server to be accessible from
- the internet in addition to the local 192.168.1.0/24 and
- dmz 192.168.2.0/24 subnetworks. Note that since the server
- is in the 192.168.2.0/24 subnetwork, we can assume that access
- to the server from that subnet will not involve the firewall
- (but see FAQ 2). Note that unless you
- have more than one external IP
- address, you can leave the ORIGINAL
-DEST column blank in the first
-rule. You cannot leave
-it blank in the second
-rule though because
- then all ftp connections originating in the local
- subnet 192.168.1.0/24 would be sent to 192.168.2.2
- regardless of the site that
- the user was trying to
- connect to. That is
- clearly not what you
- want
- .
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
-PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
DNAT
-
net
-
dmz:192.168.2.2
-
tcp
-
ftp
-
-
-
-
-
-
-
DNAT
-
loc:192.168.1.0/24
-
dmz:192.168.2.2
-
tcp
-
ftp
-
-
-
-
155.186.235.151
-
-
-
-
-
-
-
-
-
If you are running wu-ftpd, you should restrict the range of passive
- in your /etc/ftpaccess file. I only need a few simultaneous FTP sessions
- so I use port range 65500-65535. In /etc/ftpaccess,
- this entry is appropriate:
-
-
-
-
passive ports 0.0.0.0/0 65500 65534
-
-
-
If you are running pure-ftpd, you would include "-p 65500:65534" on
- the pure-ftpd runline.
-
-
The important point here is to ensure that the port range used for FTP
- passive connections is unique and will not overlap
- with any usage on the firewall system.
-
-
Example 5. You wish to allow unlimited
- DMZ access to the host with MAC address
- 02:00:08:E3:FA:55.
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
-PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
ACCEPT
-
loc:~02-00-08-E3-FA-55
-
dmz
-
all
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- Example 6. You wish to allow access
-to the SMTP server in your DMZ from all zones.
-
-
-
-
-
-
-
ACTION
-
-
SOURCE
-
-
DEST
-
-
PROTO
-
-
DEST
- PORT(S)
-
-
SOURCE
- PORT(S)
-
-
ORIGINAL
- DEST
-
-
-
-
ACCEPT
-
-
all
-
-
dmz
-
-
tcp
-
-
25
-
-
-
-
-
-
-
-
-
-
-
-
- Note: When 'all' is used as
-a source or destination, intra-zone traffic is not affected.
- In this example, if there were two DMZ interfaces then the
- above rule would NOT enable SMTP traffic between hosts on these
- interfaces.
-
- Example 7. Your firewall's
- external interface has several IP addresses but you only want to accept
- SSH connections on address 206.124.146.176.
-
-
-
-
-
-
-
ACTION
-
-
SOURCE
-
-
DEST
-
-
PROTO
-
-
DEST
- PORT(S)
-
-
SOURCE
- PORT(S)
-
-
ORIGINAL
- DEST
-
-
-
-
ACCEPT
-
-
net
-
-
fw:206.124.146.176
-
-
tcp
-
-
22
-
-
-
-
-
-
-
-
-
-
-
-
- Example 8 (For advanced users running Shorewall version
- 1.3.13 or later). From the internet, you with to forward
- tcp port 25 directed to 192.0.2.178 and 192.0.2.179 to host
- 192.0.2.177 in your DMZ. You also want to allow access from the
- internet directly to tcp port 25 on 192.0.2.177.
-
-
-
-
-
-
-
ACTION
-
-
SOURCE
-
-
DEST
-
-
PROTO
-
-
DEST
- PORT(S)
-
-
SOURCE
- PORT(S)
-
-
ORIGINAL
- DEST
-
-
-
-
DNAT-
-
-
net
-
-
dmz:192.0.2.177
-
-
tcp
-
-
25
-
-
0
-
-
192.0.2.178
-
-
-
-
DNAT-
-
-
net
-
-
dmz:192.0.2.177
-
-
tcp
-
-
25
-
-
0
-
-
192.0.2.179
-
-
-
-
ACCEPT
-
-
net
-
-
dmz:192.0.2.177
-
-
tcp
-
-
25
-
-
-
-
-
-
-
-
-
-
-
-
- Using "DNAT-" rather than "DNAT"
-avoids two extra copies of the third rule from being generated.
-
- Example 9 (Shorewall version 1.4.6 or later). You have 9 http
-servers behind a Shorewall firewall and you want connection requests to
-be distributed among your servers. The servers are 192.168.1.101-192.168.1.109.
-
-
-
Shorewall allows definition of rules that apply between
- all zones. By default, these rules
- are defined in the file
- /etc/shorewall/common.def
- but may be modified to
- suit individual
- requirements. Rather than modify /etc/shorewall/common.def,
- you should copy that
- file to
- /etc/shorewall/common
- and modify that file.
-
-
The /etc/shorewall/common
- file is expected to contain iptables
- commands; rather than
- running iptables
- directly, you should run
- it indirectly using the
- Shorewall function 'run_iptables'.
- That way, if iptables encounters
- an error, the firewall will
-be safely stopped.
-
-
/etc/shorewall/masq
-
-
The /etc/shorewall/masq file is used to define classical IP Masquerading
- and Source Network Address Translation (SNAT).
-There is one entry in the file for each subnet that
-you want to masquerade. In order to make use of this feature,
-you must have NAT enabled .
-
-
Columns are:
-
-
-
INTERFACE
- - The interface that will masquerade the subnet;
-this is normally your internet interface. This interface
- name can be optionally qualified by adding ":" and a subnet
-or host IP. When this qualification is added, only packets
-addressed to that host or subnet will be masqueraded. Beginning
-with Shorewall version 1.3.14, if you have set ADD_SNAT_ALIASES=Yes
- in /etc/shorewall/shorewall.conf, you can
-cause Shorewall to create an alias label of the form interfacename:digit
- (e.g., eth0:0) by placing that label in this column.
-See example 5 below. Alias labels created in this way allow the
-alias to be visible to the ipconfig utility. THAT IS THE ONLY
-THING THAT THIS LABEL IS GOOD FOR AND IT MAY NOT APPEAR ANYWHERE ELSE
-IN YOUR SHOREWALL CONFIGURATION.
-
SUBNET
- - The subnet that you want to have masqueraded through
- the INTERFACE. This may be expressed as a single IP address,
- a subnet or an interface name. In the latter instance,
- the interface must be configured and started before Shorewall
- is started as Shorewall will determine the subnet based on
- information obtained from the 'ip' utility. When using Shorewall 1.3.13 or earlier, when an interface
- name is specified, Shorewall will only masquerade traffic from
-the first subnetwork on the named interface; if the interface interfaces
- to more that one subnetwork, you will need to add additional entries
- to this file for each of those other subnetworks. Beginning with Shorewall
- 1.3.14, shorewall will masquerade/SNAT traffic from any host that
-is routed through the named interface.
-
- The subnet may be
- optionally followed by "!' and a comma-separated
- list of addresses and/or subnets that are to be excluded
- from masquerading.
-
ADDRESS
- - The source address to be used for outgoing packets.
- This column is optional and if left blank, the current
-primary IP address of the interface in the first column is
-used. If you have a static IP on that interface, listing it here
- makes processing of output packets a little less expensive
- for the firewall. If you specify an address in this column, it must
-be an IP address configured on the INTERFACE or you must have ADD_SNAT_ALIASES
- enabled in /etc/shorewall/shorewall.conf.
-
-
-
-
Example 1: You have eth0 connected to a cable modem and eth1
- connected to your local subnetwork 192.168.9.0/24.
- Your /etc/shorewall/masq file would look like:
-
-
-
-
-
-
-
-
-INTERFACE
-
-SUBNET
-
ADDRESS
-
-
-
eth0
-
192.168.9.0/24
-
-
-
-
-
-
-
-
-
-
-
Example 2: You have a number of IPSEC tunnels through ipsec0
- and you want to masquerade traffic from your
-192.168.9.0/24 subnet to the remote subnet 10.1.0.0/16
-only.
-
-
-
-
-
-
-
-INTERFACE
-
-SUBNET
-
ADDRESS
-
-
-
ipsec0:10.1.0.0/16
-
192.168.9.0/24
-
-
-
-
-
-
-
-
-
-
-
Example 3: You have a DSL line connected on eth0 and a local
- network (192.168.10.0/24)
- connected to eth1. You want
-all local->net connections
- to use source address
- 206.124.146.176.
-
-
-
-
-
-
-
-INTERFACE
-
-SUBNET
-
ADDRESS
-
-
-
eth0
-
192.168.10.0/24
-
206.124.146.176
-
-
-
-
-
-
-
-
-
Example 4: Same as example 3 except that
- you wish to exclude
- 192.168.10.44 and 192.168.10.45 from
- the SNAT rule.
-
-
-
-
-
-
-
-INTERFACE
-
-SUBNET
-
ADDRESS
-
-
-
eth0
-
192.168.10.0/24!192.168.10.44,192.168.10.45
-
206.124.146.176
-
-
-
-
-
-
-
- Example 5 (Shorewall version >= 1.3.14):
- You have a second IP address (206.124.146.177) assigned
-to you and wish to use it for SNAT of the subnet 192.168.12.0/24.
- You want to give that address the name eth0:0. You must have ADD_SNAT_ALIASES=Yes
- in /etc/shorewall/shorewall.conf.
-
-
-
-
-
-
-
-INTERFACE
-
-SUBNET
-
ADDRESS
-
-
-
eth0:0
-
192.168.12.0/24
-
206.124.146.177
-
-
-
-
-
-
-
-
-
- /etc/shorewall/proxyarp
-
-
If you want to use proxy ARP on an entire sub-network,
- I suggest that you
- look at
- http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/.
- If you decide to use the
- technique described in that
- HOWTO, you can set
- the proxy_arp flag
- for an interface
- (/proc/sys/net/ipv4/conf/<interface>/proxy_arp)
- by including the proxyarp
- option in the interface's
- record in
-
- /etc/shorewall/interfaces.
- When using Proxy
-ARP sub-netting, you do NOT include
- any entries in
- /etc/shorewall/proxyarp.
-
-
The /etc/shorewall/proxyarp file is used to define Proxy ARP. The file is
- typically used for
-enabling Proxy ARP on a
-small set of systems
-since you need
-one entry in this file for each
- system using proxy ARP. Columns
- are:
-
-
-
ADDRESS
- - address of the system.
-
INTERFACE
- - the interface that connects to the system. If the
- interface is obvious from the subnetting, you may
- enter "-" in this column.
-
EXTERNAL
- - the external interface that you want to honor ARP
- requests for the ADDRESS specified in the first column.
-
HAVEROUTE
- - If you already
-have a route
-through
- INTERFACE to
- ADDRESS, this column should contain
- "Yes" or "yes". If you want
-Shorewall to add the route, the
- column should
- contain
- "No" or
- "no".
-
-
-
-
Note: After you have made a change to the /etc/shorewall/proxyarp
- file, you may need to flush the ARP cache of all
- routers on the LAN segment connected to the interface
- specified in the EXTERNAL column of the change/added entry(s).
- If you are having problems communicating between an individual
- host (A) on that segment and a system whose entry has changed,
- you may need to flush the ARP cache on host A as well.
-
-
ISPs typically have ARP configured with long TTL
- (hours!) so if your ISPs router has a stale cache entry (as seen using "tcpdump
- -nei <external interface> host <IP addr>"), it may take a long
-while to time out. I personally have had to contact my ISP and ask them
-to delete a stale entry in order to restore a system to working order after
-changing my proxy ARP settings.
-
-
Example: You have public IP addresses 155.182.235.0/28. You
- configure your firewall as follows:
-
-
-
eth0 - 155.186.235.1
- (internet connection)
-
eth1 - 192.168.9.0/24
- (masqueraded local systems)
-
eth2 - 192.168.10.1
- (interface to your DMZ)
-
-
-
-
In your DMZ, you want to install a Web/FTP server with public address
- 155.186.235.4. On the Web server, you subnet just
- like the firewall's eth0 and you configure 155.186.235.1
- as the default gateway. In your /etc/shorewall/proxyarp
- file, you will have:
-
-
-
-
-
-
-
-ADDRESS
-
-INTERFACE
-
-EXTERNAL
-
HAVEROUTE
-
-
-
155.186.235.4
-
eth2
-
eth0
-
No
-
-
-
-
-
-
-
-
-
Note: You may want to configure the servers in your DMZ with a subnet
- that is smaller than the subnet of your internet
- interface. See the Proxy ARP Subnet Mini HOWTO (http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/)
- for details. In this case you will want to place
- "Yes" in the HAVEROUTE column.
-
-
Warning: Do not use Proxy ARP and FreeS/Wan
-on the same system unless you are prepared to suffer the consequences.
- If you start or restart Shorewall with an IPSEC tunnel active,
- the proxied IP addresses are mistakenly assigned to
- the IPSEC tunnel device (ipsecX) rather than to the
-interface that you specify in the INTERFACE column of /etc/shorewall/proxyarp.
- I haven't had the time to debug this problem so I can't
-say if it is a bug in the Kernel or in FreeS/Wan.
-
-
You might be able to work around this problem using the following
- (I haven't tried it):
-
-
In /etc/shorewall/init, include:
-
-
qt service ipsec stop
-
-
In /etc/shorewall/start, include:
-
-
qt service ipsec start
-
-
- /etc/shorewall/nat
-
-
The /etc/shorewall/nat file is used to define static NAT. There is one
- entry in the file for each static NAT relationship
- that you wish to define. In order to make use of this
- feature, you must have NAT enabled
- .
-
-
IMPORTANT: If all you want to do
- is forward ports
- to servers behind your firewall,
- you do NOT want to use
- static NAT. Port
- forwarding
-can be accomplished
- with simple entries in
- the
- rules file. Also, in most
- cases Proxy ARP
- provides a
- superior solution
- to static NAT
- because the
- internal systems
- are accessed using the same IP
- address internally and externally.
-
-
Columns in an entry are:
-
-
-
EXTERNAL
- - External IP address - This should NOT be
-the primary IP address of the interface named in the next
-column.
-
INTERFACE
- - Interface that you want the EXTERNAL IP address
- to appear on. Beginning with Shorewall version 1.3.14,
-if you have set ADD_IP_ALIASES=Yes in /etc/shorewall/shorewall.conf,
- you can specify an alias label of the form interfacename:digit
- (e.g., eth0:0) and Shorewall will create the alias with
- that label. Alias labels created in this way allow the alias
-to be visible to the ipconfig utility. THAT IS THE ONLY THING
- THAT THIS LABEL IS GOOD FOR AND IT MAY NOT APPEAR ANYWHERE ELSE IN
-YOUR SHOREWALL CONFIGURATION.
-
INTERNAL
- - Internal IP address.
-
ALL
- INTERFACES
- - If Yes
- or yes (or
- left
- empty),
- NAT will
-be effective from all
- hosts. If
- No or no
-then NAT will
-be effective
- only
-
-through the interface named in
- the INTERFACE
- column.
-
LOCAL
-- If Yes or yes and the ALL INTERFACES column contains
- Yes or yes, NAT will be effective from the firewall system.
- Note: For this to work, you must be running
- kernel 2.4.19 or later and iptables 1.2.6a or later and
-you must have enabled CONFIG_IP_NF_NAT_LOCAL
- in your kernel.
The /etc/shorewall/tunnels file allows you to define IPSec, GRE, IPIP,
- OpenVPN, PPTP
- and 6to4.tunnels with end-points on your firewall. To use ipsec,
- you must install version 1.9, 1.91 or the current FreeS/WAN development snapshot.
-
-
-
Note: For kernels 2.4.4 and above, you will need to use version 1.91
- or a development snapshot as patching with version
- 1.9 results in kernel compilation errors.
This file is used to set the following firewall parameters:
-
-
-
SHOREWALL_SHELL
- - Added at version 1.4.6
- This parameter is used to specify the shell program to be used to interpret
- the firewall script (/usr/share/shorewall/firewall). If not specified or
-specified as a null value, /bin/sh is assumed.
-
-
LOGFORMAT - Added at version 1.4.4.
- The value of this variable generate the --log-prefix setting
-for Shorewall logging rules. It contains a 'printf' formatting template
-which accepts three arguments (the chain name, logging rule number (optional)
- and the disposition). To use LOGFORMAT with fireparse (http://www.fireparse.com), set it
-as:
-
- LOGFORMAT="fp=%s:%d a=%s "
-
- If the LOGFORMAT value contains the substring '%d' then the logging
- rule number is calculated and formatted in that position; if that substring
- is not included then the rule number is not included. If not supplied
- or supplied as empty (LOGFORMAT="") then "Shorewall:%s:%s:" is assumed.
-
- CAUTION: /sbin/shorewall uses the leading part
-of the LOGFORMAT string (up to but not including the first '%') to
-find log messages in the 'show log', 'status' and 'hits' commands. This
-part should not be omitted (the LOGFORMAT should not begin with "%")
-and the leading part should be sufficiently unique for /sbin/shorewall
-to identify Shorewall messages.
-
-
CLEAR_TC - Added at version 1.3.13
- If this option is set to 'No' then Shorewall
- won't clear the current traffic control rules during [re]start.
- This setting is intended for use by people that prefer to configure
- traffic shaping when the network interfaces come up rather than
- when the firewall is started. If that is what you want to do, set
-TC_ENABLED=Yes and CLEAR_TC=No and do not supply an /etc/shorewall/tcstart
- file. That way, your traffic shaping rules can still use the 'fwmark'
-classifier based on packet marking defined in /etc/shorewall/tcrules.
-If not specified, CLEAR_TC=Yes is assumed.
-
-
MARK_IN_FORWARD_CHAIN - Added
- at version 1.3.12
- If your kernel has a FORWARD chain
- in the mangle table, you may set MARK_IN_FORWARD_CHAIN=Yes
- to cause the marking specified in the tcrules file to occur in that
- chain rather than in the PREROUTING chain. This permits you
- to mark inbound traffic based on its destination address when SNAT
- or Masquerading are in use. To determine if your kernel has a FORWARD
- chain in the mangle table, use the "/sbin/shorewall show mangle"
- command; if a FORWARD chain is displayed then your kernel will
- support this option. If this option is not specified or if it is
-given the empty value (e.g., MARK_IN_FORWARD_CHAIN="") then MARK_IN_FORWARD_CHAIN=No
- is assumed.
-
-
RFC1918_LOG_LEVEL - Added
- at version 1.3.12
- This parameter determines the
-level at which packets logged under the 'norfc1918' mechanism
- are logged. The value must be a valid syslog level and if no level is given,
- then info is assumed. Prior to Shorewall version 1.3.12,
- these packets are always logged at the info level.
-
TCP_FLAGS_DISPOSITION
-- Added in Version 1.3.11
- Determines the disposition of TCP
- packets that fail the checks enabled by the tcpflags interface option and must
- have a value of ACCEPT (accept the packet), REJECT (send an RST
- response) or DROP (ignore the packet). If not set or if set
- to the empty value (e.g., TCP_FLAGS_DISPOSITION="") then TCP_FLAGS_DISPOSITION=DROP
- is assumed.
-
TCP_FLAGS_LOG_LEVEL
- - Added in Version 1.3.11
- Determines the syslog level for logging packets
- that fail the checks enabled by the tcpflags interface option.The value must
- be a valid syslogd log level. If you don't want to log
-these packets, set to the empty value (e.g., TCP_FLAGS_LOG_LEVEL="").
-
-
MACLIST_DISPOSITION
- - Added in Version 1.3.10
- Determines the disposition
- of connections requests that fail MAC Verification and must have
- the value ACCEPT (accept the connection request anyway), REJECT
- (reject the connection request) or DROP (ignore the connection request).
- If not set or if set to the empty value (e.g., MACLIST_DISPOSITION="")
- then MACLIST_DISPOSITION=REJECT is assumed.
-
MACLIST_LOG_LEVEL
- - Added in Version 1.3.10
- Determines the syslog level for logging connection
- requests that fail MAC Verification.
- The value must be a valid syslogd log level. If you
- don't want to log these connection requests, set to the
-empty value (e.g., MACLIST_LOG_LEVEL="").
-
-
NEWNOTSYN -
-Added in Version 1.3.8
- When set to "Yes" or
-"yes", Shorewall will filter TCP packets that are
-not part of an established connention and that are not SYN
- packets (SYN flag on - ACK flag off). If set to "No", Shorewall
- will silently drop such packets. If not set or set to the
-empty value (e.g., "NEWNOTSYN="), NEWNOTSYN=No is assumed.
-
- If you have a HA setup
- with failover to another firewall, you should have
- NEWNOTSYN=Yes on both firewalls. You should also select NEWNOTSYN=Yes
- if you have asymmetric routing.
-
-
LOGNEWNOTSYN
- - Added in Version 1.3.6
- Beginning with version
- 1.3.6, Shorewall drops non-SYN TCP packets that are
- not part of an existing connection. If you would like
-to log these packets, set LOGNEWNOTSYN to the syslog level at which you want
-the packets logged. Example: LOGNEWNOTSYN=ULOG|
-
- Note: Packets
- logged under this option are usually the result of
- broken remote IP stacks rather than the result of any sort
- of attempt to breach your firewall.
-
-
DETECT_DNAT_ADDRS - Added in Version 1.3.4
- If set to "Yes" or "yes", Shorewall will detect
- the first IP address of the interface to the source zone and will
- include this address in DNAT rules as the original destination
- IP address. If set to "No" or "no", Shorewall will not detect
-this address and any destination IP address will match the DNAT
-rule. If not specified or empty, "DETECT_DNAT_ADDRS=Yes" is
-assumed.
-
-
MULTIPORT
- - (Removed in version 1.4.6 -- the value of this parameter is now automatically
- detected by Shorewall)
- If set to "Yes"
-or "yes", Shorewall will use the Netfilter multiport
- facility. In order to use this facility, your kernel
- must have multiport support (CONFIG_IP_NF_MATCH_MULTIPORT).
- When this support is used, Shorewall will generate a
-single rule from each record in the /etc/shorewall/rules
- file that meets these criteria:
-
-
-
-
No port range(s)
- specified
-
Specifies
-15 or fewer ports
-
-
-
-
-
-
Rules not meeting those criteria will continue to generate an individual
- rule for each listed port or port range.
-
-
-
NAT_BEFORE_RULES
- If set to "No" or
- "no", port forwarding rules can override the contents
- of the /etc/shorewall/nat file.
- If set to "Yes" or "yes", port forwarding rules cannot
-override static NAT. If not set or set to an empty value, "Yes"
- is assumed.
-
FW
- This
- parameter
- specifies the
- name of the
- firewall zone.
- If not set or
- if set to an empty string,
- the value "fw"
- is assumed.
-
SUBSYSLOCK
- This parameter
- should be set to the name of a file that the firewall
- should create if it starts successfully and remove
- when it stops. Creating and removing this file allows Shorewall
- to work with your distribution's initscripts. For RedHat,
- this should be set to /var/lock/subsys/shorewall. For
- Debian, the value is /var/state/shorewall and in LEAF it is /var/run/shorwall.
- Example: SUBSYSLOCK=/var/lock/subsys/shorewall.
-
STATEDIR
- This parameter
- specifies the name of a directory where Shorewall
- stores state information. If the directory doesn't
-exist when Shorewall starts, it will create the directory.
- Example: STATEDIR=/tmp/shorewall.
-
- NOTE: If
-you change the STATEDIR variable while the firewall
- is running, create the new directory if necessary then
-copy the contents of the old directory to the new directory.
-
-
MODULESDIR
- This parameter
- specifies the directory where your kernel netfilter
- modules may be found. If you leave the variable empty,
- Shorewall will supply the value "/lib/modules/`uname -r`/kernel/net/ipv4/netfilter.
-
LOGRATE
- and LOGBURST
- These parameters
- set the match rate and initial burst size for logged
- packets. Please see the iptables man page for a description
- of the behavior of these parameters (the iptables option
- --limit is set by LOGRATE and --limit-burst is set by LOGBURST).
- If both parameters are set empty, no rate-limiting
- will occur.
-
- Example:
- LOGRATE=10/minute
- LOGBURST=5
-
-
LOGFILE
- This parameter
- tells the
- /sbin/shorewall
- program where
- to look for
- Shorewall
- messages when processing the "show
- log", "monitor", "status"
- and "hits"
- commands. If
- not assigned
- or if assigned
- an empty
- value,
- /var/log/messages
- is assumed.
-
NAT_ENABLED
- (Removed in Shorewall 1.4.6 -- the value of this parameter is now automatically
- detected by Shorewall)
- This parameter
- determines whether Shorewall supports NAT operations.
- NAT operations include:
-
- Static
-NAT
- Port Forwarding
- Port Redirection
- Masquerading
-
- If the parameter
- has no value or has a value of "Yes" or "yes"
-then NAT is enabled. If the parameter has a value of "no"
- or "No" then NAT is disabled.
-
-
MANGLE_ENABLED
- (Removed in Shorewall 1.4.6 -- the value of this parameter is now automatically
- detected by Shorewall)
- This parameter
- determines if packet mangling is enabled. If the parameter
- has no value or has a value of "Yes" or "yes" than
- packet mangling is enabled. If the parameter has a value
- of "no" or "No" then packet mangling is disabled. If packet
- mangling is disabled, the /etc/shorewall/tos file is
- ignored.
-
-
IP_FORWARDING
- This parameter
- determines whether Shorewall enables or disables IPV4
- Packet Forwarding (/proc/sys/net/ipv4/ip_forward).
- Possible values are:
-
- On or
-on - packet forwarding will be enabled.
- Off or
-off - packet forwarding will be disabled.
- Keep or
- keep - Shorewall will neither enable nor disable
- packet forwarding.
-
- If this variable
- is not set or is given an empty value (IP_FORWARD="")
- then IP_FORWARD=On is assumed.
-
-
ADD_IP_ALIASES
- This parameter
- determines whether Shorewall automatically adds
-the external
- address(es) in /etc/shorewall/nat
- . If the variable is set to "Yes" or "yes" then Shorewall
-automatically adds these aliases. If it is set to "No" or "no",
-you must add these aliases yourself using your distribution's
-network configuration tools. RESTRICTION: Shorewall
-versions before 1.4.6 can only add addresses to the first subnetwork
-configured on an interface.
-
- If this variable
- is not set or is given an empty value (ADD_IP_ALIASES="")
- then ADD_IP_ALIASES=Yes is assumed.
-
ADD_SNAT_ALIASES
- This parameter determines
- whether Shorewall automatically adds the SNAT
- ADDRESS in /etc/shorewall/masq.
- If the variable is set to "Yes" or "yes" then Shorewall
- automatically adds these addresses. If it is set to
- "No" or "no", you must add these addresses yourself using
-your distribution's network configuration tools. RESTRICTION:
- Shorewall versions before 1.4.6 can only add addresses to
-the first subnetwork configured on an interface.
-
- If this variable
- is not set or is given an empty value (ADD_SNAT_ALIASES="")
- then ADD_SNAT_ALIASES=No is assumed.
-
-
LOGUNCLEAN
- This parameter
- determines the
- logging level
- of mangled/invalid
- packets
- controlled by
- the 'dropunclean and logunclean'
- interface
- options. If
- LOGUNCLEAN is empty
- (LOGUNCLEAN=) then packets
-selected by 'dropclean' are
- dropped
- silently ('logunclean'
- packets are
- logged
- under the 'info' log level). Otherwise,
- these packets are logged at
- the specified
- level (Example:
- LOGUNCLEAN=debug).
-
BLACKLIST_DISPOSITION
- This parameter
- determines the
- disposition of
- packets from
- blacklisted
- hosts. It may have the value DROP
- if the packets are to
- be dropped or
- REJECT if the
- packets are to
- be replied
- with an ICMP
- port
- unreachable
- reply or a TCP RST (tcp
- only). If you do not assign
- a value or if you assign an
- empty value
- then DROP is
- assumed.
-
BLACKLIST_LOGLEVEL
- This paremter
- determines if
- packets from
- blacklisted
- hosts are logged
- and it
- determines the syslog level that they are
- to be logged
-at. Its value is a syslog level
- (Example:
- BLACKLIST_LOGLEVEL=debug). If you do not
- assign a value or if you
- assign an empty value
- then packets from
- blacklisted
- hosts are not
- logged.
-
CLAMPMSS
- This parameter
- enables the
- TCP Clamp MSS
- to PMTU feature
-of Netfilter and
- is usually
- required when
- your internet
- connection is through PPPoE
- or PPTP. If
- set to
- "Yes" or
- "yes", the
- feature is enabled.
- If left
- blank or
- set to
- "No"
- or
- "no", the
-feature is
- not enabled. Note: This option
- requires CONFIG_IP_NF_TARGET_TCPMSS
- in your kernel.
-
ROUTE_FILTER
- If this parameter
- is given the value "Yes" or "yes" then route filtering
- (anti-spoofing) is enabled on all network interfaces.
- The default value is "no".
-
-
-
-
/etc/shorewall/modules Configuration
-
-
The file /etc/shorewall/modules contains commands for loading the kernel
- modules required by Shorewall-defined firewall
- rules. Shorewall will source this file during start/restart
- provided that it exists and that the directory specified
- by the MODULESDIR parameter exists (see /etc/shorewall/shorewall.conf
- above).
-
-
The file that is released with Shorewall calls the Shorewall function
- "loadmodule" for the set of modules that I load.
-
-
The loadmodule function is called as follows:
-
-
-
-
loadmodule <modulename> [
- <module parameters> ]
-
-
-
where
-
-
-
-
<modulename>
-
-
-
-
-
is the name of the modules without the trailing ".o" (example
-ip_conntrack).
-
-
-
-
<module parameters>
-
-
-
-
-
Optional parameters to the insmod utility.
-
-
-
-
The function determines if the module named by <modulename>
- is already loaded and if not then the function
- determines if the ".o" file corresponding to the
- module exists in the moduledirectory; if so,
- then the following command is executed:
If the file doesn't exist, the function determines of the ".o.gz"
-file corresponding to the module exists in the moduledirectory. If
-it does, the function assumes that the running configuration supports compressed
- modules and execute the following command:
The /etc/shorewall/tos file allows you to set the Type of Service field
- in packet headers based on packet source, packet
- destination, protocol, source port and destination
- port. In order for this file to be processed by Shorewall,
- you must have mangle support enabled
- .
-
-
Entries in the file have the following columns:
-
-
-
SOURCE
- -- The source zone. May be qualified by following
-the zone name with a colon (":") and either an IP address,
- an IP subnet, a MAC address in Shorewall Format or the
- name of an interface. This column may also contain the
- name of
- the firewall
- zone to indicate packets originating
- on the firewall itself or "all" to indicate any source.
-
DEST
- -- The destination zone. May be qualified by following
- the zone name with a colon (":") and either an IP address
- or an IP subnet. Because packets are marked prior to routing,
- you may not specify the name of an interface. This
-column may also contain "all" to indicate any destination.
-
PROTOCOL
- -- The name of a protocol in /etc/protocols or the
-protocol's number.
-
SOURCE
-PORT(S) -- The source port or a port range. For
- all ports, place a hyphen ("-") in this column.
-
DEST PORT(S)
- -- The destination port or a port range. To indicate
- all ports, place a hyphen ("-") in this column.
-
TOS
- -- The type of service. Must be one of the following:
The /etc/shorewall/tos file that is included with Shorewall contains
- the following entries.
-
-
-
-
-
-
-
SOURCE
-
DEST
-
PROTOCOL
-
SOURCE
- PORT(S)
-
DEST
- PORT(S)
-
TOS
-
-
-
all
-
all
-
tcp
-
-
-
ssh
-
16
-
-
-
all
-
all
-
tcp
-
ssh
-
-
-
16
-
-
-
all
-
all
-
tcp
-
-
-
ftp
-
16
-
-
-
all
-
all
-
tcp
-
ftp
-
-
-
16
-
-
-
all
-
all
-
tcp
-
-
-
ftp-data
-
8
-
-
-
all
-
all
-
tcp
-
ftp-data
-
-
-
8
-
+
loc2
+
eth1:192.168.1.128/25
+
+
+
-
-
-
WARNING: Users have reported that odd routing problems result from
- adding the ESP and AH protocols to the /etc/shorewall/tos
- file.
-
-
/etc/shorewall/blacklist
-
-
Each line in
- /etc/shorewall/blacklist
- contains
- an IP
- address, a MAC address in Shorewall Format
- or
- subnet
- address. Example:
-
-
130.252.100.69 206.124.146.0/24
-
-
Packets from
- hosts
- listed
- in the
- blacklist file
- will be
- disposed of
- according
- to
- the value assigned
- to
- the BLACKLIST_DISPOSITION
- and BLACKLIST_LOGLEVEL variables in
- /etc/shorewall/shorewall.conf.
- Only
- packets arriving
- on interfaces
- that
- have the
- 'blacklist'
- option in
- /etc/shorewall/interfaces
- are
- checked against the
- blacklist. The black list is designed to prevent listed
- hosts/subnets from accessing services on your
- network.
-
-
-
Beginning with Shorewall 1.3.8, the blacklist file has three columns:
-
-
-
-
ADDRESS/SUBNET
- - As described above.
-
PROTOCOL
-- Optional. If specified, only packets specifying this
- protocol will be blocked.
-
PORTS - Optional;
- may only be given if PROTOCOL is tcp, udp or icmp.
-Expressed as a comma-separated list of port numbers or service
- names (from /etc/services). If present, only packets destined
- for the specified protocol and one of the listed ports are
-blocked. When the PROTOCOL is icmp, the PORTS column contains
- a comma-separated list of ICMP type numbers or names (see "iptables
- -h icmp").
-
IMPORTANT: The Shorewall blacklist file is NOT
- designed to police your users' web browsing -- to
- do that, I suggest that you install and configure Squid
- (http://www.squid-cache.org).
-
SUBNET
- - The subnet using VLSM notation (e.g., 192.168.0.0/16).
-
TARGET
- - What to do with packets to/from the
- SUBNET:
+
Your local interface is eth1 and you have two groups of local hosts that
+ you want to consider as one zone and you want Shorewall to route
+ between them:
-
-
RETURN
- - Process the packet normally thru the rules and policies.
-
DROP
- - Silently drop the packet.
-
logdrop
- - Log then drop the packet -- see the RFC1918_LOG_LEVEL
- parameter above.
+
+
192.168.1.0/25
+
192.168.1.128/25
+
+
+
+
Your /etc/shorewall/interfaces file might look like:
+
+
+
+
+
-
-
-
-
+
+
+ ZONE
+
+ INTERFACE
+
+ BROADCAST
+
+ OPTIONS
+
+
+
net
+
eth0
+
detect
+
dhcp,norfc1918
+
+
+
loc
+
+
eth1
+
192.168.1.127,192.168.1.255
+
+
+
+
+
+
+
+
+
+
+
+
Your /etc/shorewall/hosts file might look like:
+
+
+
+
+
+
+
+
+
+ ZONE
+
+ HOST(S)
+
+ OPTIONS
+
+
+
loc
+
eth1:192.168.1.0/25
+
+
+
+
+
loc
+
eth1:192.168.1.128/25
+
+
+
+
+
+
+
+
+
+ If you are running Shorewall
+1.4.6 or later, your hosts file may look like:
+
+
+
+
+
+
+
+ ZONE
+
+ HOST(S)
+
+ OPTIONS
+
+
+
loc
+
eth1:192.168.1.0/25,192.168.1.128/25
+
+
+
+
+
+
+
+
+
+
+
+
+
Nested and Overlapping
+Zones
+
+
The /etc/shorewall/interfaces and /etc/shorewall/hosts file allow you
+ to define nested or overlapping zones. Such overlapping/nested zones
+ are allowed and Shorewall processes zones in the order that
+ they appear in the /etc/shorewall/zones file. So if you have
+ nested zones, you want the sub-zone to appear before the
+super-zone and in the case of overlapping zones, the rules
+ that will apply to hosts that belong to both zones is
+ determined by which zone appears first in /etc/shorewall/zones.
+
+
Hosts that belong to more than one zone may be managed by the rules
+ of all of those zones. This is done through use
+ of the special CONTINUE policy described
+ below.
+
+
/etc/shorewall/policy
+ Configuration.
+
+
This file is used to describe the firewall policy regarding establishment
+ of connections. Connection establishment is described
+ in terms of clients who initiate connections
+ and servers who receive those connection
+requests. Policies defined in /etc/shorewall/policy describe
+ which zones are allowed to establish connections with other
+ zones.
+
+
Policies established in /etc/shorewall/policy can be viewed as default
+ policies. If no rule in /etc/shorewall/rules
+applies to a particular connection request then the
+policy from /etc/shorewall/policy is applied.
+
+
Four policies are defined:
+
+
+
ACCEPT
+ - The connection is allowed.
+
DROP
+ - The connection request is ignored.
+
REJECT
+ - The connection request is rejected with an RST
+(TCP) or an ICMP destination-unreachable packet being
+ returned to the client.
+
CONTINUE
+ - The connection is neither ACCEPTed, DROPped
+ nor REJECTed. CONTINUE may be used when one or both of
+ the zones named in the entry are sub-zones of or intersect
+ with another zone. For more information, see below.
+
NONE - (Added in version 1.4.1) - Shorewall
+ should not set up any infrastructure for handling traffic from
+the SOURCE zone to the DEST zone. When this policy is specified,
+the LOG LEVEL and BURST:LIMIT columns
+must be left blank.
+
+
-
/etc/shorewall/routestopped (Added in Version
- 1.3.4)
+
For each policy specified in /etc/shorewall/policy, you can indicate
+ that you want a message sent to your system
+log each time that the policy is applied.
-
This file defines the hosts that are accessible from the firewall when
- the firewall is stopped. Columns in the file are:
+
Entries in /etc/shorewall/policy have four columns as follows:
POLICY - The default policy
+ for connection requests from the SOURCE zone to the DESTINATION
+ zone.
+
+
LOG LEVEL - Optional. If
+left empty, no log message is generated when the policy
+is applied. Otherwise, this column should contain an integer
+ or name indicating a syslog
+level.
+
+
LIMIT:BURST - Optional.
+ If left empty, TCP connection requests from the SOURCE
+ zone to the DEST zone will not be rate-limited.
+ Otherwise, this column specifies the maximum rate at
+ which TCP connection requests will be accepted followed by
+a colon (":") followed by the maximum burst size that will be
+ tolerated. Example: 10/sec:40 specifies that the
+ maximum rate of TCP connection requests allowed will be 10 per
+ second and a burst of 40 connections will be tolerated. Connection
+ requests in excess of these limits will be dropped.
+
+
+
+
In the SOURCE and DEST columns, you can enter "all" to indicate all
+ zones.
+
+
The policy file installed by default is as follows:
+
+
+
+
+
+
+
+
+
SOURCE
+
DEST
+
+ POLICY
+
+ LOG LEVEL
+
LIMIT:BURST
+
+
+
loc
+
net
+
ACCEPT
+
+
+
+
+
+
+
net
+
all
+
DROP
+
info
+
+
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
+
+
+
+
+
+
+
This table may be interpreted as follows:
+
+
+
All connection
+ requests from the local network to hosts on the
+ internet are accepted.
+
All connection
+ requests originating from the internet are ignored
+ and logged at level KERNEL.INFO.
+
All other connection
+ requests are rejected and logged.
+
+
+
+
WARNING:
+
+
The firewall script processes the
+ /etc/shorewall/policy file from top to bottom
+and uses the first applicable policy that it finds.
+ For example, in the following policy file, the policy
+ for (loc, loc) connections would be ACCEPT as specified
+ in the first entry even though the third entry in the file specifies
+ REJECT.
+
+
+
+
+
+
+
SOURCE
+
DEST
+
POLICY
+
LOG
+ LEVEL
+
LIMIT:BURST
+
+
+
loc
+
all
+
ACCEPT
+
+
+
+
+
+
+
net
+
all
+
DROP
+
info
+
+
+
+
+
loc
+
loc
+
REJECT
+
info
+
+
+
+
+
+
+
+
+
+
+
IntraZone Traffic
+ Shorewall allows a zone to be associated with more
+than one interface or with multiple networks that interface through
+a single interface. Beginning with Shorewall 1.4.1, Shorewall will
+ACCEPT all traffic from a zone to itself provided that there is no
+explicit policy governing traffic from that zone to itself (an explicit
+policy does not specify "all" in either the SOURCE or DEST column) and
+that there are no rules concerning connections from that zone to itself.
+If there is an explicit policy or if there are one or more rules, then
+traffic within the zone is handled just like traffic between zones is.
+
+
Any time that you have multiple interfaces associated with a single zone,
+ you should ask yourself if you really want traffic routed between
+ those interfaces. Cases where you might not want that behavior are:
+
+
+
+
Multiple 'net' interfaces to different ISPs.
+You don't want to route traffic from one ISP to the other through
+your firewall.
+
Multiple VPN clients. You don't necessarily want
+ them to all be able to communicate between themselves using your
+gateway/router.
+
+
+
+
+
The CONTINUE
+ policy
+
+
Where zones are nested or overlapping , the
+ CONTINUE policy allows hosts that are within multiple
+ zones to be managed under the rules of all of these
+ zones. Let's look at an example:
+
+
/etc/shorewall/zones:
+
+
+
+
+
+
+
+ ZONE
+
+ DISPLAY
+
+ COMMENTS
+
+
+
sam
+
Sam
+
Sam's
+ system at home
+
+
+
net
+
Internet
+
The
+Internet
+
+
+
loc
+
Loc
+
Local
+ Network
+
+
+
+
+
+
+
+
+
/etc/shorewall/interfaces:
+
+
+
+
+
+
+
+ ZONE
+
+ INTERFACE
+
+ BROADCAST
+
+ OPTIONS
+
+
+
-
+
eth0
+
detect
+
dhcp,norfc1918
+
+
+
loc
+
eth1
+
detect
+
+
+
+
+
+
+
+
+
+
+
/etc/shorewall/hosts:
+
+
+
+
+
+
+
+ ZONE
+
+ HOST(S)
+
+ OPTIONS
+
+
+
net
+
eth0:0.0.0.0/0
+
+
+
+
+
sam
+
eth0:206.191.149.197
+
+
+
+
+
+
+
+
+
+
+
Note that Sam's home system is a member of both the sam zone
+ and the
+ net zone and as described
+above , that means that sam must be listed before
+net in /etc/shorewall/zones.
+
+
/etc/shorewall/policy:
+
+
+
+
+
+
+
+ SOURCE
+
+ DEST
+
+ POLICY
+
+ LOG LEVEL
+
+
+
loc
+
net
+
ACCEPT
+
+
+
+
+
sam
+
all
+
CONTINUE
+
+
+
+
+
net
+
all
+
DROP
+
info
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
+
+
+
+
+
The second entry above says that when Sam is the client, connection
+ requests should first be process under rules
+where the source zone is sam and if there is
+no match then the connection request should be treated under
+ rules where the source zone is net. It is important
+ that this policy be listed BEFORE the next policy (net
+to all).
+
+
Partial /etc/shorewall/rules:
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
+ PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
...
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
DNAT
+
sam
+
loc:192.168.1.3
+
tcp
+
ssh
+
-
+
+
+
+
+
DNAT
+
net
+
loc:192.168.1.5
+
tcp
+
www
+
-
+
+
+
+
+
...
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
Given these two rules, Sam can connect to the firewall's internet interface
+ with ssh and the connection request will be
+forwarded to 192.168.1.3. Like all hosts in the
+net zone, Sam can connect to the firewall's internet
+ interface on TCP port 80 and the connection request will
+ be forwarded to 192.168.1.5. The order of the rules is not
+significant.
+
+
Sometimes it is necessary to suppress port forwarding
+ for a sub-zone. For example, suppose that all
+ hosts can SSH to the firewall and be forwarded to
+192.168.1.5 EXCEPT Sam. When Sam connects to the firewall's
+external IP, he should be connected to the firewall itself.
+ Because of the way that Netfilter is constructed, this requires
+ two rules as follows:
+
+
+
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
+ PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
...
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
DNAT
+
sam
+
fw
+
tcp
+
ssh
+
-
+
+
+
+
+
DNAT
+
net!sam
+
loc:192.168.1.3
+
tcp
+
ssh
+
-
+
+
+
+
+
...
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
The first rule allows Sam SSH access to the firewall. The second
+ rule says that any clients from the net zone
+ with the exception of those in the
+'sam' zone should have their
+connection port forwarded to
+ 192.168.1.3. If you need to exclude
+ more than one zone in this way, you
+ can list the zones separated
+ by commas (e.g., net!sam,joe,fred).
+ This technique also may be used when
+ the ACTION is REDIRECT.
+
+
/etc/shorewall/rules
+
+
The /etc/shorewall/rules file defines exceptions to the policies established
+ in the /etc/shorewall/policy file. There is one
+ entry in /etc/shorewall/rules for each of these rules.
+
+
+
+
Shorewall automatically enables firewall->firewall traffic over the
+ loopback interface (lo) -- that traffic cannot be
+regulated using rules and any rule that tries to regulate
+such traffic will generate a warning and will be ignored.
+
+
+
Entries in the file have the following columns:
+
+
+
ACTION
+
+
+
+
ACCEPT, DROP,
+ REJECT, CONTINUE. These have the same meaning here as
+ in the policy file above.
+
DNAT -- Causes
+ the connection request to be forwarded to the system
+ specified in the DEST column (port forwarding). "DNAT"
+ stands for "Destination Network
+ Address Translation"
+
DNAT- -- The above ACTION
+ (DNAT) generates two iptables rules: 1) and header-rewriting
+ rule in the Netfilter 'nat' table and; 2) an ACCEPT rule
+in the Netfilter 'filter' table. DNAT- works like DNAT but only
+generates the header-rewriting rule.
+
+
REDIRECT
+-- Causes the connection request to be redirected to
+ a port on the local (firewall) system.
+
REDIRECT- -- The above ACTION (REDIRECT) generates
+ two iptables rules: 1) and header-rewriting rule in the Netfilter
+ 'nat' table and; 2) an ACCEPT rule in the Netfilter 'filter'
+ table. REDIRECT- works like REDIRECT but only generates the header-rewriting
+ rule.
+
+
LOG - Log the packet -- requires a syslog
+ level (see below).
+
+
+
+
+
+
The ACTION may optionally be followed by ":" and a syslog level (example: REJECT:info).
+This causes the packet to be logged at the specified level prior
+to being processed according to the specified ACTION. Note: if the
+ACTION is LOG then you MUST specify a syslog level.
+
+ The use of DNAT
+or REDIRECT requires that you have NAT enabled.
+
+
+
SOURCE
+- Describes the source hosts to which the rule applies..
+ The contents of this field must begin with the name
+ of a zone defined in /etc/shorewall/zones, $FW or "all".
+ If the ACTION is DNAT or REDIRECT, sub-zones may be excluded
+ from the rule by following the initial zone name with "!'
+ and a comma-separated list of those sub-zones to be excluded.
+ There is an example above.
+
+ If the source is
+ not 'all' then the source may be further restricted
+ by adding a colon (":") followed by a comma-separated
+ list of qualifiers. Qualifiers are may include:
+
+
+
+
An interface
+ name - refers to any connection requests arriving
+on the specified interface (example loc:eth4). Beginning
+ with Shorwall 1.3.9, the interface name may optionally be
+followed by a colon (":") and an IP address or subnet (examples:
+loc:eth4:192.168.4.22, net:eth0:192.0.2.0/24).
+
An IP address
+ - refers to a connection request from the host with
+ the specified address (example net:155.186.235.151).
+ If the ACTION is DNAT, this must not be a DNS name.
A subnet
+- refers to a connection request from any host in the
+ specified subnet (example net:155.186.235.0/24).
+
+
+
+
+
DEST
+- Describes the destination host(s) to which the rule
+ applies. May take most of the forms described above for
+ SOURCE plus the following two additional forms:
+
+
+
+
An IP address
+ followed by a colon and the port number
+ that the server is listening on (service names from
+/etc/services are not allowed - example loc:192.168.1.3:80).
+
+
+
A single
+port number (again, service names are not allowed)
+ -- this form is only allowed if the ACTION is REDIRECT
+and refers to a server running on the firewall itself and
+ listening on the specified port.
+
+
+
+ Restrictions:
+
+
+
+
MAC addresses may not be specified.
+
In DNAT rules, only IP addresses may be
+given -- DNS names are not permitted.
+
You may not specify both an IP address
+and an interface name in the DEST column.
+
+
+
+ Unlike in the SOURCE column, a range of IP addresses may be specified
+ in the DEST column as <first address>-<last address>.
+ When the ACTION is DNAT or DNAT-, connections will be assigned to
+the addresses in the range in a round-robin fashion (load-balancing).
+
+
PROTO
+ - Protocol. Must be a protocol name from /etc/protocols,
+ a number or "all". Specifies the protocol of the connection
+ request.
+
DEST
+ PORT(S) - Port or port range (<low port>:<high
+ port>) being connected to. May only be specified
+ if the protocol is tcp, udp or icmp. For icmp, this column's
+ contents are interpreted as an icmp type. If you don't want
+ to specify DEST PORT(S) but need to include information in
+ one of the columns to the right, enter "-" in this column.
+ You may give a list of ports and/or port ranges separated by commas.
+ Port numbers may be either integers or service names from /etc/services.
+
SOURCE
+ PORTS(S) - May be used to restrict the
+ rule to a particular client port or port range (a port
+range is specified as <low port number>:<high
+port number>). If you don't want to restrict client ports but
+ want to specify something in the next column, enter "-" in this
+column. If you wish to specify a list of port number or ranges,
+separate the list elements with commas (with no embedded
+white space). Port numbers may be either integers or service
+names from /etc/services.
+
ORIGINAL
+DEST - This column may only be non-empty if the
+ ACTION is DNAT or REDIRECT.
+
+ If DNAT or REDIRECT
+ is the ACTION and the ORIGINAL DEST column is left empty,
+ any connection request arriving at the firewall from
+ the SOURCE that matches the rule will be forwarded or
+redirected. This works fine for connection requests arriving
+ from the internet where the firewall has only a single
+ external IP address. When the firewall has multiple external
+IP addresses or when the SOURCE is other than the internet,
+ there will usually be a desire for the rule to only apply
+ to those connection requests directed to particular IP addresses
+(see Example 2 below for another usage). Those IP addresses are specified
+in the ORIGINAL DEST column as a comma-separated list.
+
+ The IP address(es)
+ may be optionally followed by ":" and a second
+IP address. This latter address, if present, is used as
+the source address for packets forwarded to the server (This
+ is called "Source NAT" or SNAT.
+
+ If this list begins with "!" then the rule will only apply if the
+ original destination address matches none of the addresses listed.
+
+ Note:
+ When using SNAT, it is a good idea to qualify the source with
+ an IP address or subnet. Otherwise, it is likely that SNAT will
+ occur on connections other than those described in the rule.
+ The reason for this is that SNAT occurs in the Netfilter
+POSTROUTING hook where it is not possible to restrict the scope
+ of a rule by incoming interface.
+
+ Example:
+ DNAT loc:192.168.1.0/24 loc:192.168.1.3
+ tcp www - 206.124.146.179:192.168.1.3
+
+ If SNAT
+ is not used (no ":" and second IP address), the
+ original source address is used. If you want any destination
+ address to match the rule but want to specify SNAT,
+ simply use a colon followed by the SNAT address.
+
+
+
+
Example 1. You wish to forward all
+ ssh connection requests from the internet to
+ local system 192.168.1.3.
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
+ PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
DNAT
+
net
+
loc:192.168.1.3
+
tcp
+
ssh
+
+
+
+
+
+
+
+
+
+
+
+
+
Example 2. You want to redirect all local www connection requests
+ EXCEPT
+ those to your own http server (206.124.146.177)
+ to a Squid transparent proxy
+ running on the firewall and listening on port 3128. Squid
+ will of course require access to remote web servers. This
+example shows yet another use for the ORIGINAL
+ DEST column; here, connection
+ requests that were NOT
+ (notice
+the "!") originally destined to 206.124.146.177
+are redirected to local port 3128.
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
+ PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
REDIRECT
+
loc
+
3128
+
tcp
+
www
+
-
+
+
!206.124.146.177
+
+
+
ACCEPT
+
fw
+
net
+
tcp
+
www
+
+
+
+
+
+
+
+
+
+
+
+
+
Example 3. You want to run a web server at 155.186.235.222 in
+your DMZ and have it accessible remotely and locally. the DMZ is managed
+ by Proxy ARP or by classical sub-netting.
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
+ PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
ACCEPT
+
net
+
dmz:155.186.235.222
+
tcp
+
www
+
-
+
+
+
+
+
ACCEPT
+
loc
+
dmz:155.186.235.222
+
tcp
+
www
+
+
+
+
+
+
+
+
+
+
+
+
+
Example 4. You want to run wu-ftpd on 192.168.2.2 in your masqueraded
+ DMZ. Your internet interface address is 155.186.235.151
+ and you want the FTP server to be accessible from
+ the internet in addition to the local 192.168.1.0/24
+and dmz 192.168.2.0/24 subnetworks. Note that since the
+ server is in the 192.168.2.0/24 subnetwork, we can assume
+ that access to the server from that subnet will not involve
+ the firewall (but see FAQ 2). Note that
+ unless you have more than one external
+ IP address, you can leave
+ the ORIGINAL DEST column blank
+in the first rule. You
+ cannot leave it blank in the
+ second rule though because
+ then all ftp connections originating in
+the local subnet 192.168.1.0/24 would be
+sent to 192.168.2.2 regardless of
+ the site that the user
+was trying to connect
+ to. That is clearly
+ not what you want
+ .
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
+ PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
DNAT
+
net
+
dmz:192.168.2.2
+
tcp
+
ftp
+
+
+
+
+
+
+
DNAT
+
loc:192.168.1.0/24
+
dmz:192.168.2.2
+
tcp
+
ftp
+
-
+
+
155.186.235.151
+
+
+
+
+
+
+
+
+
If you are running wu-ftpd, you should restrict the range of passive
+ in your /etc/ftpaccess file. I only need a few simultaneous FTP sessions
+ so I use port range 65500-65535. In /etc/ftpaccess,
+ this entry is appropriate:
+
+
+
+
passive ports 0.0.0.0/0 65500 65534
+
+
+
If you are running pure-ftpd, you would include "-p 65500:65534" on
+ the pure-ftpd runline.
+
+
The important point here is to ensure that the port range used for FTP
+ passive connections is unique and will not overlap
+ with any usage on the firewall system.
+
+
Example 5. You wish to allow unlimited
+ DMZ access to the host with MAC address
+ 02:00:08:E3:FA:55.
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
+ PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
ACCEPT
+
loc:~02-00-08-E3-FA-55
+
dmz
+
all
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ Example 6. You wish to allow access
+ to the SMTP server in your DMZ from all zones.
+
+
+
+
+
+
+
ACTION
+
+
SOURCE
+
+
DEST
+
+
PROTO
+
+
DEST
+ PORT(S)
+
+
SOURCE
+ PORT(S)
+
+
ORIGINAL
+ DEST
+
+
+
+
ACCEPT
+
+
all
+
+
dmz
+
+
tcp
+
+
25
+
+
+
+
+
+
+
+
+
+
+
+
+ Note: When 'all' is used as
+ a source or destination, intra-zone traffic is not affected.
+ In this example, if there were two DMZ interfaces then the
+ above rule would NOT enable SMTP traffic between hosts on these
+ interfaces.
+
+ Example 7. Your firewall's
+ external interface has several IP addresses but you only want to accept
+ SSH connections on address 206.124.146.176.
+
+
+
+
+
+
+
ACTION
+
+
SOURCE
+
+
DEST
+
+
PROTO
+
+
DEST
+ PORT(S)
+
+
SOURCE
+ PORT(S)
+
+
ORIGINAL
+ DEST
+
+
+
+
ACCEPT
+
+
net
+
+
fw:206.124.146.176
+
+
tcp
+
+
22
+
+
+
+
+
+
+
+
+
+
+
+
+ Example 8 (For advanced users running Shorewall version
+ 1.3.13 or later). From the internet, you with to forward
+ tcp port 25 directed to 192.0.2.178 and 192.0.2.179 to host
+ 192.0.2.177 in your DMZ. You also want to allow access from
+ the internet directly to tcp port 25 on 192.0.2.177.
+
+
+
+
+
+
+
ACTION
+
+
SOURCE
+
+
DEST
+
+
PROTO
+
+
DEST
+ PORT(S)
+
+
SOURCE
+ PORT(S)
+
+
ORIGINAL
+ DEST
+
+
+
+
DNAT-
+
+
net
+
+
dmz:192.0.2.177
+
+
tcp
+
+
25
+
+
0
+
+
192.0.2.178
+
+
+
+
DNAT-
+
+
net
+
+
dmz:192.0.2.177
+
+
tcp
+
+
25
+
+
0
+
+
192.0.2.179
+
+
+
+
ACCEPT
+
+
net
+
+
dmz:192.0.2.177
+
+
tcp
+
+
25
+
+
+
+
+
+
+
+
+
+
+
+
+ Using "DNAT-" rather than "DNAT"
+ avoids two extra copies of the third rule from being generated.
+
+ Example 9 (Shorewall version 1.4.6 or later). You have 9 http
+ servers behind a Shorewall firewall and you want connection requests to
+ be distributed among your servers. The servers are 192.168.1.101-192.168.1.109.
+
+
+
Shorewall allows definition of rules that apply between
+ all zones. By default, these rules
+ are defined in the file
+ /etc/shorewall/common.def
+ but may be modified to
+ suit individual
+ requirements. Rather than modify /etc/shorewall/common.def,
+ you should copy that
+ file to
+ /etc/shorewall/common
+ and modify that file.
+
+
The /etc/shorewall/common
+ file is expected to contain
+ iptables commands; rather than
+ running iptables
+ directly, you should run
+ it indirectly using the
+ Shorewall function
+ 'run_iptables'. That way, if iptables
+ encounters an error, the
+ firewall will be safely
+ stopped.
+
+
/etc/shorewall/masq
+
+
The /etc/shorewall/masq file is used to define classical IP Masquerading
+ and Source Network Address Translation (SNAT).
+ There is one entry in the file for each subnet that
+ you want to masquerade. In order to make use of this
+feature, you must have NAT enabled
+ .
+
+
Columns are:
+
+
+
INTERFACE
+ - The interface that will masquerade the subnet; this
+ is normally your internet interface. This interface
+ name can be optionally qualified by adding ":" and a subnet or
+ host IP. When this qualification is added, only packets addressed
+ to that host or subnet will be masqueraded. Beginning with
+Shorewall version 1.3.14, if you have set ADD_SNAT_ALIASES=Yes in
+ /etc/shorewall/shorewall.conf, you can cause
+Shorewall to create an alias label of the form interfacename:digit
+ (e.g., eth0:0) by placing that label in this column.
+See example 5 below. Alias labels created in this way allow the
+alias to be visible to the ipconfig utility. THAT IS THE ONLY
+THING THAT THIS LABEL IS GOOD FOR AND IT MAY NOT APPEAR ANYWHERE ELSE
+IN YOUR SHOREWALL CONFIGURATION.
+
SUBNET
+ - The subnet that you want to have masqueraded through
+ the INTERFACE. This may be expressed as a single IP address,
+ a subnet or an interface name. In the latter instance,
+ the interface must be configured and started before Shorewall
+ is started as Shorewall will determine the subnet based
+ on information obtained from the 'ip' utility. When using Shorewall 1.3.13 or earlier, when an interface
+ name is specified, Shorewall will only masquerade traffic from
+ the first subnetwork on the named interface; if the interface interfaces
+ to more that one subnetwork, you will need to add additional entries
+ to this file for each of those other subnetworks. Beginning with
+Shorewall 1.3.14, shorewall will masquerade/SNAT traffic from any
+host that is routed through the named interface.
+
+ The subnet may
+be optionally followed by "!' and a comma-separated
+ list of addresses and/or subnets that are to be
+excluded from masquerading.
+
ADDRESS
+ - The source address to be used for outgoing packets.
+ This column is optional and if left blank, the current
+ primary IP address of the interface in the first column
+ is used. If you have a static IP on that interface, listing it
+here makes processing of output packets a little less expensive
+ for the firewall. If you specify an address in this column, it
+must be an IP address configured on the INTERFACE or you must have
+ADD_SNAT_ALIASES enabled in /etc/shorewall/shorewall.conf.
+
+
+
+
Example 1: You have eth0 connected to a cable modem and eth1
+ connected to your local subnetwork 192.168.9.0/24.
+ Your /etc/shorewall/masq file would look like:
+
+
+
+
+
+
+
+
+ INTERFACE
+
+ SUBNET
+
ADDRESS
+
+
+
eth0
+
192.168.9.0/24
+
+
+
+
+
+
+
+
+
+
+
Example 2: You have a number of IPSEC tunnels through ipsec0
+ and you want to masquerade traffic from your
+ 192.168.9.0/24 subnet to the remote subnet 10.1.0.0/16
+ only.
+
+
+
+
+
+
+
+ INTERFACE
+
+ SUBNET
+
ADDRESS
+
+
+
ipsec0:10.1.0.0/16
+
192.168.9.0/24
+
+
+
+
+
+
+
+
+
+
+
Example 3: You have a DSL line connected on eth0 and a local
+ network (192.168.10.0/24)
+ connected to eth1. You want
+ all local->net connections
+ to use source address
+ 206.124.146.176.
+
+
+
+
+
+
+
+ INTERFACE
+
+ SUBNET
+
ADDRESS
+
+
+
eth0
+
192.168.10.0/24
+
206.124.146.176
+
+
+
+
+
+
+
+
+
Example 4: Same as example 3 except that
+ you wish to exclude
+ 192.168.10.44 and 192.168.10.45 from
+ the SNAT rule.
+
+
+
+
+
+
+
+ INTERFACE
+
+ SUBNET
+
ADDRESS
+
+
+
eth0
+
192.168.10.0/24!192.168.10.44,192.168.10.45
+
206.124.146.176
+
+
+
+
+
+
+
+ Example 5 (Shorewall version >= 1.3.14):
+ You have a second IP address (206.124.146.177) assigned
+ to you and wish to use it for SNAT of the subnet 192.168.12.0/24.
+ You want to give that address the name eth0:0. You must have ADD_SNAT_ALIASES=Yes
+ in /etc/shorewall/shorewall.conf.
+
+
+
+
+
+
+
+ INTERFACE
+
+ SUBNET
+
ADDRESS
+
+
+
eth0:0
+
192.168.12.0/24
+
206.124.146.177
+
+
+
+
+
+
+
+
+
+ /etc/shorewall/proxyarp
+
+
If you want to use proxy ARP on an entire sub-network,
+ I suggest that you
+ look at
+ http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/.
+ If you decide to use the
+ technique described in that
+ HOWTO, you can set
+ the proxy_arp flag
+ for an interface
+ (/proc/sys/net/ipv4/conf/<interface>/proxy_arp)
+ by including the proxyarp
+ option in the interface's
+ record in
+
+ /etc/shorewall/interfaces.
+ When using Proxy
+ ARP sub-netting, you do NOT include
+ any entries in
+ /etc/shorewall/proxyarp.
+
+
The /etc/shorewall/proxyarp file is used to define Proxy ARP. The file is
+ typically used for enabling
+Proxy ARP on a small set
+of systems since
+you need one
+entry in this file for each
+ system using proxy ARP. Columns
+ are:
+
+
+
ADDRESS
+ - address of the system.
+
INTERFACE
+ - the interface that connects to the system. If the
+ interface is obvious from the subnetting, you may
+enter "-" in this column.
+
EXTERNAL
+ - the external interface that you want to honor
+ARP requests for the ADDRESS specified in the first
+ column.
+
HAVEROUTE
+ - If you already
+ have a route
+ through
+ INTERFACE to
+ ADDRESS, this column should contain
+ "Yes" or "yes". If you want
+ Shorewall to add the route, the
+ column should
+ contain
+ "No" or
+ "no".
+
+
+
+
Note: After you have made a change to the /etc/shorewall/proxyarp
+ file, you may need to flush the ARP cache of all
+ routers on the LAN segment connected to the interface
+ specified in the EXTERNAL column of the change/added entry(s).
+ If you are having problems communicating between an individual
+ host (A) on that segment and a system whose entry has
+changed, you may need to flush the ARP cache on host A as well.
+
+
ISPs typically have ARP configured with long
+TTL (hours!) so if your ISPs router has a stale cache entry (as seen using
+"tcpdump -nei <external interface> host <IP addr>"), it may
+take a long while to time out. I personally have had to contact my ISP
+and ask them to delete a stale entry in order to restore a system to working
+order after changing my proxy ARP settings.
+
+
Example: You have public IP addresses 155.182.235.0/28. You
+ configure your firewall as follows:
+
+
+
eth0 - 155.186.235.1
+ (internet connection)
+
eth1 - 192.168.9.0/24
+ (masqueraded local systems)
+
eth2 - 192.168.10.1
+ (interface to your DMZ)
+
+
+
+
In your DMZ, you want to install a Web/FTP server with public address
+ 155.186.235.4. On the Web server, you subnet
+just like the firewall's eth0 and you configure
+155.186.235.1 as the default gateway. In your /etc/shorewall/proxyarp
+ file, you will have:
+
+
+
+
+
+
+
+ ADDRESS
+
+ INTERFACE
+
+ EXTERNAL
+
HAVEROUTE
+
+
+
155.186.235.4
+
eth2
+
eth0
+
No
+
+
+
+
+
+
+
+
+
Note: You may want to configure the servers in your DMZ with a subnet
+ that is smaller than the subnet of your internet
+ interface. See the Proxy ARP Subnet Mini HOWTO (http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/)
+ for details. In this case you will want to place
+ "Yes" in the HAVEROUTE column.
+
+
Warning: Do not use Proxy ARP and
+FreeS/Wan on the same system unless you are prepared to suffer the consequences.
+ If you start or restart Shorewall with an IPSEC tunnel active,
+ the proxied IP addresses are mistakenly assigned
+to the IPSEC tunnel device (ipsecX) rather than to
+the interface that you specify in the INTERFACE column of
+ /etc/shorewall/proxyarp. I haven't had the time to debug this
+ problem so I can't say if it is a bug in the Kernel or in FreeS/Wan.
+
+
+
You might be able to work around this problem using the following
+ (I haven't tried it):
+
+
In /etc/shorewall/init, include:
+
+
qt service ipsec stop
+
+
In /etc/shorewall/start, include:
+
+
qt service ipsec start
+
+
+ /etc/shorewall/nat
+
+
The /etc/shorewall/nat file is used to define static NAT. There is one
+ entry in the file for each static NAT relationship
+ that you wish to define. In order to make use of
+ this feature, you must have NAT enabled
+ .
+
+
IMPORTANT: If all you want to do
+ is forward ports
+ to servers behind your firewall,
+ you do NOT want to use
+ static NAT. Port
+ forwarding
+ can be
+accomplished with simple entries
+in the
+ rules file. Also, in
+most cases
+ Proxy ARP
+ provides a
+ superior solution
+ to static NAT
+ because the
+ internal systems
+ are accessed using the same IP
+ address internally and externally.
+
+
Columns in an entry are:
+
+
+
EXTERNAL
+ - External IP address - This should NOT be
+ the primary IP address of the interface named in the next
+ column.
+
INTERFACE
+ - Interface that you want the EXTERNAL IP address
+to appear on. Beginning with Shorewall version 1.3.14, if
+you have set ADD_IP_ALIASES=Yes in /etc/shorewall/shorewall.conf,
+ you can specify an alias label of the form interfacename:digit
+ (e.g., eth0:0) and Shorewall will create the alias with
+ that label. Alias labels created in this way allow the alias
+to be visible to the ipconfig utility. THAT IS THE ONLY THING
+ THAT THIS LABEL IS GOOD FOR AND IT MAY NOT APPEAR ANYWHERE ELSE IN
+YOUR SHOREWALL CONFIGURATION.
+
INTERNAL
+ - Internal IP address.
+
ALL
+ INTERFACES
+ - If Yes
+ or yes (or
+ left
+ empty),
+ NAT will
+ be effective from all
+ hosts. If
+ No or no
+ then NAT will
+be effective
+ only
+ through
+ the interface named in
+ the INTERFACE
+ column.
+
LOCAL
+ - If Yes or yes and the ALL INTERFACES column contains
+ Yes or yes, NAT will be effective from the firewall system.
+ Note: For this to work, you must be running
+ kernel 2.4.19 or later and iptables 1.2.6a or later and
+you must have enabled CONFIG_IP_NF_NAT_LOCAL
+ in your kernel.
The /etc/shorewall/tunnels file allows you to define IPSec, GRE, IPIP,
+ OpenVPN, PPTP
+ and 6to4.tunnels with end-points on your firewall. To use ipsec,
+ you must install version 1.9, 1.91 or the current FreeS/WAN development
+snapshot.
+
+
Note: For kernels 2.4.4 and above, you will need to use version 1.91
+ or a development snapshot as patching with
+version 1.9 results in kernel compilation errors.
This file is used to set the following firewall parameters:
+
+
+
SHOREWALL_SHELL
+ - Added at version 1.4.6
+ This parameter is used to specify the shell program to be used to interpret
+ the firewall script (/usr/share/shorewall/firewall). If not specified or
+ specified as a null value, /bin/sh is assumed.
+
+
LOGFORMAT - Added at version 1.4.4.
+ The value of this variable generate the --log-prefix setting
+for Shorewall logging rules. It contains a 'printf' formatting template
+which accepts three arguments (the chain name, logging rule number (optional)
+ and the disposition). To use LOGFORMAT with fireparse (http://www.fireparse.com), set it as:
+
+ LOGFORMAT="fp=%s:%d a=%s "
+
+ If the LOGFORMAT value contains the substring '%d' then the
+logging rule number is calculated and formatted in that position; if
+that substring is not included then the rule number is not included.
+If not supplied or supplied as empty (LOGFORMAT="") then "Shorewall:%s:%s:"
+ is assumed.
+
+ CAUTION: /sbin/shorewall uses the leading part
+of the LOGFORMAT string (up to but not including the first '%') to
+find log messages in the 'show log', 'status' and 'hits' commands. This
+part should not be omitted (the LOGFORMAT should not begin with "%")
+and the leading part should be sufficiently unique for /sbin/shorewall
+to identify Shorewall messages.
+
+
CLEAR_TC - Added at version 1.3.13
+ If this option is set to 'No' then Shorewall
+ won't clear the current traffic control rules during [re]start.
+ This setting is intended for use by people that prefer to configure
+ traffic shaping when the network interfaces come up rather
+than when the firewall is started. If that is what you want to do,
+set TC_ENABLED=Yes and CLEAR_TC=No and do not supply an /etc/shorewall/tcstart
+ file. That way, your traffic shaping rules can still use the 'fwmark'
+ classifier based on packet marking defined in /etc/shorewall/tcrules.
+ If not specified, CLEAR_TC=Yes is assumed.
+
+
MARK_IN_FORWARD_CHAIN - Added
+ at version 1.3.12
+ If your kernel has a FORWARD chain
+ in the mangle table, you may set MARK_IN_FORWARD_CHAIN=Yes
+ to cause the marking specified in the tcrules file to occur in that
+ chain rather than in the PREROUTING chain. This permits you
+ to mark inbound traffic based on its destination address when
+SNAT or Masquerading are in use. To determine if your kernel has
+ a FORWARD chain in the mangle table, use the "/sbin/shorewall
+ show mangle" command; if a FORWARD chain is displayed then your
+kernel will support this option. If this option is not specified
+or if it is given the empty value (e.g., MARK_IN_FORWARD_CHAIN="") then
+ MARK_IN_FORWARD_CHAIN=No is assumed.
+
+
RFC1918_LOG_LEVEL - Added
+ at version 1.3.12
+ This parameter determines the
+level at which packets logged under the 'norfc1918' mechanism
+ are logged. The value must be a valid syslog level and if no level is given,
+ then info is assumed. Prior to Shorewall version 1.3.12,
+ these packets are always logged at the info level.
+
TCP_FLAGS_DISPOSITION
+- Added in Version 1.3.11
+ Determines the disposition of
+TCP packets that fail the checks enabled by the tcpflags interface option and must
+ have a value of ACCEPT (accept the packet), REJECT (send an RST
+ response) or DROP (ignore the packet). If not set or if set
+ to the empty value (e.g., TCP_FLAGS_DISPOSITION="") then TCP_FLAGS_DISPOSITION=DROP
+ is assumed.
+
TCP_FLAGS_LOG_LEVEL
+ - Added in Version 1.3.11
+ Determines the syslog level for logging packets
+ that fail the checks enabled by the tcpflags interface option.The value must
+ be a valid syslogd log level. If you don't want to log these
+ packets, set to the empty value (e.g., TCP_FLAGS_LOG_LEVEL="").
+
+
MACLIST_DISPOSITION
+ - Added in Version 1.3.10
+ Determines the disposition
+ of connections requests that fail MAC Verification and must have
+the value ACCEPT (accept the connection request anyway), REJECT
+(reject the connection request) or DROP (ignore the connection request).
+ If not set or if set to the empty value (e.g., MACLIST_DISPOSITION="")
+ then MACLIST_DISPOSITION=REJECT is assumed.
+
MACLIST_LOG_LEVEL
+ - Added in Version 1.3.10
+ Determines the syslog level for logging connection
+ requests that fail MAC Verification.
+ The value must be a valid syslogd log level. If you
+ don't want to log these connection requests, set to the
+ empty value (e.g., MACLIST_LOG_LEVEL="").
+
+
NEWNOTSYN -
+ Added in Version 1.3.8
+ When set to "Yes" or
+"yes", Shorewall will filter TCP packets that are not
+ part of an established connention and that are not SYN
+packets (SYN flag on - ACK flag off). If set to "No", Shorewall
+ will silently drop such packets. If not set or set to the empty
+value (e.g., "NEWNOTSYN="), NEWNOTSYN=No is assumed.
+
+ If you have a HA setup
+ with failover to another firewall, you should have
+ NEWNOTSYN=Yes on both firewalls. You should also select NEWNOTSYN=Yes
+ if you have asymmetric routing.
+
+
LOGNEWNOTSYN
+ - Added in Version 1.3.6
+ Beginning with
+version 1.3.6, Shorewall drops non-SYN TCP packets
+ that are not part of an existing connection. If you
+ would like to log these packets, set LOGNEWNOTSYN to
+ the syslog level at which
+ you want the packets logged. Example: LOGNEWNOTSYN=ULOG|
+
+ Note: Packets
+ logged under this option are usually the result
+of broken remote IP stacks rather than the result of any
+sort of attempt to breach your firewall.
+
+
DETECT_DNAT_ADDRS - Added in Version 1.3.4
+ If set to "Yes" or "yes", Shorewall will detect
+ the first IP address of the interface to the source zone and
+will include this address in DNAT rules as the original destination
+ IP address. If set to "No" or "no", Shorewall will not detect
+ this address and any destination IP address will match the
+ DNAT rule. If not specified or empty, "DETECT_DNAT_ADDRS=Yes"
+ is assumed.
+
+
MULTIPORT
+ - (Removed in version 1.4.6 -- the value of this parameter is now automatically
+ detected by Shorewall)
+ If set to "Yes"
+or "yes", Shorewall will use the Netfilter multiport
+ facility. In order to use this facility, your kernel
+ must have multiport support (CONFIG_IP_NF_MATCH_MULTIPORT).
+ When this support is used, Shorewall will generate
+a single rule from each record in the /etc/shorewall/rules
+ file that meets these criteria:
+
+
+
+
No port range(s)
+ specified
+
Specifies
+15 or fewer ports
+
+
+
+
+
+
Rules not meeting those criteria will continue to generate an individual
+ rule for each listed port or port range.
+
+
+
NAT_BEFORE_RULES
+ If set to "No"
+or "no", port forwarding rules can override the contents
+ of the /etc/shorewall/nat file.
+ If set to "Yes" or "yes", port forwarding rules cannot override
+ static NAT. If not set or set to an empty value, "Yes"
+is assumed.
+
FW
+ This
+ parameter
+ specifies the
+ name of the
+ firewall zone.
+ If not set or
+ if set to an empty string,
+ the value "fw"
+ is assumed.
+
SUBSYSLOCK
+ This parameter
+ should be set to the name of a file that the firewall
+ should create if it starts successfully and remove
+ when it stops. Creating and removing this file allows Shorewall
+ to work with your distribution's initscripts. For RedHat,
+ this should be set to /var/lock/subsys/shorewall. For
+ Debian, the value is /var/state/shorewall and in LEAF it is /var/run/shorwall.
+ Example: SUBSYSLOCK=/var/lock/subsys/shorewall.
+
STATEDIR
+ This parameter
+ specifies the name of a directory where Shorewall
+ stores state information. If the directory doesn't
+ exist when Shorewall starts, it will create the directory.
+ Example: STATEDIR=/tmp/shorewall.
+
+ NOTE: If
+you change the STATEDIR variable while the firewall
+ is running, create the new directory if necessary then
+copy the contents of the old directory to the new directory.
+
+
MODULESDIR
+ This parameter
+ specifies the directory where your kernel netfilter
+ modules may be found. If you leave the variable empty,
+ Shorewall will supply the value "/lib/modules/`uname -r`/kernel/net/ipv4/netfilter.
+
LOGRATE
+ and LOGBURST
+ These parameters
+ set the match rate and initial burst size for logged
+ packets. Please see the iptables man page for a description
+ of the behavior of these parameters (the iptables
+ option --limit is set by LOGRATE and --limit-burst is set
+by LOGBURST). If both parameters are set empty, no
+rate-limiting will occur.
+
+ Example:
+ LOGRATE=10/minute
+ LOGBURST=5
+
+
LOGFILE
+ This parameter
+ tells the
+ /sbin/shorewall
+ program where
+ to look for
+ Shorewall
+ messages when processing the "show
+ log", "monitor", "status"
+ and "hits"
+ commands. If
+ not assigned
+ or if assigned
+ an empty
+ value,
+ /var/log/messages
+ is assumed.
+
NAT_ENABLED
+ (Removed in Shorewall 1.4.6 -- the value of this parameter is now automatically
+ detected by Shorewall)
+ This parameter
+ determines whether Shorewall supports NAT operations.
+ NAT operations include:
+
+ Static
+ NAT
+ Port
+Forwarding
+ Port
+Redirection
+ Masquerading
+
+ If the parameter
+ has no value or has a value of "Yes" or "yes"
+ then NAT is enabled. If the parameter has a value of
+"no" or "No" then NAT is disabled.
+
+
MANGLE_ENABLED
+ (Removed in Shorewall 1.4.6 -- the value of this parameter is now automatically
+ detected by Shorewall)
+ This parameter
+ determines if packet mangling is enabled. If the
+parameter has no value or has a value of "Yes" or "yes"
+ than packet mangling is enabled. If the parameter
+has a value of "no" or "No" then packet mangling is disabled.
+ If packet mangling is disabled, the /etc/shorewall/tos
+ file is ignored.
+
+
IP_FORWARDING
+ This parameter
+ determines whether Shorewall enables or disables
+ IPV4 Packet Forwarding (/proc/sys/net/ipv4/ip_forward).
+ Possible values are:
+
+ On or
+on - packet forwarding will be enabled.
+ Off or
+ off - packet forwarding will be disabled.
+ Keep
+or keep - Shorewall will neither enable nor disable
+ packet forwarding.
+
+ If this variable
+ is not set or is given an empty value (IP_FORWARD="")
+ then IP_FORWARD=On is assumed.
+
+
ADD_IP_ALIASES
+ This parameter
+ determines whether Shorewall automatically adds the
+ external address(es)
+ in /etc/shorewall/nat . If the variable
+ is set to "Yes" or "yes" then Shorewall automatically adds
+ these aliases. If it is set to "No" or "no", you must add
+ these aliases yourself using your distribution's network configuration
+ tools. RESTRICTION: Shorewall versions before
+1.4.6 can only add addresses to the first subnetwork configured on
+an interface.
+
+ If this variable
+ is not set or is given an empty value (ADD_IP_ALIASES="")
+ then ADD_IP_ALIASES=Yes is assumed.
+
ADD_SNAT_ALIASES
+ This parameter
+determines whether Shorewall automatically adds the
+ SNAT ADDRESS in /etc/shorewall/masq.
+ If the variable is set to "Yes" or "yes" then Shorewall
+ automatically adds these addresses. If it is set to
+ "No" or "no", you must add these addresses yourself using
+your distribution's network configuration tools. RESTRICTION:
+ Shorewall versions before 1.4.6 can only add addresses to
+the first subnetwork configured on an interface.
+
+ If this variable
+ is not set or is given an empty value (ADD_SNAT_ALIASES="")
+ then ADD_SNAT_ALIASES=No is assumed.
+
+
LOGUNCLEAN
+ This parameter
+ determines the
+ logging level
+ of mangled/invalid
+ packets
+ controlled by
+ the 'dropunclean and logunclean'
+ interface
+ options. If
+ LOGUNCLEAN is empty
+(LOGUNCLEAN=) then packets selected
+ by 'dropclean' are
+ dropped
+ silently ('logunclean'
+ packets are
+ logged
+ under the 'info' log level). Otherwise,
+ these packets are logged at
+ the specified
+ level (Example:
+ LOGUNCLEAN=debug).
+
BLACKLIST_DISPOSITION
+ This parameter
+ determines the
+ disposition of
+ packets from
+ blacklisted
+ hosts. It may have the value DROP
+ if the packets are to
+ be dropped or
+ REJECT if the
+ packets are to
+ be replied
+ with an ICMP
+ port
+ unreachable
+ reply or a TCP RST (tcp
+ only). If you do not assign
+ a value or if you assign an
+ empty value
+ then DROP is
+ assumed.
+
BLACKLIST_LOGLEVEL
+ This paremter
+ determines if
+ packets from
+ blacklisted
+ hosts are
+logged and it
+ determines the syslog level that they
+are to be logged
+ at. Its value is
+a syslog level
+ (Example:
+ BLACKLIST_LOGLEVEL=debug). If you do not
+ assign a value or if you
+ assign an empty value
+ then packets
+from blacklisted
+ hosts are not
+ logged.
+
CLAMPMSS
+ This parameter
+ enables the
+ TCP Clamp MSS
+ to PMTU feature
+of Netfilter and
+ is usually
+ required when
+ your
+internet connection is through
+ PPPoE or PPTP. If
+ set to
+ "Yes" or
+ "yes",
+ the feature is
+ enabled. If
+ left blank or
+ set to
+ "No"
+ or
+ "no",
+ the feature is
+ not enabled. Note: This
+ option requires CONFIG_IP_NF_TARGET_TCPMSS
+ in your kernel.
+
ROUTE_FILTER
+ If this parameter
+ is given the value "Yes" or "yes" then route filtering
+ (anti-spoofing) is enabled on all network interfaces.
+ The default value is "no".
+
+
+
+
/etc/shorewall/modules Configuration
+
+
The file /etc/shorewall/modules contains commands for loading the kernel
+ modules required by Shorewall-defined firewall
+ rules. Shorewall will source this file during start/restart
+ provided that it exists and that the directory specified
+ by the MODULESDIR parameter exists (see /etc/shorewall/shorewall.conf
+ above).
+
+
The file that is released with Shorewall calls the Shorewall function
+ "loadmodule" for the set of modules that I load.
+
+
The loadmodule function is called as follows:
+
+
+
+
loadmodule <modulename> [
+ <module parameters> ]
+
+
+
where
+
+
+
+
<modulename>
+
+
+
+
+
is the name of the modules without the trailing ".o" (example ip_conntrack).
+
+
+
+
<module parameters>
+
+
+
+
+
Optional parameters to the insmod utility.
+
+
+
+
The function determines if the module named by <modulename>
+ is already loaded and if not then the
+function determines if the ".o" file corresponding
+to the module exists in the moduledirectory;
+ if so, then the following command is executed:
If the file doesn't exist, the function determines of the ".o.gz" file
+ corresponding to the module exists in the moduledirectory. If it
+ does, the function assumes that the running configuration supports compressed
+ modules and execute the following command:
The /etc/shorewall/tos file allows you to set the Type of Service field
+ in packet headers based on packet source,
+packet destination, protocol, source port and
+destination port. In order for this file to be processed
+ by Shorewall, you must have mangle
+support enabled .
+
+
Entries in the file have the following columns:
-
INTERFACE
- - The firewall interface through which the
- host(s) comminicate with the firewall.
-
HOST(S)
- - (Optional) - A comma-separated list of IP/Subnet
- addresses. If not supplied or supplied as "-" then 0.0.0.0/0
- is assumed.
-
+
SOURCE
+ -- The source zone. May be qualified by following
+ the zone name with a colon (":") and either an IP
+address, an IP subnet, a MAC address in Shorewall Format or the
+ name of an interface. This column may also contain
+ the name of
+ the firewall
+ zone to indicate packets
+originating on the firewall itself or "all" to indicate any
+ source.
+
DEST
+ -- The destination zone. May be qualified by following
+ the zone name with a colon (":") and either an IP
+ address or an IP subnet. Because packets are marked prior
+to routing, you may not specify the name of an interface.
+ This column may also contain "all" to indicate any destination.
+
PROTOCOL
+ -- The name of a protocol in /etc/protocols or the
+ protocol's number.
+
SOURCE
+ PORT(S) -- The source port or a port range. For
+ all ports, place a hyphen ("-") in this column.
+
DEST
+PORT(S) -- The destination port or a port range.
+ To indicate all ports, place a hyphen ("-") in this
+ column.
+
TOS
+ -- The type of service. Must be one of the following:
+
-
Example: When your firewall is stopped, you want firewall accessibility
- from local hosts 192.168.1.0/24 and from your DMZ.
- Your DMZ interfaces through eth1 and your local hosts
- through eth2.
The /etc/shorewall/tos file that is included with Shorewall contains
+ the following entries.
+
+
+
+
+
+
+
SOURCE
+
DEST
+
PROTOCOL
+
SOURCE
+ PORT(S)
+
DEST
+ PORT(S)
+
TOS
+
+
+
all
+
all
+
tcp
+
-
+
ssh
+
16
+
+
+
all
+
all
+
tcp
+
ssh
+
-
+
16
+
+
+
all
+
all
+
tcp
+
-
+
ftp
+
16
+
+
+
all
+
all
+
tcp
+
ftp
+
-
+
16
+
+
+
all
+
all
+
tcp
+
-
+
ftp-data
+
8
+
+
+
all
+
all
+
tcp
+
ftp-data
+
-
+
8
+
+
+
+
+
+
+
+
+
WARNING: Users have reported that odd routing problems result from
+ adding the ESP and AH protocols to the /etc/shorewall/tos
+ file.
+
+
/etc/shorewall/blacklist
+
+
Each line in
+ /etc/shorewall/blacklist
+ contains
+ an IP
+ address, a MAC address in Shorewall Format
+ or
+ subnet
+ address. Example:
+
+
130.252.100.69 206.124.146.0/24
+
+
Packets from
+ hosts
+ listed
+ in the
+ blacklist file
+ will be
+ disposed of
+ according
+ to
+ the value assigned
+ to
+ the BLACKLIST_DISPOSITION
+ and BLACKLIST_LOGLEVEL variables in
+ /etc/shorewall/shorewall.conf.
+ Only
+ packets arriving
+ on interfaces
+ that
+ have the
+ 'blacklist'
+ option in
+ /etc/shorewall/interfaces
+ are
+ checked against the
+ blacklist. The black list is designed to prevent listed
+ hosts/subnets from accessing services on your
+ network.
+
+
+
Beginning with Shorewall 1.3.8, the blacklist file has three columns:
+
+
+
+
ADDRESS/SUBNET
+ - As described above.
+
PROTOCOL
+ - Optional. If specified, only packets specifying
+ this protocol will be blocked.
+
PORTS - Optional;
+ may only be given if PROTOCOL is tcp, udp or icmp.
+Expressed as a comma-separated list of port numbers or service
+ names (from /etc/services). If present, only packets destined
+ for the specified protocol and one of the listed ports are blocked.
+ When the PROTOCOL is icmp, the PORTS column contains a comma-separated
+ list of ICMP type numbers or names (see "iptables -h icmp").
+
IMPORTANT: The Shorewall blacklist file is NOT
+ designed to police your users' web browsing --
+to do that, I suggest that you install and configure
+Squid (http://www.squid-cache.org).
+
SUBNET
+ - The subnet using VLSM notation (e.g., 192.168.0.0/16).
+
TARGET
+ - What to do with packets to/from the
+SUBNET:
+
+
+
RETURN
+ - Process the packet normally thru the rules and
+policies.
+
DROP
+ - Silently drop the packet.
+
logdrop
+ - Log then drop the packet -- see the RFC1918_LOG_LEVEL
+ parameter above.
+
+
+
+
+
+
+
+
/etc/shorewall/routestopped (Added in Version
+ 1.3.4)
+
+
This file defines the hosts that are accessible from the firewall when
+ the firewall is stopped. Columns in the file
+are:
+
+
+
INTERFACE
+ - The firewall interface through which the
+ host(s) comminicate with the firewall.
+
HOST(S)
+ - (Optional) - A comma-separated list of IP/Subnet
+ addresses. If not supplied or supplied as "-" then 0.0.0.0/0
+ is assumed.
+
+
+
+
Example: When your firewall is stopped, you want firewall accessibility
+ from local hosts 192.168.1.0/24 and from your
+DMZ. Your DMZ interfaces through eth1 and your local
+hosts through eth2.
-
-Explicit Congestion Notification (ECN) is described in RFC 3168 and is a
-proposed internet standard. Unfortunately, not all sites support ECN and
-when a TCP connection offering ECN is sent to sites that don't support it,
-the result is often that the connection request is ignored.
-
-To allow ECN to be used, Shorewall allows you to enable ECN on your Linux
-systems then disable it in your firewall when the destination matches a list
+
+ Explicit Congestion Notification (ECN) is described in RFC 3168 and is a
+proposed internet standard. Unfortunately, not all sites support ECN and when
+a TCP connection offering ECN is sent to sites that don't support it, the
+result is often that the connection request is ignored.
+
+ To allow ECN to be used, Shorewall allows you to enable ECN on your Linux
+systems then disable it in your firewall when the destination matches a list
that you create (the /etc/shorewall/ecn file).
-
-You enable ECN by
-
-
-
echo 1 > /proc/sys/net/ipv4/tcp_ecn
-
-You must arrange for that command to be executed at system boot. Most distributions
-have a method for doing that -- on RedHat, you make an entry in /etc/sysctl.conf.
-
-
-
net.ipv4.tcp_ecn = 1
-
-Entries in /etc/shorewall/ecn have two columns as follows:
-
-INTERFACE - The name of an interface on your system
-
-HOST(S) - An address (host or subnet)
-of a system or group of systems accessed through the interface in the
-first column. You may include a comma-separated list of such addresses in
-this column.
-
-Example: Your external interface is eth0 and you want to disable ECN for
-tcp connections to 192.0.2.0/24:
-
-In /etc/shorewall/ecn:
-
-
-
-
-
-
INTERFACE
-
-
HOST(S)
-
-
-
-
eth0
-
-
192.0.2.0/24
-
-
-
-
-
-
-Last updated 3/28/2003 - Tom Eastep
+
+ You enable ECN by
+
+
+
echo 1 > /proc/sys/net/ipv4/tcp_ecn
+
+ You must arrange for that command to be executed at system boot. Most distributions
+have a method for doing that -- on RedHat, you make an entry in /etc/sysctl.conf.
+
+
+
+
net.ipv4.tcp_ecn = 1
+
+ Entries in /etc/shorewall/ecn have two columns as follows:
+
+ INTERFACE - The name of an interface on your system
+
+ HOST(S) - An address (host or subnet)
+of a system or group of systems accessed through the interface in the
+first column. You may include a comma-separated list of such addresses in
+this column.
+
+ Example: Your external interface is eth0 and you want to disable ECN for
+tcp connections to 192.0.2.0/24:
+
+ In /etc/shorewall/ecn:
+
+
+
1. I want to forward UDP port 7777 to
+ my my personal PC with IP address 192.168.1.5.
+ I've looked everywhere and can't find how to
+do it.
+
Answer: The first example in the rules file documentation shows how to
- do port forwarding under Shorewall. The format
- of a port-forwarding rule to a local system is as follows:
-
-
+ href="Documentation.htm#Rules">rules file documentation shows how to
+ do port forwarding under Shorewall. The format
+ of a port-forwarding rule to a local system is as
+ follows:
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE
- PORT
-
ORIG.
- DEST.
-
-
-
DNAT
-
net
-
loc:<local
- IP address>[:<local port>]
-
<protocol>
-
<port
- #>
-
-
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE
+ PORT
+
ORIG.
+ DEST.
+
+
+
DNAT
+
net
+
loc:<local
+ IP address>[:<local port>]
+
<protocol>
+
<port
+ #>
+
+
+
+
+
+
+
+
+
+
-
-
-
So to forward UDP port 7777 to internal system 192.168.1.5,
- the rule is:
-
-
+
+
+
So to forward UDP port 7777 to internal system 192.168.1.5,
+ the rule is:
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE
- PORT
-
ORIG.
- DEST.
-
-
-
DNAT
-
net
-
loc:192.168.1.5
-
udp
-
7777
-
-
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE
+ PORT
+
ORIG.
+ DEST.
+
+
+
DNAT
+
net
+
loc:192.168.1.5
+
udp
+
7777
+
+
+
+
+
+
+
+
+
+
-
-
-
If
- you want to forward requests directed to a particular
-address ( <external IP> ) on your firewall to
-an internal system:
-
-
+
+
+
If
+ you want to forward requests directed to a particular
+ address ( <external IP> ) on your firewall
+ to an internal system:
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE
- PORT
-
ORIG.
- DEST.
-
-
-
DNAT
-
net
-
loc:<local
- IP address>[:<local port>]
-
<protocol>
-
<port
- #>
-
-
-
<external
- IP>
-
-
-
-
-
- Finally, if you need to forward a range of ports,
- in the PORT column specify the range as low-port:high-port.
-
-
1a. Ok -- I followed those instructions
- but it doesn't work
-
-
Answer: That is usually the result of one of three
- things:
-
-
-
You
-are trying to test from inside your firewall (no, that
- won't work -- see FAQ #2).
-
You
-have a more basic problem with your local system such
- as an incorrect default gateway configured (it should
- be set to the IP address of your firewall's internal
-interface).
-
Your ISP is blocking that particular port inbound.
-
-
-
-
-
1b. I'm still having problems with port
- forwarding
- Answer: To further
- diagnose this problem:
-
-
-
As root, type
-"iptables -t nat -Z". This clears the NetFilter counters
- in the nat table.
-
Try to connect
-to the redirected port from an external host.
-
As root type "shorewall
- show nat"
-
Locate the appropriate
- DNAT rule. It will be in a chain called <source
- zone>_dnat ('net_dnat' in the above examples).
-
Is the packet
-count in the first column non-zero? If so, the connection
- request is reaching the firewall and is being redirected
- to the server. In this case, the problem is usually a missing
- or incorrect default gateway setting on the server (the
- server's default gateway should be the IP address of the
-firewall's interface to the server).
-
If the packet
-count is zero:
-
-
-
the connection
- request is not reaching your server (possibly it is
- being blocked by your ISP); or
-
you are trying
- to connect to a secondary IP address on your firewall
- and your rule is only redirecting the primary IP address (You
- need to specify the secondary IP address in the "ORIG. DEST."
-column in your DNAT rule); or
-
your DNAT rule
- doesn't match the connection request in some other
- way. In that case, you may have to use a packet sniffer such
- as tcpdump or ethereal to further diagnose the problem.
-
-
-
-
-
-
-
1c. From the internet, I want
- to connect to port 1022 on my firewall and have the firewall forward
- the connection to port 22 on local system 192.168.1.3. How do I do that?
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE
- PORT
-
ORIG.
- DEST.
-
-
-
DNAT
-
net
-
-
loc:192.168.1.3:22
-
tcp
-
1022
-
-
-
-
-
-
-
-
-
-
-
-
-
2. I port forward www requests to www.mydomain.com
- (IP 130.151.100.69) to system 192.168.1.5 in
- my local network. External clients can browse http://www.mydomain.com
- but internal clients can't.
-
-
Answer: I have two objections to this setup.
-
-
-
Having
- an internet-accessible server in your local network
- is like raising foxes in the corner of your hen house.
- If the server is compromised, there's nothing between
- that server and your other internal systems. For the
-cost of another NIC and a cross-over cable, you can put
-your server in a DMZ such that it is isolated from your local systems
- - assuming that the Server can be located near the Firewall,
- of course :-)
-
The
-accessibility problem is best solved using Bind Version 9 "views"
- (or using a separate DNS server for local clients) such that www.mydomain.com
- resolves to 130.141.100.69 externally and 192.168.1.5
- internally. That's what I do here at shorewall.net for my
- local systems that use static NAT.
-
-
-
-
If you insist on an IP solution to the accessibility problem
- rather than a DNS solution, then assuming that
- your external interface is eth0 and your internal
- interface is eth1 and that eth1 has IP address 192.168.1.254
- with subnet 192.168.1.0/24.
-
-
-
If you are running Shorewall 1.4.0 or earlier see the 1.3 FAQ for instructions suitable for those
-releases.
-
-
-
If you are running Shorewall 1.4.1 or Shorewall 1.4.1a, please
- upgrade to Shorewall 1.4.2 or later.
-
-
-
Otherwise:
-
-
-
-
-
-
-
-
-
-
-
-
In /etc/shorewall/interfaces:
-
-
-
-
-
-
-
-
ZONE
-
-
INTERFACE
-
-
BROADCAST
-
-
OPTIONS
-
-
-
-
loc
-
-
eth1
-
-
detect
-
-
routeback
-
-
-
-
-
-
-
-
-
-
-
-
-
In /etc/shorewall/rules:
-
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
DNAT
-
-
loc
-
web:192.168.1.5
-
-
tcp
-
www
-
-
-
-
130.151.100.69:192.168.1.254
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE
+ PORT
+
ORIG.
+ DEST.
+
+
+
DNAT
+
net
+
loc:<local
+ IP address>[:<local port>]
+
<protocol>
+
<port
+ #>
+
-
+
<external
+ IP>
+
-
+
+
-
-
-
-
That rule only works of course if you have a static external
- IP address. If you have a dynamic IP address
- and are running Shorewall 1.3.4 or later then include
- this in /etc/shorewall/init:
-
-
-
-
ETH0_IP=`find_interface_address eth0`
-
-
-
-
and make your DNAT rule:
-
-
-
-
+
+ Finally, if you need to forward a range of
+ports, in the PORT column specify the range as low-port:high-port.
+
+
1a. Ok -- I followed those instructions
+ but it doesn't work
+
+
Answer: That is usually the result of one of three
+ things:
+
+
+
You
+ are trying to test from inside your firewall (no, that
+ won't work -- see FAQ #2).
+
You
+ have a more basic problem with your local system such
+ as an incorrect default gateway configured (it should
+ be set to the IP address of your firewall's internal
+interface).
+
Your ISP is blocking that particular port inbound.
+
+
+
+
+
1b. I'm still having problems with port
+ forwarding
+ Answer: To
+further diagnose this problem:
+
+
+
As root, type
+ "iptables -t nat -Z". This clears the NetFilter counters
+ in the nat table.
+
Try to connect
+ to the redirected port from an external host.
+
As root type
+ "shorewall show nat"
+
Locate the
+appropriate DNAT rule. It will be in a chain called
+ <source zone>_dnat ('net_dnat' in the above
+ examples).
+
Is the packet
+ count in the first column non-zero? If so, the connection
+ request is reaching the firewall and is being redirected
+ to the server. In this case, the problem is usually a missing
+ or incorrect default gateway setting on the server (the
+ server's default gateway should be the IP address of the
+firewall's interface to the server).
+
If the packet
+ count is zero:
+
+
+
the connection
+ request is not reaching your server (possibly it
+ is being blocked by your ISP); or
+
you are trying
+ to connect to a secondary IP address on your firewall
+ and your rule is only redirecting the primary IP address
+ (You need to specify the secondary IP address in the "ORIG.
+ DEST." column in your DNAT rule); or
+
your DNAT
+rule doesn't match the connection request in some other
+ way. In that case, you may have to use a packet sniffer such
+ as tcpdump or ethereal to further diagnose the problem.
+
+
+
+
+
+
+
1c. From the internet, I want
+ to connect to port 1022 on my firewall and have the firewall forward
+ the connection to port 22 on local system 192.168.1.3. How do I do
+that?
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE
- PORT
-
ORIG.
- DEST.
-
-
-
DNAT
-
loc
-
web:192.168.1.5
-
tcp
-
www
-
-
-
$ETH0_IP:192.168.1.254
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE
+ PORT
+
ORIG.
+ DEST.
+
+
+
DNAT
+
net
+
+
loc:192.168.1.3:22
+
tcp
+
1022
+
+
+
+
+
+
+
+
+
-
-
-
-
-
Using this technique, you will want to configure your DHCP/PPPoE
- client to automatically restart Shorewall each
- time that you get a new IP address.
-
-
-
2a. I have a zone "Z" with an RFC1918
- subnet and I use static NAT to assign non-RFC1918
- addresses to hosts in Z. Hosts in Z cannot communicate
- with each other using their external (non-RFC1918
-addresses) so they can't access each other using their DNS
- names.
-
-
Answer: This is another problem that is best solved
- using Bind Version 9 "views". It allows both
- external and internal clients to access a NATed
-host using the host's DNS name.
-
-
Another good way to approach this problem is to switch from
- static NAT to Proxy ARP. That way, the hosts
- in Z have non-RFC1918 addresses and can be accessed
- externally and internally using the same address.
-
-
If you don't like those solutions and prefer routing all
-Z->Z traffic through your firewall then:
+
+
+
+
2. I port forward www requests to www.mydomain.com
+ (IP 130.151.100.69) to system 192.168.1.5
+in my local network. External clients can browse
+http://www.mydomain.com but internal clients can't.
+
+
Answer: I have two objections to this setup.
+
+
+
Having
+ an internet-accessible server in your local network
+ is like raising foxes in the corner of your hen house.
+ If the server is compromised, there's nothing between
+ that server and your other internal systems. For the
+ cost of another NIC and a cross-over cable, you can put
+ your server in a DMZ such that it is isolated from your local
+systems - assuming that the Server can be located near the
+Firewall, of course :-)
+
The
+ accessibility problem is best solved using Bind Version 9 "views"
+ (or using a separate DNS server for local clients) such that www.mydomain.com
+ resolves to 130.141.100.69 externally and 192.168.1.5
+ internally. That's what I do here at shorewall.net for
+ my local systems that use static NAT.
+
+
+
+
If you insist on an IP solution to the accessibility problem
+ rather than a DNS solution, then assuming
+ that your external interface is eth0 and your
+internal interface is eth1 and that eth1 has IP address
+ 192.168.1.254 with subnet 192.168.1.0/24.
+
+
+
If you are running Shorewall 1.4.0 or earlier see the 1.3 FAQ for instructions suitable for
+those releases.
+
+
If you are running Shorewall 1.4.1 or Shorewall 1.4.1a, please
+ upgrade to Shorewall 1.4.2 or later.
+
+
+
Otherwise:
+
+
+
+
+
+
+
+
+
+
+
+
In /etc/shorewall/interfaces:
+
+
+
+
+
+
+
+
ZONE
+
+
INTERFACE
+
+
BROADCAST
+
+
OPTIONS
+
+
+
+
loc
+
+
eth1
+
+
detect
+
+
routeback
+
+
+
+
+
+
+
+
+
+
+
+
+
+
In /etc/shorewall/rules:
+
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
DNAT
+
+
loc
+
web:192.168.1.5
+
+
tcp
+
www
+
-
+
+
130.151.100.69:192.168.1.254
+
+
+
+
+
+
+
+
+
+
That rule only works of course if you have a static external
+ IP address. If you have a dynamic IP address
+ and are running Shorewall 1.3.4 or later then
+include this in /etc/shorewall/init:
+
+
+
+
ETH0_IP=`find_interface_address eth0`
+
+
+
+
and make your DNAT rule:
+
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE
+ PORT
+
ORIG.
+ DEST.
+
+
+
DNAT
+
loc
+
web:192.168.1.5
+
tcp
+
www
+
-
+
$ETH0_IP:192.168.1.254
+
+
+
+
+
+
+
+
+
+
Using this technique, you will want to configure your DHCP/PPPoE
+ client to automatically restart Shorewall
+ each time that you get a new IP address.
+
+
+
2a. I have a zone "Z" with an RFC1918
+ subnet and I use static NAT to assign non-RFC1918
+ addresses to hosts in Z. Hosts in Z cannot communicate
+ with each other using their external (non-RFC1918
+ addresses) so they can't access each other using their
+ DNS names.
+
+
Answer: This is another problem that is best solved
+ using Bind Version 9 "views". It allows both
+ external and internal clients to access a NATed
+ host using the host's DNS name.
+
+
Another good way to approach this problem is to switch from
+ static NAT to Proxy ARP. That way, the hosts
+ in Z have non-RFC1918 addresses and can be accessed
+ externally and internally using the same address.
+
+
If you don't like those solutions and prefer routing all Z->Z
+traffic through your firewall then:
+
a) Set the Z->Z policy to ACCEPT.
- b) Masquerade
- Z to itself.
-
- Example:
3. I want to use Netmeeting or MSN Instant
- Messenger with Shorewall. What do I do?
-
+
+
+
3. I want to use Netmeeting or MSN Instant
+ Messenger with Shorewall. What do I do?
+
Answer: There is an H.323 connection
- tracking/NAT module that may help with Netmeeting.
- Look here for
- a solution for MSN IM but be aware that there are significant
-security risks involved with this solution. Also check the Netfilter
- mailing list archives at http://www.netfilter.org.
-
-
-
4. I just used an online port scanner
- to check my firewall and it shows some ports
- as 'closed' rather than 'blocked'. Why?
-
-
Answer: The common.def included with version 1.3.x
- always rejects connection requests on TCP
- port 113 rather than dropping them. This is necessary
- to prevent outgoing connection problems to services
- that use the 'Auth' mechanism for identifying requesting
- users. Shorewall also rejects TCP ports 135, 137 and
- 139 as well as UDP ports 137-139. These are ports that are
- used by Windows (Windows can be configured to use the
-DCE cell locator on port 135). Rejecting these connection requests
- rather than dropping them cuts down slightly on the amount of
-Windows chatter on LAN segments connected to the Firewall.
-
-
-
If you are seeing port 80 being 'closed', that's probably
- your ISP preventing you from running a web
- server in violation of your Service Agreement.
-
-
4a. I just ran an nmap UDP scan of my
- firewall and it showed 100s of ports as open!!!!
-
-
Answer: Take a deep breath and read the nmap man page
- section about UDP scans. If nmap gets nothing
- back from your firewall then it reports the port
- as open. If you want to see which UDP ports are really
- open, temporarily change your net->all policy to
-REJECT, restart Shorewall and do the nmap UDP scan again.
-
-
-
4b. I have a port that I can't close no matter how
- I change my rules.
- I had a rule that allowed telnet from my local network to my firewall;
- I removed that rule and restarted Shorewall but my telnet session still
- works!!!
-
- Answer: Rules only govern the establishment of new connections.
- Once a connection is established through the firewall it will be usable
- until disconnected (tcp) or until it times out (other protocols). If you
- stop telnet and try to establish a new session your firerwall will block
-that attempt.
-
-
5. I've installed Shorewall and now I
- can't ping through the firewall
-
-
Answer: If you want your firewall to be totally open
- for "ping",
-
-
a) Create /etc/shorewall/common if it doesn't already exist.
+ href="http://www.kfki.hu/%7Ekadlec/sw/netfilter/newnat-suite/"> H.323 connection
+ tracking/NAT module that may help with
+ Netmeeting. Look here for a solution
+ for MSN IM but be aware that there are significant security risks
+involved with this solution. Also check the Netfilter mailing
+ list archives at http://www.netfilter.org.
+
+
+
4. I just used an online port scanner
+ to check my firewall and it shows some
+ports as 'closed' rather than 'blocked'. Why?
+
+
Answer: The common.def included with version 1.3.x
+ always rejects connection requests on
+TCP port 113 rather than dropping them. This is
+ necessary to prevent outgoing connection problems to
+ services that use the 'Auth' mechanism for identifying
+ requesting users. Shorewall also rejects TCP ports
+135, 137 and 139 as well as UDP ports 137-139. These are
+ ports that are used by Windows (Windows can be configured
+ to use the DCE cell locator on port 135). Rejecting these connection
+ requests rather than dropping them cuts down slightly on the amount
+ of Windows chatter on LAN segments connected to the Firewall.
+
+
+
If you are seeing port 80 being 'closed', that's probably
+ your ISP preventing you from running a
+web server in violation of your Service Agreement.
+
+
4a. I just ran an nmap UDP scan of my
+ firewall and it showed 100s of ports as
+ open!!!!
+
+
Answer: Take a deep breath and read the nmap man page
+ section about UDP scans. If nmap gets
+nothing back from your firewall then it
+reports the port as open. If you want to see which
+ UDP ports are really open, temporarily change your net->all
+ policy to REJECT, restart Shorewall and do the nmap
+UDP scan again.
+
+
+
4b. I have a port that I can't close no matter how
+ I change my rules.
+ I had a rule that allowed telnet from my local network to my firewall;
+ I removed that rule and restarted Shorewall but my telnet session still
+ works!!!
- b) Be sure
-that the first command in the file is ". /etc/shorewall/common.def"
- c) Add the
-following to /etc/shorewall/common
-
-
- For a complete description of Shorewall
- 'ping' management, see this page.
-
-
6. Where are the log messages written
- and how do I change the destination?
-
-
Answer: NetFilter uses the kernel's equivalent of
-syslog (see "man syslog") to log messages. It always uses the LOG_KERN (kern)
-facility (see "man openlog") and you get to choose the log level (again,
-see "man syslog") in your policies
- and rules. The destination for messaged
- logged by syslog is controlled by /etc/syslog.conf (see "man syslog.conf").
- When you have changed /etc/syslog.conf, be sure
- to restart syslogd (on a RedHat system, "service syslog
- restart").
-
-
By default, older versions of Shorewall ratelimited log messages
- through settings
- in /etc/shorewall/shorewall.conf -- If you want
- to log all messages, set:
-
-
+ Answer: Rules only govern the establishment of new connections.
+ Once a connection is established through the firewall it will be usable
+ until disconnected (tcp) or until it times out (other protocols). If you
+ stop telnet and try to establish a new session your firerwall will block
+ that attempt.
+
+
4c. How to I use Shorewall with
+PortSentry?
+ Here's
+a writeup on a nice integration of Shorewall and PortSentry.
+
+
5. I've installed Shorewall and now I
+ can't ping through the firewall
+
+
Answer: If you want your firewall to be totally open
+ for "ping",
+
+
a) Create /etc/shorewall/common if it doesn't already exist.
+
+ b) Be sure
+ that the first command in the file is ". /etc/shorewall/common.def"
+ c) Add
+the following to /etc/shorewall/common
+ For a complete description of
+Shorewall 'ping' management, see this
+page.
+
6. Where are the log messages written
+ and how do I change the destination?
+
+
Answer: NetFilter uses the kernel's equivalent of syslog
+(see "man syslog") to log messages. It always uses the LOG_KERN (kern) facility
+(see "man openlog") and you get to choose the log level (again, see "man
+syslog") in your policies and rules. The destination for messaged
+logged by syslog is controlled by /etc/syslog.conf (see "man syslog.conf").
+ When you have changed /etc/syslog.conf, be sure
+ to restart syslogd (on a RedHat system, "service syslog
+ restart").
+
+
By default, older versions of Shorewall ratelimited log messages
+ through settings
+ in /etc/shorewall/shorewall.conf -- If you
+want to log all messages, set:
- I personnaly use Logwatch. It
-emails me a report each day from my various systems with
-each report summarizing the logged activity on the corresponding
- system.
-
6b. DROP messages on port 10619
- are flooding the logs with their connect requests. Can
- i exclude these error messages for this port temporarily from
-logging in Shorewall?
- Temporarily add the following rule:
-
+ http://www.logwatch.org
+ http://gege.org/iptables
+
+
+ I personnaly use Logwatch.
+It emails me a report each day from my various systems
+with each report summarizing the logged activity on the corresponding
+ system.
+
6b. DROP messages on port 10619
+ are flooding the logs with their connect requests.
+ Can i exclude these error messages for this port temporarily
+from logging in Shorewall?
+ Temporarily add the following rule:
+
DROP net fw udp 10619
-
-
6c. All day long I get a steady flow
- of these DROP messages from port 53 to some high numbered port.
- They get dropped, but what the heck are they?
-
+
+
6c. All day long I get a steady flow
+ of these DROP messages from port 53 to some high numbered
+ port. They get dropped, but what the heck are they?
- Answer: There are two possibilities:
-
+ Answer: There are two possibilities:
+
-
They are late-arriving replies to DNS
- queries.
-
They are corrupted reply packets.
-
+
They are late-arriving replies to
+DNS queries.
+
They are corrupted reply packets.
+
- You can distinguish the difference by setting
- the logunclean option (/etc/shorewall/interfaces)
- on your external interface (eth0 in the above example). If they get
- logged twice, they are corrupted. I solve this problem by using
- an /etc/shorewall/common file like this:
-
-
+ You can distinguish the difference by setting
+ the logunclean option (/etc/shorewall/interfaces)
+ on your external interface (eth0 in the above example). If they get
+ logged twice, they are corrupted. I solve this problem by using
+ an /etc/shorewall/common file like this:
+
+
# # Include the standard common.def file # . /etc/shorewall/common.def # # The following rule is non-standard and compensates for tardy # DNS replies # run_iptables -A common -p udp --sport 53 -mstate --state NEW -j DROP
-
- The above file is also include in all of my
- sample configurations available in the Quick Start Guides and in
- the common.def file in Shorewall 1.4.0 and later.
-
-
6d. Why is the MAC address in
- Shorewall log messages so long? I thought MAC addresses were only
- 6 bytes in length.
- What is labeled as the MAC address in a Shorewall log message
- is actually the Ethernet frame header. IT contains:
-
+
+ The above file is also include in all of
+ my sample configurations available in the Quick Start Guides and in
+ the common.def file in Shorewall 1.4.0 and later.
+
+
6d. Why is the MAC address in
+ Shorewall log messages so long? I thought MAC addresses were
+ only 6 bytes in length.
+ What is labeled as the MAC address in a Shorewall log
+ message is actually the Ethernet frame header. IT contains:
+
7. When I stop Shorewall using 'shorewall
- stop', I can't connect to anything. Why doesn't
- that command work?
-
-
The 'stop' command is intended to place your firewall into
- a safe state whereby only those hosts listed
- in /etc/shorewall/routestopped' are activated.
-If you want to totally open up your firewall, you must use
-the 'shorewall clear' command.
-
-
8. When I try to start Shorewall on RedHat,
- I get messages about insmod failing -- what's wrong?
-
-
Answer: The output you will see looks something like
- this:
-
+
+
7. When I stop Shorewall using 'shorewall
+ stop', I can't connect to anything. Why
+doesn't that command work?
+
+
The 'stop' command is intended to place your firewall into
+ a safe state whereby only those hosts listed
+ in /etc/shorewall/routestopped' are activated.
+ If you want to totally open up your firewall, you must
+ use the 'shorewall clear' command.
+
+
8. When I try to start Shorewall on RedHat,
+ I get messages about insmod failing -- what's wrong?
+
+
Answer: The output you will see looks something like
+ this:
+
/lib/modules/2.4.17/kernel/net/ipv4/netfilter/ip_tables.o: init_module: Device or resource busy Hint: insmod errors can be caused by incorrect module parameters, including invalid IO or IRQ parameters /lib/modules/2.4.17/kernel/net/ipv4/netfilter/ip_tables.o: insmod /lib/modules/2.4.17/kernel/net/ipv4/netfilter/ip_tables.o failed /lib/modules/2.4.17/kernel/net/ipv4/netfilter/ip_tables.o: insmod ip_tables failed iptables v1.2.3: can't initialize iptables table `nat': iptables who? (do you need to insmod?) Perhaps iptables or your kernel needs to be upgraded.
-
-
This is usually cured by the following sequence of commands:
-
-
-
+
+
This is usually cured by the following sequence of commands:
+
+
+
service ipchains stop chkconfig --delete ipchains rmmod ipchains
-
-
-
-
Also, be sure to check the errata
- for problems concerning the version of iptables
- (v1.2.3) shipped with RH7.2.
-
-
-
8a. When I try to start Shorewall on RedHat
- I get a message referring me to FAQ #8
- Answer: This is usually cured by the sequence of commands
- shown above in FAQ #8
-
-
-
9. Why can't Shorewall detect my interfaces
- properly at startup?
-
-
I just installed Shorewall and when I issue the start command,
- I see the following:
-
-
+
+
+
+
Also, be sure to check the errata
+ for problems concerning the version of iptables
+ (v1.2.3) shipped with RH7.2.
+
+
+
8a. When I try to start Shorewall on RedHat
+ I get a message referring me to FAQ #8
+ Answer: This is usually cured by the sequence of
+ commands shown above in FAQ #8
+
+
+
9. Why can't Shorewall detect my interfaces
+ properly at startup?
+
+
I just installed Shorewall and when I issue the start command,
+ I see the following:
+
+
Processing /etc/shorewall/params ... Processing /etc/shorewall/shorewall.conf ... Starting Shorewall... Loading Modules... Initializing... Determining Zones... Zones: net loc Validating interfaces file... Validating hosts file... Determining Hosts in Zones... Net Zone: eth0:0.0.0.0/0 Local Zone: eth1:0.0.0.0/0 Deleting user chains... Creating input Chains... ...
-
-
-
+
+
+
Why can't Shorewall detect my interfaces properly?
-
-
-
-
Answer: The above output is perfectly normal. The
-Net zone is defined as all hosts that are connected through eth0 and the
-local zone is defined as all hosts connected through eth1
-
-
-
10. What Distributions does it work
- with?
-
-
Shorewall works with any GNU/Linux distribution that includes
- the
+
+
Answer: Shorewall is a concatenation of "Shoreline"
- (the
- city where I live) and "Firewall". The full
- name of the product is actually "Shoreline Firewall" but "Shorewall"
- is must more commonly used.
-
-
14. I'm connected via a cable modem
- and it has an internal web server that allows
- me to configure/monitor it but as expected if I
- enable rfc1918 blocking for my eth0 interface (the internet
- one), it also blocks the cable modems web server.
-
-
Is there any way it can add a rule before the rfc1918 blocking
- that will let all traffic to and from the 192.168.100.1
- address of the modem in/out but still block all
-other rfc1918 addresses?
-
-
Answer: If you are running a version of Shorewall
-earlier than 1.3.1, create /etc/shorewall/start and in it, place the
-following:
-
-
+
+
Answer: Shorewall is a concatenation of "Shoreline"
+ (the city where I live)
+ and "Firewall". The full name of the product
+ is actually "Shoreline Firewall" but "Shorewall" is must more
+commonly used.
+
+
14. I'm connected via a cable modem
+ and it has an internal web server that allows
+ me to configure/monitor it but as expected if
+I enable rfc1918 blocking for my eth0 interface (the
+ internet one), it also blocks the cable modems web server.
+
+
Is there any way it can add a rule before the rfc1918 blocking
+ that will let all traffic to and from the
+192.168.100.1 address of the modem in/out but
+still block all other rfc1918 addresses?
+
+
Answer: If you are running a version of Shorewall earlier
+than 1.3.1, create /etc/shorewall/start and in it, place the following:
Be sure that you add the entry ABOVE the entry for 192.168.0.0/16.
+
+
+
Note: If you add a second IP address to your external firewall
+ interface to correspond to the modem address,
+ you must also make an entry in /etc/shorewall/rfc1918
+ for that address. For example, if you configure the
+address 192.168.100.2 on your firewall, then you would add
+two entries to /etc/shorewall/rfc1918:
+
+
+
+
+
+
+
SUBNET
+
+
TARGET
+
-
192.168.100.1
-
RETURN
-
-
-
-
-
-
-
-
-
Be sure that you add the entry ABOVE the entry for 192.168.0.0/16.
-
-
-
Note: If you add a second IP address to your external firewall
- interface to correspond to the modem address,
- you must also make an entry in /etc/shorewall/rfc1918
- for that address. For example, if you configure the address
- 192.168.100.2 on your firewall, then you would add two entries
- to /etc/shorewall/rfc1918:
-
-
-
-
-
-
-
SUBNET
-
-
TARGET
-
-
-
-
192.168.100.1
-
-
+
RETURN
-
-
-
-
+
+
+
192.168.100.2
-
-
+
RETURN
-
-
-
-
+
+
+
+
+
-
-
-
-
-
14a. Even though it assigns public
-IP addresses, my ISP's DHCP server has an RFC 1918 address. If I enable
-RFC 1918 filtering on my external interface, my DHCP client cannot renew
-its lease.
-
-
-
-
The solution is the same as FAQ 14 above. Simply substitute
- the IP address of your ISPs DHCP server.
-
-
-
15. My local systems can't see out to
- the net
-
-
Answer: Every time I read "systems can't see out to
- the net", I wonder where the poster bought
-computers with eyes and what those computers will
-"see" when things are working properly. That aside,
- the most common causes of this problem are:
-
+
+
+
+
+
14a. Even though it assigns public IP
+ addresses, my ISP's DHCP server has an RFC 1918 address. If I enable RFC
+1918 filtering on my external interface, my DHCP client cannot renew its
+lease.
+
+
+
+
The solution is the same as FAQ 14 above. Simply substitute
+ the IP address of your ISPs DHCP server.
+
+
+
15. My local systems can't see out to
+ the net
+
+
Answer: Every time I read "systems can't see out to
+ the net", I wonder where the poster bought
+ computers with eyes and what those computers will
+ "see" when things are working properly. That aside,
+ the most common causes of this problem are:
+
-
-
-
The default gateway on each local system isn't set to
- the IP address of the local firewall interface.
-
-
-
-
The entry for the local network in the /etc/shorewall/masq
- file is wrong or missing.
-
-
-
-
The DNS settings on the local systems are wrong or the
- user is running a DNS server on the firewall
- and hasn't enabled UDP and TCP port 53 from
+
+
+
The default gateway on each local system isn't set to
+ the IP address of the local firewall interface.
+
+
+
+
The entry for the local network in the /etc/shorewall/masq
+ file is wrong or missing.
+
+
+
+
The DNS settings on the local systems are wrong or the
+ user is running a DNS server on the firewall
+ and hasn't enabled UDP and TCP port 53 from
the firewall to the internet.
-
-
+
+
-
-
16. Shorewall is writing log messages
- all over my console making it unusable!
-
-
Answer: If you are running Shorewall version 1.4.4
- or 1.4.4a then check the errata. Otherwise, see
- the 'dmesg' man page ("man dmesg"). You must add a suitable 'dmesg' command
- to your startup scripts or place it in /etc/shorewall/start.
- Under RedHat, the max log level that is sent
- to the console is specified in /etc/sysconfig/init
-in the LOGLEVEL variable.
-
-
-
17. How do I find out why this traffic is getting
- logged?
- Answer: Logging
- occurs out of a number of chains (as indicated in
- the log message) in Shorewall:
-
+
+
16. Shorewall is writing log messages
+ all over my console making it unusable!
+
+
Answer: If you are running Shorewall version 1.4.4
+ or 1.4.4a then check the errata. Otherwise, see
+ the 'dmesg' man page ("man dmesg"). You must add a suitable 'dmesg' command
+ to your startup scripts or place it in /etc/shorewall/start.
+ Under RedHat, the max log level that is sent
+ to the console is specified in /etc/sysconfig/init
+ in the LOGLEVEL variable.
+
+
+
17. How do I find out why this traffic is getting
+ logged?
+ Answer: Logging
+ occurs out of a number of chains (as indicated in
+ the log message) in Shorewall:
+
-
man1918
- or logdrop - The destination address is
- listed in /etc/shorewall/rfc1918 with a logdrop target
- -- see /etc/shorewall/rfc1918.
rfc1918
+ or logdrop - The source address is listed in /etc/shorewall/rfc1918
+ with a logdrop target -- see /etc/shorewall/rfc1918.
-
all2<zone>,
- <zone>2all or all2all
- - You have a policy
-that specifies a log level and this packet is being
-logged under that policy. If you intend to ACCEPT this traffic
-then you need a rule to that effect.
-
-
<zone1>2<zone2>
- - Either you have a policy for <zone1>
- to <zone2> that specifies a log level and
- this packet is being logged under that policy or this packet
- matches a rule that
- includes a log level.
-
<interface>_mac
- - The packet is being logged under the maclist
- interface option.
-
-
logpkt
- - The packet is being logged under the logunclean
- interface option.
-
badpkt
- - The packet is being logged under the dropunclean
- interface option
- as specified in the LOGUNCLEAN setting in all2<zone>,
+ <zone>2all or all2all
+ - You have a policy
+ that specifies a log level and this packet is being
+ logged under that policy. If you intend to ACCEPT this
+ traffic then you need a rule to
+that effect.
+
+
<zone1>2<zone2>
+ - Either you have a policy for <zone1>
+ to <zone2> that specifies a log level and
+ this packet is being logged under that policy or this
+ packet matches a rule
+ that includes a log level.
+
<interface>_mac
+ - The packet is being logged under the maclist
+ interface option.
+
+
logpkt
+ - The packet is being logged under the logunclean
+ interface option.
blacklst
- - The packet is being logged because the source IP
- is blacklisted in the /etc/shorewall/blacklist
- file.
-
newnotsyn
- - The packet is being logged because it is
+
blacklst
+ - The packet is being logged because the source
+ IP is blacklisted in the
+ /etc/shorewall/blacklist file.
+
newnotsyn
+ - The packet is being logged because it is
a TCP packet that is not part of any current connection
yet it is not a syn packet. Options affecting the logging
of such packets include NEWNOTSYN and
LOGNEWNOTSYN in /etc/shorewall/shorewall.conf.
-
INPUT
- or FORWARD - The packet has a source IP address
- that isn't in any of your defined zones ("shorewall check"
- and look at the printed zone definitions) or the chain is
-FORWARD and the destination IP isn't in any of your defined
- zones.
- 192.0.2.3 is external on my
- firewall... 172.16.0.0/24 is my internal LAN
-
- Answer: While most
-people associate the Internet Control Message Protocol
-(ICMP) with 'ping', ICMP is a key piece of the internet.
- ICMP is used to report problems back to the sender of a packet;
-this is what is happening here. Unfortunately, where NAT is involved
- (including SNAT, DNAT and Masquerade), there are a lot of broken
- implementations. That is what you are seeing with these messages.
-
- Here is my interpretation of
- what is happening -- to confirm this analysis, one would
- have to have packet sniffers placed a both ends of the connection.
-
- Host 172.16.1.10 behind NAT
-gateway 206.124.146.179 sent a UDP DNS query to 192.0.2.3
-and your DNS server tried to send a response (the response information
- is in the brackets -- note source port 53 which marks this as
- a DNS reply). When the response was returned to to 206.124.146.179,
- it rewrote the destination IP TO 172.16.1.10 and forwarded the
- packet to 172.16.1.10 who no longer had a connection on UDP port
- 2857. This causes a port unreachable (type 3, code 3) to be generated
- back to 192.0.2.3. As this packet is sent back through 206.124.146.179,
- that box correctly changes the source address in the packet to 206.124.146.179
- but doesn't reset the DST IP in the original DNS response similarly.
- When the ICMP reaches your firewall (192.0.2.3), your firewall has
- no record of having sent a DNS reply to 172.16.1.10 so this ICMP
-doesn't appear to be related to anything that was sent. The final
- result is that the packet gets logged and dropped in the all2all chain.
-I have also seen cases where the source IP in the ICMP itself isn't
-set back to the external IP of the remote NAT gateway; that causes your
-firewall to log and drop the packet out of the rfc1918 chain because
- the source IP is reserved by RFC 1918.
-
-
22. I have some iptables commands that
- I want to run when Shorewall starts. Which file
-do I put them in?
- You can place these commands
- in one of the Shorewall Extension
- Scripts. Be sure that you look at the contents of the chain(s)
-that you will be modifying with your commands to be sure
-that the commands will do what they are intended. Many iptables
-commands published in HOWTOs and other instructional material
-use the -A command which adds the rules to the end of the chain. Most
-chains that Shorewall constructs end with an unconditional DROP, ACCEPT
-or REJECT rule and any rules that you add after that will be ignored.
- Check "man iptables" and look at the -I (--insert) command.
-
-
23. Why do you use such ugly fonts on your
- web site?
- The Shorewall web site is almost font
- neutral (it doesn't explicitly specify fonts except on a
-few pages) so the fonts you see are largely the default fonts
-configured in your browser. If you don't like them then reconfigure
+
+ 192.0.2.3 is external on
+ my firewall... 172.16.0.0/24 is my internal LAN
+
+ Answer: While most
+ people associate the Internet Control Message Protocol
+ (ICMP) with 'ping', ICMP is a key piece of the internet.
+ ICMP is used to report problems back to the sender of a packet;
+ this is what is happening here. Unfortunately, where NAT is involved
+ (including SNAT, DNAT and Masquerade), there are a lot of broken
+ implementations. That is what you are seeing with these messages.
+
+ Here is my interpretation
+ of what is happening -- to confirm this analysis, one
+would have to have packet sniffers placed a both ends of the
+connection.
+
+ Host 172.16.1.10 behind
+NAT gateway 206.124.146.179 sent a UDP DNS query
+to 192.0.2.3 and your DNS server tried to send a response (the
+response information is in the brackets -- note source port 53
+which marks this as a DNS reply). When the response was returned
+ to to 206.124.146.179, it rewrote the destination IP TO 172.16.1.10
+ and forwarded the packet to 172.16.1.10 who no longer had a connection
+ on UDP port 2857. This causes a port unreachable (type 3, code
+ 3) to be generated back to 192.0.2.3. As this packet is sent back
+through 206.124.146.179, that box correctly changes the source address
+ in the packet to 206.124.146.179 but doesn't reset the DST IP
+in the original DNS response similarly. When the ICMP reaches
+your firewall (192.0.2.3), your firewall has no record of having
+ sent a DNS reply to 172.16.1.10 so this ICMP doesn't appear to
+be related to anything that was sent. The final result is that the
+packet gets logged and dropped in the all2all chain. I have also seen
+cases where the source IP in the ICMP itself isn't set back to the external
+IP of the remote NAT gateway; that causes your firewall to log and
+drop the packet out of the rfc1918 chain because the source IP is
+reserved by RFC 1918.
+
+
22. I have some iptables commands that
+ I want to run when Shorewall starts. Which file
+ do I put them in?
+ You can place these commands
+ in one of the Shorewall
+ Extension Scripts. Be sure that you look at the contents of the
+ chain(s) that you will be modifying with your commands to
+ be sure that the commands will do what they are intended. Many
+ iptables commands published in HOWTOs and other instructional material
+ use the -A command which adds the rules to the end of the chain.
+ Most chains that Shorewall constructs end with an unconditional DROP,
+ ACCEPT or REJECT rule and any rules that you add after that will
+be ignored. Check "man iptables" and look at the -I (--insert) command.
+
+
23. Why do you use such ugly fonts on your
+ web site?
+ The Shorewall web site is almost
+font neutral (it doesn't explicitly specify fonts except
+on a few pages) so the fonts you see are largely the default fonts
+configured in your browser. If you don't like them then reconfigure
your browser.
-
-
24. How can I allow conections to let's say
- the ssh port only from specific IP Addresses on the
- internet?
- In the SOURCE column of the rule, follow
- "net" by a colon and a list of the host/subnet addresses as
- a comma-separated list.
-
+
+
24. How can I allow conections to let's say
+ the ssh port only from specific IP Addresses on
+the internet?
+ In the SOURCE column of the rule, follow
+ "net" by a colon and a list of the host/subnet addresses as
+ a comma-separated list.
+
net:<ip1>,<ip2>,...
- Example:
-
+ Example:
+
ACCEPT net:192.0.2.16/28,192.0.2.44 fw tcp 22
-
+
-
-
25. How to I tell which version of Shorewall
- I am running?
-
- At the shell prompt, type:
-
- /sbin/shorewall version
-
-
26. When I try to use any of the SYN options
- in nmap on or behind the firewall, I get "operation not permitted". How can
- I use nmap with Shorewall?"
- Edit /etc/shorewall/shorewall.conf and change "NEWNOTSYN=No" to "NEWNOTSYN=Yes"
- then restart Shorewall.
-
-
- First take a look at the Shorewall kernel configuration
-page. You probably also want to be sure that you have selected the "NAT
-of local connections (READ HELP)" on the Netfilter Configuration menu.
-Otherwise, DNAT rules with your firewall as the source zone won't work with
-your new kernel.
+
+
25. How to I tell which version of Shorewall
+ I am running?
+
+ At the shell prompt, type:
+
+ /sbin/shorewall version
+
+
26. When I try to use any of the SYN options
+ in nmap on or behind the firewall, I get "operation not permitted". How
+ can I use nmap with Shorewall?"
+ Edit /etc/shorewall/shorewall.conf and change "NEWNOTSYN=No" to "NEWNOTSYN=Yes"
+ then restart Shorewall.
+
+
+ First take a look at the Shorewall kernel configuration
+ page. You probably also want to be sure that you have selected the
+"NAT of local connections (READ HELP)" on the Netfilter Configuration
+menu. Otherwise, DNAT rules with your firewall as the source zone won't
+work with your new kernel.
+
28. How do I use Shorewall as a Bridging Firewall?
-
- Basically, you don't. While there are kernel patches that allow you to route
-bridge traffic through Netfilter, the environment is so different from the
-Layer 3 firewalling environment that very little of Shorewall works. In fact,
-so much of Shorewall doesn't work that my official position is that "Shorewall
-doesn't work with Layer 2 Bridging".
-
- Last updated 7/9/2003 - Tom Eastep
+
+ Basically, you don't. While there are kernel patches that allow you to
+ route bridge traffic through Netfilter, the environment is so different
+from the Layer 3 firewalling environment that very little of Shorewall works.
+In fact, so much of Shorewall doesn't work that my official position is that
+ "Shorewall doesn't work with Layer 2 Bridging".
+
+ Last updated 7/9/2003 - Tom Eastep
Copyright (C) 2000 Free Software Foundation, Inc.
-59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-Everyone is permitted to copy and distribute verbatim copies
-of this license document, but changing it is not allowed.
-
+
+
Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
+
0. PREAMBLE
-
The purpose of this License is to make a manual, textbook, or other written
-document "free" in the sense of freedom: to assure everyone the effective
-freedom to copy and redistribute it, with or without modifying it, either
-commercially or noncommercially. Secondarily, this License preserves for the
-author and publisher a way to get credit for their work, while not being
+
+
The purpose of this License is to make a manual, textbook, or other written
+document "free" in the sense of freedom: to assure everyone the effective
+freedom to copy and redistribute it, with or without modifying it, either
+commercially or noncommercially. Secondarily, this License preserves for
+the author and publisher a way to get credit for their work, while not being
considered responsible for modifications made by others.
-
This License is a kind of "copyleft", which means that derivative works of
-the document must themselves be free in the same sense. It complements the GNU
-General Public License, which is a copyleft license designed for free software.
-
-
We have designed this License in order to use it for manuals for free
-software, because free software needs free documentation: a free program should
-come with manuals providing the same freedoms that the software does. But this
-License is not limited to software manuals; it can be used for any textual work,
-regardless of subject matter or whether it is published as a printed book. We
-recommend this License principally for works whose purpose is instruction or
-reference.
+
+
This License is a kind of "copyleft", which means that derivative works
+of the document must themselves be free in the same sense. It complements
+the GNU General Public License, which is a copyleft license designed for
+free software.
+
+
We have designed this License in order to use it for manuals for free software,
+because free software needs free documentation: a free program should come
+with manuals providing the same freedoms that the software does. But this
+License is not limited to software manuals; it can be used for any textual
+work, regardless of subject matter or whether it is published as a printed
+book. We recommend this License principally for works whose purpose is instruction
+or reference.
+
1. APPLICABILITY AND DEFINITIONS
-
This License applies to any manual or other work that contains a notice
-placed by the copyright holder saying it can be distributed under the terms of
-this License. The "Document", below, refers to any such manual or work. Any
-member of the public is a licensee, and is addressed as "you".
-
A "Modified Version" of the Document means any work containing the Document
-or a portion of it, either copied verbatim, or with modifications and/or
-translated into another language.
-
A "Secondary Section" is a named appendix or a front-matter section of the
-Document that deals exclusively with the relationship of the publishers or
-authors of the Document to the Document's overall subject (or to related
-matters) and contains nothing that could fall directly within that overall
-subject. (For example, if the Document is in part a textbook of mathematics, a
-Secondary Section may not explain any mathematics.) The relationship could be a
-matter of historical connection with the subject or with related matters, or of
-legal, commercial, philosophical, ethical or political position regarding them.
-
-
The "Invariant Sections" are certain Secondary Sections whose titles are
-designated, as being those of Invariant Sections, in the notice that says that
-the Document is released under this License.
-
The "Cover Texts" are certain short passages of text that are listed, as
-Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document
-is released under this License.
-
A "Transparent" copy of the Document means a machine-readable copy,
-represented in a format whose specification is available to the general public,
-whose contents can be viewed and edited directly and straightforwardly with
-generic text editors or (for images composed of pixels) generic paint programs
-or (for drawings) some widely available drawing editor, and that is suitable for
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-suitable for input to text formatters. A copy made in an otherwise Transparent
-file format whose markup has been designed to thwart or discourage subsequent
-modification by readers is not Transparent. A copy that is not "Transparent" is
-called "Opaque".
-
Examples of suitable formats for Transparent copies include plain ASCII
-without markup, Texinfo input format, LaTeX input format, SGML or XML using a
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-modification. Opaque formats include PostScript, PDF, proprietary formats that
-can be read and edited only by proprietary word processors, SGML or XML for
-which the DTD and/or processing tools are not generally available, and the
-machine-generated HTML produced by some word processors for output purposes
-only.
-
The "Title Page" means, for a printed book, the title page itself, plus such
-following pages as are needed to hold, legibly, the material this License
-requires to appear in the title page. For works in formats which do not have any
-title page as such, "Title Page" means the text near the most prominent
-appearance of the work's title, preceding the beginning of the body of the text.
-
+
+
This License applies to any manual or other work that contains a notice
+placed by the copyright holder saying it can be distributed under the terms
+of this License. The "Document", below, refers to any such manual or work.
+Any member of the public is a licensee, and is addressed as "you".
+
+
A "Modified Version" of the Document means any work containing the Document
+or a portion of it, either copied verbatim, or with modifications and/or translated
+into another language.
+
+
A "Secondary Section" is a named appendix or a front-matter section of
+the Document that deals exclusively with the relationship of the publishers
+or authors of the Document to the Document's overall subject (or to related
+matters) and contains nothing that could fall directly within that overall
+subject. (For example, if the Document is in part a textbook of mathematics,
+a Secondary Section may not explain any mathematics.) The relationship could
+be a matter of historical connection with the subject or with related matters,
+or of legal, commercial, philosophical, ethical or political position regarding
+them.
+
+
The "Invariant Sections" are certain Secondary Sections whose titles are
+designated, as being those of Invariant Sections, in the notice that says
+that the Document is released under this License.
+
+
The "Cover Texts" are certain short passages of text that are listed,
+as Front-Cover Texts or Back-Cover Texts, in the notice that says that the
+Document is released under this License.
+
+
A "Transparent" copy of the Document means a machine-readable copy, represented
+in a format whose specification is available to the general public, whose
+contents can be viewed and edited directly and straightforwardly with generic
+text editors or (for images composed of pixels) generic paint programs or
+(for drawings) some widely available drawing editor, and that is suitable
+for input to text formatters or for automatic translation to a variety of
+formats suitable for input to text formatters. A copy made in an otherwise
+Transparent file format whose markup has been designed to thwart or discourage
+subsequent modification by readers is not Transparent. A copy that is not
+"Transparent" is called "Opaque".
+
+
Examples of suitable formats for Transparent copies include plain ASCII
+without markup, Texinfo input format, LaTeX input format, SGML or XML using
+a publicly available DTD, and standard-conforming simple HTML designed for
+human modification. Opaque formats include PostScript, PDF, proprietary formats
+that can be read and edited only by proprietary word processors, SGML or
+XML for which the DTD and/or processing tools are not generally available,
+and the machine-generated HTML produced by some word processors for output
+purposes only.
+
+
The "Title Page" means, for a printed book, the title page itself, plus
+such following pages as are needed to hold, legibly, the material this License
+requires to appear in the title page. For works in formats which do not have
+any title page as such, "Title Page" means the text near the most prominent
+appearance of the work's title, preceding the beginning of the body of the
+text.
+
2. VERBATIM COPYING
-
You may copy and distribute the Document in any medium, either commercially
-or noncommercially, provided that this License, the copyright notices, and the
-license notice saying this License applies to the Document are reproduced in all
-copies, and that you add no other conditions whatsoever to those of this
-License. You may not use technical measures to obstruct or control the reading
-or further copying of the copies you make or distribute. However, you may accept
-compensation in exchange for copies. If you distribute a large enough number of
-copies you must also follow the conditions in section 3.
-
You may also lend copies, under the same conditions stated above, and you may
-publicly display copies.
+
+
You may copy and distribute the Document in any medium, either commercially
+or noncommercially, provided that this License, the copyright notices, and
+the license notice saying this License applies to the Document are reproduced
+in all copies, and that you add no other conditions whatsoever to those of
+this License. You may not use technical measures to obstruct or control the
+reading or further copying of the copies you make or distribute. However,
+you may accept compensation in exchange for copies. If you distribute a large
+enough number of copies you must also follow the conditions in section 3.
+
+
+
You may also lend copies, under the same conditions stated above, and
+you may publicly display copies.
+
3. COPYING IN QUANTITY
-
If you publish printed copies of the Document numbering more than 100, and
-the Document's license notice requires Cover Texts, you must enclose the copies
-in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover
-Texts on the front cover, and Back-Cover Texts on the back cover. Both covers
-must also clearly and legibly identify you as the publisher of these copies. The
-front cover must present the full title with all words of the title equally
-prominent and visible. You may add other material on the covers in addition.
-Copying with changes limited to the covers, as long as they preserve the title
-of the Document and satisfy these conditions, can be treated as verbatim copying
-in other respects.
-
If the required texts for either cover are too voluminous to fit legibly, you
-should put the first ones listed (as many as fit reasonably) on the actual
+
+
If you publish printed copies of the Document numbering more than 100,
+and the Document's license notice requires Cover Texts, you must enclose
+the copies in covers that carry, clearly and legibly, all these Cover Texts:
+Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover.
+Both covers must also clearly and legibly identify you as the publisher of
+these copies. The front cover must present the full title with all words
+of the title equally prominent and visible. You may add other material on
+the covers in addition. Copying with changes limited to the covers, as long
+as they preserve the title of the Document and satisfy these conditions,
+can be treated as verbatim copying in other respects.
+
+
If the required texts for either cover are too voluminous to fit legibly,
+you should put the first ones listed (as many as fit reasonably) on the actual
cover, and continue the rest onto adjacent pages.
-
If you publish or distribute Opaque copies of the Document numbering more
-than 100, you must either include a machine-readable Transparent copy along with
-each Opaque copy, or state in or with each Opaque copy a publicly-accessible
-computer-network location containing a complete Transparent copy of the
-Document, free of added material, which the general network-using public has
-access to download anonymously at no charge using public-standard network
-protocols. If you use the latter option, you must take reasonably prudent steps,
-when you begin distribution of Opaque copies in quantity, to ensure that this
-Transparent copy will remain thus accessible at the stated location until at
-least one year after the last time you distribute an Opaque copy (directly or
-through your agents or retailers) of that edition to the public.
-
It is requested, but not required, that you contact the authors of the
-Document well before redistributing any large number of copies, to give them a
-chance to provide you with an updated version of the Document.
+
+
If you publish or distribute Opaque copies of the Document numbering more
+than 100, you must either include a machine-readable Transparent copy along
+with each Opaque copy, or state in or with each Opaque copy a publicly-accessible
+computer-network location containing a complete Transparent copy of the Document,
+free of added material, which the general network-using public has access
+to download anonymously at no charge using public-standard network protocols.
+If you use the latter option, you must take reasonably prudent steps, when
+you begin distribution of Opaque copies in quantity, to ensure that this Transparent
+copy will remain thus accessible at the stated location until at least one
+year after the last time you distribute an Opaque copy (directly or through
+your agents or retailers) of that edition to the public.
+
+
It is requested, but not required, that you contact the authors of the
+Document well before redistributing any large number of copies, to give them
+a chance to provide you with an updated version of the Document.
+
4. MODIFICATIONS
-
You may copy and distribute a Modified Version of the Document under the
-conditions of sections 2 and 3 above, provided that you release the Modified
-Version under precisely this License, with the Modified Version filling the role
-of the Document, thus licensing distribution and modification of the Modified
-Version to whoever possesses a copy of it. In addition, you must do these things
-in the Modified Version:
-
+
+
You may copy and distribute a Modified Version of the Document under the
+conditions of sections 2 and 3 above, provided that you release the Modified
+Version under precisely this License, with the Modified Version filling the
+role of the Document, thus licensing distribution and modification of the
+Modified Version to whoever possesses a copy of it. In addition, you must
+do these things in the Modified Version:
+
+
+
-
A. Use in the Title Page (and on the covers, if any) a
- title distinct from that of the Document, and from those of previous versions
- (which should, if there were any, be listed in the History section of the
- Document). You may use the same title as a previous version if the original
- publisher of that version gives permission.
-
B. List on the Title Page, as authors, one or more
- persons or entities responsible for authorship of the modifications in the
- Modified Version, together with at least five of the principal authors of the
- Document (all of its principal authors, if it has less than five).
-
C. State on the Title page the name of the publisher of
- the Modified Version, as the publisher.
-
D. Preserve all the copyright notices of the Document.
+
A. Use in the Title Page (and on the covers, if any)
+a title distinct from that of the Document, and from those of previous
+versions (which should, if there were any, be listed in the History section
+of the Document). You may use the same title as a previous version if the
+original publisher of that version gives permission.
+
B. List on the Title Page, as authors, one or more
+ persons or entities responsible for authorship of the modifications in
+the Modified Version, together with at least five of the principal authors
+of the Document (all of its principal authors, if it has less than five).
-
E. Add an appropriate copyright notice for your
- modifications adjacent to the other copyright notices.
-
F. Include, immediately after the copyright notices, a
- license notice giving the public permission to use the Modified Version under
- the terms of this License, in the form shown in the Addendum below.
-
G. Preserve in that license notice the full lists of
- Invariant Sections and required Cover Texts given in the Document's license
- notice.
-
H. Include an unaltered copy of this License.
-
I. Preserve the section entitled "History", and its
- title, and add to it an item stating at least the title, year, new authors,
- and publisher of the Modified Version as given on the Title Page. If there is
- no section entitled "History" in the Document, create one stating the title,
- year, authors, and publisher of the Document as given on its Title Page, then
- add an item describing the Modified Version as stated in the previous
- sentence.
-
J. Preserve the network location, if any, given in the
- Document for public access to a Transparent copy of the Document, and likewise
- the network locations given in the Document for previous versions it was based
- on. These may be placed in the "History" section. You may omit a network
- location for a work that was published at least four years before the Document
- itself, or if the original publisher of the version it refers to gives
- permission.
-
K. In any section entitled "Acknowledgements" or
- "Dedications", preserve the section's title, and preserve in the section all
- the substance and tone of each of the contributor acknowledgements and/or
- dedications given therein.
-
L. Preserve all the Invariant Sections of the Document,
- unaltered in their text and in their titles. Section numbers or the equivalent
+
C. State on the Title page the name of the publisher
+of the Modified Version, as the publisher.
+
D. Preserve all the copyright notices of the Document.
+
+
E. Add an appropriate copyright notice for your
+ modifications adjacent to the other copyright notices.
+
F. Include, immediately after the copyright notices,
+a license notice giving the public permission to use the Modified Version
+under the terms of this License, in the form shown in the Addendum below.
+
+
G. Preserve in that license notice the full lists
+of Invariant Sections and required Cover Texts given in the Document's
+license notice.
+
H. Include an unaltered copy of this License.
+
I. Preserve the section entitled "History", and its
+ title, and add to it an item stating at least the title, year, new authors,
+ and publisher of the Modified Version as given on the Title Page. If there
+is no section entitled "History" in the Document, create one stating the
+title, year, authors, and publisher of the Document as given on its Title
+Page, then add an item describing the Modified Version as stated in the
+previous sentence.
+
J. Preserve the network location, if any, given in
+the Document for public access to a Transparent copy of the Document, and
+likewise the network locations given in the Document for previous versions
+it was based on. These may be placed in the "History" section. You may
+omit a network location for a work that was published at least four years
+before the Document itself, or if the original publisher of the version
+it refers to gives permission.
+
K. In any section entitled "Acknowledgements" or
+ "Dedications", preserve the section's title, and preserve in the section
+all the substance and tone of each of the contributor acknowledgements
+and/or dedications given therein.
+
L. Preserve all the Invariant Sections of the Document,
+ unaltered in their text and in their titles. Section numbers or the equivalent
are not considered part of the section titles.
-
M. Delete any section entitled "Endorsements". Such a
- section may not be included in the Modified Version.
-
N. Do not retitle any existing section as "Endorsements"
+
M. Delete any section entitled "Endorsements". Such
+a section may not be included in the Modified Version.
+
N. Do not retitle any existing section as "Endorsements"
or to conflict in title with any Invariant Section.
+
-
If the Modified Version includes new front-matter sections or appendices that
-qualify as Secondary Sections and contain no material copied from the Document,
-you may at your option designate some or all of these sections as invariant. To
-do this, add their titles to the list of Invariant Sections in the Modified
-Version's license notice. These titles must be distinct from any other section
-titles.
-
You may add a section entitled "Endorsements", provided it contains nothing
-but endorsements of your Modified Version by various parties--for example,
-statements of peer review or that the text has been approved by an organization
+
+
If the Modified Version includes new front-matter sections or appendices
+that qualify as Secondary Sections and contain no material copied from the
+Document, you may at your option designate some or all of these sections
+as invariant. To do this, add their titles to the list of Invariant Sections
+in the Modified Version's license notice. These titles must be distinct from
+any other section titles.
+
+
You may add a section entitled "Endorsements", provided it contains nothing
+but endorsements of your Modified Version by various parties--for example,
+statements of peer review or that the text has been approved by an organization
as the authoritative definition of a standard.
-
You may add a passage of up to five words as a Front-Cover Text, and a
-passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover
-Texts in the Modified Version. Only one passage of Front-Cover Text and one of
-Back-Cover Text may be added by (or through arrangements made by) any one
-entity. If the Document already includes a cover text for the same cover,
-previously added by you or by arrangement made by the same entity you are acting
-on behalf of, you may not add another; but you may replace the old one, on
-explicit permission from the previous publisher that added the old one.
-
The author(s) and publisher(s) of the Document do not by this License give
-permission to use their names for publicity for or to assert or imply
+
+
You may add a passage of up to five words as a Front-Cover Text, and a
+passage of up to 25 words as a Back-Cover Text, to the end of the list of
+Cover Texts in the Modified Version. Only one passage of Front-Cover Text
+and one of Back-Cover Text may be added by (or through arrangements made
+by) any one entity. If the Document already includes a cover text for the
+same cover, previously added by you or by arrangement made by the same entity
+you are acting on behalf of, you may not add another; but you may replace
+the old one, on explicit permission from the previous publisher that added
+the old one.
+
+
The author(s) and publisher(s) of the Document do not by this License
+give permission to use their names for publicity for or to assert or imply
endorsement of any Modified Version.
+
5. COMBINING DOCUMENTS
-
You may combine the Document with other documents released under this
-License, under the terms defined in section 4 above for modified versions,
-provided that you include in the combination all of the Invariant Sections of
-all of the original documents, unmodified, and list them all as Invariant
-Sections of your combined work in its license notice.
-
The combined work need only contain one copy of this License, and multiple
-identical Invariant Sections may be replaced with a single copy. If there are
-multiple Invariant Sections with the same name but different contents, make the
-title of each such section unique by adding at the end of it, in parentheses,
-the name of the original author or publisher of that section if known, or else a
-unique number. Make the same adjustment to the section titles in the list of
-Invariant Sections in the license notice of the combined work.
-
In the combination, you must combine any sections entitled "History" in the
-various original documents, forming one section entitled "History"; likewise
-combine any sections entitled "Acknowledgements", and any sections entitled
-"Dedications". You must delete all sections entitled "Endorsements."
+
+
You may combine the Document with other documents released under this License,
+under the terms defined in section 4 above for modified versions, provided
+that you include in the combination all of the Invariant Sections of all
+of the original documents, unmodified, and list them all as Invariant Sections
+of your combined work in its license notice.
+
+
The combined work need only contain one copy of this License, and multiple
+identical Invariant Sections may be replaced with a single copy. If there
+are multiple Invariant Sections with the same name but different contents,
+make the title of each such section unique by adding at the end of it, in
+parentheses, the name of the original author or publisher of that section
+if known, or else a unique number. Make the same adjustment to the section
+titles in the list of Invariant Sections in the license notice of the combined
+work.
+
+
In the combination, you must combine any sections entitled "History" in
+the various original documents, forming one section entitled "History"; likewise
+combine any sections entitled "Acknowledgements", and any sections entitled
+"Dedications". You must delete all sections entitled "Endorsements."
+
6. COLLECTIONS OF DOCUMENTS
-
You may make a collection consisting of the Document and other documents
-released under this License, and replace the individual copies of this License
-in the various documents with a single copy that is included in the collection,
-provided that you follow the rules of this License for verbatim copying of each
-of the documents in all other respects.
-
You may extract a single document from such a collection, and distribute it
-individually under this License, provided you insert a copy of this License into
-the extracted document, and follow this License in all other respects regarding
-verbatim copying of that document.
+
+
You may make a collection consisting of the Document and other documents
+released under this License, and replace the individual copies of this License
+in the various documents with a single copy that is included in the collection,
+provided that you follow the rules of this License for verbatim copying of
+each of the documents in all other respects.
+
+
You may extract a single document from such a collection, and distribute
+it individually under this License, provided you insert a copy of this License
+into the extracted document, and follow this License in all other respects
+regarding verbatim copying of that document.
+
7. AGGREGATION WITH INDEPENDENT WORKS
-
A compilation of the Document or its derivatives with other separate and
-independent documents or works, in or on a volume of a storage or distribution
-medium, does not as a whole count as a Modified Version of the Document,
-provided no compilation copyright is claimed for the compilation. Such a
-compilation is called an "aggregate", and this License does not apply to the
-other self-contained works thus compiled with the Document, on account of their
-being thus compiled, if they are not themselves derivative works of the
-Document.
-
If the Cover Text requirement of section 3 is applicable to these copies of
-the Document, then if the Document is less than one quarter of the entire
-aggregate, the Document's Cover Texts may be placed on covers that surround only
-the Document within the aggregate. Otherwise they must appear on covers around
-the whole aggregate.
+
+
A compilation of the Document or its derivatives with other separate and
+independent documents or works, in or on a volume of a storage or distribution
+medium, does not as a whole count as a Modified Version of the Document, provided
+no compilation copyright is claimed for the compilation. Such a compilation
+is called an "aggregate", and this License does not apply to the other self-contained
+works thus compiled with the Document, on account of their being thus compiled,
+if they are not themselves derivative works of the Document.
+
+
If the Cover Text requirement of section 3 is applicable to these copies
+of the Document, then if the Document is less than one quarter of the entire
+aggregate, the Document's Cover Texts may be placed on covers that surround
+only the Document within the aggregate. Otherwise they must appear on covers
+around the whole aggregate.
+
8. TRANSLATION
-
Translation is considered a kind of modification, so you may distribute
-translations of the Document under the terms of section 4. Replacing Invariant
-Sections with translations requires special permission from their copyright
-holders, but you may include translations of some or all Invariant Sections in
-addition to the original versions of these Invariant Sections. You may include a
-translation of this License provided that you also include the original English
-version of this License. In case of a disagreement between the translation and
-the original English version of this License, the original English version will
-prevail.
+
+
Translation is considered a kind of modification, so you may distribute
+translations of the Document under the terms of section 4. Replacing Invariant
+Sections with translations requires special permission from their copyright
+holders, but you may include translations of some or all Invariant Sections
+in addition to the original versions of these Invariant Sections. You may
+include a translation of this License provided that you also include the
+original English version of this License. In case of a disagreement between
+the translation and the original English version of this License, the original
+English version will prevail.
+
9. TERMINATION
-
You may not copy, modify, sublicense, or distribute the Document except as
-expressly provided for under this License. Any other attempt to copy, modify,
-sublicense or distribute the Document is void, and will automatically terminate
-your rights under this License. However, parties who have received copies, or
-rights, from you under this License will not have their licenses terminated so
-long as such parties remain in full compliance.
+
+
You may not copy, modify, sublicense, or distribute the Document except
+as expressly provided for under this License. Any other attempt to copy,
+modify, sublicense or distribute the Document is void, and will automatically
+terminate your rights under this License. However, parties who have received
+copies, or rights, from you under this License will not have their licenses
+terminated so long as such parties remain in full compliance.
+
10. FUTURE REVISIONS OF THIS LICENSE
-
The Free Software Foundation may publish new, revised versions of the GNU
-Free Documentation License from time to time. Such new versions will be similar
-in spirit to the present version, but may differ in detail to address new
-problems or concerns. See http://www.gnu.org/copyleft/.
-
Each version of the License is given a distinguishing version number. If the
-Document specifies that a particular numbered version of this License "or any
-later version" applies to it, you have the option of following the terms and
-conditions either of that specified version or of any later version that has
-been published (not as a draft) by the Free Software Foundation. If the Document
-does not specify a version number of this License, you may choose any version
-ever published (not as a draft) by the Free Software Foundation.
-
-
+
+
The Free Software Foundation may publish new, revised versions of the
+GNU Free Documentation License from time to time. Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns. See http://www.gnu.org/copyleft/.
+
+
Each version of the License is given a distinguishing version number.
+If the Document specifies that a particular numbered version of this License
+"or any later version" applies to it, you have the option of following the
+terms and conditions either of that specified version or of any later version
+that has been published (not as a draft) by the Free Software Foundation.
+If the Document does not specify a version number of this License, you may
+choose any version ever published (not as a draft) by the Free Software Foundation.
+
+
+
+
-
-
\ No newline at end of file
+
diff --git a/Shorewall-docs/IPIP.htm b/Shorewall-docs/IPIP.htm
index 02e4bd63c..28370194a 100644
--- a/Shorewall-docs/IPIP.htm
+++ b/Shorewall-docs/IPIP.htm
@@ -1,248 +1,249 @@
-
+
GRE/IPIP Tunnels
-
+
-
+
-
+
Warning: GRE and IPIP Tunnels are insecure
when used over the internet; use them at your own risk
-
-
GRE and IPIP tunneling with Shorewall can be used to bridge two masqueraded
+
+
GRE and IPIP tunneling with Shorewall can be used to bridge two masqueraded
networks.
-
-
The simple scripts described in the Linux
-Advanced Routing and Shaping HOWTO work fine with Shorewall. Shorewall
-also includes a tunnel script for automating tunnel configuration. If you
-have installed the RPM, the tunnel script may be found in the Shorewall documentation
+
+
The simple scripts described in the Linux
+Advanced Routing and Shaping HOWTO work fine with Shorewall. Shorewall
+also includes a tunnel script for automating tunnel configuration. If you
+have installed the RPM, the tunnel script may be found in the Shorewall documentation
directory (usually /usr/share/doc/shorewall-<version>/).
-
+
Bridging two Masqueraded Networks
-
+
Suppose that we have the following situation:
-
+
-
-
-
We want systems in the 192.168.1.0/24 subnetwork to be able
-to communicate with the systems in the 10.0.0.0/8 network. This is accomplished
-through use of the /etc/shorewall/tunnels file, the /etc/shorewall/policy
+
+
+
We want systems in the 192.168.1.0/24 subnetwork to be able
+to communicate with the systems in the 10.0.0.0/8 network. This is accomplished
+through use of the /etc/shorewall/tunnels file, the /etc/shorewall/policy
file and the /etc/shorewall/tunnel script that is included with Shorewall.
-
-
The 'tunnel' script is not installed in /etc/shorewall by
-default -- If you install using the tarball, the script is included in the
-tarball; if you install using the RPM, the file is in your Shorewall documentation
+
+
The 'tunnel' script is not installed in /etc/shorewall by
+default -- If you install using the tarball, the script is included in the
+tarball; if you install using the RPM, the file is in your Shorewall documentation
directory (normally /usr/share/doc/shorewall-<version>).
-
-
In the /etc/shorewall/tunnel script, set the 'tunnel_type'
+
+
In the /etc/shorewall/tunnel script, set the 'tunnel_type'
parameter to the type of tunnel that you want to create.
-
+
Example:
-
-
+
+
tunnel_type=gre
-
-
-
On each firewall, you will need to declare a zone to represent
- the remote subnet. We'll assume that this zone is called 'vpn' and declare
+
+
+
On each firewall, you will need to declare a zone to represent
+ the remote subnet. We'll assume that this zone is called 'vpn' and declare
it in /etc/shorewall/zones on both systems as follows.
-
-
+
+
-
+
+
+
ZONE
+
DISPLAY
+
COMMENTS
+
+
+
vpn
+
VPN
+
Remote Subnet
+
+
+
+
+
+
+
On system A, the 10.0.0.0/8 will comprise the vpn zone.
+In /etc/shorewall/interfaces:
+
+
+
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
-
ZONE
-
DISPLAY
-
COMMENTS
-
-
-
vpn
-
VPN
-
Remote Subnet
-
-
-
+
vpn
+
tosysb
+
10.255.255.255
+
+
+
+
-
-
On system A, the 10.0.0.0/8 will comprise the vpn
-zone. In /etc/shorewall/interfaces:
-
-
-
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
vpn
-
tosysb
-
10.255.255.255
-
-
-
-
-
-
-
+
In /etc/shorewall/tunnels on system A, we need the following:
-
-
+
+
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
ipip
-
net
-
134.28.54.2
-
-
-
-
+
ipip
+
net
+
134.28.54.2
+
+
+
+
-
-
-
This entry in /etc/shorewall/tunnels, opens the firewall so that the IP
+
+
+
This entry in /etc/shorewall/tunnels, opens the firewall so that the IP
encapsulation protocol (4) will be accepted to/from the remote gateway.
Similarly, On system B the 192.168.1.0/24 subnet will comprise the vpn
+ myrealip=206.161.148.9 (for GRE tunnel only)
+ myip=192.168.1.1
+ hisip=10.0.0.1
+ gateway=134.28.54.2
+ subnet=10.0.0.0/8
+
+
+
Similarly, On system B the 192.168.1.0/24 subnet will comprise the vpn
zone. In /etc/shorewall/interfaces:
You can rename the modified tunnel scripts if you like; be sure that they
+ myrealip=134.28.54.2 (for GRE tunnel only)
+ myip=10.0.0.1
+ hisip=192.168.1.1
+ gateway=206.191.148.9
+ subnet=192.168.1.0/24
+
+
+
You can rename the modified tunnel scripts if you like; be sure that they
are secured so that root can execute them.
-
-
You will need to allow traffic between the "vpn" zone and
- the "loc" zone on both systems -- if you simply want to admit all
-traffic in both directions, you can use the policy file:
-
-
+
+
You will need to allow traffic between the "vpn" zone and
+ the "loc" zone on both systems -- if you simply want to admit all traffic
+ in both directions, you can use the policy file:
+
+
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG LEVEL
-
-
-
loc
-
vpn
-
ACCEPT
-
-
-
-
vpn
-
loc
-
ACCEPT
-
-
-
-
+
+
+
SOURCE
+
DEST
+
POLICY
+
LOG LEVEL
+
+
+
loc
+
vpn
+
ACCEPT
+
+
+
+
vpn
+
loc
+
ACCEPT
+
+
+
+
-
-
-
On both systems, restart Shorewall and run the modified tunnel script
-with the "start" argument on each system. The systems in the two masqueraded
-subnetworks can now talk to each other
On both systems, restart Shorewall and run the modified tunnel script with
+the "start" argument on each system. The systems in the two masqueraded subnetworks
+can now talk to each other
- There is an excellent guide to configuring IPSEC tunnels at http://www.geocities.com/jixen66/
- . I highly recommend that you consult that site for information about configuring
- FreeS/Wan.
-
Warning: Do not use Proxy ARP and
- FreeS/Wan on the same system unless you are prepared to suffer the consequences.
- If you start or restart Shorewall with an IPSEC tunnel active, the proxied
- IP addresses are mistakenly assigned to the IPSEC tunnel device (ipsecX)
- rather than to the interface that you specify in the INTERFACE column
-of /etc/shorewall/proxyarp. I haven't had the time to debug this problem
-so I can't say if it is a bug in the Kernel or in FreeS/Wan.
-
-
You might be able to work around this problem using the following
+ There is an excellent guide to configuring IPSEC tunnels at http://www.geocities.com/jixen66/
+ . I highly recommend that you consult that site for information about configuring
+ FreeS/Wan.
+
Warning: Do not use Proxy ARP and
+ FreeS/Wan on the same system unless you are prepared to suffer the consequences.
+ If you start or restart Shorewall with an IPSEC tunnel active, the proxied
+ IP addresses are mistakenly assigned to the IPSEC tunnel device (ipsecX)
+ rather than to the interface that you specify in the INTERFACE column of
+ /etc/shorewall/proxyarp. I haven't had the time to debug this problem so
+ I can't say if it is a bug in the Kernel or in FreeS/Wan.
+
+
You might be able to work around this problem using the following
(I haven't tried it):
-
+
In /etc/shorewall/init, include:
-
+
qt service ipsec stop
-
+
In /etc/shorewall/start, include:
-
+
qt service ipsec start
-
+
IPSec Gateway on the Firewall System
-
+
Suppose that we have the following sutuation:
-
+
-
-
-
We want systems in the 192.168.1.0/24 sub-network to be able
+
+
+
We want systems in the 192.168.1.0/24 sub-network to be able
to communicate with systems in the 10.0.0.0/8 network.
-
+
To make this work, we need to do two things:
-
-
a) Open the firewall so that the IPSEC tunnel can be established
+
+
a) Open the firewall so that the IPSEC tunnel can be established
(allow the ESP and AH protocols and UDP Port 500).
-
+
b) Allow traffic through the tunnel.
-
-
Opening the firewall for the IPSEC tunnel is accomplished
+
+
Opening the firewall for the IPSEC tunnel is accomplished
by adding an entry to the /etc/shorewall/tunnels file.
-
+
In /etc/shorewall/tunnels on system A, we need the following
-
-
+
+
-
-
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
ipsec
-
net
-
134.28.54.2
-
-
-
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
+
+
ipsec
+
net
+
134.28.54.2
+
+
+
+
-
-
+
+
In /etc/shorewall/tunnels on system B, we would have:
-
-
+
+
-
-
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
ipsec
-
net
-
206.161.148.9
-
-
-
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
+
+
ipsec
+
net
+
206.161.148.9
+
+
+
+
-
-
-
Note: If either of the endpoints is behind a NAT gateway
- then the tunnels file entry on the other endpoint should
-specify a tunnel type of ipsecnat rather than ipsec and the
-GATEWAY address should specify the external address of the NAT gateway.
-
-
-
You need to define a zone for the remote subnet or include
- it in your local zone. In this example, we'll assume that you have
+
+
+
Note: If either of the endpoints is behind a NAT gateway
+ then the tunnels file entry on the other endpoint should specify
+ a tunnel type of ipsecnat rather than ipsec and the GATEWAY
+ address should specify the external address of the NAT gateway.
+
+
+
You need to define a zone for the remote subnet or include
+ it in your local zone. In this example, we'll assume that you have
created a zone called "vpn" to represent the remote subnet.
-
-
+
+
-
-
-
ZONE
-
DISPLAY
-
COMMENTS
-
-
-
vpn
-
VPN
-
Remote Subnet
-
-
-
+
+
+
ZONE
+
DISPLAY
+
COMMENTS
+
+
+
vpn
+
VPN
+
Remote Subnet
+
+
+
-
-
-
At both systems, ipsec0 would be included in /etc/shorewall/interfaces
+
+
+
At both systems, ipsec0 would be included in /etc/shorewall/interfaces
as a "vpn" interface:
-
-
+
+
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
vpn
-
ipsec0
-
-
-
-
-
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
+
+
vpn
+
ipsec0
+
+
+
+
+
-
-
-
You will need to allow traffic between the "vpn" zone and
- the "loc" zone -- if you simply want to admit all traffic in both
+
+
+
You will need to allow traffic between the "vpn" zone and
+ the "loc" zone -- if you simply want to admit all traffic in both
directions, you can use the policy file:
-
-
+
+
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG LEVEL
-
-
-
loc
-
vpn
-
ACCEPT
-
-
-
-
vpn
-
loc
-
ACCEPT
-
-
-
-
+
+
+
SOURCE
+
DEST
+
POLICY
+
LOG LEVEL
+
+
+
loc
+
vpn
+
ACCEPT
+
+
+
+
vpn
+
loc
+
ACCEPT
+
+
+
+
-
-
-
Once you have these entries in place, restart Shorewall (type
-shorewall restart); you are now ready to configure the tunnel in
+
+
- Shorewall can be used in a VPN Hub environment where multiple remote networks
-are connected to a gateway running Shorewall. This environment is shown in
-this diatram.
-
+ Shorewall can be used in a VPN Hub environment where multiple remote networks
+ are connected to a gateway running Shorewall. This environment is shown
+in this diatram.
+
-
-
-
-
We want systems in the 192.168.1.0/24 sub-network to be able
- to communicate with systems in the 10.0.0.0/16 and 10.1.0.0/16 networks
-and we want the 10.0.0.0/16 and 10.1.0.0/16 networks to be able to communicate.
-
+
+
+
+
We want systems in the 192.168.1.0/24 sub-network to be able
+ to communicate with systems in the 10.0.0.0/16 and 10.1.0.0/16 networks
+ and we want the 10.0.0.0/16 and 10.1.0.0/16 networks to be able to communicate.
+
To make this work, we need to do several things:
-
-
a) Open the firewall so that two IPSEC tunnels can be established
+
+
a) Open the firewall so that two IPSEC tunnels can be established
(allow the ESP and AH protocols and UDP Port 500).
-
-
b) Allow traffic through the tunnels two/from the local zone
-(192.168.1.0/24).
-
-
-
c) Deny traffic through the tunnels between the two remote
-networks.
-
-
-
Opening the firewall for the IPSEC tunnels is accomplished
+
+
b) Allow traffic through the tunnels two/from the local zone
+ (192.168.1.0/24).
+
+
+
c) Deny traffic through the tunnels between the two remote
+ networks.
+
+
+
Opening the firewall for the IPSEC tunnels is accomplished
by adding two entries to the /etc/shorewall/tunnels file.
-
+
In /etc/shorewall/tunnels on system A, we need the following
-
-
+
+
-
-
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
ipsec
-
-
net
-
134.28.54.2
-
-
-
-
ipsec
-
-
net
-
-
130.152.100.14
-
-
-
-
-
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
+
+
ipsec
+
+
net
+
134.28.54.2
+
+
+
+
ipsec
+
+
net
+
+
130.152.100.14
+
+
+
+
+
+
-
-
+
+
In /etc/shorewall/tunnels on systems B and C, we would have:
-
-
+
+
-
-
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
ipsec
-
net
-
206.161.148.9
-
-
-
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
+
+
ipsec
+
net
+
206.161.148.9
+
+
+
+
-
-
+
+
-
-
Note: If either of the endpoints is behind a NAT gateway
- then the tunnels file entry on the other endpoint should
-specify a tunnel type of ipsecnat rather than ipsec
- and the GATEWAY address should specify the external address of the
-NAT gateway.
-
-
-
On each system, we will create a zone to represent the remote
-networks. On System A:
-
-
-
-
-
-
-
ZONE
-
DISPLAY
-
COMMENTS
-
-
-
vpn1
-
VPN1
-
Remote Subnet on system B
-
-
-
vpn2
-
-
VPN2
-
-
Remote Subnet on system C
-
-
-
-
-
-
-
-
On systems B and C:
-
-
-
-
-
-
-
ZONE
-
DISPLAY
-
COMMENTS
-
-
-
vpn
-
VPN
-
Remote Subnet on system A
-
-
-
-
-
-
-
At system A, ipsec0 represents two zones so we have the following
-in /etc/shorewall/interfaces:
-
-
-
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
-
-
-
ipsec0
-
-
-
-
-
-
-
-
-
-
The /etc/shorewall/hosts file on system A defines the two
-VPN zones:
-
-
-
-
-
-
-
ZONE
-
HOSTS
-
-
OPTIONS
-
-
-
vpn1
-
-
ipsec0:10.0.0.0/16
-
-
-
-
-
vpn2
-
-
ipsec0:10.1.0.0/16
-
-
-
-
-
-
-
-
-
-
At systems B and C, ipsec0 represents a single zone so we
-have the following in /etc/shorewall/interfaces:
-
-
-
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
vpn
-
-
ipsec0
-
-
-
-
-
-
-
-
-
On systems A, you will need to allow traffic between the "vpn1"
-zone and the "loc" zone as well as between "vpn2" and the "loc" zone
--- if you simply want to admit all traffic in both directions, you
-can use the following policy file entries on all three gateways:
-
-
-
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG LEVEL
-
-
-
loc
-
vpn1
-
ACCEPT
-
-
-
-
vpn1
-
loc
-
ACCEPT
-
-
-
-
loc
-
-
vpn2
-
-
ACCEPT
-
-
-
-
-
-
vpn2
-
-
loc
-
-
ACCEPT
-
-
-
-
+
Note: If either of the endpoints is behind a NAT gateway
+ then the tunnels file entry on the other endpoint should specify
+ a tunnel type of ipsecnat rather than ipsec
+ and the GATEWAY address should specify the external address of the
+ NAT gateway.
+
-
-
-
-
On systems B and C, you will need to allow traffic between
-the "vpn" zone and the "loc" zone -- if you simply want to admit all
-traffic in both directions, you can use the following policy file entries
-on all three gateways:
-
-
-
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG LEVEL
-
-
-
loc
-
vpn
-
ACCEPT
-
-
-
-
vpn
-
loc
-
ACCEPT
-
-
-
-
-
-
-
-
Once you have the Shorewall entries added, restart Shorewall
-on each gateway (type shorewall restart); you are now ready to configure
-the tunnels in FreeS/WAN
- .
- Note that to allow traffic between the networks attached to systems B and
-C, it is necessary to simply add two additional entries to the /etc/shorewall/policy
-file on system A.
-
-
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG LEVEL
-
-
-
vpn1
-
-
vpn2
-
ACCEPT
-
-
-
-
vpn2
-
vpn1
-
-
ACCEPT
-
-
-
-
-
-
-
-
-
Mobile System
-(Road Warrior)
-
-
Suppose that you have a laptop system (B) that you take with you when you
-travel and you want to be able to establish a secure connection back to your
-local network.
-
-
-
-
-
-
You need to define a zone for the laptop or include it in
- your local zone. In this example, we'll assume that you have created
- a zone called "vpn" to represent the remote host.
-
-
-
-
-
-
ZONE
-
DISPLAY
-
COMMENTS
-
-
-
vpn
-
VPN
-
Remote Subnet
-
-
-
-
-
-
-
In this instance, the mobile system (B) has IP address 134.28.54.2
- but that cannot be determined in advance. In the /etc/shorewall/tunnels
-file on system A, the following entry should be made:
-
-
-
-
-
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
ipsec
-
net
-
0.0.0.0/0
-
vpn
-
-
-
-
-
-
-
Note that the GATEWAY ZONE column contains the name of the zone corresponding
- to peer subnetworks. This indicates that the gateway system itself comprises
- the peer subnetwork; in other words, the remote gateway is a standalone
-system.
-
-
You will need to configure /etc/shorewall/interfaces and establish
- your "through the tunnel" policy as shown under the first example above.
+
On each system, we will create a zone to represent the remote
+ networks. On System A:
-
-
Dynamic RoadWarrior Zones
- Beginning with Shorewall release 1.3.10, you can define multiple VPN
-zones and add and delete remote endpoints dynamically using /sbin/shorewall.
-In /etc/shorewall/zones:
-
-
-
-
-
-
-
ZONE
-
-
DISPLAY
-
-
COMMENTS
-
-
-
-
vpn1
-
-
VPN-1
-
-
First VPN Zone
-
-
-
-
vpn2
-
-
VPN-2
-
-
Second VPN Zone
-
-
-
-
vpn3
-
-
VPN-3
-
-
Third VPN Zone
-
-
-
-
+
+
+
+
+
+
ZONE
+
DISPLAY
+
COMMENTS
+
+
+
vpn1
+
VPN1
+
Remote Subnet on system B
+
+
+
vpn2
+
+
VPN2
+
+
Remote Subnet on system C
+
+
+
+
-
-
- In /etc/shorewall/tunnels:
-
-
+
+
+
On systems B and C:
+
+
+
+
+
+
+
ZONE
+
DISPLAY
+
COMMENTS
+
+
+
vpn
+
VPN
+
Remote Subnet on system A
+
+
+
+
+
+
+
At system A, ipsec0 represents two zones so we have the following
+ in /etc/shorewall/interfaces:
+
+
+
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
+
+
-
+
+
ipsec0
+
+
+
+
+
+
+
+
+
+
The /etc/shorewall/hosts file on system A defines the two
+ VPN zones:
+
+
+
+
+
+
+
ZONE
+
HOSTS
+
+
OPTIONS
+
+
+
vpn1
+
+
ipsec0:10.0.0.0/16
+
+
+
+
+
vpn2
+
+
ipsec0:10.1.0.0/16
+
+
+
+
+
+
+
+
+
+
At systems B and C, ipsec0 represents a single zone so we
+ have the following in /etc/shorewall/interfaces:
+
+
+
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
+
+
vpn
+
+
ipsec0
+
+
+
+
+
+
+
+
+
+
+
On systems A, you will need to allow traffic between the
+"vpn1" zone and the "loc" zone as well as between "vpn2" and the
+"loc" zone -- if you simply want to admit all traffic in both directions,
+you can use the following policy file entries on all three gateways:
+
+
+
+
+
+
SOURCE
+
DEST
+
POLICY
+
LOG LEVEL
+
+
+
loc
+
vpn1
+
ACCEPT
+
+
+
+
vpn1
+
loc
+
ACCEPT
+
+
+
+
loc
+
+
vpn2
+
+
ACCEPT
+
+
+
+
+
+
vpn2
+
+
loc
+
+
ACCEPT
+
+
+
+
+
+
+
+
+
+
On systems B and C, you will need to allow traffic between
+ the "vpn" zone and the "loc" zone -- if you simply want to admit
+all traffic in both directions, you can use the following policy file
+entries on all three gateways:
+
+
+
+
+
+
SOURCE
+
DEST
+
POLICY
+
LOG LEVEL
+
+
+
loc
+
vpn
+
ACCEPT
+
+
+
+
vpn
+
loc
+
ACCEPT
+
+
+
+
+
+
+
+
Once you have the Shorewall entries added, restart Shorewall
+ on each gateway (type shorewall restart); you are now ready to configure
+ the tunnels in FreeS/WAN
+ .
+ Note that to allow traffic between the networks attached to systems B and
+ C, it is necessary to simply add two additional entries to the /etc/shorewall/policy
+ file on system A.
+
+
+
+
+
+
SOURCE
+
DEST
+
POLICY
+
LOG LEVEL
+
+
+
vpn1
+
+
vpn2
+
ACCEPT
+
+
+
+
vpn2
+
vpn1
+
+
ACCEPT
+
+
+
+
+
+
+
+
+
Mobile System
+ (Road Warrior)
+
+
Suppose that you have a laptop system (B) that you take with you when
+you travel and you want to be able to establish a secure connection back
+to your local network.
+
+
+
+
+
+
You need to define a zone for the laptop or include it in
+ your local zone. In this example, we'll assume that you have created
+ a zone called "vpn" to represent the remote host.
+
+
+
+
+
+
ZONE
+
DISPLAY
+
COMMENTS
+
+
+
vpn
+
VPN
+
Remote Subnet
+
+
+
+
+
+
+
In this instance, the mobile system (B) has IP address 134.28.54.2
+ but that cannot be determined in advance. In the /etc/shorewall/tunnels
+file on system A, the following entry should be made:
+
+
+
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
+
+
ipsec
+
net
+
0.0.0.0/0
+
vpn
+
+
+
+
+
+
+
Note that the GATEWAY ZONE column contains the name of the zone corresponding
+ to peer subnetworks. This indicates that the gateway system itself comprises
+ the peer subnetwork; in other words, the remote gateway is a standalone
+system.
+
+
You will need to configure /etc/shorewall/interfaces and establish
+ your "through the tunnel" policy as shown under the first example above.
+
+
+
Dynamic RoadWarrior Zones
+ Beginning with Shorewall release 1.3.10, you can define multiple VPN
+ zones and add and delete remote endpoints dynamically using /sbin/shorewall.
+ In /etc/shorewall/zones:
+
+
+
+
+
+
+
ZONE
+
+
DISPLAY
+
+
COMMENTS
+
+
+
+
vpn1
+
+
VPN-1
+
+
First VPN Zone
+
+
+
+
vpn2
+
+
VPN-2
+
+
Second VPN Zone
+
+
+
+
vpn3
+
+
VPN-3
+
+
Third VPN Zone
+
+
+
+
+
+
+
+ In /etc/shorewall/tunnels:
+
+
-
-
-
TYPE
-
-
ZONE
-
-
GATEWAY
-
-
GATEWAY ZONE
-
-
-
-
ipsec
-
-
net
-
-
0.0.0.0/0
-
-
vpn1,vpn2,vpn3
-
-
-
-
+
+
+
TYPE
+
+
ZONE
+
+
GATEWAY
+
+
GATEWAY ZONE
+
+
+
+
ipsec
+
+
net
+
+
0.0.0.0/0
+
+
vpn1,vpn2,vpn3
+
+
+
+
-
-
- When Shorewall is started, the zones vpn[1-3] will all be empty and
-Shorewall will issue warnings to that effect. These warnings may be safely
-ignored. FreeS/Wan may now be configured to have three different Road Warrior
-connections with the choice of connection being based on X-509 certificates
-or some other means. Each of these connectioins will utilize a different
-updown script that adds the remote station to the appropriate zone when the
-connection comes up and that deletes the remote station when the connection
-comes down. For example, when 134.28.54.2 connects for the vpn2 zone the
+
+
+ When Shorewall is started, the zones vpn[1-3] will all be empty and
+Shorewall will issue warnings to that effect. These warnings may be safely
+ignored. FreeS/Wan may now be configured to have three different Road Warrior
+connections with the choice of connection being based on X-509 certificates
+or some other means. Each of these connectioins will utilize a different
+updown script that adds the remote station to the appropriate zone when the
+connection comes up and that deletes the remote station when the connection
+comes down. For example, when 134.28.54.2 connects for the vpn2 zone the
'up' part of the script will issue the command":
-
-
+
+
/sbin/shorewall add ipsec0:134.28.54.2 vpn2
-
- and the 'down' part will:
-
+
+ and the 'down' part will:
+
/sbin/shorewall delete ipsec0:134.28.54.2 vpn
-
-
-
+
+
+
Limitations of Dynamic Zones
- If you include a dynamic zone in the exclude list of a DNAT rule, the dynamically-added
- hosts are not excluded from the rule.
-
- Example with dyn=dynamic zone:
-
-
-
+ If you include a dynamic zone in the exclude list of a DNAT rule, the
+dynamically-added hosts are not excluded from the rule.
+
+ Example with dyn=dynamic zone:
+
+
+
-
-
-
ACTION
-
-
SOURCE
-
-
DESTINATION
-
-
PROTOCOL
-
-
PORT(S)
-
-
CLIENT
- PORT(S)
-
-
ORIGINAL
- DESTINATION
-
-
-
-
DNAT
-
-
z:dyn
-
-
loc:192.168.1.3
-
-
tcp
-
-
80
-
-
-
-
-
-
-
-
+
+
+
ACTION
+
+
SOURCE
+
+
DESTINATION
+
+
PROTOCOL
+
+
PORT(S)
+
+
CLIENT
+ PORT(S)
+
+
ORIGINAL
+ DESTINATION
+
+
+
+
DNAT
+
+
z:dyn
+
+
loc:192.168.1.3
+
+
tcp
+
+
80
+
+
+
+
+
+
+
+
-
- Dynamic changes to the zone dyn will have no effect on the above
-rule.
+
+ Dynamic changes to the zone dyn will have no effect on the above
+ rule.
Before attempting installation, I strongly urge you to
-read and print a copy of the Shorewall QuickStart Guide
- for the configuration that most closely matches your own.
-
-
+
+
+
Before attempting installation, I strongly urge you
+to read and print a copy of the Shorewall QuickStart Guide
+ for the configuration that most closely matches your own.
+
If you have RedHat 7.2 and are running iptables version 1.2.3 (at a
- shell prompt, type "/sbin/iptables --version"), you must upgrade to
-version 1.2.4 either from the RedHat update
- site or from the Shorewall Errata page
-before attempting to start Shorewall.
-
+
+
If you have RedHat 7.2 and are running iptables version 1.2.3 (at a
+ shell prompt, type "/sbin/iptables --version"), you must upgrade to version
+ 1.2.4 either from the RedHat update
+ site or from the Shorewall Errata page before
+ attempting to start Shorewall.
+
-
Install the RPM (rpm -ivh <shorewall rpm>).
-
- Note1: Some SuSE users have encountered a problem whereby
- rpm reports a conflict with kernel <= 2.2 even though a 2.4 kernel
- is installed. If this happens, simply use the --nodeps option to rpm
+
Install the RPM (rpm -ivh <shorewall rpm>).
+
+ Note1: Some SuSE users have encountered a problem whereby
+ rpm reports a conflict with kernel <= 2.2 even though a 2.4 kernel
+ is installed. If this happens, simply use the --nodeps option to rpm
(rpm -ivh --nodeps <shorewall rpm>.
-
- Note2: Beginning with Shorewall 1.4.0, Shorewall is dependent
- on the iproute package. Unfortunately, some distributions call this package
- iproute2 which will cause the installation of Shorewall to fail with the
- diagnostic:
-
- error: failed dependencies:iproute is needed by shorewall-1.4.x-1
-
- This may be worked around by using the --nodeps option of rpm (rpm -ivh
- --nodeps <shorewall rpm>).
-
-
-
Edit the configuration files
-to match your configuration. WARNING - YOU CAN
- NOT SIMPLY INSTALL THE RPM AND ISSUE A "shorewall start" COMMAND.
-SOME CONFIGURATION IS REQUIRED BEFORE THE FIREWALL WILL START. IF YOU
-ISSUE A "start" COMMAND AND THE FIREWALL FAILS TO START, YOUR SYSTEM WILL
-NO LONGER ACCEPT ANY NETWORK TRAFFIC. IF THIS HAPPENS, ISSUE A "shorewall
-clear" COMMAND TO RESTORE NETWORK CONNECTIVITY.
-
Start the firewall by typing "shorewall start"
-
+ Note2: Beginning with Shorewall 1.4.0, Shorewall is dependent
+ on the iproute package. Unfortunately, some distributions call this package
+ iproute2 which will cause the installation of Shorewall to fail with the
+ diagnostic:
+
+ error: failed dependencies:iproute is needed by shorewall-1.4.x-1
+
+
+ This may be worked around by using the --nodeps option of rpm (rpm -ivh
+ --nodeps <shorewall rpm>).
+
+
+
Edit the configuration files
+ to match your configuration. WARNING - YOU CAN
+ NOT SIMPLY INSTALL THE RPM AND ISSUE A "shorewall start"
+COMMAND. SOME CONFIGURATION IS REQUIRED BEFORE THE FIREWALL WILL START.
+IF YOU ISSUE A "start" COMMAND AND THE FIREWALL FAILS TO START, YOUR
+SYSTEM WILL NO LONGER ACCEPT ANY NETWORK TRAFFIC. IF THIS HAPPENS, ISSUE
+A "shorewall clear" COMMAND TO RESTORE NETWORK CONNECTIVITY.
+
Start the firewall by typing "shorewall start"
+
-
-
To install Shorewall using the tarball
+
+
To install Shorewall using the tarball
and install script:
-
+
-
unpack the tarball (tar -zxf shorewall-x.y.z.tgz).
-
cd to the shorewall directory (the version is encoded in
+
unpack the tarball (tar -zxf shorewall-x.y.z.tgz).
+
cd to the shorewall directory (the version is encoded in
the directory name as in "shorewall-1.1.10").
If the install script was unable to configure Shorewall
+to be started automatically at boot, see these instructions.
-
+
-
-
To install my version of Shorewall on a fresh Bering
- disk, simply replace the "shorwall.lrp" file on the image with the file
- that you downloaded. See the two-interface QuickStart
- Guide for information about further steps required.
-
-
If you already have the Shorewall RPM installed
+
+
To install my version of Shorewall on a fresh Bering
+ disk, simply replace the "shorwall.lrp" file on the image with the file
+ that you downloaded. See the two-interface
+QuickStart Guide for information about further steps required.
+
+
If you already have the Shorewall RPM installed
and are upgrading to a new version:
-
-
If you are upgrading from a 1.2 version of Shorewall to a 1.4 version
-or and you have entries in the /etc/shorewall/hosts file then please check
- your /etc/shorewall/interfaces file to be sure that it contains an entry
- for each interface mentioned in the hosts file. Also, there are certain
- 1.2 rule forms that are no longer supported under 1.4 (you must use the
- new 1.4 syntax). See the upgrade issues for
- details.
-
+
+
If you are upgrading from a 1.2 version of Shorewall to a 1.4 version or
+and you have entries in the /etc/shorewall/hosts file then please check
+your /etc/shorewall/interfaces file to be sure that it contains an entry
+ for each interface mentioned in the hosts file. Also, there are certain
+ 1.2 rule forms that are no longer supported under 1.4 (you must use the
+ new 1.4 syntax). See the upgrade issues for
+ details.
+
-
Upgrade the RPM (rpm -Uvh <shorewall rpm file>) Note:
- If you are installing version 1.2.0 and have one of the 1.2.0
- Beta RPMs installed, you must use the "--oldpackage" option to rpm
-(e.g., "rpm -Uvh --oldpackage shorewall-1.2-0.noarch.rpm").
-
-
Note1: Some SuSE users have encountered a problem whereby
- rpm reports a conflict with kernel <= 2.2 even though a 2.4 kernel
- is installed. If this happens, simply use the --nodeps option to rpm
- (rpm -Uvh --nodeps <shorewall rpm>).
+
Upgrade the RPM (rpm -Uvh <shorewall rpm file>) Note:
+ If you are installing version 1.2.0 and have one of the 1.2.0
+ Beta RPMs installed, you must use the "--oldpackage" option to rpm
+(e.g., "rpm -Uvh --oldpackage shorewall-1.2-0.noarch.rpm").
+
+
Note1: Some SuSE users have encountered a problem whereby
+ rpm reports a conflict with kernel <= 2.2 even though a 2.4 kernel
+ is installed. If this happens, simply use the --nodeps option to rpm
+ (rpm -Uvh --nodeps <shorewall rpm>).
+
+ Note3: Beginning with Shorewall 1.4.0, Shorewall is dependent
+ on the iproute package. Unfortunately, some distributions call this package
+ iproute2 which will cause the upgrade of Shorewall to fail with the diagnostic:
- Note3: Beginning with Shorewall 1.4.0, Shorewall is dependent
- on the iproute package. Unfortunately, some distributions call this package
- iproute2 which will cause the upgrade of Shorewall to fail with the diagnostic:
-
- error: failed dependencies:iproute is needed by shorewall-1.4.0-1
+ error: failed dependencies:iproute is needed by shorewall-1.4.0-1
-
- This may be worked around by using the --nodeps option of rpm (rpm -Uvh
- --nodeps <shorewall rpm>).
-
-
See if there are any incompatibilities between your configuration
- and the new Shorewall version (type "shorewall check") and correct
-as necessary.
-
Restart the firewall (shorewall restart).
-
+
+ This may be worked around by using the --nodeps option of rpm (rpm
+-Uvh --nodeps <shorewall rpm>).
+
+
See if there are any incompatibilities between your configuration
+ and the new Shorewall version (type "shorewall check") and correct as
+ necessary.
+
Restart the firewall (shorewall restart).
+
-
-
If you already have Shorewall installed and
-are upgrading to a new version using the tarball:
-
-
If you are upgrading from a 1.2 version of Shorewall to a 1.4 version and
-you have entries in the /etc/shorewall/hosts file then please check your
- /etc/shorewall/interfaces file to be sure that it contains an entry for
-each interface mentioned in the hosts file. Also, there are certain 1.2
-rule forms that are no longer supported under 1.4 (you must use the new
-1.4 syntax). See the upgrade issues for
-details.
-
+
+
If you already have Shorewall installed
+and are upgrading to a new version using the tarball:
+
+
If you are upgrading from a 1.2 version of Shorewall to a 1.4 version
+and you have entries in the /etc/shorewall/hosts file then please check
+your /etc/shorewall/interfaces file to be sure that it contains an entry
+for each interface mentioned in the hosts file. Also, there are certain
+1.2 rule forms that are no longer supported under 1.4 (you must use the
+new 1.4 syntax). See the upgrade issues
+for details.
+
-
unpack the tarball (tar -zxf shorewall-x.y.z.tgz).
-
cd to the shorewall directory (the version is encoded in
+
unpack the tarball (tar -zxf shorewall-x.y.z.tgz).
+
cd to the shorewall directory (the version is encoded in
the directory name as in "shorewall-3.0.1").
If you are using SuSe then
- type "./install.sh /etc/init.d"
-
If your distribution has directory /etc/rc.d/init.d
+
If you are using SuSe
+then type "./install.sh /etc/init.d"
+
If your distribution has directory /etc/rc.d/init.d
or /etc/init.d then type "./install.sh"
-
For other distributions, determine where your
- distribution installs init scripts and type "./install.sh
-<init script directory>
-
See if there are any incompatibilities between your configuration
- and the new Shorewall version (type "shorewall check") and correct
-as necessary.
-
Restart the firewall by typing "shorewall restart"
-
+
For other distributions, determine where your
+ distribution installs init scripts and type "./install.sh
+ <init script directory>
+
See if there are any incompatibilities between your configuration
+ and the new Shorewall version (type "shorewall check") and correct as
+ necessary.
+
Restart the firewall by typing "shorewall restart"
+
- If you already have a running Bering
- installation and wish to upgrade to a later version of Shorewall:
-
- UNDER CONSTRUCTION...
-
+ If you already have a running
+Bering installation and wish to upgrade to a later version of Shorewall:
+
+ UNDER CONSTRUCTION...
+
Configuring Shorewall
-
-
You will need to edit some or all of the configuration files to match
-your setup. In most cases, the Shorewall
+
+
-
- All traffic from an interface or from a subnet on an interface
- can be verified to originate from a defined set of MAC addresses. Furthermore,
- each MAC address may be optionally associated with one or more IP addresses.
-
-
- Your kernel must include MAC match support (CONFIG_IP_NF_MATCH_MAC
- - module name ipt_mac.o).
-
- There are four components to this facility.
-
-
-
The maclist interface option in /etc/shorewall/interfaces. When this
-option is specified, all traffic arriving on the interface is subjet to MAC
-verification.
-
The maclist option in /etc/shorewall/hosts. When this option
- is specified for a subnet, all traffic from that subnet is subject to MAC
- verification.
-
The /etc/shorewall/maclist file. This file is used to associate
- MAC addresses with interfaces and to optionally associate IP addresses
- with MAC addresses.
-
The MACLIST_DISPOSITION and MACLIST_LOG_LEVEL
- variables in /etc/shorewall/shorewall.conf.
- The MACLIST_DISPOSITION variable has the value DROP, REJECT or ACCEPT
-and determines the disposition of connection requests that fail MAC verification.
- The MACLIST_LOG_LEVEL variable gives the syslogd level at which connection
- requests that fail verification are to be logged. If set the the empty
-value (e.g., MACLIST_LOG_LEVEL="") then failing connection requests are
-not logged.
-
-
-
- The columns in /etc/shorewall/maclist are:
-
-
-
INTERFACE - The name of an ethernet interface on the Shorewall
- system.
-
MAC - The MAC address of a device on the ethernet segment
- connected by INTERFACE. It is not necessary to use the Shorewall MAC
-format in this column although you may use that format if you so choose.
-
IP Address - An optional comma-separated list of IP addresses
- for the device whose MAC is listed in the MAC column.
-
-
-
-
Example 1: Here are my files (look here for
-details about my setup):
- As shown above, I use MAC Verification on my wireless zone.
-
- Note: While marketed as a wireless bridge, the WET11 behaves like
-a wireless router with DHCP relay. When forwarding DHCP traffic, it uses
-the MAC address of the host (TIPPER) but for other forwarded traffic it uses
-it's own MAC address. Consequently, I list the IP addresses of both devices
-in /etc/shorewall/maclist.
-
-
Example 2: Router in Wireless Zone
- Suppose now that I add a second wireless segment to my wireless
- zone and gateway that segment via a router with MAC address 00:06:43:45:C6:15
- and IP address 192.168.3.253. Hosts in the second segment have IP addresses
- in the subnet 192.168.4.0/24. I would add the following entry to my /etc/shorewall/maclist
- file:
-
-
- This entry accomodates traffic from the router itself (192.168.3.253)
- and from the second wireless segment (192.168.4.0/24). Remember that all
-traffic being sent to my firewall from the 192.168.4.0/24 segment will
-be forwarded by the router so that traffic's MAC address will be that
-of the router (00:06:43:45:C6:15) and not that of the host sending the
-traffic.
-
+
+ All traffic from an interface or from a subnet on an interface
+ can be verified to originate from a defined set of MAC addresses. Furthermore,
+ each MAC address may be optionally associated with one or more IP addresses.
+
+
+ Your kernel must include MAC match support (CONFIG_IP_NF_MATCH_MAC
+ - module name ipt_mac.o).
+
+ There are four components to this facility.
-
The maclist interface option in /etc/shorewall/interfaces. When
+this option is specified, all traffic arriving on the interface is subjet
+to MAC verification.
+
The maclist option in /etc/shorewall/hosts. When this option
+ is specified for a subnet, all traffic from that subnet is subject to
+MAC verification.
+
The /etc/shorewall/maclist file. This file is used to associate
+ MAC addresses with interfaces and to optionally associate IP addresses
+ with MAC addresses.
+
The MACLIST_DISPOSITION and MACLIST_LOG_LEVEL
+ variables in /etc/shorewall/shorewall.conf.
+ The MACLIST_DISPOSITION variable has the value DROP, REJECT or ACCEPT
+ and determines the disposition of connection requests that fail MAC verification.
+ The MACLIST_LOG_LEVEL variable gives the syslogd level at which connection
+ requests that fail verification are to be logged. If set the the empty
+ value (e.g., MACLIST_LOG_LEVEL="") then failing connection requests are
+ not logged.
+
+
+
+ The columns in /etc/shorewall/maclist are:
+
+
+
INTERFACE - The name of an ethernet interface on the Shorewall
+ system.
+
MAC - The MAC address of a device on the ethernet segment
+ connected by INTERFACE. It is not necessary to use the Shorewall MAC
+format in this column although you may use that format if you so choose.
+
IP Address - An optional comma-separated list of IP addresses
+ for the device whose MAC is listed in the MAC column.
+
+
+
+
Example 1: Here are my files (look here for
+details about my setup):
+ As shown above, I use MAC Verification on my wireless zone.
+
+ Note: While marketed as a wireless bridge, the WET11 behaves like
+a wireless router with DHCP relay. When forwarding DHCP traffic, it uses the
+MAC address of the host (TIPPER) but for other forwarded traffic it uses it's
+own MAC address. Consequently, I list the IP addresses of both devices in
+/etc/shorewall/maclist.
+
+
Example 2: Router in Wireless Zone
+ Suppose now that I add a second wireless segment to my wireless
+ zone and gateway that segment via a router with MAC address 00:06:43:45:C6:15
+ and IP address 192.168.3.253. Hosts in the second segment have IP addresses
+ in the subnet 192.168.4.0/24. I would add the following entry to my /etc/shorewall/maclist
+ file:
+
+
+ This entry accomodates traffic from the router itself (192.168.3.253)
+ and from the second wireless segment (192.168.4.0/24). Remember that
+all traffic being sent to my firewall from the 192.168.4.0/24 segment
+will be forwarded by the router so that traffic's MAC address will be
+that of the router (00:06:43:45:C6:15) and not that of the host sending
+the traffic.
+
IMPORTANT: If all you want to do is forward
- ports to servers behind your firewall, you do NOT want to use static
- NAT. Port forwarding can be accomplished with simple entries in the
- rules file.
-
-
Static NAT is a way to make systems behind a firewall and configured
- with private IP addresses (those reserved for private use in RFC1918)
- appear to have public IP addresses. Before you try to use this technique,
- I strongly recommend that you read the
+
IMPORTANT: If all you want to do is forward
+ ports to servers behind your firewall, you do NOT want to use static
+ NAT. Port forwarding can be accomplished with simple entries in the
+ rules file.
+
+
Static NAT is a way to make systems behind a firewall and configured
+ with private IP addresses (those reserved for private use in RFC1918)
+ appear to have public IP addresses. Before you try to use this technique,
+ I strongly recommend that you read the Shorewall Setup Guide.
-
-
The following figure represents a static NAT environment.
-
+
+
The following figure represents a static NAT environment.
+
-
-
+
+
-
-
Static NAT can be used to make the systems with the 10.1.1.*
-addresses appear to be on the upper (130.252.100.*) subnet. If we assume
-that the interface to the upper subnet is eth0, then the following /etc/shorewall/NAT
-file would make the lower left-hand system appear to have IP address 130.252.100.18
-and the right-hand one to have IP address 130.252.100.19.
-
-
-
-
-
EXTERNAL
-
INTERFACE
-
INTERNAL
-
ALL INTERFACES
-
LOCAL
-
-
-
130.252.100.18
-
eth0
-
10.1.1.2
-
yes
-
yes
-
-
-
130.252.100.19
-
eth0
-
10.1.1.3
-
yes
-
yes
-
-
-
-
-
-
Be sure that the internal system(s) (10.1.1.2 and 10.1.1.3 in the above
- example) is (are) not included in any specification in /etc/shorewall/masq
- or /etc/shorewall/proxyarp.
-
-
Note 1: The "ALL INTERFACES" column is used
-to specify whether access to the external IP from all firewall interfaces
-should undergo NAT (Yes or yes) or if only access from the interface in
-the INTERFACE column should undergo NAT. If you leave this column empty,
-"Yes" is assumed. The ALL INTERFACES column was added in version 1.1.6.
-
-
Note 2: Shorewall will automatically add the external address to the
- specified interface unless you specify
+
Be sure that the internal system(s) (10.1.1.2 and 10.1.1.3 in the above
+ example) is (are) not included in any specification in /etc/shorewall/masq
+ or /etc/shorewall/proxyarp.
+
+
Note 1: The "ALL INTERFACES" column is used
+ to specify whether access to the external IP from all firewall interfaces
+ should undergo NAT (Yes or yes) or if only access from the interface in
+ the INTERFACE column should undergo NAT. If you leave this column empty,
+ "Yes" is assumed. The ALL INTERFACES column was added in version 1.1.6.
+
+
Note 2: Shorewall will automatically add the external address to the
+ specified interface unless you specify ADD_IP_ALIASES="no" (or "No") in
- /etc/shorewall/shorewall.conf; If you do not set ADD_IP_ALIASES or if
- you set it to "Yes" or "yes" then you must NOT configure your own alias(es).
- RESTRICTION: Shorewall versions earlier than 1.4.6 can only add
-external addresses to an interface that is configured with a single subnetwork
--- if your external interface has addresses in more than one subnetwork,
+ /etc/shorewall/shorewall.conf; If you do not set ADD_IP_ALIASES or
+if you set it to "Yes" or "yes" then you must NOT configure your own alias(es).
+ RESTRICTION: Shorewall versions earlier than 1.4.6 can only add
+ external addresses to an interface that is configured with a single subnetwork
+ -- if your external interface has addresses in more than one subnetwork,
Shorewall 1.4.5 and earlier can only add addresses to the first one.
-
-
Note 3: The contents of the "LOCAL" column
- determine whether packets originating on the firewall itself and destined
- for the EXTERNAL address are redirected to the internal ADDRESS. If
-this column contains "yes" or "Yes" (and the ALL INTERFACES COLUMN also
-contains "Yes" or "yes") then such packets are redirected; otherwise,
+
+
Note 3: The contents of the "LOCAL" column
+ determine whether packets originating on the firewall itself and destined
+ for the EXTERNAL address are redirected to the internal ADDRESS. If
+ this column contains "yes" or "Yes" (and the ALL INTERFACES COLUMN
+also contains "Yes" or "yes") then such packets are redirected; otherwise,
such packets are not redirected. The LOCAL column was added in version
1.1.8.
A problem seen on RH7.3 systems where Shorewall encountered start errors
-when started using the "service" mechanism has been worked around.
+
A problem seen on RH7.3 systems where Shorewall encountered start
+ errors when started using the "service" mechanism has been worked around.
+
+
+
Where a list of IP addresses appears in the DEST column of a DNAT[-]
+ rule, Shorewall incorrectly created multiple DNAT rules in the nat table
+ (one for each element in the list). Shorewall now correctly creates a single
+ DNAT rule with multiple "--to-destination" clauses.
+
+
+
Corrected a problem in Beta 1 where DNS names containing a "-" were
+ mis-handled when they appeared in the DEST column of a rule.
-
-
Where a list of IP addresses appears in the DEST column of a DNAT[-]
- rule, Shorewall incorrectly created multiple DNAT rules in the nat table
-(one for each element in the list). Shorewall now correctly creates a single
-DNAT rule with multiple "--to-destination" clauses.
-
-
-
Corrected a problem in Beta 1 where DNS names containing a "-" were
-mis-handled when they appeared in the DEST column of a rule.
-
-
-
A number of problems with rule parsing have been corrected. Corrections
-involve the handling of "z1!z2" in the SOURCE column as well as lists in
+
+
A number of problems with rule parsing have been corrected. Corrections
+ involve the handling of "z1!z2" in the SOURCE column as well as lists in
the ORIGINAL DESTINATION column.
-
+
+
-
+
Migration Issues:
-
-
+
+
-
In earlier versions, an undocumented feature allowed entries in the
-host file as follows:
-
- z eth1:192.168.1.0/24,eth2:192.168.2.0/24
-
- This capability was never documented and has been removed in 1.4.6 to allow
-entries of the following format:
-
- z eth1:192.168.1.0/24,192.168.2.0/24
-
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have been removed
-from /etc/shorewall/shorewall.conf. These capabilities are now automatically
- detected by Shorewall (see below).
-
+
In earlier versions, an undocumented feature allowed entries in the
+ host file as follows:
+
+ z eth1:192.168.1.0/24,eth2:192.168.2.0/24
+
+ This capability was never documented and has been removed in 1.4.6 to
+allow entries of the following format:
+
+ z eth1:192.168.1.0/24,192.168.2.0/24
+
+
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have been removed
+ from /etc/shorewall/shorewall.conf. These capabilities are now automatically
+ detected by Shorewall (see below).
+
+
-
+
New Features:
-
-
+
+
-
A 'newnotsyn' interface option has been added. This option may be specified
-in /etc/shorewall/interfaces and overrides the setting NEWNOTSYN=No for
-packets arriving on the associated interface.
-
-
-
The means for specifying a range of IP addresses in /etc/shorewall/masq
- to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for address
- ranges.
-
-
-
Shorewall can now add IP addresses to subnets other than the first
- one on an interface.
-
-
-
DNAT[-] rules may now be used to load balance (round-robin) over a
- set of servers. Servers may be specified in a range of addresses given as
-<first address>-<last address>.
-
- Example:
-
- DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
-
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration options
- have been removed and have been replaced by code that detects whether these
- capabilities are present in the current kernel. The output of the start,
-restart and check commands have been enhanced to report the outcome:
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Verifying Configuration...
-
-
-
Support for the Connection Tracking Match Extension has been added.
- This extension is available in recent kernel/iptables releases and allows
- for rules which match against elements in netfilter's connection tracking
- table. Shorewall automatically detects the availability of this extension
- and reports its availability in the output of the start, restart and check
- commands.
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Connection Tracking Match: Available
- Verifying Configuration...
-
- If this extension is available, the ruleset generated by Shorewall is
-changed in the following ways:
+
A 'newnotsyn' interface option has been added. This option may be
+specified in /etc/shorewall/interfaces and overrides the setting NEWNOTSYN=No
+ for packets arriving on the associated interface.
+
+
+
The means for specifying a range of IP addresses in /etc/shorewall/masq
+ to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for address
+ ranges.
+
+
+
Shorewall can now add IP addresses to subnets other than the first
+ one on an interface.
+
+
+
DNAT[-] rules may now be used to load balance (round-robin) over
+a set of servers. Servers may be specified in a range of addresses given
+as <first address>-<last address>.
+
+ Example:
+
+ DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
+
+
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration options
+ have been removed and have been replaced by code that detects whether these
+ capabilities are present in the current kernel. The output of the start,
+ restart and check commands have been enhanced to report the outcome:
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Verifying Configuration...
+
+
+
Support for the Connection Tracking Match Extension has been added.
+ This extension is available in recent kernel/iptables releases and allows
+ for rules which match against elements in netfilter's connection tracking
+ table. Shorewall automatically detects the availability of this extension
+ and reports its availability in the output of the start, restart and check
+ commands.
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Connection Tracking Match: Available
+ Verifying Configuration...
+
+ If this extension is available, the ruleset generated by Shorewall is
+ changed in the following ways:
+
-
To handle 'norfc1918' filtering, Shorewall will not create chains
- in the mangle table but will rather do all 'norfc1918' filtering in the
+
To handle 'norfc1918' filtering, Shorewall will not create chains
+ in the mangle table but will rather do all 'norfc1918' filtering in the
filter table (rfc1918 chain).
-
Recall that Shorewall DNAT rules generate two netfilter rules; one
- in the nat table and one in the filter table. If the Connection Tracking
-Match Extension is available, the rule in the filter table is extended to
-check that the original destination address was the same as specified (or
-defaulted to) in the DNAT rule.
-
-
+
Recall that Shorewall DNAT rules generate two netfilter rules;
+one in the nat table and one in the filter table. If the Connection Tracking
+ Match Extension is available, the rule in the filter table is extended to
+ check that the original destination address was the same as specified (or
+ defaulted to) in the DNAT rule.
+
+
+
-
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
- may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
-
-
-
An 'ipcalc' command has been added to /sbin/shorewall.
-
- ipcalc [ <address> <netmask> | <address>/<vlsm>
-]
-
- Examples:
-
- [root@wookie root]# shorewall ipcalc 192.168.1.0/24
- CIDR=192.168.1.0/24
- NETMASK=255.255.255.0
- NETWORK=192.168.1.0
- BROADCAST=192.168.1.255
- [root@wookie root]#
-
- [root@wookie root]# shorewall ipcalc 192.168.1.0 255.255.255.0
- CIDR=192.168.1.0/24
- NETMASK=255.255.255.0
- NETWORK=192.168.1.0
- BROADCAST=192.168.1.255
- [root@wookie root]#
-
- Warning:
-
- If your shell only supports 32-bit signed arithmatic (ash or dash), then
- the ipcalc command produces incorrect information for IP addresses 128.0.0.0-1
- and for /1 networks. Bash should produce correct information for all valid
- IP addresses.
-
+
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
+ may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
+
-
An 'iprange' command has been added to /sbin/shorewall.
-
- iprange <address>-<address>
-
- This command decomposes a range of IP addressses into a list of network
-and host addresses. The command can be useful if you need to construct an
-efficient set of rules that accept connections from a range of network addresses.
-
- Note: If your shell only supports 32-bit signed arithmetic (ash or dash)
-then the range may not span 128.0.0.0.
-
- Example:
-
- [root@gateway root]# shorewall iprange 192.168.1.4-192.168.12.9
- 192.168.1.4/30
- 192.168.1.8/29
- 192.168.1.16/28
- 192.168.1.32/27
- 192.168.1.64/26
- 192.168.1.128/25
- 192.168.2.0/23
- 192.168.4.0/22
- 192.168.8.0/22
- 192.168.12.0/29
- 192.168.12.8/31
- [root@gateway root]#
-
-
-
A list of host/net addresses is now allowed in an entry in /etc/shorewall/hosts.
-
- Example:
-
- foo eth1:192.168.1.0/24,192.168.2.0/24
+
An 'ipcalc' command has been added to /sbin/shorewall.
+
+ ipcalc [ <address> <netmask> | <address>/<vlsm>
+ ]
+
+ Examples:
+
+ [root@wookie root]# shorewall ipcalc 192.168.1.0/24
+ CIDR=192.168.1.0/24
+ NETMASK=255.255.255.0
+ NETWORK=192.168.1.0
+ BROADCAST=192.168.1.255
+ [root@wookie root]#
+
+ [root@wookie root]# shorewall ipcalc 192.168.1.0 255.255.255.0
+ CIDR=192.168.1.0/24
+ NETMASK=255.255.255.0
+ NETWORK=192.168.1.0
+ BROADCAST=192.168.1.255
+ [root@wookie root]#
+
+ Warning:
+
+ If your shell only supports 32-bit signed arithmatic (ash or dash), then
+ the ipcalc command produces incorrect information for IP addresses 128.0.0.0-1
+ and for /1 networks. Bash should produce correct information for all valid
+ IP addresses.
+
+
+
An 'iprange' command has been added to /sbin/shorewall.
+
+ iprange <address>-<address>
+
+ This command decomposes a range of IP addressses into a list of network
+ and host addresses. The command can be useful if you need to construct an
+ efficient set of rules that accept connections from a range of network addresses.
+
+ Note: If your shell only supports 32-bit signed arithmetic (ash or dash)
+ then the range may not span 128.0.0.0.
+
+ Example:
+
+ [root@gateway root]# shorewall iprange 192.168.1.4-192.168.12.9
+ 192.168.1.4/30
+ 192.168.1.8/29
+ 192.168.1.16/28
+ 192.168.1.32/27
+ 192.168.1.64/26
+ 192.168.1.128/25
+ 192.168.2.0/23
+ 192.168.4.0/22
+ 192.168.8.0/22
+ 192.168.12.0/29
+ 192.168.12.8/31
+ [root@gateway root]#
+
+
+
A list of host/net addresses is now allowed in an entry in /etc/shorewall/hosts.
+
+ Example:
+
+ foo eth1:192.168.1.0/24,192.168.2.0/24
+
+
7/7/2003 - Shorewall-1.4.6 Beta 2
-
+
Problems Corrected:
-
-
-
-
A problem seen on RH7.3 systems where Shorewall encountered start
-errors when started using the "service" mechanism has been worked around.
-
-
-
Where a list of IP addresses appears in the DEST column of a DNAT[-]
- rule, Shorewall incorrectly created multiple DNAT rules in the nat table
-(one for each element in the list). Shorewall now correctly creates a single
-DNAT rule with multiple "--to-destination" clauses.
-
-
-
Corrected a problem in Beta 1 where DNS names containing a "-" were
-mis-handled when they appeared in the DEST column of a rule.
-
-
-
-
-
Migration Issues:
-
-
-
-
In earlier versions, an undocumented feature allowed entries in the
-host file as follows:
-
- z eth1:192.168.1.0/24,eth2:192.168.2.0/24
-
- This capability was never documented and has been removed in 1.4.6 to allow
-entries of the following format:
-
- z eth1:192.168.1.0/24,192.168.2.0/24
-
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have been removed
-from /etc/shorewall/shorewall.conf. These capabilities are now automatically
-detected by Shorewall (see below).
-
-
-
-
-
New Features:
-
-
-
-
A 'newnotsyn' interface option has been added. This option may be
-specified in /etc/shorewall/interfaces and overrides the setting NEWNOTSYN=No
-for packets arriving on the associated interface.
-
-
-
The means for specifying a range of IP addresses in /etc/shorewall/masq
- to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for address
- ranges.
-
-
-
Shorewall can now add IP addresses to subnets other than the first
- one on an interface.
-
-
-
DNAT[-] rules may now be used to load balance (round-robin) over a
- set of servers. Servers may be specified in a range of addresses given as
-<first address>-<last address>.
-
- Example:
-
- DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
-
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration options
- have been removed and have been replaced by code that detects whether these
- capabilities are present in the current kernel. The output of the start,
-restart and check commands have been enhanced to report the outcome:
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Verifying Configuration...
-
-
-
Support for the Connection Tracking Match Extension has been added.
- This extension is available in recent kernel/iptables releases and allows
- for rules which match against elements in netfilter's connection tracking
- table. Shorewall automatically detects the availability of this extension
- and reports its availability in the output of the start, restart and check
- commands.
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Connection Tracking Match: Available
- Verifying Configuration...
-
- If this extension is available, the ruleset generated by Shorewall is
-changed in the following ways:
-
-
-
To handle 'norfc1918' filtering, Shorewall will not create chains
- in the mangle table but will rather do all 'norfc1918' filtering in the filter
- table (rfc1918 chain).
-
Recall that Shorewall DNAT rules generate two netfilter rules; one
- in the nat table and one in the filter table. If the Connection Tracking
-Match Extension is available, the rule in the filter table is extended to
-check that the original destination address was the same as specified (or
-defaulted to) in the DNAT rule.
-
-
-
-
-
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
- may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
-
-
-
An 'ipcalc' command has been added to /sbin/shorewall.
-
- ipcalc [ <address> <netmask> | <address>/<vlsm>
-]
-
- Examples:
-
- [root@wookie root]# shorewall ipcalc 192.168.1.0/24
- CIDR=192.168.1.0/24
- NETMASK=255.255.255.0
- NETWORK=192.168.1.0
- BROADCAST=192.168.1.255
- [root@wookie root]#
-
- [root@wookie root]# shorewall ipcalc 192.168.1.0 255.255.255.0
- CIDR=192.168.1.0/24
- NETMASK=255.255.255.0
- NETWORK=192.168.1.0
- BROADCAST=192.168.1.255
- [root@wookie root]#
-
- Warning:
-
- If your shell only supports 32-bit signed arithmatic (ash or dash), then
-the ipcalc command produces incorrect information for IP addresses 128.0.0.0-1
-and for /1 networks. Bash should produce correct information for all valid
-IP addresses.
-
-
-
An 'iprange' command has been added to /sbin/shorewall.
-
- iprange <address>-<address>
-
- This command decomposes a range of IP addressses into a list of network
-and host addresses. The command can be useful if you need to construct an
-efficient set of rules that accept connections from a range of network addresses.
-
- Note: If your shell only supports 32-bit signed arithmetic (ash or dash)
-then the range may not span 128.0.0.0.
-
- Example:
-
- [root@gateway root]# shorewall iprange 192.168.1.4-192.168.12.9
- 192.168.1.4/30
- 192.168.1.8/29
- 192.168.1.16/28
- 192.168.1.32/27
- 192.168.1.64/26
- 192.168.1.128/25
- 192.168.2.0/23
- 192.168.4.0/22
- 192.168.8.0/22
- 192.168.12.0/29
- 192.168.12.8/31
- [root@gateway root]#
-
-
-
A list of host/net addresses is now allowed in an entry in /etc/shorewall/hosts.
-
- Example:
-
- foo eth1:192.168.1.0/24,192.168.2.0/24
-
-
-
-
-
-
7/4/2003 - Shorewall-1.4.6 Beta 1
-
-
Problems Corrected:
-
-
+
+
A problem seen on RH7.3 systems where Shorewall encountered start
errors when started using the "service" mechanism has been worked around.
+
+
+
Where a list of IP addresses appears in the DEST column of a DNAT[-]
+ rule, Shorewall incorrectly created multiple DNAT rules in the nat table
+ (one for each element in the list). Shorewall now correctly creates a single
+ DNAT rule with multiple "--to-destination" clauses.
-
Where a list of IP addresses appears in the DEST column of a DNAT[-]
- rule, Shorewall incorrectly created multiple DNAT rules in the nat table
-(one for each element in the list). Shorewall now correctly creates a single
-DNAT rule with multiple "--to-destination" clauses.
+
Corrected a problem in Beta 1 where DNS names containing a "-" were
+ mis-handled when they appeared in the DEST column of a rule.
+
+
+
+
+
Migration Issues:
+
+
+
+
In earlier versions, an undocumented feature allowed entries in
+the host file as follows:
+
+ z eth1:192.168.1.0/24,eth2:192.168.2.0/24
+
+ This capability was never documented and has been removed in 1.4.6 to
+allow entries of the following format:
+
+ z eth1:192.168.1.0/24,192.168.2.0/24
+
+
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have been
+removed from /etc/shorewall/shorewall.conf. These capabilities are now automatically
+ detected by Shorewall (see below).
New Features:
-
-
+
+
A 'newnotsyn' interface option has been added. This option may be
specified in /etc/shorewall/interfaces and overrides the setting NEWNOTSYN=No
for packets arriving on the associated interface.
-
-
+
+
The means for specifying a range of IP addresses in /etc/shorewall/masq
- to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for address
- ranges.
-
-
+ to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for address
+ ranges.
+
+
Shorewall can now add IP addresses to subnets other than the first
- one on an interface.
-
-
+ one on an interface.
+
+
DNAT[-] rules may now be used to load balance (round-robin) over
-a set of servers. Up to 256 servers may be specified in a range of addresses
- given as <first address>-<last address>.
-
- Example:
-
- DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
-
- Note that this capability has previously been available using a combination
- of a DNAT- rule and one or more ACCEPT rules. That technique is still preferable
- for load-balancing over a large number of servers (> 16) since specifying
- a range in the DNAT rule causes one filter table ACCEPT rule to be generated
- for each IP address in the range.
-
-
+a set of servers. Servers may be specified in a range of addresses given
+as <first address>-<last address>.
+
+ Example:
+
+ DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
+
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration options
- have been removed and have been replaced by code that detects whether these
- capabilities are present in the current kernel. The output of the start,
-restart and check commands have been enhanced to report the outcome:
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Verifying Configuration...
-
-
+ have been removed and have been replaced by code that detects whether these
+ capabilities are present in the current kernel. The output of the start,
+ restart and check commands have been enhanced to report the outcome:
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Verifying Configuration...
+
+
Support for the Connection Tracking Match Extension has been added.
- This extension is available in recent kernel/iptables releases and allows
- for rules which match against elements in netfilter's connection tracking
- table. Shorewall automatically detects the availability of this extension
- and reports its availability in the output of the start, restart and check
- commands.
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Connection Tracking Match: Available
- Verifying Configuration...
-
- If this extension is available, the ruleset generated by Shorewall is
-changed in the following ways:
-
-
-
-
+ This extension is available in recent kernel/iptables releases and allows
+ for rules which match against elements in netfilter's connection tracking
+ table. Shorewall automatically detects the availability of this extension
+ and reports its availability in the output of the start, restart and check
+ commands.
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Connection Tracking Match: Available
+ Verifying Configuration...
+
+ If this extension is available, the ruleset generated by Shorewall is
+ changed in the following ways:
To handle 'norfc1918' filtering, Shorewall will not create chains
- in the mangle table but will rather do all 'norfc1918' filtering in the filter
- table (rfc1918 chain).
+ in the mangle table but will rather do all 'norfc1918' filtering in the
+filter table (rfc1918 chain).
Recall that Shorewall DNAT rules generate two netfilter rules;
-one in the nat table and one in the filter table. If the Connection Tracking
-Match Extension is available, the rule in the filter table is extended to
-check that the original destination address was the same as specified (or
-defaulted to) in the DNAT rule.
-
-
+one in the nat table and one in the filter table. If the Connection Tracking
+ Match Extension is available, the rule in the filter table is extended to
+ check that the original destination address was the same as specified (or
+ defaulted to) in the DNAT rule.
+
+
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
- may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
+ may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
+
+
+
An 'ipcalc' command has been added to /sbin/shorewall.
+
+ ipcalc [ <address> <netmask> | <address>/<vlsm>
+ ]
+
+ Examples:
+
+ [root@wookie root]# shorewall ipcalc 192.168.1.0/24
+ CIDR=192.168.1.0/24
+ NETMASK=255.255.255.0
+ NETWORK=192.168.1.0
+ BROADCAST=192.168.1.255
+ [root@wookie root]#
+
+ [root@wookie root]# shorewall ipcalc 192.168.1.0 255.255.255.0
+ CIDR=192.168.1.0/24
+ NETMASK=255.255.255.0
+ NETWORK=192.168.1.0
+ BROADCAST=192.168.1.255
+ [root@wookie root]#
+
+ Warning:
+
+ If your shell only supports 32-bit signed arithmatic (ash or dash), then
+ the ipcalc command produces incorrect information for IP addresses 128.0.0.0-1
+ and for /1 networks. Bash should produce correct information for all valid
+ IP addresses.
+
+
+
An 'iprange' command has been added to /sbin/shorewall.
+
+ iprange <address>-<address>
+
+ This command decomposes a range of IP addressses into a list of network
+ and host addresses. The command can be useful if you need to construct an
+ efficient set of rules that accept connections from a range of network addresses.
+
+ Note: If your shell only supports 32-bit signed arithmetic (ash or dash)
+ then the range may not span 128.0.0.0.
+
+ Example:
+
+ [root@gateway root]# shorewall iprange 192.168.1.4-192.168.12.9
+ 192.168.1.4/30
+ 192.168.1.8/29
+ 192.168.1.16/28
+ 192.168.1.32/27
+ 192.168.1.64/26
+ 192.168.1.128/25
+ 192.168.2.0/23
+ 192.168.4.0/22
+ 192.168.8.0/22
+ 192.168.12.0/29
+ 192.168.12.8/31
+ [root@gateway root]#
+
+
+
A list of host/net addresses is now allowed in an entry in /etc/shorewall/hosts.
+
+ Example:
+
+ foo eth1:192.168.1.0/24,192.168.2.0/24
+
-
6/17/2003 - Shorewall-1.4.5
-
-
Problems Corrected:
-
-
-
-
The command "shorewall debug try <directory>" now correctly
- traces the attempt.
-
The INCLUDE directive now works properly in the zones file; previously,
- INCLUDE in that file was ignored.
-
/etc/shorewall/routestopped records with an empty second column
-are no longer ignored.
-
-
-
-
-
New Features:
-
-
-
-
The ORIGINAL DEST column in a DNAT[-] or REDIRECT[-] rule may now
- contain a list of addresses. If the list begins with "!' then the rule will
- take effect only if the original destination address in the connection request
- does not match any of the addresses listed.
-
-
-
-
6/15/2003 - Shorewall, Kernel 2.4.21 and iptables 1.2.8
+
7/4/2003 - Shorewall-1.4.6 Beta 1
-
The firewall at shorewall.net has been upgraded to the 2.4.21 kernel and
- iptables 1.2.8 (using the "official" RPM from netfilter.org). No problems
- have been encountered with this set of software. The Shorewall version is
- 1.4.4b plus the accumulated changes for 1.4.5.
+
Problems Corrected:
-
6/8/2003 - Updated Samples
+
+
A problem seen on RH7.3 systems where Shorewall encountered start
+ errors when started using the "service" mechanism has been worked around.
+
+
+
Where a list of IP addresses appears in the DEST column of a DNAT[-]
+ rule, Shorewall incorrectly created multiple DNAT rules in the nat table
+ (one for each element in the list). Shorewall now correctly creates a single
+ DNAT rule with multiple "--to-destination" clauses.
+
+
+
+
+
New Features:
+
+
+
+
A 'newnotsyn' interface option has been added. This option may
+be specified in /etc/shorewall/interfaces and overrides the setting NEWNOTSYN=No
+ for packets arriving on the associated interface.
+
+
+
The means for specifying a range of IP addresses in /etc/shorewall/masq
+ to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for address
+ ranges.
+
+
+
Shorewall can now add IP addresses to subnets other than the first
+ one on an interface.
+
+
+
DNAT[-] rules may now be used to load balance (round-robin) over
+ a set of servers. Up to 256 servers may be specified in a range of addresses
+ given as <first address>-<last address>.
+
+ Example:
+
+ DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
+
+ Note that this capability has previously been available using a combination
+ of a DNAT- rule and one or more ACCEPT rules. That technique is still preferable
+ for load-balancing over a large number of servers (> 16) since specifying
+ a range in the DNAT rule causes one filter table ACCEPT rule to be generated
+ for each IP address in the range.
+
+
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration options
+ have been removed and have been replaced by code that detects whether these
+ capabilities are present in the current kernel. The output of the start,
+ restart and check commands have been enhanced to report the outcome:
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Verifying Configuration...
+
+
+
Support for the Connection Tracking Match Extension has been added.
+ This extension is available in recent kernel/iptables releases and allows
+ for rules which match against elements in netfilter's connection tracking
+ table. Shorewall automatically detects the availability of this extension
+ and reports its availability in the output of the start, restart and check
+ commands.
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Connection Tracking Match: Available
+ Verifying Configuration...
+
+ If this extension is available, the ruleset generated by Shorewall is
+ changed in the following ways:
+
+
+
+
+
+
+
To handle 'norfc1918' filtering, Shorewall will not create chains
+ in the mangle table but will rather do all 'norfc1918' filtering in the
+filter table (rfc1918 chain).
+
Recall that Shorewall DNAT rules generate two netfilter rules;
+ one in the nat table and one in the filter table. If the Connection Tracking
+ Match Extension is available, the rule in the filter table is extended to
+ check that the original destination address was the same as specified (or
+ defaulted to) in the DNAT rule.
+
+
+
+
+
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
+ may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
+
+
+
+
+
6/17/2003 - Shorewall-1.4.5
-
Thanks to Francesca Smith, the samples have been updated to Shorewall
-version 1.4.4.
+
Problems Corrected:
+
-
5/29/2003 - Shorewall-1.4.4b
+
+
The command "shorewall debug try <directory>" now correctly
+ traces the attempt.
+
The INCLUDE directive now works properly in the zones file; previously,
+ INCLUDE in that file was ignored.
+
/etc/shorewall/routestopped records with an empty second column
+ are no longer ignored.
+
+
+
+
+
New Features:
+
+
+
+
The ORIGINAL DEST column in a DNAT[-] or REDIRECT[-] rule may
+now contain a list of addresses. If the list begins with "!' then the rule
+will take effect only if the original destination address in the connection
+request does not match any of the addresses listed.
+
+
+
+
6/15/2003 - Shorewall, Kernel 2.4.21 and iptables 1.2.8
-
Groan -- This version corrects a problem whereby the --log-level was not
- being set when logging via syslog. The most commonly reported symptom was
- that Shorewall messages were being written to the console even though console
- logging was correctly configured per FAQ 16.
+
The firewall at shorewall.net has been upgraded to the 2.4.21 kernel and
+ iptables 1.2.8 (using the "official" RPM from netfilter.org). No problems
+ have been encountered with this set of software. The Shorewall version
+is 1.4.4b plus the accumulated changes for 1.4.5.
+
6/8/2003 - Updated Samples
+
+
Thanks to Francesca Smith, the samples have been updated to Shorewall
+version 1.4.4.
+
+
5/29/2003 - Shorewall-1.4.4b
+
+
Groan -- This version corrects a problem whereby the --log-level was not
+ being set when logging via syslog. The most commonly reported symptom
+was that Shorewall messages were being written to the console even though
+console logging was correctly configured per FAQ 16.
+
+
5/27/2003 - Shorewall-1.4.4a
- The Fireparse --log-prefix fiasco continues. Tuomo Soini has pointed
- out that the code in 1.4.4 restricts the length of short zone names
-to 4 characters. I've produced version 1.4.4a that restores the previous
-5-character limit by conditionally omitting the log rule number when
-the LOGFORMAT doesn't contain '%d'.
-
+ The Fireparse --log-prefix fiasco continues. Tuomo Soini has
+pointed out that the code in 1.4.4 restricts the length of short zone
+names to 4 characters. I've produced version 1.4.4a that restores the
+previous 5-character limit by conditionally omitting the log rule number
+when the LOGFORMAT doesn't contain '%d'.
+
5/23/2003 - Shorewall-1.4.4
- I apologize for the rapid-fire releases but since there is a potential
- configuration change required to go from 1.4.3a to 1.4.4, I decided to
- make it a full release rather than just a bug-fix release.
-
- Problems corrected:
-
+ I apologize for the rapid-fire releases but since there is a
+potential configuration change required to go from 1.4.3a to 1.4.4,
+I decided to make it a full release rather than just a bug-fix release.
+
+
+ Problems corrected:
+
None.
-
- New Features:
-
+
+ New Features:
+
-
A REDIRECT- rule target has been added. This target behaves
- for REDIRECT in the same way as DNAT- does for DNAT in that the Netfilter
- nat table REDIRECT rule is added but not the companion filter table
+
A REDIRECT- rule target has been added. This target behaves
+ for REDIRECT in the same way as DNAT- does for DNAT in that the Netfilter
+ nat table REDIRECT rule is added but not the companion filter table
ACCEPT rule.
-
-
-
The LOGMARKER variable has been renamed LOGFORMAT and has
- been changed to a 'printf' formatting template which accepts three arguments
- (the chain name, logging rule number and the disposition). To use LOGFORMAT
- with fireparse (http://www.fireparse.com),
- set it as:
-
- LOGFORMAT="fp=%s:%d a=%s "
-
- CAUTION: /sbin/shorewall uses the leading part of the
- LOGFORMAT string (up to but not including the first '%') to find log
-messages in the 'show log', 'status' and 'hits' commands. This part should
-not be omitted (the LOGFORMAT should not begin with "%") and the leading
-part should be sufficiently unique for /sbin/shorewall to identify Shorewall
- messages.
-
-
-
When logging is specified on a DNAT[-] or REDIRECT[-] rule,
- the logging now takes place in the nat table rather than in the filter
- table. This way, only those connections that actually undergo DNAT or
- redirection will be logged.
-
-
-
-
-
5/20/2003 - Shorewall-1.4.3a
-
- This version primarily corrects the documentation included in
- the .tgz and in the .rpm. In addition:
-
-
-
(This change is in 1.4.3 but is not documented) If you
-are running iptables 1.2.7a and kernel 2.4.20, then Shorewall will return
- reject replies as follows:
- a) tcp - RST
- b) udp - ICMP port unreachable
- c) icmp - ICMP host unreachable
- d) Otherwise - ICMP host prohibited
- If you are running earlier software, Shorewall will follow
-it's traditional convention:
- a) tcp - RST
- b) Otherwise - ICMP port unreachable
-
UDP port 135 is now silently dropped in the common.def
-chain. Remember that this chain is traversed just before a DROP or REJECT
-policy is enforced.
-
-
-
-
-
5/18/2003 - Shorewall 1.4.3
-
- Problems Corrected:
-
-
-
There were several cases where Shorewall would fail to
- remove a temporary directory from /tmp. These cases have been corrected.
-
The rules for allowing all traffic via the loopback interface
- have been moved to before the rule that drops status=INVALID packets.
- This insures that all loopback traffic is allowed even if Netfilter connection
- tracking is confused.
-
-
- New Features:
-
-
-
IPV6-IPV4 (6to4) tunnels are now supported in the /etc/shorewall/tunnels
- file.
-
You may now change the leading portion of the
- --log-prefix used by Shorewall using the LOGMARKER variable in shorewall.conf.
- By default, "Shorewall:" is used.
+
-
+
The LOGMARKER variable has been renamed LOGFORMAT and
+has been changed to a 'printf' formatting template which accepts three
+arguments (the chain name, logging rule number and the disposition).
+To use LOGFORMAT with fireparse (http://www.fireparse.com), set it
+ as:
+
+ LOGFORMAT="fp=%s:%d a=%s "
+
+ CAUTION: /sbin/shorewall uses the leading part of
+the LOGFORMAT string (up to but not including the first '%') to find
+log messages in the 'show log', 'status' and 'hits' commands. This part
+should not be omitted (the LOGFORMAT should not begin with "%") and the
+leading part should be sufficiently unique for /sbin/shorewall to identify
+Shorewall messages.
+
+
+
When logging is specified on a DNAT[-] or REDIRECT[-]
+rule, the logging now takes place in the nat table rather than in the
+filter table. This way, only those connections that actually undergo
+DNAT or redirection will be logged.
+
+
-
-
5/10/2003 - Shorewall Mirror in Asia
-
-
-
Ed Greshko has established a mirror in Taiwan -- Thanks Ed!
+
+
5/20/2003 - Shorewall-1.4.3a
+ This version primarily corrects the documentation included
+in the .tgz and in the .rpm. In addition:
+
+
(This change is in 1.4.3 but is not documented) If you
+ are running iptables 1.2.7a and kernel 2.4.20, then Shorewall will return
+ reject replies as follows:
+ a) tcp - RST
+ b) udp - ICMP port unreachable
+ c) icmp - ICMP host unreachable
+ d) Otherwise - ICMP host prohibited
+ If you are running earlier software, Shorewall will follow
+ it's traditional convention:
+ a) tcp - RST
+ b) Otherwise - ICMP port unreachable
+
UDP port 135 is now silently dropped in the common.def
+ chain. Remember that this chain is traversed just before a DROP or
+REJECT policy is enforced.
+
+
+
+
+
5/18/2003 - Shorewall 1.4.3
+
+ Problems Corrected:
+
+
+
There were several cases where Shorewall would fail
+to remove a temporary directory from /tmp. These cases have been corrected.
+
The rules for allowing all traffic via the loopback
+interface have been moved to before the rule that drops status=INVALID
+packets. This insures that all loopback traffic is allowed even if Netfilter
+connection tracking is confused.
+
+
+ New Features:
+
+
+
IPV6-IPV4 (6to4) tunnels are now supported in the
+/etc/shorewall/tunnels file.
+
You may now change the leading portion of
+the --log-prefix used by Shorewall using the LOGMARKER variable in
+shorewall.conf. By default, "Shorewall:" is used.
+
+
+
+
+
5/10/2003 - Shorewall Mirror in Asia
+
+
+
Ed Greshko has established a mirror in Taiwan -- Thanks Ed!
+
+
5/8/2003 - Shorewall Mirror in Chile
- Thanks to Darcy Ganga, there is now an HTTP mirror
-in Santiago Chile.
+ Thanks to Darcy Ganga, there is now an HTTP mirror
+ in Santiago Chile.
4/21/2003 - Samples updated for Shorewall version 1.4.2
-
+
Thanks to Francesca Smith, the sample configurations are now upgraded to
Shorewall version 1.4.2.
-
+
4/9/2003 - Shorewall 1.4.2
-
-
+
+
Problems Corrected:
-
+
-
+
-
TCP connection requests rejected out of the common
- chain are now properly rejected with TCP RST; previously, some of
- these requests were rejected with an ICMP port-unreachable response.
-
'traceroute -I' from behind the firewall previously
- timed out on the first hop (e.g., to the firewall). This has been
- worked around.
-
-
+
TCP connection requests rejected out of the
+ common chain are now properly rejected with TCP RST;
+previously, some of these requests were rejected with an ICMP port-unreachable
+response.
+
'traceroute -I' from behind the firewall previously
+ timed out on the first hop (e.g., to the firewall). This has been
+ worked around.
+
+
-
-
+
+
New Features:
-
+
-
Where an entry in the/etc/shorewall/hosts file specifies
- a particular host or network, Shorewall now creates an intermediate
- chain for handling input from the related zone. This can substantially
- reduce the number of rules traversed by connections requests from such
- zones.
-
-
-
Any file may include an INCLUDE directive. An INCLUDE
- directive consists of the word INCLUDE followed by a file name and
- causes the contents of the named file to be logically included into
- the file containing the INCLUDE. File names given in an INCLUDE directive
- are assumed to reside in /etc/shorewall or in an alternate configuration
- directory if one has been specified for the command.
-
- Examples:
- shorewall/params.mgmt:
- MGMT_SERVERS=1.1.1.1,2.2.2.2,3.3.3.3
- TIME_SERVERS=4.4.4.4
- BACKUP_SERVERS=5.5.5.5
- ----- end params.mgmt -----
-
-
- shorewall/params:
- # Shorewall 1.3 /etc/shorewall/params
- [..]
- #######################################
-
- INCLUDE params.mgmt
-
- # params unique to this host here
- #LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO
-NOT REMOVE
- ----- end params -----
-
-
- shorewall/rules.mgmt:
- ACCEPT net:$MGMT_SERVERS $FW tcp 22
- ACCEPT $FW net:$TIME_SERVERS udp 123
- ACCEPT $FW net:$BACKUP_SERVERS tcp 22
- ----- end rules.mgmt -----
-
- shorewall/rules:
- # Shorewall version 1.3 - Rules File
- [..]
- #######################################
-
- INCLUDE rules.mgmt
-
- # rules unique to this host here
- #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE --
-DO NOT REMOVE
- ----- end rules -----
-
- INCLUDE's may be nested to a level of 3 -- further nested
- INCLUDE directives are ignored with a warning message.
-
+
Where an entry in the/etc/shorewall/hosts file
+specifies a particular host or network, Shorewall now creates an
+intermediate chain for handling input from the related zone. This
+can substantially reduce the number of rules traversed by connections
+requests from such zones.
+
-
Routing traffic from an interface back out that
-interface continues to be a problem. While I firmly believe that
-this should never happen, people continue to want to do it. To limit
-the damage that such nonsense produces, I have added a new 'routeback'
-option in /etc/shorewall/interfaces and /etc/shorewall/hosts. When
+
Any file may include an INCLUDE directive. An
+INCLUDE directive consists of the word INCLUDE followed by a file
+name and causes the contents of the named file to be logically included
+into the file containing the INCLUDE. File names given in an INCLUDE
+directive are assumed to reside in /etc/shorewall or in an alternate
+configuration directory if one has been specified for the command.
+
+
+ Examples:
+ shorewall/params.mgmt:
+ MGMT_SERVERS=1.1.1.1,2.2.2.2,3.3.3.3
+ TIME_SERVERS=4.4.4.4
+ BACKUP_SERVERS=5.5.5.5
+ ----- end params.mgmt -----
+
+
+ shorewall/params:
+ # Shorewall 1.3 /etc/shorewall/params
+ [..]
+ #######################################
+
+ INCLUDE params.mgmt
+
+ # params unique to this host here
+ #LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE -
+DO NOT REMOVE
+ ----- end params -----
+
+
+ shorewall/rules.mgmt:
+ ACCEPT net:$MGMT_SERVERS $FW tcp
+22
+ ACCEPT $FW net:$TIME_SERVERS udp
+123
+ ACCEPT $FW net:$BACKUP_SERVERS tcp
+22
+ ----- end rules.mgmt -----
+
+ shorewall/rules:
+ # Shorewall version 1.3 - Rules File
+ [..]
+ #######################################
+
+ INCLUDE rules.mgmt
+
+ # rules unique to this host here
+ #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE
+-- DO NOT REMOVE
+ ----- end rules -----
+
+ INCLUDE's may be nested to a level of 3 -- further
+nested INCLUDE directives are ignored with a warning message.
+
+
+
Routing traffic from an interface back out that
+ interface continues to be a problem. While I firmly believe that
+ this should never happen, people continue to want to do it. To limit
+ the damage that such nonsense produces, I have added a new 'routeback'
+ option in /etc/shorewall/interfaces and /etc/shorewall/hosts. When
used in /etc/shorewall/interfaces, the 'ZONE' column may not contain
'-'; in other words, 'routeback' can't be used as an option for a multi-zone
- interface. The 'routeback' option CAN be specified however on individual
- group entries in /etc/shorewall/hosts.
-
- The 'routeback' option is similar to the old 'multi'
-option with two exceptions:
-
- a) The option pertains to a particular zone,interface,address
- tuple.
-
- b) The option only created infrastructure to pass
-traffic from (zone,interface,address) tuples back to themselves (the
-'multi' option affected all (zone,interface,address) tuples associated
-with the given 'interface').
-
- See the 'Upgrade Issues'
- for information about how this new option may affect your configuration.
-
-
+ interface. The 'routeback' option CAN be specified however on individual
+ group entries in /etc/shorewall/hosts.
+
+ The 'routeback' option is similar to the old 'multi'
+ option with two exceptions:
+
+ a) The option pertains to a particular zone,interface,address
+ tuple.
+
+ b) The option only created infrastructure to pass
+ traffic from (zone,interface,address) tuples back to themselves
+(the 'multi' option affected all (zone,interface,address) tuples
+associated with the given 'interface').
+
+ See the 'Upgrade Issues'
+ for information about how this new option may affect your configuration.
+
+
-
+
3/24/2003 - Shorewall 1.4.1
-
+
@@ -817,1778 +835,1807 @@ with the given 'interface').
-
+
This release follows up on 1.4.0. It corrects a problem introduced in
1.4.0 and removes additional warts.
-
- Problems Corrected:
-
-
+
+ Problems Corrected:
+
+
-
When Shorewall 1.4.0 is run under the ash shell
-(such as on Bering/LEAF), it can attempt to add ECN disabling rules
-even if the /etc/shorewall/ecn file is empty. That problem has been
-corrected so that ECN disabling rules are only added if there are entries
-in /etc/shorewall/ecn.
-
+
When Shorewall 1.4.0 is run under the ash shell
+ (such as on Bering/LEAF), it can attempt to add ECN disabling rules
+ even if the /etc/shorewall/ecn file is empty. That problem has been
+ corrected so that ECN disabling rules are only added if there are
+entries in /etc/shorewall/ecn.
+
- New Features:
-
+ New Features:
+
Note: In the list that follows, the term group refers to
a particular network or subnetwork (which may be 0.0.0.0/0 or it may be a
host address) accessed through a particular interface. Examples:
-
+
+ You can use the "shorewall check" command to see the
+ groups associated with each of your zones.
- You can use the "shorewall check" command to see the
-groups associated with each of your zones.
-
-
+
-
Beginning with Shorewall 1.4.1, if a zone Z comprises
- more than one groupthen if there is no explicit Z to Z policy
- and there are no rules governing traffic from Z to Z then Shorewall
-will permit all traffic between the groups in the zone.
-
Beginning with Shorewall 1.4.1, Shorewall will
-never create rules to handle traffic from a group to itself.
-
A NONE policy is introduced in 1.4.1. When a policy
- of NONE is specified from Z1 to Z2:
-
+
Beginning with Shorewall 1.4.1, if a zone Z comprises
+ more than one groupthen if there is no explicit Z to Z policy
+ and there are no rules governing traffic from Z to Z then Shorewall
+ will permit all traffic between the groups in the zone.
+
Beginning with Shorewall 1.4.1, Shorewall will
+ never create rules to handle traffic from a group to itself.
+
A NONE policy is introduced in 1.4.1. When a
+policy of NONE is specified from Z1 to Z2:
+
-
+
-
There may be no rules created that govern connections
- from Z1 to Z2.
-
Shorewall will not create any infrastructure to
-handle traffic from Z1 to Z2.
-
+
There may be no rules created that govern connections
+ from Z1 to Z2.
+
Shorewall will not create any infrastructure
+to handle traffic from Z1 to Z2.
+
- See the upgrade issues
- for a discussion of how these changes may affect your configuration.
-
+ See the upgrade issues
+ for a discussion of how these changes may affect your configuration.
+
3/17/2003 - Shorewall 1.4.0
- Shorewall
- 1.4 represents the next step in the evolution of Shorewall. The
- main thrust of the initial release is simply to remove the cruft
+ Shorewall
+ 1.4 represents the next step in the evolution of Shorewall.
+The main thrust of the initial release is simply to remove the cruft
that has accumulated in Shorewall over time.
-
- IMPORTANT: Shorewall 1.4.0 requiresthe
- iproute package ('ip' utility).
-
- Function from 1.3 that has been omitted from
- this version include:
-
+
+ IMPORTANT: Shorewall 1.4.0 requiresthe
+ iproute package ('ip' utility).
+
+ Function from 1.3 that has been omitted from
+ this version include:
+
-
The MERGE_HOSTS variable in shorewall.conf
- is no longer supported. Shorewall 1.4 behavior is the same as
+
The MERGE_HOSTS variable in shorewall.conf
+ is no longer supported. Shorewall 1.4 behavior is the same as
1.3 with MERGE_HOSTS=Yes.
+
+
+
Interface names of the form <device>:<integer>
+ in /etc/shorewall/interfaces now generate an error.
+
+
+
Shorewall 1.4 implements behavior consistent
+ with OLD_PING_HANDLING=No. OLD_PING_HANDLING=Yes will generate
+ an error at startup as will specification of the 'noping' or
+ 'filterping' interface options.
+
+
+
The 'routestopped' option in the /etc/shorewall/interfaces
+ and /etc/shorewall/hosts files is no longer supported and will
+ generate an error at startup if specified.
+
+
+
The Shorewall 1.2 syntax for DNAT and
+ REDIRECT rules is no longer accepted.
+
+
+
The ALLOWRELATED variable in shorewall.conf
+ is no longer supported. Shorewall 1.4 behavior is the same
+as 1.3 with ALLOWRELATED=Yes.
-
Interface names of the form <device>:<integer>
- in /etc/shorewall/interfaces now generate an error.
-
+
The icmp.def file has been removed.
-
Shorewall 1.4 implements behavior consistent
- with OLD_PING_HANDLING=No. OLD_PING_HANDLING=Yes will generate
- an error at startup as will specification of the 'noping' or
- 'filterping' interface options.
-
-
-
The 'routestopped' option in the /etc/shorewall/interfaces
- and /etc/shorewall/hosts files is no longer supported and will
- generate an error at startup if specified.
-
-
-
The Shorewall 1.2 syntax for DNAT and
-REDIRECT rules is no longer accepted.
-
-
-
The ALLOWRELATED variable in shorewall.conf
- is no longer supported. Shorewall 1.4 behavior is the same as
- 1.3 with ALLOWRELATED=Yes.
-
-
-
The icmp.def file has been removed.
-
-
+
- Changes for 1.4 include:
-
+ Changes for 1.4 include:
+
-
The /etc/shorewall/shorewall.conf file
-has been completely reorganized into logical sections.
+
The /etc/shorewall/shorewall.conf file
+ has been completely reorganized into logical sections.
+
+
+
LOG is now a valid action for a rule
+(/etc/shorewall/rules).
+
+
+
The firewall script and version file
+are now installed in /usr/share/shorewall.
+
+
+
Late arriving DNS replies are now silently
+ dropped in the common chain by default.
+
+
+
In addition to behaving like OLD_PING_HANDLING=No,
+ Shorewall 1.4 no longer unconditionally accepts outbound ICMP
+ packets. So if you want to 'ping' from the firewall, you will
+need the appropriate rule or policy.
+
+
+
CONTINUE is now a valid action for a rule
+(/etc/shorewall/rules).
+
+
+
802.11b devices with names of the form wlan<n>
+ now support the 'maclist' option.
+
+
+
Explicit Congestion Notification (ECN - RFC
+ 3168) may now be turned off on a host or network basis using
+the new /etc/shorewall/ecn file. To use this facility:
+
+ a) You must be running kernel 2.4.20
+ b) You must have applied the patch in
+ http://www.shorewall/net/pub/shorewall/ecn/patch.
+ c) You must have iptables 1.2.7a installed.
+
+
+
The /etc/shorewall/params file is now processed
+ first so that variables may be used in the /etc/shorewall/shorewall.conf
+ file.
+
+
+
Shorewall now gives a more helpful
+ diagnostic when the 'ipchains' compatibility kernel module is loaded
+ and a 'shorewall start' command is issued.
-
LOG is now a valid action for a rule (/etc/shorewall/rules).
+
The SHARED_DIR variable has been removed from
+ shorewall.conf. This variable was for use by package maintainers
+ and was not documented for general use.
-
The firewall script and version file are
- now installed in /usr/share/shorewall.
-
-
-
Late arriving DNS replies are now silently
- dropped in the common chain by default.
-
-
-
In addition to behaving like OLD_PING_HANDLING=No,
- Shorewall 1.4 no longer unconditionally accepts outbound ICMP
- packets. So if you want to 'ping' from the firewall, you will need
- the appropriate rule or policy.
-
-
-
CONTINUE is now a valid action for a rule (/etc/shorewall/rules).
-
-
-
802.11b devices with names of the form wlan<n>
- now support the 'maclist' option.
-
-
-
Explicit Congestion Notification (ECN - RFC
-3168) may now be turned off on a host or network basis using the
-new /etc/shorewall/ecn file. To use this facility:
-
- a) You must be running kernel 2.4.20
- b) You must have applied the patch in
- http://www.shorewall/net/pub/shorewall/ecn/patch.
- c) You must have iptables 1.2.7a installed.
-
-
-
The /etc/shorewall/params file is now processed
- first so that variables may be used in the /etc/shorewall/shorewall.conf
- file.
-
-
-
Shorewall now gives a more helpful
-diagnostic when the 'ipchains' compatibility kernel module is loaded
-and a 'shorewall start' command is issued.
-
-
-
The SHARED_DIR variable has been removed from
-shorewall.conf. This variable was for use by package maintainers
-and was not documented for general use.
-
-
-
Shorewall now ignores 'default' routes when detecting
- masq'd networks.
-
+
Shorewall now ignores 'default' routes when
+detecting masq'd networks.
+
-
+
3/10/2003 - Shoreall 1.3.14a
-
+
A roleup of the following bug fixes and other updates:
-
+
-
There is an updated rfc1918 file that reflects
-the resent allocation of 222.0.0.0/8 and 223.0.0.0/8.
-
-
-
-
-
The documentation for the routestopped file claimed
- that a comma-separated list could appear in the second column
- while the code only supported a single host or network address.
-
Log messages produced by 'logunclean' and 'dropunclean'
- were not rate-limited.
-
802.11b devices with names of the form wlan<n>
- don't support the 'maclist' interface option.
-
Log messages generated by RFC 1918 filtering are
- not rate limited.
-
The firewall fails to start in the case where
-you have "eth0 eth1" in /etc/shorewall/masq and the default route
-is through eth1
-
-
+
There is an updated rfc1918 file that reflects
+ the resent allocation of 222.0.0.0/8 and 223.0.0.0/8.
+
+
+
+
The documentation for the routestopped file
+claimed that a comma-separated list could appear in the second
+column while the code only supported a single host or network address.
+
Log messages produced by 'logunclean' and 'dropunclean'
+ were not rate-limited.
+
802.11b devices with names of the form wlan<n>
+ don't support the 'maclist' interface option.
+
Log messages generated by RFC 1918 filtering
+are not rate limited.
+
The firewall fails to start in the case where
+ you have "eth0 eth1" in /etc/shorewall/masq and the default route
+ is through eth1
+
+
+
2/8/2003 - Shoreawall 1.3.14
-
+
New features include
-
-
-
An OLD_PING_HANDLING option has been
- added to shorewall.conf. When set to Yes, Shorewall ping
-handling is as it has always been (see http://www.shorewall.net/ping.html).
-
- When OLD_PING_HANDLING=No, icmp echo
- (ping) is handled via rules and policies just like any
-other connection request. The FORWARDPING=Yes option in shorewall.conf
- and the 'noping' and 'filterping' options in /etc/shorewall/interfaces
- will all generate an error.
-
-
-
It is now possible to direct Shorewall
- to create a "label" such as "eth0:0" for IP addresses that
- it creates under ADD_IP_ALIASES=Yes and ADD_SNAT_ALIASES=Yes.
- This is done by specifying the label instead of just the interface
- name:
-
- a) In the INTERFACE column of /etc/shorewall/masq
- b) In the INTERFACE column of /etc/shorewall/nat
-
-
Support for OpenVPN Tunnels.
-
-
-
Support for VLAN devices with names
- of the form $DEV.$VID (e.g., eth0.0)
-
-
-
In /etc/shorewall/tcrules, the MARK
-value may be optionally followed by ":" and either 'F' or 'P'
-to designate that the marking will occur in the FORWARD or PREROUTING
-chains respectively. If this additional specification is omitted,
-the chain used to mark packets will be determined by the setting
- of the MARK_IN_FORWARD_CHAIN option in shorewall.conf.
-
-
-
When an interface name is entered
-in the SUBNET column of the /etc/shorewall/masq file, Shorewall
- previously masqueraded traffic from only the first subnet defined
- on that interface. It did not masquerade traffic from:
-
- a) The subnets associated with other
- addresses on the interface.
- b) Subnets accessed through local
- routers.
-
- Beginning with Shorewall 1.3.14, if
-you enter an interface name in the SUBNET column, shorewall
-will use the firewall's routing table to construct the masquerading/SNAT
- rules.
-
- Example 1 -- This is how it works in
- 1.3.14.
-
-
-
-
-
-
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
-
-
-
-
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254
-
-
-
-
-
[root@gateway test]# shorewall start ... Masqueraded Subnets and Hosts: To 0.0.0.0/0 from 192.168.1.0/24 through eth0 using 206.124.146.176 To 0.0.0.0/0 from 192.168.10.0/24 through eth0 using 206.124.146.176 Processing /etc/shorewall/tos...
-
- When upgrading to Shorewall 1.3.14,
-if you have multiple local subnets connected to an interface
- that is specified in the SUBNET column of an /etc/shorewall/masq
- entry, your /etc/shorewall/masq file will need changing. In
- most cases, you will simply be able to remove redundant entries.
- In some cases though, you might want to change from using the interface
- name to listing specific subnetworks if the change described above
-will cause masquerading to occur on subnetworks that you don't wish
-to masquerade.
-
- Example 2 -- Suppose that your current
- config is as follows:
-
-
-
-
-
-
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 eth0 192.168.10.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
-
-
-
-
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
-
- In this case, the second entry in
- /etc/shorewall/masq is no longer required.
-
- Example 3 -- What if your current configuration
- is like this?
-
-
-
-
-
-
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
-
-
-
-
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
-
- In this case, you would want to
-change the entry in /etc/shorewall/masq to:
-
-
-
-
-
#INTERFACE SUBNET ADDRESS eth0 192.168.1.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
-
-
-
-
- 2/5/2003 - Shorewall Support included
-in Webmin 1.060
-
-
Webmin version 1.060 now has Shorewall support included as standard. See
- http://www.webmin.com.
-
- 2/4/2003 - Shorewall 1.3.14-RC1
-
Includes the Beta 2 content plus support for OpenVPN tunnels.
-
-
1/28/2003 - Shorewall 1.3.14-Beta2
-
-
Includes the Beta 1 content plus restores VLAN device names of the form
- $dev.$vid (e.g., eth0.1)
-
-
1/25/2003 - Shorewall 1.3.14-Beta1
-
-
-
-
The Beta includes the following changes:
-
-
-
-
An OLD_PING_HANDLING option has
- been added to shorewall.conf. When set to Yes, Shorewall
-ping handling is as it has always been (see http://www.shorewall.net/ping.html).
-
- When OLD_PING_HANDLING=No, icmp echo
- (ping) is handled via rules and policies just like any
+
An OLD_PING_HANDLING option has
+been added to shorewall.conf. When set to Yes, Shorewall
+ping handling is as it has always been (see http://www.shorewall.net/ping.html).
+
+ When OLD_PING_HANDLING=No, icmp echo
+ (ping) is handled via rules and policies just like any
other connection request. The FORWARDPING=Yes option in shorewall.conf
- and the 'noping' and 'filterping' options in /etc/shorewall/interfaces
- will all generate an error.
-
-
-
It is now possible to direct
-Shorewall to create a "label" such as "eth0:0" for IP addresses
-that it creates under ADD_IP_ALIASES=Yes and ADD_SNAT_ALIASES=Yes.
- This is done by specifying the label instead of just the interface
+ and the 'noping' and 'filterping' options in /etc/shorewall/interfaces
+ will all generate an error.
+
+
+
It is now possible to direct Shorewall
+ to create a "label" such as "eth0:0" for IP addresses that
+ it creates under ADD_IP_ALIASES=Yes and ADD_SNAT_ALIASES=Yes.
+ This is done by specifying the label instead of just the interface
name:
-
- a) In the INTERFACE column of /etc/shorewall/masq
- b) In the INTERFACE column of /etc/shorewall/nat
-
-
When an interface name is entered
- in the SUBNET column of the /etc/shorewall/masq file, Shorewall
- previously masqueraded traffic from only the first subnet
- defined on that interface. It did not masquerade traffic from:
-
- a) The subnets associated with other
- addresses on the interface.
- b) Subnets accessed through local
- routers.
-
- Beginning with Shorewall 1.3.14, if
-you enter an interface name in the SUBNET column, shorewall
-will use the firewall's routing table to construct the masquerading/SNAT
- rules.
-
- Example 1 -- This is how it works in
- 1.3.14.
-
+
+ a) In the INTERFACE column of
+/etc/shorewall/masq
+ b) In the INTERFACE column of
+/etc/shorewall/nat
+
+
Support for OpenVPN Tunnels.
+
+
+
Support for VLAN devices with names
+ of the form $DEV.$VID (e.g., eth0.0)
+
+
+
In /etc/shorewall/tcrules, the MARK
+ value may be optionally followed by ":" and either 'F' or
+'P' to designate that the marking will occur in the FORWARD
+or PREROUTING chains respectively. If this additional specification
+ is omitted, the chain used to mark packets will be determined by
+the setting of the MARK_IN_FORWARD_CHAIN option in shorewall.conf.
+
+
+
When an interface name is entered
+ in the SUBNET column of the /etc/shorewall/masq file, Shorewall
+ previously masqueraded traffic from only the first subnet
+defined on that interface. It did not masquerade traffic from:
+
+ a) The subnets associated with
+other addresses on the interface.
+ b) Subnets accessed through local
+ routers.
+
+ Beginning with Shorewall 1.3.14,
+if you enter an interface name in the SUBNET column, shorewall
+ will use the firewall's routing table to construct the masquerading/SNAT
+ rules.
+
+ Example 1 -- This is how it works
+in 1.3.14.
+
-
+
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
+
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254
-
+
[root@gateway test]# shorewall start ... Masqueraded Subnets and Hosts: To 0.0.0.0/0 from 192.168.1.0/24 through eth0 using 206.124.146.176 To 0.0.0.0/0 from 192.168.10.0/24 through eth0 using 206.124.146.176 Processing /etc/shorewall/tos...
-
- When upgrading to Shorewall 1.3.14,
-if you have multiple local subnets connected to an interface
- that is specified in the SUBNET column of an /etc/shorewall/masq
- entry, your /etc/shorewall/masq file will need changing. In
- most cases, you will simply be able to remove redundant entries.
+
+ When upgrading to Shorewall 1.3.14,
+ if you have multiple local subnets connected to an interface
+ that is specified in the SUBNET column of an /etc/shorewall/masq
+ entry, your /etc/shorewall/masq file will need changing.
+In most cases, you will simply be able to remove redundant entries.
In some cases though, you might want to change from using the interface
- name to listing specific subnetworks if the change described above
-will cause masquerading to occur on subnetworks that you don't wish
+ name to listing specific subnetworks if the change described above
+ will cause masquerading to occur on subnetworks that you don't wish
to masquerade.
-
- Example 2 -- Suppose that your current
- config is as follows:
-
+
+ Example 2 -- Suppose that your current
+ config is as follows:
+
-
+
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 eth0 192.168.10.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
+
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
-
- In this case, the second entry in
- /etc/shorewall/masq is no longer required.
-
- Example 3 -- What if your current configuration
- is like this?
-
+
+ In this case, the second entry
+in /etc/shorewall/masq is no longer required.
+
+ Example 3 -- What if your current
+configuration is like this?
+
-
+
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
+
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
-
- In this case, you would want to
-change the entry in /etc/shorewall/masq to:
+
+ In this case, you would want to
+ change the entry in /etc/shorewall/masq to:
-
+
#INTERFACE SUBNET ADDRESS eth0 192.168.1.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
+
+
+
+
+
+ 2/5/2003 - Shorewall Support included
+ in Webmin 1.060
+
+
Webmin version 1.060 now has Shorewall support included as standard. See
+ http://www.webmin.com.
+
+ 2/4/2003 - Shorewall 1.3.14-RC1
+
+
Includes the Beta 2 content plus support for OpenVPN tunnels.
+
+
1/28/2003 - Shorewall 1.3.14-Beta2
-
+
+
Includes the Beta 1 content plus restores VLAN device names of the form
+ $dev.$vid (e.g., eth0.1)
+
+
+
1/25/2003 - Shorewall 1.3.14-Beta1
+
+
+
+
The Beta includes the following changes:
+
+
+
+
+
An OLD_PING_HANDLING option
+has been added to shorewall.conf. When set to Yes, Shorewall
+ ping handling is as it has always been (see http://www.shorewall.net/ping.html).
+
+ When OLD_PING_HANDLING=No, icmp echo
+ (ping) is handled via rules and policies just like any
+other connection request. The FORWARDPING=Yes option in shorewall.conf
+ and the 'noping' and 'filterping' options in /etc/shorewall/interfaces
+ will all generate an error.
+
+
+
It is now possible to direct
+ Shorewall to create a "label" such as "eth0:0" for IP
+addresses that it creates under ADD_IP_ALIASES=Yes and ADD_SNAT_ALIASES=Yes.
+ This is done by specifying the label instead of just the interface
+ name:
+
+ a) In the INTERFACE column of
+/etc/shorewall/masq
+ b) In the INTERFACE column of
+/etc/shorewall/nat
+
+
When an interface name is entered
+ in the SUBNET column of the /etc/shorewall/masq file, Shorewall
+ previously masqueraded traffic from only the first subnet
+ defined on that interface. It did not masquerade traffic from:
+
+ a) The subnets associated with
+other addresses on the interface.
+ b) Subnets accessed through local
+ routers.
+
+ Beginning with Shorewall 1.3.14,
+if you enter an interface name in the SUBNET column, shorewall
+ will use the firewall's routing table to construct the masquerading/SNAT
+ rules.
+
+ Example 1 -- This is how it works
+in 1.3.14.
+
+
+
+
+
+
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
+
+
+
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254
+
+
+
+
+
[root@gateway test]# shorewall start ... Masqueraded Subnets and Hosts: To 0.0.0.0/0 from 192.168.1.0/24 through eth0 using 206.124.146.176 To 0.0.0.0/0 from 192.168.10.0/24 through eth0 using 206.124.146.176 Processing /etc/shorewall/tos...
+
+ When upgrading to Shorewall 1.3.14,
+ if you have multiple local subnets connected to an interface
+ that is specified in the SUBNET column of an /etc/shorewall/masq
+ entry, your /etc/shorewall/masq file will need changing.
+In most cases, you will simply be able to remove redundant entries.
+ In some cases though, you might want to change from using the interface
+ name to listing specific subnetworks if the change described above
+ will cause masquerading to occur on subnetworks that you don't wish
+to masquerade.
+
+ Example 2 -- Suppose that your current
+ config is as follows:
+
+
+
+
+
+
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 eth0 192.168.10.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
+
+
+
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
+
+ In this case, the second entry
+in /etc/shorewall/masq is no longer required.
+
+ Example 3 -- What if your current
+configuration is like this?
+
+
+
+
+
+
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
+
+
+
[root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
+
+ In this case, you would want to
+ change the entry in /etc/shorewall/masq to:
+
+
+
+
+
#INTERFACE SUBNET ADDRESS eth0 192.168.1.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
+
-
+
1/18/2003 - Shorewall 1.3.13 Documentation in PDF Format
-
+
Juraj Ontkanin has produced a PDF containing the Shorewall 1.3.13 documenation.
- the PDF may be downloaded from
Thanks to the generosity of Alex Martin and Rett Consulting, www.shorewall.net and ftp.shorewall.net
are now hosted on a system in Bellevue, Washington. A big thanks to Alex
for making this happen.
-
+
-
+
1/13/2003 - Shorewall 1.3.13
-
+
-
+
Just includes a few things that I had on the burner:
-
+
-
+
-
A new 'DNAT-' action has
-been added for entries in the /etc/shorewall/rules file.
-DNAT- is intended for advanced users who wish to minimize the
-number of rules that connection requests must traverse.
-
- A Shorewall DNAT rule actually
-generates two iptables rules: a header rewriting rule
+
A new 'DNAT-' action has
+ been added for entries in the /etc/shorewall/rules file.
+ DNAT- is intended for advanced users who wish to minimize the
+ number of rules that connection requests must traverse.
+
+ A Shorewall DNAT rule actually
+ generates two iptables rules: a header rewriting rule
in the 'nat' table and an ACCEPT rule in the 'filter' table.
A DNAT- rule only generates the first of these rules. This
is handy when you have several DNAT rules that would generate the
same ACCEPT rule.
-
- Here are three rules from my
-previous rules file:
-
- DNAT net dmz:206.124.146.177
- tcp smtp - 206.124.146.178
- DNAT net dmz:206.124.146.177
- tcp smtp - 206.124.146.179
- ACCEPT net dmz:206.124.146.177
- tcp www,smtp,ftp,...
-
- These three rules ended up generating
- _three_ copies of
-
- ACCEPT net dmz:206.124.146.177
- tcp smtp
-
- By writing the rules this way,
- I end up with only one copy of the ACCEPT rule.
-
- DNAT- net dmz:206.124.146.177
- tcp smtp - 206.124.146.178
- DNAT- net dmz:206.124.146.177
- tcp smtp - 206.124.146.179
- ACCEPT net dmz:206.124.146.177
- tcp www,smtp,ftp,....
-
-
-
The 'shorewall check' command
- now prints out the applicable policy between each pair
-of zones.
-
-
-
A new CLEAR_TC option has
-been added to shorewall.conf. If this option is set to 'No'
-then Shorewall won't clear the current traffic control rules
- during [re]start. This setting is intended for use by people
-that prefer to configure traffic shaping when the network interfaces
+
+ Here are three rules from
+my previous rules file:
+
+ DNAT net dmz:206.124.146.177
+ tcp smtp - 206.124.146.178
+ DNAT net dmz:206.124.146.177
+ tcp smtp - 206.124.146.179
+ ACCEPT net dmz:206.124.146.177
+ tcp www,smtp,ftp,...
+
+ These three rules ended up
+generating _three_ copies of
+
+ ACCEPT net dmz:206.124.146.177
+ tcp smtp
+
+ By writing the rules this
+way, I end up with only one copy of the ACCEPT rule.
+
+ DNAT- net dmz:206.124.146.177
+ tcp smtp - 206.124.146.178
+ DNAT- net dmz:206.124.146.177
+ tcp smtp - 206.124.146.179
+ ACCEPT net dmz:206.124.146.177
+ tcp www,smtp,ftp,....
+
+
+
The 'shorewall check' command
+ now prints out the applicable policy between each pair
+ of zones.
+
+
+
A new CLEAR_TC option has
+ been added to shorewall.conf. If this option is set to
+'No' then Shorewall won't clear the current traffic control
+ rules during [re]start. This setting is intended for use by people
+ that prefer to configure traffic shaping when the network interfaces
come up rather than when the firewall is started. If that is what
you want to do, set TC_ENABLED=Yes and CLEAR_TC=No and do not supply
an /etc/shorewall/tcstart file. That way, your traffic shaping
rules can still use the 'fwmark' classifier based on packet marking
defined in /etc/shorewall/tcrules.
-
-
-
A new SHARED_DIR variable
-has been added that allows distribution packagers to easily
-move the shared directory (default /usr/lib/shorewall). Users
-should never have a need to change the value of this shorewall.conf
- setting.
-
+
+
+
A new SHARED_DIR variable
+ has been added that allows distribution packagers to easily
+ move the shared directory (default /usr/lib/shorewall). Users
+ should never have a need to change the value of this shorewall.conf
+ setting.
+
-
+
-
+
1/6/2003 - BURNOUT
-
+
Until further notice, I will not be involved in either Shorewall Development
- or Shorewall Support
+ or Shorewall Support
-
+
-Tom Eastep
-
+
-
+
12/30/2002 - Shorewall Documentation in PDF Format
-
+
Juraj Ontkanin has produced a PDF containing the Shorewall 1.3.12 documenation.
- the PDF may be downloaded from
"shorewall refresh" now
- reloads the traffic shaping rules (tcrules and tcstart).
-
"shorewall debug [re]start"
- now turns off debugging after an error occurs. This
- places the point of the failure near the end of the trace
+
"shorewall refresh"
+now reloads the traffic shaping rules (tcrules and
+tcstart).
+
"shorewall debug [re]start"
+ now turns off debugging after an error occurs. This
+ places the point of the failure near the end of the trace
rather than up in the middle of it.
-
"shorewall [re]start"
-has been speeded up by more than 40% with my configuration.
- Your milage may vary.
-
A "shorewall show classifiers"
- command has been added which shows the current packet
- classification filters. The output from this command is
- also added as a separate page in "shorewall monitor"
-
ULOG (must be all caps)
- is now accepted as a valid syslog level and causes
+
"shorewall [re]start"
+ has been speeded up by more than 40% with my configuration.
+ Your milage may vary.
+
A "shorewall show classifiers"
+ command has been added which shows the current packet
+ classification filters. The output from this command is
+ also added as a separate page in "shorewall monitor"
If you are running a kernel
- that has a FORWARD chain in the mangle table ("shorewall
- show mangle" will show you the chains in the mangle table),
- you can set MARK_IN_FORWARD_CHAIN=Yes in shorewall.conf. This allows for
-marking input packets based on their destination even when you
- are using Masquerading or SNAT.
-
I have cluttered up the
- /etc/shorewall directory with empty 'init', 'start',
- 'stop' and 'stopped' files. If you already have a file with
- one of these names, don't worry -- the upgrade process won't
- overwrite your file.
-
I have added a new RFC1918_LOG_LEVEL
- variable to shorewall.conf.
- This variable specifies the syslog level at which packets
- are logged as a result of entries in the /etc/shorewall/rfc1918
- file. Previously, these packets were always logged at the 'info'
- level.
-
+
If you are running a
+kernel that has a FORWARD chain in the mangle table
+("shorewall show mangle" will show you the chains in the mangle
+ table), you can set MARK_IN_FORWARD_CHAIN=Yes in shorewall.conf. This allows for
+ marking input packets based on their destination even when
+you are using Masquerading or SNAT.
+
I have cluttered up
+the /etc/shorewall directory with empty 'init',
+'start', 'stop' and 'stopped' files. If you already have a
+ file with one of these names, don't worry -- the upgrade
+process won't overwrite your file.
+
I have added a new RFC1918_LOG_LEVEL
+ variable to shorewall.conf.
+ This variable specifies the syslog level at which packets
+ are logged as a result of entries in the /etc/shorewall/rfc1918
+ file. Previously, these packets were always logged at the
+'info' level.
+
-
+
-
+
12/20/2002 - Shorewall 1.3.12 Beta 3
-
- This version corrects a problem
- with Blacklist logging. In Beta 2, if BLACKLIST_LOG_LEVEL
- was set to anything but ULOG, the firewall would fail to start
- and "shorewall refresh" would also fail.
+
+ This version corrects a problem
+ with Blacklist logging. In Beta 2, if BLACKLIST_LOG_LEVEL
+ was set to anything but ULOG, the firewall would fail to
+start and "shorewall refresh" would also fail.
-
+
12/20/2002 - Shorewall 1.3.12 Beta 2
-
+
The first public Beta version of Shorewall 1.3.12 is now available (Beta
- 1 was made available only to a limited audience).
-
- Features include:
+ 1 was made available only to a limited audience).
+
+ Features include:
-
+
-
"shorewall refresh"
- now reloads the traffic shaping rules (tcrules and
- tcstart).
-
"shorewall debug
-[re]start" now turns off debugging after an error
- occurs. This places the point of the failure near the end of
- the trace rather than up in the middle of it.
-
"shorewall [re]start"
- has been speeded up by more than 40% with my configuration.
- Your milage may vary.
-
A "shorewall show
-classifiers" command has been added which shows the
-current packet classification filters. The output from this
- command is also added as a separate page in "shorewall monitor"
"shorewall debug
+ [re]start" now turns off debugging after an error
+ occurs. This places the point of the failure near the end
+of the trace rather than up in the middle of it.
+
"shorewall [re]start"
+ has been speeded up by more than 40% with my configuration.
+ Your milage may vary.
+
A "shorewall show
+ classifiers" command has been added which shows the
+ current packet classification filters. The output from this
+ command is also added as a separate page in "shorewall monitor"
+
ULOG (must be all
+ caps) is now accepted as a valid syslog level and causes
+ the subject packets to be logged using the ULOG target rather
+ than the LOG target. This allows you to run ulogd (available
+from http://www.gnumonks.org/projects/ulogd)
+ and log all Shorewall messages to a separate log file.
-
If you are running
- a kernel that has a FORWARD chain in the mangle table
- ("shorewall show mangle" will show you the chains in the
-mangle table), you can set MARK_IN_FORWARD_CHAIN=Yes in shorewall.conf.
- This allows for marking input packets based on their destination
- even when you are using Masquerading or SNAT.
-
I have cluttered
-up the /etc/shorewall directory with empty 'init',
- 'start', 'stop' and 'stopped' files. If you already have a
+
If you are running
+ a kernel that has a FORWARD chain in the mangle table
+ ("shorewall show mangle" will show you the chains in the
+ mangle table), you can set MARK_IN_FORWARD_CHAIN=Yes in shorewall.conf.
+ This allows for marking input packets based on their destination
+ even when you are using Masquerading or SNAT.
+
I have cluttered
+ up the /etc/shorewall directory with empty 'init',
+ 'start', 'stop' and 'stopped' files. If you already have a
file with one of these names, don't worry -- the upgrade process
won't overwrite your file.
-
+
- You may download the Beta
- from:
+ You may download the
+Beta from:
-
+
Two months and 3 days after I ordered Mandrake 9.0, it was finally delivered.
- I have installed 9.0 on one of my systems and
+ I have installed 9.0 on one of my systems and
I am now in a position to support Shorewall users who
run Mandrake 9.0.
This is a bug-fix roll up which includes Roger Aich's fix for DNAT with
- excluded subnets (e.g., "DNAT foo!bar ...").
+ excluded subnets (e.g., "DNAT foo!bar ...").
Current 1.3.11 users who don't need rules of this
type need not upgrade to 1.3.11.
It is now
-allowed to use 'all' in the SOURCE or DEST column in
- a rule. When used,
- 'all' must appear by itself (in may not be qualified) and it does
+
It is now
+ allowed to use 'all' in the SOURCE or DEST column
+in a rule. When used,
+ 'all' must appear by itself (in may not be qualified) and it does
not enable intra-zone traffic. For example, the rule
-
- ACCEPT loc all
- tcp 80
-
- does not enable
-http traffic from 'loc' to 'loc'.
-
Shorewall's
- use of the 'echo' command is now compatible with bash
- clones such as ash and dash.
-
fw->fw
-policies now generate a startup error. fw->fw rules
- generate a warning and are ignored
+
+ ACCEPT loc
+all tcp 80
+
+ does not enable
+ http traffic from 'loc' to 'loc'.
+
Shorewall's
+ use of the 'echo' command is now compatible with
+bash clones such as ash and dash.
+
fw->fw
+ policies now generate a startup error. fw->fw
+rules generate a warning and are ignored
-
+
-
+
11/14/2002 - Shorewall Documentation in PDF Format
-
+
Juraj Ontkanin has produced a PDF containing the Shorewall 1.3.10 documenation.
- the PDF may be downloaded from
Shorewall
+ can now do MAC verification
+ on ethernet segments. You can specify the set of allowed MAC addresses
+ on the segment and you can optionally tie each MAC address to
+ one or more IP addresses.
+
PPTP
+Servers and Clients running on the firewall system
+ may now be defined in the /etc/shorewall/tunnels
+ file.
The main
+ firewall script is now /usr/lib/shorewall/firewall.
+ The script in /etc/init.d/shorewall is very small and uses
+ /sbin/shorewall to do the real work. This change makes
+ custom distributions such as for Debian and for Gentoo
+ easier to manage since it is /etc/init.d/shorewall that
+ tends to have distribution-dependent code
Shorewall
- can now do MAC verification
- on ethernet segments. You can specify the set of allowed MAC addresses
- on the segment and you can optionally tie each MAC address to
-one or more IP addresses.
-
PPTP Servers
- and Clients running on the firewall system may
-now be defined in the /etc/shorewall/tunnels
- file.
The main
- firewall script is now /usr/lib/shorewall/firewall.
- The script in /etc/init.d/shorewall is very small and uses
- /sbin/shorewall to do the real work. This change makes
- custom distributions such as for Debian and for Gentoo
- easier to manage since it is /etc/init.d/shorewall that
-tends to have distribution-dependent code
Shorewall
- can now do MAC verification
- on ethernet segments. You can specify the set of
+
Shorewall
+ can now do MAC verification
+ on ethernet segments. You can specify the set of
allowed MAC addresses on the segment and you can optionally
-tie each MAC address to one or more IP addresses.
-
PPTP Servers
- and Clients running on the firewall system may now
- be defined in the /etc/shorewall/tunnels
- file.
The main
- firewall script is now /usr/lib/shorewall/firewall.
- The script in /etc/init.d/shorewall is very small and uses
- /sbin/shorewall to do the real work. This change makes
- custom distributions such as for Debian and for Gentoo
- easier to manage since it is /etc/init.d/shorewall that
-tends to have distribution-dependent code.
- This release
- rolls up fixes to the installer and to the firewall
- script.
+
The
+main firewall script is now /usr/lib/shorewall/firewall.
+ The script in /etc/init.d/shorewall is very small and
+uses /sbin/shorewall to do the real work. This change
+makes custom distributions such as for Debian and
+for Gentoo easier to manage since it is /etc/init.d/shorewall
+ that tends to have distribution-dependent code.
-
10/6/2002 - Shorewall.net now running on RH8.0
-
- The firewall
- and server here at shorewall.net are now running
-RedHat release 8.0.
-
-
- 9/30/2002
-- Shorewall 1.3.9a
DNS Names are
-now allowed in Shorewall config files (although I recommend against
- using them).
-
The
- connection SOURCE may now be qualified by both interface
- and IP address in a Shorewall rule.
-
Shorewall
- startup is now disabled after initial installation
- until the file /etc/shorewall/startup_disabled is removed.
- This avoids nasty surprises during reboot for users
- who install Shorewall but don't configure it.
-
The
- 'functions' and 'version' files and the 'firewall'
- symbolic link have been moved from /var/lib/shorewall
- to /usr/lib/shorewall to appease the LFS police
-at Debian.
-
-
-
-
-
-
9/23/2002 - Full Shorewall Site/Mailing List Archive Search Capability
- Restored
-
-
-
-
-
-A couple of recent configuration changes at www.shorewall.net
- broke the Search facility:
-
-
-
-
-
-
-
-
-
-
Mailing List Archive Search was not available.
-
-
The Site Search index was incomplete
-
-
Only one page of matches was presented.
-
-
-
-
-
-
-
-
- Hopefully these problems are now corrected.
-
-
9/23/2002 - Full Shorewall Site/Mailing List Archive Search Capability
- Restored
-
- A
-couple of recent configuration changes at www.shorewall.net
- had the negative effect of breaking the Search
- facility:
+ You may
+download the Beta from:
-
-
-
Mailing List Archive Search was not available.
-
-
The Site Search index was incomplete
-
-
Only one page of matches was presented.
-
-
-
- Hopefully
- these problems are now corrected.
-
-
-
A NEWNOTSYN option
- has been added to shorewall.conf. This option determines whether
- Shorewall accepts TCP packets which are not part
- of an established connection and that are not 'SYN'
- packets (SYN flag on and ACK flag off).
-
-
The need for the 'multi' option to communicate
- between zones za and zb on the same interface
-is removed in the case where the chain 'za2zb' and/or 'zb2za'
- exists. 'za2zb' will exist if:
-
-
-
-
-
-
-
-
There is a policy for za to zb; or
-
-
-
There is at least one rule for za to zb.
-
-
-
-
-
-
-
-
+
-
-
-
-
-
The /etc/shorewall/blacklist file now contains
- three columns. In addition to the SUBNET/ADDRESS
- column, there are optional PROTOCOL and PORT columns to
-block only certain applications from the blacklisted addresses.
-
-
+ This release
+ rolls up fixes to the installer and to the firewall
+ script.
+
+
+
10/6/2002 - Shorewall.net now running on RH8.0
+
+ The firewall
+ and server here at shorewall.net are now running
+ RedHat release 8.0.
+
+
+ 9/30/2002
+ - Shorewall 1.3.9a
DNS Names
+ are now allowed in Shorewall config files (although I recommend against
+ using them).
+
+
The connection SOURCE may now be qualified by
+ both interface and IP address in a Shorewall rule.
+
+
Shorewall startup is now disabled after initial
+ installation until the file /etc/shorewall/startup_disabled
+ is removed. This avoids nasty surprises during
+reboot for users who install Shorewall but don't configure
+it.
+
The
+ 'functions' and 'version' files and the 'firewall'
+ symbolic link have been moved from /var/lib/shorewall
+ to /usr/lib/shorewall to appease the LFS police
+at Debian.
+
+
+
+
+
+
+
9/23/2002 - Full Shorewall Site/Mailing List Archive Search Capability
+ Restored
+
+
+
+
+
+ A couple of recent configuration changes at www.shorewall.net
+ broke the Search facility:
+
+
+
+
+
+
+
+
+
+
Mailing List Archive Search was not available.
+
+
The Site Search index was incomplete
+
+
Only one page of matches was presented.
+
+
+
+
+
+
+
+
+ Hopefully these problems are now corrected.
+
+
9/23/2002 - Full Shorewall Site/Mailing List Archive Search Capability
+ Restored
+
+
+
+A couple of recent configuration changes at www.shorewall.net
+ had the negative effect of breaking the Search
+ facility:
+
+
+
+
+
Mailing List Archive Search was not available.
+
+
The Site Search index was incomplete
+
+
Only one page of matches was presented.
+
+
+
+
+Hopefully these problems are now corrected.
+
+
+
A NEWNOTSYN
+ option has been added to shorewall.conf. This option determines
+ whether Shorewall accepts TCP packets which
+are not part of an established connection and that
+are not 'SYN' packets (SYN flag on and ACK flag off).
+
+
The need for the 'multi' option to communicate
+ between zones za and zb on the same interface
+ is removed in the case where the chain 'za2zb' and/or
+'zb2za' exists. 'za2zb' will exist if:
+
+
+
+
+
+
+
+
There is a policy for za to zb; or
+
+
+
There is at least one rule for za to
+zb.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
The /etc/shorewall/blacklist file now contains
+ three columns. In addition to the SUBNET/ADDRESS
+ column, there are optional PROTOCOL and PORT columns to
+ block only certain applications from the blacklisted addresses.
+
+
8/22/2002 - Shorewall 1.3.7 Wins a Brown Paper Bag Award for its Author
+ -- Shorewall 1.3.7a released
+
+
+
+
+
1.3.7a corrects problems occurring in rules file processing when starting
- Shorewall 1.3.7.
+ Shorewall 1.3.7.
-
+
8/22/2002 - Shorewall 1.3.7 Released 8/13/2002
-
+
Features in this release include:
-
+
-
The 'icmp.def' file is now empty! The rules
- in that file were required in ipchains firewalls
- but are not required in Shorewall. Users who have
- ALLOWRELATED=No in shorewall.conf
- should see the Upgrade Issues.
+
The 'icmp.def' file is now empty! The rules
+ in that file were required in ipchains firewalls
+ but are not required in Shorewall. Users who have
+ ALLOWRELATED=No in shorewall.conf
+ should see the Upgrade
+Issues.
-
A 'FORWARDPING' option has been added to
- shorewall.conf.
+
A 'FORWARDPING' option has been added to
+ shorewall.conf.
The effect of setting this variable to Yes is
-the same as the effect of adding an ACCEPT rule
- for ICMP echo-request in /etc/shorewall/icmpdef.
Users who have such a rule in icmpdef are
encouraged to switch to FORWARDPING=Yes.
-
The loopback CLASS A Network (127.0.0.0/8)
- has been added to the rfc1918 file.
+
The loopback CLASS A Network (127.0.0.0/8)
+ has been added to the rfc1918 file.
-
Shorewall now works with iptables 1.2.7
+
Shorewall now works with iptables 1.2.7
-
The documentation and web site no longer
-uses FrontPage themes.
+
The documentation and web site no longer
+ uses FrontPage themes.
-
+
-
+
I would like to thank John Distler for his valuable input regarding TCP
- SYN and ICMP treatment in Shorewall.
- That input has led to marked improvement in
- Shorewall in the last two releases.
+ SYN and ICMP treatment in Shorewall.
+ That input has led to marked improvement in
+ Shorewall in the last two releases.
-
+
This branch will only be updated after I release a new version of Shorewall
- so you can always update from this
-branch to get the latest stable tree.
+ so you can always update from this
+ branch to get the latest stable tree.
-
+
Shorewall will now DROP TCP packets that
-are not part of or related to an existing connection
- and that are not SYN packets. These "New not SYN"
-packets may be optionally logged by setting the LOGNEWNOTSYN
- option in /etc/shorewall/shorewall.conf.
+
Shorewall will now DROP TCP packets that
+ are not part of or related to an existing connection
+ and that are not SYN packets. These "New not SYN"
+ packets may be optionally logged by setting the LOGNEWNOTSYN
+ option in /etc/shorewall/shorewall.conf.
The first draft of this guide is available at http://www.shorewall.net/shorewall_setup_guide.htm.
- The guide is intended for use by people
- who are setting up Shorewall to manage multiple
- public IP addresses and by people who want to learn
- more about Shorewall than is described in the single-address
- guides. Feedback on the new guide is welcome.
+ The guide is intended for use by
+people who are setting up Shorewall to manage
+multiple public IP addresses and by people who want
+to learn more about Shorewall than is described in the
+ single-address guides. Feedback on the new guide is
+welcome.
-
+
7/28/2002 - Shorewall 1.3.5 Debian Package Available
This interim release restores correct handling of REDIRECT rules.
-
+
7/26/2002 - Shorewall 1.3.5 Released
-
+
This will be the last Shorewall release for a while. I'm going to be
focusing on rewriting a lot of the documentation.
-
+
In this version:
-
+
-
Empty and invalid source and destination
- qualifiers are now detected in the rules file.
-It is a good idea to use the 'shorewall check' command
- before you issue a 'shorewall restart' command be be
-sure that you don't have any configuration problems
- that will prevent a successful restart.
+
Empty and invalid source and destination
+ qualifiers are now detected in the rules file.
+ It is a good idea to use the 'shorewall check' command
+ before you issue a 'shorewall restart' command be be
+ sure that you don't have any configuration problems
+ that will prevent a successful restart.
-
Added MERGE_HOSTS variable in
- shorewall.conf to
-provide saner behavior of the /etc/shorewall/hosts
- file.
+
Added MERGE_HOSTS variable in
+ shorewall.conf
+to provide saner behavior of the /etc/shorewall/hosts
+ file.
-
The time that the counters were last reset
- is now displayed in the heading of the 'status'
- and 'show' commands.
+
The time that the counters were last reset
+ is now displayed in the heading of the 'status'
+ and 'show' commands.
+ Specifying the proxyarp option
+for an interface causes Shorewall to set
+ /proc/sys/net/ipv4/conf/<interface>/proxy_arp.
-
The Samples have been updated to reflect
-the new capabilities in this release.
+
The Samples have been updated to reflect
+ the new capabilities in this release.
-
+
-
+
7/16/2002 - New Mirror in Argentina
-
+
Thanks to Arturo "Buanzo" Busleiman, there is now a Shorewall mirror in
- Argentina. Thanks Buanzo!!!
+ Argentina. Thanks Buanzo!!!
-
+
7/16/2002 - Shorewall 1.3.4 Released
-
+
In this version:
-
+
-
A new /etc/shorewall/routestopped
- file has been added. This file is intended
- to eventually replace the routestopped
- option in the /etc/shorewall/interface and /etc/shorewall/hosts
- files. This new file makes remote firewall
- administration easier by allowing any IP or subnet to be
- enabled while Shorewall is stopped.
+
A new
+ /etc/shorewall/routestopped file
+has been added. This file is intended to eventually
+ replace the routestopped option in the
+ /etc/shorewall/interface and /etc/shorewall/hosts
+ files. This new file makes remote firewall administration
+ easier by allowing any IP or subnet to be enabled
+ while Shorewall is stopped.
+ added. This script is invoked after Shorewall
+ has stopped.
-
A DETECT_DNAT_ADDRS option has
- been added to /etc/shoreall/shorewall.conf.
- When this option is selected, DNAT rules only
- apply when the destination address is the
- external interface's primary IP address.
+
A DETECT_DNAT_ADDRS option
+has been added to /etc/shoreall/shorewall.conf.
+ When this option is selected, DNAT rules only
+ apply when the destination address is the
+ external interface's primary IP address.
-
The QuickStart
- Guide has been broken into three
-guides and has been almost entirely rewritten.
+
The QuickStart
+ Guide has been broken into three
+ guides and has been almost entirely rewritten.
-
The Samples have been updated to reflect
-the new capabilities in this release.
+
The Samples have been updated to reflect
+ the new capabilities in this release.
-
+
-
+
7/8/2002 - Shorewall 1.3.3 Debian Package Available
Entries in /etc/shorewall/interface that
-use the wildcard character ("+") now have the "multi"
- option assumed.
+
Entries in /etc/shorewall/interface that
+ use the wildcard character ("+") now have the "multi"
+ option assumed.
-
The 'rfc1918' chain in the mangle table has
- been renamed 'man1918' to make log messages
-generated from that chain distinguishable from those
- generated by the 'rfc1918' chain in the filter table.
+
The 'rfc1918' chain in the mangle table
+ has been renamed 'man1918' to make log messages
+ generated from that chain distinguishable from those
+ generated by the 'rfc1918' chain in the filter table.
-
Interface names appearing in the hosts file
- are now validated against the interfaces file.
+
Interface names appearing in the hosts
+file are now validated against the interfaces
+ file.
-
The TARGET column in the rfc1918 file is now
- checked for correctness.
+
The TARGET column in the rfc1918 file is
+ now checked for correctness.
-
The chain structure in the nat table has
- been changed to reduce the number of rules that a
-packet must traverse and to correct problems with
- NAT_BEFORE_RULES=No
+
The chain structure in the nat table has
+ been changed to reduce the number of rules that a
+ packet must traverse and to correct problems with
+ NAT_BEFORE_RULES=No
-
The "hits" command has been enhanced.
+
The "hits" command has been enhanced.
-
+
-
+
6/25/2002 - Samples Updated for 1.3.2
-
+
The comments in the sample configuration files have been updated to reflect
- new features introduced in Shorewall
- 1.3.2.
+ new features introduced in Shorewall
+ 1.3.2.
-
+
6/25/2002 - Shorewall 1.3.1 Debian Package Available
The files firewall, functions and
- version have been moved from /etc/shorewall
- to /var/lib/shorewall.
+
The files firewall, functions and
+ version have been moved from /etc/shorewall
+ to /var/lib/shorewall.
-
+
-
+
6/6/2002 - Why CVS Web access is Password Protected
-
+
Last weekend, I installed the CVS Web package to provide brower-based
access to the Shorewall CVS repository. Since then, I have had several
instances where my server was almost unusable due to the high load generated
by website copying tools like HTTrack and WebStripper. These mindless tools:
-
+
-
Ignore robot.txt files.
+
Ignore robot.txt files.
-
Recursively copy everything that they find.
+
Recursively copy everything that they find.
-
Should be classified as weapons rather than
- tools.
+
Should be classified as weapons rather than
+ tools.
-
+
-
+
These tools/weapons are particularly damaging when combined with CVS Web
- because they doggedly follow every
-link in the cgi-generated HTML resulting in
- 1000s of executions of the cvsweb.cgi script. Yesterday,
- I spend several hours implementing measures to block
- these tools but unfortunately, these measures resulted
- in my server OOM-ing under even moderate load.
+ because they doggedly follow every
+ link in the cgi-generated HTML resulting
+in 1000s of executions of the cvsweb.cgi script.
+Yesterday, I spend several hours implementing measures
+to block these tools but unfortunately, these measures
+ resulted in my server OOM-ing under even moderate
+load.
-
+
Until I have the time to understand the cause of the OOM (or until I buy
- more RAM if that is what is required),
- CVS Web access will remain Password Protected.
-
+ more RAM if that is what is required),
+ CVS Web access will remain Password Protected.
+
-
+
6/5/2002 - Shorewall 1.3.1 Debian Package Available
The 1.3.0 samples configurations had several serious problems that prevented
- DNS and SSH from working properly.
-These problems have been corrected in the
+ DNS and SSH from working properly.
+ These problems have been corrected in the
1.3.1 samples.
-
+
6/1/2002 - Shorewall 1.3.1 Released
-
+
Hot on the heels of 1.3.0, this release:
-
+
-
Corrects a serious problem with "all <zone>
- CONTINUE" policies. This problem is present in
-all versions of Shorewall that support the CONTINUE
- policy. These previous versions optimized away the
-"all2<zone>" chain and replaced it with
- the "all2all" chain with the usual result that a policy of
-REJECT was enforced rather than the intended CONTINUE policy.
+
Corrects a serious problem with "all
+ <zone> CONTINUE" policies. This
+ problem is present in all versions of Shorewall that
+ support the CONTINUE policy. These previous versions
+ optimized away the "all2<zone>"
+chain and replaced it with the "all2all" chain with the usual
+ result that a policy of REJECT was enforced rather than the
+intended CONTINUE policy.
In addition to the changes in Beta 1, Beta 2 and RC1, Shorewall 1.3.0
includes:
-
+
-
A 'filterping' interface option that allows
- ICMP echo-request (ping) requests addressed
- to the firewall to be handled by entries in /etc/shorewall/rules
- and /etc/shorewall/policy.
+
A 'filterping' interface option that allows
+ ICMP echo-request (ping) requests addressed
+ to the firewall to be handled by entries in /etc/shorewall/rules
+ and /etc/shorewall/policy.
-
+
-
+
5/23/2002 - Shorewall 1.3 RC1 Available
-
+
In addition to the changes in Beta 1 and Beta 2, RC1 (Version 1.2.92)
incorporates the following:
-
+
-
Support for the /etc/shorewall/whitelist
- file has been withdrawn. If you need whitelisting,
- see these
- instructions.
+
Support for the /etc/shorewall/whitelist
+ file has been withdrawn. If you need whitelisting,
+ see these
+ instructions.
-
+
-
+
5/19/2002 - Shorewall 1.3 Beta 2 Available
-
+
In addition to the changes in Beta 1, this release which carries the
designation 1.2.91 adds:
-
+
-
The structure of the firewall is changed
-markedly. There is now an INPUT and a FORWARD
- chain for each interface; this reduces the number
- of rules that a packet must traverse, especially in
+
The structure of the firewall is changed
+ markedly. There is now an INPUT and a FORWARD
+ chain for each interface; this reduces the number
+ of rules that a packet must traverse, especially in
complicated setups.
The names of the columns in a number of the
- configuration files have been changed to be more
- consistent and self-explanatory and the documentation
- has been updated accordingly.
+
The names of the columns in a number of
+the configuration files have been changed to
+ be more consistent and self-explanatory and the documentation
+ has been updated accordingly.
-
The sample configurations have been updated
- for 1.3.
+
The sample configurations have been updated
+ for 1.3.
-
+
-
+
5/17/2002 - Shorewall 1.3 Beta 1 Available
-
+
Beta 1 carries the version designation 1.2.90 and implements the following
- features:
+ features:
-
+
-
Simplified rule syntax which makes the intent
- of each rule clearer and hopefully makes Shorewall
- easier to learn.
+
Simplified rule syntax which makes the intent
+ of each rule clearer and hopefully makes Shorewall
+ easier to learn.
-
Upward compatibility with 1.2 configuration
- files has been maintained so that current users
- can migrate to the new syntax at their convenience.
+
Upward compatibility with 1.2 configuration
+ files has been maintained so that current users
+ can migrate to the new syntax at their convenience.
-
WARNING: Compatibility with
- the old parameterized sample configurations has NOT been
- maintained. Users still running those configurations
- should migrate to the new sample configurations
- before upgrading to 1.3 Beta 1.
+
WARNING: Compatibility
+ with the old parameterized sample configurations has NOT
+been maintained. Users still running those configurations
+ should migrate to the new sample configurations
+ before upgrading to 1.3 Beta 1.
+ now inherit the VLSM and Broadcast Address
+of the interface's primary IP address.
-
The order in which port forwarding DNAT and
- Static DNAT can
- now be reversed so that port forwarding rules can
- override the contents of /etc/shorewall/nat.
-
The 'try' command now accepts an optional
- timeout. If the timeout is given in the command,
- the standard configuration will automatically be
- restarted after the new configuration has been running
- for that length of time. This prevents a remote admin
- from being locked out of the firewall in the case where
- the new configuration starts but prevents access.
+
The 'try' command now accepts an optional
+ timeout. If the timeout is given in the command,
+ the standard configuration will automatically be
+ restarted after the new configuration has been running
+ for that length of time. This prevents a remote admin
+ from being locked out of the firewall in the case where
+ the new configuration starts but prevents access.
-
Kernel route filtering may now be enabled
- globally using the new ROUTE_FILTER parameter
- in /etc/shorewall/shorewall.conf.
+
Kernel route filtering may now be enabled
+ globally using the new ROUTE_FILTER parameter
+ in /etc/shorewall/shorewall.conf.
-
Individual IP source addresses and/or subnets
- may now be excluded from masquerading/SNAT.
+
Individual IP source addresses and/or subnets
+ may now be excluded from masquerading/SNAT.
-
Simple "Yes/No" and "On/Off" values are now
- case-insensitive in /etc/shorewall/shorewall.conf.
+
Simple "Yes/No" and "On/Off" values are
+now case-insensitive in /etc/shorewall/shorewall.conf.
4/10/2002 - Shorewall QuickStart Guide Version 1.1 Available
-
+
Version 1.1 of the QuickStart
- Guide is now available. Thanks
-to those who have read version 1.0 and offered
-their suggestions. Corrections have also been made
- to the sample scripts.
+ Guide is now available. Thanks
+ to those who have read version 1.0 and offered
+ their suggestions. Corrections have also been made
+ to the sample scripts.
-
+
4/9/2002 - Shorewall QuickStart Guide Version 1.0 Available
-
+
Version 1.0 of the QuickStart
- Guide is now available. This Guide
- and its accompanying sample configurations
- are expected to provide a replacement for the recently
- withdrawn parameterized samples.
+ Guide is now available. This
+Guide and its accompanying sample configurations
+ are expected to provide a replacement for the recently
+ withdrawn parameterized samples.
-
+
4/8/2002 - Parameterized Samples Withdrawn
-
+
Although the parameterized
- samples have allowed people to
-get a firewall up and running quickly, they
- have unfortunately set the wrong level of expectation
- among those who have used them. I am therefore
- withdrawing support for the samples and I am recommending
- that they not be used in new Shorewall installations.
+ samples have allowed people to
+ get a firewall up and running quickly, they
+ have unfortunately set the wrong level of expectation
+ among those who have used them. I am therefore
+ withdrawing support for the samples and I am recommending
+ that they not be used in new Shorewall installations.
-
+
The quick search on the home page now excludes the mailing list archives.
- The Extended
- Search allows excluding the archives
- or restricting the search to just the archives. An archive
- search form is also available on the Extended
+ Search allows excluding the archives
+ or restricting the search to just the archives. An archive
+ search form is also available on the mailing list information
- page.
+ page.
-
+
3/28/2002 - Debian Shorewall News (From Lorenzo Martignoni)
A "shorewall try" command has been added
-(syntax: shorewall try <configuration
- directory>). This command attempts "shorewall
- -c <configuration directory> start"
-and if that results in the firewall being stopped due
- to an error, a "shorewall start" command is executed. The
- 'try' command allows you to create a new configuration and attempt
- to start it; if there is an error that leaves your firewall
- in the stopped state, it will automatically be restarted
- using the default configuration (in /etc/shorewall).
-
-
A new variable ADD_SNAT_ALIASES has been
-added to /etc/shorewall/shorewall.conf.
- If this variable is set to "Yes", Shorewall
-will automatically add IP addresses listed in
-the third column of the /etc/shorewall/masq
- file.
-
-
Copyright notices have been added to the
-documenation.
-
-
-
-
-
-
-
-
3/11/2002 - Shorewall 1.2.9 Released
-
-
-
-
In this version:
-
-
-
-
-
-
Filtering by MAC
- address has been added. MAC addresses may be used
-as the source address in:
-
-
-
-
-
-
A "shorewall try" command has been added
+ (syntax: shorewall try <configuration
+ directory>). This command attempts "shorewall
+ -c <configuration directory> start"
+ and if that results in the firewall being stopped due
+ to an error, a "shorewall start" command is executed. The
+ 'try' command allows you to create a new configuration and attempt
+ to start it; if there is an error that leaves your firewall
+ in the stopped state, it will automatically be restarted
+ using the default configuration (in /etc/shorewall).
+
+
A new variable ADD_SNAT_ALIASES has been
+ added to /etc/shorewall/shorewall.conf.
+ If this variable is set to "Yes", Shorewall
+ will automatically add IP addresses listed
+in the third column of the
+ /etc/shorewall/masq file.
+
+
Copyright notices have been added to the
+ documenation.
+
+
+
+
+
+
+
+
3/11/2002 - Shorewall 1.2.9 Released
+
+
+
+
In this version:
+
+
+
+
+
+
Filtering by MAC
+ address has been added. MAC addresses may be used
+ as the source address in:
+
+
+
+
+
+
Do to a serious problem with 1.2.7, I am releasing 1.2.8. It corrects
problems associated with the lock file used to prevent multiple state-changing
- operations from occuring simultaneously.
- My apologies for any inconvenience my carelessness
- may have caused.
+ operations from occuring simultaneously.
+ My apologies for any inconvenience my
+carelessness may have caused.
-
+
2/22/2002 - Shorewall 1.2.7 Released
-
+
In this version:
-
+
-
UPnP probes (UDP destination port 1900) are
- now silently dropped in the common chain
+
UPnP probes (UDP destination port 1900)
+are now silently dropped in the common
+ chain
-
RFC 1918 checking in the mangle table has
- been streamlined to no longer require packet
+
RFC 1918 checking in the mangle table has
+ been streamlined to no longer require packet
marking. RFC 1918 checking in the filter table has
been changed to require half as many rules as previously.
-
A 'shorewall check' command has been added
- that does a cursory validation of the zones, interfaces,
- hosts, rules and policy files.
+
A 'shorewall check' command has been added
+ that does a cursory validation of the zones,
+interfaces, hosts, rules and policy files.
$-variables may now be used anywhere in the
- configuration files except /etc/shorewall/zones.
+
$-variables may now be used anywhere in
+the configuration files except /etc/shorewall/zones.
-
The interfaces and hosts files now have their
- contents validated before any changes are made
- to the existing Netfilter configuration. The appearance
- of a zone name that isn't defined in /etc/shorewall/zones
- causes "shorewall start" and "shorewall restart"
- to abort without changing the Shorewall state.
-Unknown options in either file cause a warning to be issued.
+
The interfaces and hosts files now have
+ their contents validated before any changes are
+made to the existing Netfilter configuration. The appearance
+ of a zone name that isn't defined in /etc/shorewall/zones
+ causes "shorewall start" and "shorewall restart"
+ to abort without changing the Shorewall state.
+ Unknown options in either file cause a warning to be issued.
-
A problem occurring when BLACKLIST_LOGLEVEL
- was not set has been corrected.
+
A problem occurring when BLACKLIST_LOGLEVEL
+ was not set has been corrected.
-
+
-
+
2/4/2002 - Shorewall 1.2.5 Debian Package Available
The default value of the STATEDIR variable
- in /etc/shorewall/shorewall.conf has been changed
- to /var/lib/shorewall in order to conform to the
- GNU/Linux File Hierarchy Standard, Version 2.2.
+
The default value of the STATEDIR variable
+ in /etc/shorewall/shorewall.conf has been changed
+ to /var/lib/shorewall in order to conform to the
+ GNU/Linux File Hierarchy Standard, Version 2.2.
You may now place end-of-line comments (preceded
- by '#') in any of the configuration files
+
You may now place end-of-line comments (preceded
+ by '#') in any of the configuration files
-
There is now protection against against two
- state changing operations occuring concurrently.
- This is implemented using the 'lockfile' utility
- if it is available (lockfile is part of procmail);
- otherwise, a less robust technique is used. The lockfile
- is created in the STATEDIR defined in /etc/shorewall/shorewall.conf
- and has the name "lock".
+
There is now protection against against
+two state changing operations occuring concurrently.
+ This is implemented using the 'lockfile' utility
+ if it is available (lockfile is part of procmail);
+ otherwise, a less robust technique is used. The lockfile
+ is created in the STATEDIR defined in /etc/shorewall/shorewall.conf
+ and has the name "lock".
Corrects a problem with BLACKLIST_LOGLEVEL. See the
- errata for details.
+ errata for details.
-
+
1/19/2002 - Shorewall 1.2.3 Released
-
+
This is a minor feature and bugfix release. The single new feature is:
-
+
-
Support for TCP MSS Clamp to PMTU -- This
-support is usually required when the internet
- connection is via PPPoE or PPTP and may be enabled
+
Support for TCP MSS Clamp to PMTU -- This
+ support is usually required when the internet
+ connection is via PPPoE or PPTP and may be enabled
using the CLAMPMSS
option in /etc/shorewall/shorewall.conf.
-
+
-
+
The following problems were corrected:
-
+
-
The "shorewall status" command no longer hangs.
+
The "shorewall status" command no longer
+ hangs.
-
The "shorewall monitor" command now displays
- the icmpdef chain
+
The "shorewall monitor" command now displays
+ the icmpdef chain
-
The CLIENT PORT(S) column in tcrules is no
- longer ignored
+
The CLIENT PORT(S) column in tcrules is no
+ longer ignored
-
+
-
+
1/18/2002 - Shorewall 1.2.2 packaged with new LEAF release
-
+
Jacques Nilo and Eric Wolzak have released a kernel 2.4.16 LEAF distribution
- that includes Shorewall 1.2.2. See http://leaf.sourceforge.net/devel/jnilo
- for details.
+ for details.
-
+
1/11/2002 - Debian Package (.deb) Now Available - Thanks to Lorenzo Martignoni, a 1.2.2
- Shorewall Debian package is now available.
- There is a link to Lorenzo's site from the
+ Shorewall Debian package is now available.
+ There is a link to Lorenzo's site from the
Shorewall download page.
-
+
1/9/2002 - Updated 1.2.2 /sbin/shorewall available - This corrected version restores
- the "shorewall status" command to health.
+ the "shorewall status" command to health.
-
+
1/8/2002 - Shorewall 1.2.2 Released
-
+
In version 1.2.2
-
+
-
Support for IP blacklisting has been added
+
Support for IP blacklisting has been added
+
-
-
+
-
You specify whether you want packets
-from blacklisted hosts dropped or rejected using
-the BLACKLIST_DISPOSITION
- setting in /etc/shorewall/shorewall.conf
+
You specify whether you want packets
+ from blacklisted hosts dropped or rejected
+ using the BLACKLIST_DISPOSITION
+ setting in /etc/shorewall/shorewall.conf
-
You specify whether you want packets
-from blacklisted hosts logged and at what syslog
-level using the BLACKLIST_LOGLEVEL
- setting in /etc/shorewall/shorewall.conf
+
You specify whether you want packets
+ from blacklisted hosts logged and at what
+syslog level using the BLACKLIST_LOGLEVEL
+ setting in /etc/shorewall/shorewall.conf
You specify the interfaces you want checked
- against the blacklist using the new "blacklist" option
- in /etc/shorewall/interfaces.
+
You specify the interfaces you want
+checked against the blacklist using the
+ new "blacklist"
+ option in /etc/shorewall/interfaces.
-
The black list is refreshed from /etc/shorewall/blacklist
- by the "shorewall refresh" command.
+
The black list is refreshed from /etc/shorewall/blacklist
+ by the "shorewall refresh" command.
-
+
-
+
-
Use of TCP RST replies has been expanded
+
Use of TCP RST replies has been expanded
-
+
-
TCP connection requests rejected because
- of a REJECT policy are now replied with a TCP
+
TCP connection requests rejected because
+ of a REJECT policy are now replied with a TCP
RST packet.
-
TCP connection requests rejected because
- of a protocol=all rule in /etc/shorewall/rules
- are now replied with a TCP RST packet.
+
TCP connection requests rejected because
+ of a protocol=all rule in /etc/shorewall/rules
+ are now replied with a TCP RST packet.
-
+
-
+
-
A LOGFILE
-specification has been added to /etc/shorewall/shorewall.conf.
- LOGFILE is used to tell the /sbin/shorewall program
+
A LOGFILE
+ specification has been added to /etc/shorewall/shorewall.conf.
+ LOGFILE is used to tell the /sbin/shorewall program
where to look for Shorewall messages.
-
+
-
+
1/5/2002 - New Parameterized Samples (version 1.2.0) released. These are minor updates
- to the previously-released samples.
+ to the previously-released samples.
There are two new rules added:
-
+
-
Unless you have explicitly enabled Auth connections
- (tcp port 113) to your firewall, these connections
- will be REJECTED rather than DROPPED. This speeds
- up connection establishment to some servers.
+
Unless you have explicitly enabled Auth connections
+ (tcp port 113) to your firewall, these connections
+ will be REJECTED rather than DROPPED. This speeds
+ up connection establishment to some servers.
For the next month or so, I will continue to provide corrections to version
- 1.1.18 as necessary so that current
-version 1.1.x users will not be forced into a
- quick upgrade to 1.2.0 just to have access to bug fixes.
+ 1.1.18 as necessary so that current
+ version 1.1.x users will not be forced into
+a quick upgrade to 1.2.0 just to have access to bug fixes.
-
+
For those of you who have installed one of the Beta RPMS, you will need
- to use the "--oldpackage" option when
- upgrading to 1.2.0:
+ to use the "--oldpackage" option when
+ upgrading to 1.2.0:
-
+
10/22/2001 - The current version of Shorewall is 1.1.16. In this
- version:
+ version:
-
+
-
A new "shorewall show connections" command
- has been added.
+
A new "shorewall show connections" command
+ has been added.
-
In the "shorewall monitor" output, the currently
- tracked connections are now shown on a separate
- page.
+
In the "shorewall monitor" output, the currently
+ tracked connections are now shown on a separate
+ page.
-
Prior to this release, Shorewall unconditionally
- added the external IP adddress(es) specified in
- /etc/shorewall/nat. Beginning with version 1.1.16,
- a new parameter (ADD_IP_ALIASES)
- may be set to "no" (or "No") to inhibit
- this behavior. This allows IP aliases created
+
Prior to this release, Shorewall unconditionally
+ added the external IP adddress(es) specified
+in /etc/shorewall/nat. Beginning with version
+ 1.1.16, a new parameter (ADD_IP_ALIASES)
+ may be set to "no" (or "No") to inhibit
+ this behavior. This allows IP aliases created
using your distribution's network configuration
tools to be used in static NAT.
-
+
+
+
10/15/2001 - The current version of Shorewall is 1.1.15. In this
+ version:
+
+
-
10/15/2001 - The current version of Shorewall is 1.1.15. In this
- version:
-
-
-
-
Support for nested zones has been improved.
- See the documentation
- for details
+
Support for nested zones has been improved.
+ See the documentation
+ for details
-
Shorewall now correctly checks the alternate
- configuration directory for the 'zones' file.
+
Shorewall now correctly checks the alternate
+ configuration directory for the 'zones' file.
-
+
-
+
10/4/2001 - The current version of Shorewall is 1.1.14. In this
- version
+ version
-
+
-
Shorewall now supports alternate configuration
- directories. When an alternate directory is
- specified when starting or restarting Shorewall
- (e.g., "shorewall -c /etc/testconf restart"), Shorewall
- will first look for configuration files in the alternate
- directory then in /etc/shorewall. To create an alternate
- configuration simply:
+
Shorewall now supports alternate configuration
+ directories. When an alternate directory
+is specified when starting or restarting Shorewall
+ (e.g., "shorewall -c /etc/testconf restart"), Shorewall
+ will first look for configuration files in the alternate
+ directory then in /etc/shorewall. To create an alternate
+ configuration simply:
- 1. Create a New Directory
+ 1. Create a New Directory
- 2. Copy to that directory any of your configuration
- files that you want to change.
+ 2. Copy to that directory any of your configuration
+ files that you want to change.
- 3. Modify the copied files as needed.
+ 3. Modify the copied files as needed.
- 4. Restart Shorewall specifying the new directory.
+ 4. Restart Shorewall specifying the new directory.
-
The rules for allowing/disallowing icmp echo-requests
- (pings) are now moved after rules created
- when processing the rules file. This allows you to
- add rules that selectively allow/deny ping based on source
- or destination address.
+
The rules for allowing/disallowing icmp
+echo-requests (pings) are now moved after rules
+ created when processing the rules file. This allows
+ you to add rules that selectively allow/deny ping based
+ on source or destination address.
-
Rules that specify multiple client ip addresses
- or subnets no longer cause startup failures.
+
Rules that specify multiple client ip addresses
+ or subnets no longer cause startup failures.
-
Zone names in the policy file are now validated
- against the zones file.
+
Zone names in the policy file are now validated
+ against the zones file.
-
If you have If you have packet mangling
support enabled, the "norfc1918"
@@ -3552,505 +3604,512 @@ interface option now logs and drops any incoming packets on
the interface that have an RFC 1918 destination address.
-
+
-
+
9/12/2001 - The current version of Shorewall is 1.1.13. In this
- version
+ version
-
+
-
Shell variables can now be used to parameterize
- Shorewall rules.
+
Shell variables can now be used to parameterize
+ Shorewall rules.
-
The second column in the hosts file may now
- contain a comma-separated list.
+
The second column in the hosts file may now
+ contain a comma-separated list.
-
+
- Example:
+ Example:
- sea eth0:130.252.100.0/24,206.191.149.0/24
8/28/2001 - The current version of Shorewall is 1.1.12. In this
- version
+ version
-
+
-
Several columns in the rules file may now
- contain comma-separated lists.
+
Several columns in the rules file may now
+ contain comma-separated lists.
-
Shorewall is now more rigorous in parsing
-the options in /etc/shorewall/interfaces.
+
Shorewall is now more rigorous in parsing
+ the options in /etc/shorewall/interfaces.
-
Complementation using "!" is now supported
- in rules.
+
Complementation using "!" is now supported
+ in rules.
-
+
-
+
7/28/2001 - The current version of Shorewall is 1.1.11. In this
- version
+ version
-
+
-
A "shorewall refresh" command has been added
- to allow for refreshing the rules associated
- with the broadcast address on a dynamic interface.
- This command should be used in place of "shorewall
- restart" when the internet interface's IP address changes.
+
A "shorewall refresh" command has been added
+ to allow for refreshing the rules associated
+ with the broadcast address on a dynamic interface.
+ This command should be used in place of "shorewall
+ restart" when the internet interface's IP address changes.
-
The /etc/shorewall/start file (if any) is
-now processed after all temporary rules have
+
The /etc/shorewall/start file (if any) is
+ now processed after all temporary rules have
been deleted. This change prevents the accidental
removal of rules added during the processing of that
file.
-
The "dhcp" interface option is now applicable
- to firewall interfaces used by a DHCP server running
- on the firewall.
+
The "dhcp" interface option is now applicable
+ to firewall interfaces used by a DHCP server
+running on the firewall.
-
The RPM can now be built from the .tgz file
- using "rpm -tb"
+
The RPM can now be built from the .tgz file
+ using "rpm -tb"
-
+
-
+
7/6/2001 - The current version of Shorewall is 1.1.10. In this
version
-
+
-
Shorewall now enables Ipv4 Packet Forwarding
- by default. Packet forwarding may be disabled
- by specifying IP_FORWARD=Off in /etc/shorewall/shorewall.conf.
- If you don't want Shorewall to enable or
- disable packet forwarding, add IP_FORWARDING=Keep
-to your /etc/shorewall/shorewall.conf file.
+
Shorewall now enables Ipv4 Packet Forwarding
+ by default. Packet forwarding may be disabled
+ by specifying IP_FORWARD=Off in /etc/shorewall/shorewall.conf.
+ If you don't want Shorewall to enable or
+ disable packet forwarding, add IP_FORWARDING=Keep
+ to your /etc/shorewall/shorewall.conf file.
-
The "shorewall hits" command no longer lists
- extraneous service names in its last report.
+
The "shorewall hits" command no longer lists
+ extraneous service names in its last report.
-
Erroneous instructions in the comments at
-the head of the firewall script have been corrected.
+
Erroneous instructions in the comments at
+ the head of the firewall script have been corrected.
-
+
-
+
6/23/2001 - The current version of Shorewall is 1.1.9. In this
version
-
+
-
The "tunnels" file really is in
-the RPM now.
+
The "tunnels" file really is in
+ the RPM now.
-
SNAT can now be applied to port-forwarded
-connections.
+
SNAT can now be applied to port-forwarded
+ connections.
-
A bug which would cause firewall start failures
- in some dhcp configurations has been fixed.
+
A bug which would cause firewall start failures
+ in some dhcp configurations has been fixed.
-
The firewall script now issues a message if
- you have the name of an interface in the second
- column in an entry in /etc/shorewall/masq and that
- interface is not up.
+
The firewall script now issues a message
+ if you have the name of an interface in the second
+ column in an entry in /etc/shorewall/masq and that
+ interface is not up.
Previous versions of Shorewall have
-an implementation of Static NAT which violates the
- principle of least surprise. NAT only occurs for packets
- arriving at (DNAT) or send from (SNAT) the interface
- named in the INTERFACE column of /etc/shorewall/nat. Beginning
- with version 1.1.6, NAT effective regardless of
-which interface packets come from or are destined to. To get
- compatibility with prior versions, I have added a new "ALL
- "ALL INTERFACES" column
- to /etc/shorewall/nat. By placing "no" or "No" in
- the new column, the NAT behavior of prior versions may
- be retained.
+
Previous versions of Shorewall have
+ an implementation of Static NAT which violates the
+ principle of least surprise. NAT only occurs for
+packets arriving at (DNAT) or send from (SNAT) the
+interface named in the INTERFACE column of /etc/shorewall/nat.
+Beginning with version 1.1.6, NAT effective regardless
+ of which interface packets come from or are destined to.
+To get compatibility with prior versions, I have added
+a new "ALL "ALL INTERFACES"
+ column to /etc/shorewall/nat. By placing "no" or
+ "No" in the new column, the NAT behavior of prior
+versions may be retained.
-
The treatment of IPSEC
- Tunnels where the remote gateway is a standalone system
- has been improved. Previously, it was necessary to include
- an additional rule allowing UDP port 500 traffic to pass
- through the tunnel. Shorewall will now create this rule automatically
- when you place the name of the remote peer's zone in a new
-GATEWAY ZONE column in /etc/shorewall/tunnels.
+
The treatment of IPSEC Tunnels where the remote
+ gateway is a standalone system has been improved. Previously,
+ it was necessary to include an additional rule allowing
+ UDP port 500 traffic to pass through the tunnel. Shorewall
+ will now create this rule automatically when you place the
+name of the remote peer's zone in a new GATEWAY ZONE column in
+/etc/shorewall/tunnels.
-
+
-
+
5/20/2001 - The current version of Shorewall is 1.1.5. In this
version
Corrected problem where if "shorewall start"
- aborted early (due to kernel configuration errors
- for example), superfluous 'sed' error messages
- were reported.
+
Corrected problem where if "shorewall start"
+ aborted early (due to kernel configuration errors
+ for example), superfluous 'sed' error messages
+ were reported.
-
Corrected rules generated for port redirection.
+
Corrected rules generated for port redirection.
-
The order in which iptables kernel modules
- are loaded has been corrected (Thanks to Mark
- Pavlidis).
+
The order in which iptables kernel modules
+ are loaded has been corrected (Thanks to Mark
+ Pavlidis).
-
+
-
+
4/28/2001 - The current version of Shorewall is 1.1.3. In this
version
-
+
-
Correct message issued when Proxy ARP address
- added (Thanks to Jason Kirtland).
+
Correct message issued when Proxy ARP address
+ added (Thanks to Jason Kirtland).
-
/tmp/shorewallpolicy-$$ is now removed if
- there is an error while starting the firewall.
+
/tmp/shorewallpolicy-$$ is now removed if
+ there is an error while starting the firewall.
-
/etc/shorewall/icmp.def and /etc/shorewall/common.def
- are now used to define the icmpdef and common
- chains unless overridden by the presence of /etc/shorewall/icmpdef
- or /etc/shorewall/common.
+
/etc/shorewall/icmp.def and /etc/shorewall/common.def
+ are now used to define the icmpdef and
+common chains unless overridden by the presence
+ of /etc/shorewall/icmpdef or /etc/shorewall/common.
-
In the .lrp, the file /var/lib/lrpkg/shorwall.conf
- has been corrected. An extra space after
+
In the .lrp, the file /var/lib/lrpkg/shorwall.conf
+ has been corrected. An extra space after
"/etc/shorwall/policy" has been removed and "/etc/shorwall/rules"
has been added.
-
When a sub-shell encounters a fatal error
- and has stopped the firewall, it now kills the
-main shell so that the main shell will not continue.
+
When a sub-shell encounters a fatal error
+ and has stopped the firewall, it now kills
+the main shell so that the main shell will not continue.
-
A problem has been corrected where a sub-shell
- stopped the firewall and main shell continued
- resulting in a perplexing error message referring
- to "common.so" resulted.
+
A problem has been corrected where a sub-shell
+ stopped the firewall and main shell continued
+ resulting in a perplexing error message referring
+ to "common.so" resulted.
-
Previously, placing "-" in the PORT(S) column
- in /etc/shorewall/rules resulted in an error
- message during start. This has been corrected.
+
Previously, placing "-" in the PORT(S) column
+ in /etc/shorewall/rules resulted in an error
+ message during start. This has been corrected.
-
The first line of "install.sh" has been corrected
- -- I had inadvertently deleted the initial "#".
+
The first line of "install.sh" has been corrected
+ -- I had inadvertently deleted the initial "#".
-
+
-
+
4/12/2001 - The current version of Shorewall is 1.1.2. In this
version
The firewall no longer fails to start if "routefilter"
- is specified for an interface that isn't started.
- A warning message is now issued in this case.
+
The firewall no longer fails to start if
+"routefilter" is specified for an interface that
+ isn't started. A warning message is now issued
+ in this case.
-
The LRP Version is renamed "shorwall" for
- 8,3 MSDOS file system compatibility.
+
The LRP Version is renamed "shorwall" for
+ 8,3 MSDOS file system compatibility.
-
A couple of LRP-specific problems were corrected.
+
A couple of LRP-specific problems were corrected.
-
+
-
+
4/8/2001 - Shorewall is now affiliated with the Leaf Project
-
+
-
+
4/5/2001 - The current version of Shorewall is 1.1.1. In this version:
-
+
-
The common chain is traversed from INPUT,
-OUTPUT and FORWARD before logging occurs
+
The common chain is traversed from INPUT,
+ OUTPUT and FORWARD before logging occurs
-
The source has been cleaned up dramatically
+
The source has been cleaned up dramatically
-
DHCP DISCOVER packets with RFC1918 source
-addresses no longer generate log messages. Linux
- DHCP clients generate such packets and it's
- annoying to see them logged.
+
DHCP DISCOVER packets with RFC1918 source
+ addresses no longer generate log messages. Linux
+ DHCP clients generate such packets and it's
+ annoying to see them logged.
-
+
-
+
3/25/2001 - The current version of Shorewall is 1.1.0. In this version:
-
+
-
Log messages now indicate the packet disposition.
+
Log messages now indicate the packet disposition.
-
Error messages have been improved.
+
Error messages have been improved.
-
The ability to define zones consisting of
-an enumerated set of hosts and/or subnetworks has
- been added.
+
The ability to define zones consisting of
+ an enumerated set of hosts and/or subnetworks has
+ been added.
-
The zone-to-zone chain matrix is now sparse
- so that only those chains that contain meaningful
- rules are defined.
+
The zone-to-zone chain matrix is now sparse
+ so that only those chains that contain meaningful
+ rules are defined.
-
240.0.0.0/4 and 169.254.0.0/16 have been added
- to the source subnetworks whose packets are dropped
- under the norfc1918 interface option.
+
240.0.0.0/4 and 169.254.0.0/16 have been
+ added to the source subnetworks whose packets
+ are dropped under the norfc1918 interface
+ option.
-
Exits are now provided for executing an user-defined
- script when a chain is defined, when the
-firewall is initialized, when the firewall is
- started, when the firewall is stopped and when the
-firewall is cleared.
+
Exits are now provided for executing an
+user-defined script when a chain is defined,
+when the firewall is initialized, when the firewall
+ is started, when the firewall is stopped and
+when the firewall is cleared.
-
The Linux kernel's route filtering facility
- can now be specified selectively on network
- interfaces.
+
The Linux kernel's route filtering facility
+ can now be specified selectively on network
+ interfaces.
-
+
-
+
3/19/2001 - The current version of Shorewall is 1.0.4. This version:
-
+
-
Allows user-defined zones. Shorewall now has
- only one pre-defined zone (fw) with the remaining
- zones being defined in the new configuration
- file /etc/shorewall/zones. The /etc/shorewall/zones file
- released in this version provides behavior that
- is compatible with Shorewall 1.0.3.
+
Allows user-defined zones. Shorewall now
+ has only one pre-defined zone (fw) with the remaining
+ zones being defined in the new configuration
+ file /etc/shorewall/zones. The /etc/shorewall/zones file
+ released in this version provides behavior that
+ is compatible with Shorewall 1.0.3.
-
Adds the ability to specify logging in entries
- in the /etc/shorewall/rules file.
+
Adds the ability to specify logging in entries
+ in the /etc/shorewall/rules file.
-
Correct handling of the icmp-def chain so
-that only ICMP packets are sent through the
+
Correct handling of the icmp-def chain so
+ that only ICMP packets are sent through the
chain.
-
Compresses the output of "shorewall monitor"
- if awk is installed. Allows the command to work
- if awk isn't installed (although it's not pretty).
+
Compresses the output of "shorewall monitor"
+ if awk is installed. Allows the command to work
+ if awk isn't installed (although it's not pretty).
-
+
-
+
3/13/2001 - The current version of Shorewall is 1.0.3. This is a bug-fix
- release with no new features.
+ release with no new features.
-
+
-
The PATH variable in the firewall script now
- includes /usr/local/bin and /usr/local/sbin.
+
The PATH variable in the firewall script
+now includes /usr/local/bin and /usr/local/sbin.
-
DMZ-related chains are now correctly deleted
- if the DMZ is deleted.
+
DMZ-related chains are now correctly deleted
+ if the DMZ is deleted.
-
The interface OPTIONS for "gw" interfaces
- are no longer ignored.
+
The interface OPTIONS for "gw" interfaces
+ are no longer ignored.
-
+
-
+
3/8/2001 - The current version of Shorewall is 1.0.2. It supports an
- additional "gw" (gateway) zone for
-tunnels and it supports IPSEC tunnels with end-points
- on the firewall. There is also a .lrp available now.
+ additional "gw" (gateway) zone for
+ tunnels and it supports IPSEC tunnels with
+end-points on the firewall. There is also a .lrp available
+ now.
-
+
OpenVPN is a robust and highly configurable VPN (Virtual Private Network)
- daemon which can be used to securely link two or more private networks using
- an encrypted tunnel over the internet. OpenVPN is an Open Source project
-and is licensed under
+
+
+
OpenVPN support was added to Shorewall in version 1.3.14.
-
-
+
+
Bridging two Masqueraded Networks
-
+
Suppose that we have the following situation:
-
+
-
-
-
We want systems in the 192.168.1.0/24 subnetwork to be able
- to communicate with the systems in the 10.0.0.0/8 network. This is accomplished
- through use of the /etc/shorewall/tunnels file and the /etc/shorewall/policy
+
+
+
We want systems in the 192.168.1.0/24 subnetwork to be able
+ to communicate with the systems in the 10.0.0.0/8 network. This is accomplished
+ through use of the /etc/shorewall/tunnels file and the /etc/shorewall/policy
file and OpenVPN.
-
-
While it was possible to use the Shorewall start and stop
- script to start and stop OpenVPN, I decided to use the init script of OpenVPN
+
+
While it was possible to use the Shorewall start and stop
+ script to start and stop OpenVPN, I decided to use the init script of OpenVPN
to start and stop it.
-
-
On each firewall, you will need to declare a zone to represent
- the remote subnet. We'll assume that this zone is called 'vpn' and declare
+
+
On each firewall, you will need to declare a zone to represent
+ the remote subnet. We'll assume that this zone is called 'vpn' and declare
it in /etc/shorewall/zones on both systems as follows.
-
-
+
+
-
-
-
ZONE
-
DISPLAY
-
COMMENTS
-
-
-
vpn
-
VPN
-
Remote Subnet
-
-
-
+
+
+
ZONE
+
DISPLAY
+
COMMENTS
+
+
+
vpn
+
VPN
+
Remote Subnet
+
+
+
+
+
+
+
On system A, the 10.0.0.0/8 will comprise the vpn zone.
+In /etc/shorewall/interfaces:
+
+
+
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
+
+
vpn
+
tun0
+
+
+
+
+
+
-
-
On system A, the 10.0.0.0/8 will comprise the vpn
-zone. In /etc/shorewall/interfaces:
-
-
-
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
vpn
-
tun0
-
-
-
-
-
-
-
-
-
+
In /etc/shorewall/tunnels on system A, we need the following:
-
-
+
+
-
-
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
openvpn
-
net
-
134.28.54.2
-
-
-
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
+
+
openvpn
+
net
+
134.28.54.2
+
+
+
+
-
-
-
This entry in /etc/shorewall/tunnels opens the firewall so that OpenVPN
- traffic on the default port 5000/udp will be accepted to/from the remote
-gateway. If you change the port used by OpenVPN to 7777, you can define /etc/shorewall/tunnels
+
+
+
This entry in /etc/shorewall/tunnels opens the firewall so that OpenVPN
+ traffic on the default port 5000/udp will be accepted to/from the remote
+gateway. If you change the port used by OpenVPN to 7777, you can define /etc/shorewall/tunnels
like this:
-
-
-
+
+
+
-
-
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
openvpn:7777
-
net
-
134.28.54.2
-
-
-
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
+
+
openvpn:7777
+
net
+
134.28.54.2
+
+
+
+
-
-
+
+
This is the OpenVPN config on system A:
-
-
+
+
-
-
-
+
+
+
dev tun
- local 206.162.148.9
- remote 134.28.54.2
- ifconfig 192.168.99.1 192.168.99.2
- up ./route-a.up
- tls-server
- dh dh1024.pem
- ca ca.crt
- cert my-a.crt
- key my-a.key
- comp-lzo
- verb 5
-
-
-
-
Similarly, On system B the 192.168.1.0/24 subnet will comprise the vpn
+ local 206.162.148.9
+ remote 134.28.54.2
+ ifconfig 192.168.99.1 192.168.99.2
+ up ./route-a.up
+ tls-server
+ dh dh1024.pem
+ ca ca.crt
+ cert my-a.crt
+ key my-a.key
+ comp-lzo
+ verb 5
+
+
+
+
Similarly, On system B the 192.168.1.0/24 subnet will comprise the vpn
zone. In /etc/shorewall/interfaces:
-
-
+
+
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
vpn
-
tun0
-
192.168.1.255
-
-
-
-
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
+
+
vpn
+
tun0
+
192.168.1.255
+
+
+
+
-
-
+
+
In /etc/shorewall/tunnels on system B, we have:
-
-
+
+
-
-
-
TYPE
-
ZONE
-
GATEWAY
-
GATEWAY ZONE
-
-
-
openvpn
-
net
-
206.191.148.9
-
-
-
-
+
+
+
TYPE
+
ZONE
+
GATEWAY
+
GATEWAY ZONE
+
+
+
openvpn
+
net
+
206.191.148.9
+
+
+
+
-
-
+
+
And in the OpenVPN config on system B:
-
-
+
+
dev tun
- local 134.28.54.2
- remote 206.162.148.9
- ifconfig 192.168.99.2 192.168.99.1
- up ./route-b.up
- tls-client
- ca ca.crt
- cert my-b.crt
- key my-b.key
- comp-lzo
- verb 5
-
-
-
-
You will need to allow traffic between the "vpn" zone and
- the "loc" zone on both systems -- if you simply want to admit all
-traffic in both directions, you can use the policy file:
You will need to allow traffic between the "vpn" zone and
+ the "loc" zone on both systems -- if you simply want to admit all traffic
+ in both directions, you can use the policy file:
+
+
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG LEVEL
-
-
-
loc
-
vpn
-
ACCEPT
-
-
-
-
vpn
-
loc
-
ACCEPT
-
-
-
-
+
+
+
SOURCE
+
DEST
+
POLICY
+
LOG LEVEL
+
+
+
loc
+
vpn
+
ACCEPT
+
+
+
+
vpn
+
loc
+
ACCEPT
+
+
+
+
-
-
-
On both systems, restart Shorewall and start OpenVPN. The systems in the
+
+
+
On both systems, restart Shorewall and start OpenVPN. The systems in the
two masqueraded subnetworks can now talk to each other.
NOTE: I am no longer attempting to maintain MPPE patches for current
-Linux kernel's and pppd. I recommend that you refer to the following URLs
-for information about installing MPPE into your kernel and pppd.
-
The Linux PPTP client project
-has a nice GUI for configuring and managing VPN connections where your
-Linux system is the PPTP client. This is what I currently use. I am no longer
-running PoPToP but rather I use the PPTP Server included with XP Professional
-(see PPTP Server running behind your Firewall
-below).
I am leaving the instructions for building MPPE-enabled kernels and pppd
-in the text below for those who may wish to obtain the relevant current patches
-and "roll their own".
-
-
-
Shorewall easily supports PPTP in a number of configurations:
I will try to give you an idea of how to set up a PPTP server on your
-firewall system. This isn't a detailed HOWTO but rather an example of how
-I have set up a working PPTP server on my own firewall.
Un-tar the pppd source and uncompress the patches into one directory (the
- patches and the ppp-2.4.1 directory are all in a single parent directory):
-
-
-
cd ppp-2.4.1
-
patch -p1 < ../ppp-2.4.0-openssl-0.9.6-mppe.patch
-
patch -p1 < ../ppp-2.4.1-MSCHAPv2-fix.patch
-
(Optional) patch -p1 < ../require-mppe.diff
-
./configure
-
make
-
-
-
-
You will need to install the resulting binary on your firewall system.
-To do that, I NFS mount my source filesystem and use "make install" from
-the ppp-2.4.1 directory.
-
-
Patching and Building your Kernel
-
-
You will need one of the following patches depending on your kernel version:
Now configure your kernel. Here is my ppp configuration:
-
-
-
-
-
-
-
Configuring Samba
-
-
You will need a WINS server (Samba configured to run as a WINS server
-is fine). Global section from /etc/samba/smb.conf on my WINS server (192.168.1.3)
-is:
-
-
-
[global] workgroup = TDM-NSTOP netbios name = WOOKIE server string = GNU/Linux Box encrypt passwords = Yes log file = /var/log/samba/%m.log max log size = 0 socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192 os level = 65 domain master = True preferred master = True dns proxy = No wins support = Yes printing = lprng
[homes] comment = Home Directories valid users = %S read only = No create mask = 0664 directory mask = 0775
System 192.168.1.3 acts as a WINS server so I have included that
-IP as the 'ms-wins' value.
-
I have pointed the remote clients at my DNS server -- it has external
- address 206.124.146.177.
-
I am requiring 128-bit stateless compression (my kernel is built
-with the 'require-mppe.diff' patch mentioned above.
-
-
-
-
Here's my /etc/ppp/chap-secrets:
-
-
-
Secrets for authentication using CHAP
- # client server secret IP addresses
- CPQTDM\\TEastep * <shhhhhh> 192.168.1.7
- TEastep * <shhhhhh> 192.168.1.7
-
-
-
I am the only user who connects to the server but I may connect either
-with or without a domain being specified. The system I connect from is my
-laptop so I give it the same IP address when tunneled in at it has when I
-use its wireless LAN card around the house.
-
-
You will also want the following in /etc/modules.conf:
-
-
alias ppp-compress-18 ppp_mppe alias ppp-compress-21 bsd_comp alias ppp-compress-24 ppp_deflate alias ppp-compress-26 ppp_deflate
I specify the /etc/ppp/options.poptop file as my ppp options file
-(I have several).
-
The local IP is the same as my internal interface's (192.168.1.254).
-
I have assigned a remote IP range that overlaps my local network.
-This, together with 'proxyarp' in my /etc/ppp/options.poptop file make
-the remote hosts look like they are part of the local subnetwork.
-
-
-
-
I use this file to start/stop pptpd -- I have this in /etc/init.d/pptpd:
I consider hosts connected to my PPTP server to be just like local systems.
- My key Shorewall entries are:
-
-
/etc/shorewall/zones:
-
-
-
-
-
-
ZONE
-
DISPLAY
-
COMMENTS
-
-
-
net
-
Internet
-
The Internet
-
-
-
loc
-
Local
-
My Local Network including remote PPTP clients
-
-
-
-
-
-
-
/etc/shorewall/interfaces:
-
-
-
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
net
-
eth0
-
206.124.146.255
-
norfc1918
-
-
-
loc
-
eth2
-
192.168.1.255
-
-
-
-
-
-
ppp+
-
-
-
-
-
-
-
-
-
/etc/shorewall/hosts:
-
-
-
-
-
-
ZONE
-
HOST(S)
-
OPTIONS
-
-
-
loc
-
eth2:192.168.1.0/24
-
-
-
-
loc
-
ppp+:192.168.1.0/24
-
-
-
-
-
-
-
-
/etc/shorewall/policy:
-
-
-
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG LEVEL
-
-
-
loc
-
loc
-
ACCEPT
-
-
-
-
-
-
-
-
/etc/shorewall/rules (For Shorewall versions up to and including 1.3.9b):
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
ACCEPT
-
net
-
fw
-
tcp
-
1723
-
-
-
-
-
ACCEPT
-
net
-
fw
-
47
-
-
-
-
-
-
-
ACCEPT
-
fw
-
net
-
47
-
-
-
-
-
-
-
-
-
-
-
/etc/shoreawll/tunnels (For Shorewall versions 1.3.10 and
-later)
-
-
-
-
-
-
-
TYPE
-
-
ZONE
-
-
GATEWAY
-
-
GATEWAY ZONE
-
-
-
-
pptpserver
-
-
net
-
-
0.0.0.0/0
-
-
-
-
-
-
-
-
-
-
- Note: I have multiple ppp interfaces on my firewall. If you have a single
-ppp interface, you probably want:
-
-
/etc/shorewall/interfaces:
-
-
-
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
net
-
eth0
-
206.124.146.255
-
norfc1918
-
-
-
loc
-
eth2
-
192.168.1.255
-
-
-
-
loc
-
ppp0
-
-
-
-
-
-
-
-
-
and no entries in /etc/shorewall/hosts.
-
-
2. PPTP Server Running Behind
-your Firewall
-
-
If you have a single external IP address, add the following to your
-/etc/shorewall/rules file:
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
DNAT
-
net
-
loc:<server address>
-
tcp
-
1723
-
-
-
-
-
DNAT
-
net
-
loc:<server address>
-
47
-
-
-
-
-
-
-
+
+
+
-
-
If you have multiple external IP address and you want to forward a single
-<external address>, add the following to your /etc/shorewall/rules
-file:
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
DNAT
-
net
-
loc:<server address>
-
tcp
-
1723
-
-
-
<external address>
-
-
-
DNAT
-
net
-
loc:<server address>
-
47
-
-
-
-
-
<external address>
-
-
-
-
-
-
3. PPTP Clients Running Behind
-your Firewall
-
-
You shouldn't have to take any special action for this case unless you
-wish to connect multiple clients to the same external server. In that case,
-you will need to follow the instructions at http://www.impsec.org/linux/masquerade/ip_masq_vpn.html.
- I recommend that you also add these two lines to your /etc/shorewall/modules
- file:
The PPTP GNU/Linux client is available at http://sourceforge.net/projects/pptpclient/.
- Rather than use the configuration script that comes with the client, I built
-my own. I also build my own kernel as described above
- rather than using the mppe package that is available with the client. My
-/etc/ppp/options file is mostly unchanged from what came with the client (see
-below).
-
-
The key elements of this setup are as follows:
-
+
NOTE: I am no longer attempting to maintain MPPE patches for current Linux
+kernel's and pppd. I recommend that you refer to the following URLs for information
+about installing MPPE into your kernel and pppd.
+
+
The Linux PPTP client project
+has a nice GUI for configuring and managing VPN connections where your
+Linux system is the PPTP client. This is what I currently use. I am no longer
+running PoPToP but rather I use the PPTP Server included with XP Professional
+(see PPTP Server running behind your Firewall
+below).
I am leaving the instructions for building MPPE-enabled kernels and pppd
+in the text below for those who may wish to obtain the relevant current patches
+and "roll their own".
+
+
+
+
Shorewall easily supports PPTP in a number of configurations:
I will try to give you an idea of how to set up a PPTP server on your firewall
+system. This isn't a detailed HOWTO but rather an example of how I have set
+up a working PPTP server on my own firewall.
+
+
The steps involved are:
+
-
Define a zone for the remote network accessed via PPTP.
-
Associate that zone with a ppp interface.
-
Define rules for PPTP traffic to/from the firewall.
-
Define rules for traffic two and from the remote zone.
Un-tar the pppd source and uncompress the patches into one directory (the
+ patches and the ppp-2.4.1 directory are all in a single parent directory):
+
+
+
cd ppp-2.4.1
+
patch -p1 < ../ppp-2.4.0-openssl-0.9.6-mppe.patch
+
patch -p1 < ../ppp-2.4.1-MSCHAPv2-fix.patch
+
(Optional) patch -p1 < ../require-mppe.diff
+
./configure
+
make
+
+
+
+
You will need to install the resulting binary on your firewall system.
+ To do that, I NFS mount my source filesystem and use "make install" from
+the ppp-2.4.1 directory.
+
+
Patching and Building your Kernel
+
+
You will need one of the following patches depending on your kernel version:
Now configure your kernel. Here is my ppp configuration:
+
+
+
+
+
+
+
Configuring Samba
+
+
You will need a WINS server (Samba configured to run as a WINS server is
+ fine). Global section from /etc/samba/smb.conf on my WINS server (192.168.1.3)
+ is:
+
+
+
[global] workgroup = TDM-NSTOP netbios name = WOOKIE server string = GNU/Linux Box encrypt passwords = Yes log file = /var/log/samba/%m.log max log size = 0 socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192 os level = 65 domain master = True preferred master = True dns proxy = No wins support = Yes printing = lprng
[homes] comment = Home Directories valid users = %S read only = No create mask = 0664 directory mask = 0775
System 192.168.1.3 acts as a WINS server so I have included that
+ IP as the 'ms-wins' value.
+
I have pointed the remote clients at my DNS server -- it has external
+ address 206.124.146.177.
+
I am requiring 128-bit stateless compression (my kernel is built
+ with the 'require-mppe.diff' patch mentioned above.
+
+
+
+
Here's my /etc/ppp/chap-secrets:
+
+
+
Secrets for authentication using CHAP
+ # client server secret IP addresses
+ CPQTDM\\TEastep * <shhhhhh> 192.168.1.7
+ TEastep * <shhhhhh> 192.168.1.7
+
+
+
I am the only user who connects to the server but I may connect either
+ with or without a domain being specified. The system I connect from is my
+ laptop so I give it the same IP address when tunneled in at it has when
+I use its wireless LAN card around the house.
+
+
You will also want the following in /etc/modules.conf:
+
+
alias ppp-compress-18 ppp_mppe alias ppp-compress-21 bsd_comp alias ppp-compress-24 ppp_deflate alias ppp-compress-26 ppp_deflate
I specify the /etc/ppp/options.poptop file as my ppp options file
+ (I have several).
+
The local IP is the same as my internal interface's (192.168.1.254).
+
I have assigned a remote IP range that overlaps my local network.
+ This, together with 'proxyarp' in my /etc/ppp/options.poptop file make
+ the remote hosts look like they are part of the local subnetwork.
+
+
+
+
I use this file to start/stop pptpd -- I have this in /etc/init.d/pptpd:
+ Note: I have multiple ppp interfaces on my firewall. If you have a single
+ ppp interface, you probably want:
+
+
/etc/shorewall/interfaces:
+
+
+
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
+
+
net
+
eth0
+
206.124.146.255
+
norfc1918
+
+
+
loc
+
eth2
+
192.168.1.255
+
+
+
+
loc
+
ppp0
+
+
+
+
+
+
+
+
+
and no entries in /etc/shorewall/hosts.
+
+
2. PPTP Server Running Behind
+ your Firewall
+
+
If you have a single external IP address, add the following to your /etc/shorewall/rules
+file:
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
DNAT
+
net
+
loc:<server address>
+
tcp
+
1723
+
+
+
+
+
DNAT
+
net
+
loc:<server address>
+
47
+
-
+
+
+
+
+
+
+
+
If you have multiple external IP address and you want to forward a single
+ <external address>, add the following to your /etc/shorewall/rules
+ file:
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
DNAT
+
net
+
loc:<server address>
+
tcp
+
1723
+
-
+
<external address>
+
+
+
DNAT
+
net
+
loc:<server address>
+
47
+
-
+
-
+
<external address>
+
+
+
+
+
+
+
3. PPTP Clients Running Behind
+ your Firewall
+
+
You shouldn't have to take any special action for this case unless you
+ wish to connect multiple clients to the same external server. In that case,
+ you will need to follow the instructions at http://www.impsec.org/linux/masquerade/ip_masq_vpn.html.
+ I recommend that you also add these two lines to your /etc/shorewall/modules
+ file:
The PPTP GNU/Linux client is available at http://sourceforge.net/projects/pptpclient/.
+ Rather than use the configuration script that comes with the client, I
+built my own. I also build my own kernel as described
+above rather than using the mppe package that is available with the
+client. My /etc/ppp/options file is mostly unchanged from what came with
+the client (see below).
+
+
The key elements of this setup are as follows:
+
+
+
Define a zone for the remote network accessed via PPTP.
+
Associate that zone with a ppp interface.
+
Define rules for PPTP traffic to/from the firewall.
+
Define rules for traffic two and from the remote zone.
+
+
+
+
Here are examples from my setup:
+
+
/etc/shorewall/zones
+
+
+
+
+
+
ZONE
+
DISPLAY
+
COMMENTS
+
+
+
cpq
+
Compaq
+
Compaq Intranet
+
+
+
+
+
+
+
/etc/shorewall/interfaces
+
+
+
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
+
+
-
+
ppp+
+
+
+
+
+
+
+
+
+
/etc/shorewall/hosts
+
+
+
+
+
+
ZONE
+
HOST(S)
+
OPTIONS
+
+
+
-
+
ppp+:!192.168.1.0/24
+
+
+
+
+
+
+
+
/etc/shorewall/rules (For Shorewall versions up to and including 1.3.9b)
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
ACCEPT
+
fw
+
net
+
tcp
+
1723
+
+
+
+
+
ACCEPT
+
fw
+
net
+
47
+
-
+
+
+
+
+
+
+
+
/etc/shorewall/tunnels (For Shorewall versions 1.3.10 and later)
-
-
-
+
+
+
-
-
-
TYPE
-
-
ZONE
-
-
GATEWAY
-
-
GATEWAY ZONE
-
-
-
-
pptpclient
-
-
net
-
-
0.0.0.0/0
-
-
-
-
-
-
+
+
+
TYPE
+
+
ZONE
+
+
GATEWAY
+
+
GATEWAY ZONE
+
+
+
+
pptpclient
+
+
net
+
+
0.0.0.0/0
+
+
+
+
+
+
-
-
-
-
I use the combination of interface and hosts file to define the 'cpq'
-zone because I also run a PPTP server on my firewall (see above). Using this
- technique allows me to distinguish clients of my own PPTP server from arbitrary
- hosts at Compaq; I assign addresses in 192.168.1.0/24 to my PPTP clients
+
+
+
+
I use the combination of interface and hosts file to define the 'cpq' zone
+because I also run a PPTP server on my firewall (see above). Using this
+technique allows me to distinguish clients of my own PPTP server from arbitrary
+ hosts at Compaq; I assign addresses in 192.168.1.0/24 to my PPTP clients
and Compaq doesn't use that RFC1918 Class C subnet.
-
-
I use this script in /etc/init.d to control the client. The reason that
-I disable ECN when connecting is that the Compaq tunnel servers don't do
-ECN yet and reject the initial TCP connection request if I enable ECN :-(
+
+
I use this script in /etc/init.d to control the client. The reason that
+ I disable ECN when connecting is that the Compaq tunnel servers don't do
+ECN yet and reject the initial TCP connection request if I enable ECN :-(
Proxy ARP allows you to insert a firewall in front of a set of servers
- without changing their IP addresses and without having to re-subnet.
- Before you try to use this technique, I strongly recommend that you read
+
+
Proxy ARP allows you to insert a firewall in front of a set of servers
+ without changing their IP addresses and without having to re-subnet.
+ Before you try to use this technique, I strongly recommend that you read
the Shorewall Setup Guide.
-
+
The following figure represents a Proxy ARP environment.
-
-
+
+
-
-
+
+
-
-
-
Proxy ARP can be used to make the systems with addresses
- 130.252.100.18 and 130.252.100.19 appear to be on the upper (130.252.100.*)
- subnet. Assuming that the upper firewall interface is eth0 and the
- lower interface is eth1, this is accomplished using the following entries
+
+
+
Proxy ARP can be used to make the systems with addresses
+ 130.252.100.18 and 130.252.100.19 appear to be on the upper (130.252.100.*)
+ subnet. Assuming that the upper firewall interface is eth0 and the
+ lower interface is eth1, this is accomplished using the following entries
in /etc/shorewall/proxyarp:
-
-
+
+
-
-
-
ADDRESS
-
INTERFACE
-
EXTERNAL
-
HAVEROUTE
-
+
-
130.252.100.18
-
eth1
-
eth0
-
no
-
-
-
130.252.100.19
-
eth1
-
eth0
-
no
-
-
-
+
ADDRESS
+
INTERFACE
+
EXTERNAL
+
HAVEROUTE
+
+
+
130.252.100.18
+
eth1
+
eth0
+
no
+
+
+
130.252.100.19
+
eth1
+
eth0
+
no
+
+
+
-
-
-
Be sure that the internal systems (130.242.100.18 and 130.252.100.19
- in the above example) are not included in any specification in /etc/shorewall/masq
+
+
+
Be sure that the internal systems (130.242.100.18 and 130.252.100.19
+ in the above example) are not included in any specification in /etc/shorewall/masq
or /etc/shorewall/nat.
-
-
Note that I've used an RFC1918 IP address for eth1 - that IP address is
+
+
Note that I've used an RFC1918 IP address for eth1 - that IP address is
irrelevant.
-
-
The lower systems (130.252.100.18 and 130.252.100.19) should have their
- subnet mask and default gateway configured exactly the same way that
- the Firewall system's eth0 is configured. In other words, they should
-be configured just like they would be if they were parallel to the firewall
+
+
The lower systems (130.252.100.18 and 130.252.100.19) should have their
+ subnet mask and default gateway configured exactly the same way that
+ the Firewall system's eth0 is configured. In other words, they should
+be configured just like they would be if they were parallel to the firewall
rather than behind it.
-
-
-
NOTE: Do not add the Proxy ARP'ed address(es)
-(130.252.100.18 and 130.252.100.19 in the above example) to the external
+
+
+
NOTE: Do not add the Proxy ARP'ed address(es)
+(130.252.100.18 and 130.252.100.19 in the above example) to the external
interface (eth0 in this example) of the firewall.
-
+
+
-
-
-
A word of warning is in order here. ISPs typically configure
- their routers with a long ARP cache timeout. If you move a system from
- parallel to your firewall to behind your firewall with Proxy ARP, it will
- probably be HOURS before that system can communicate with the internet.
+
+
+
A word of warning is in order here. ISPs typically configure
+ their routers with a long ARP cache timeout. If you move a system from
+ parallel to your firewall to behind your firewall with Proxy ARP, it
+will probably be HOURS before that system can communicate with the internet.
There are a couple of things that you can try:
-
-
+
+
-
(Courtesy of Bradey Honsinger) A reading of Stevens' TCP/IP Illustrated,
- Vol 1 reveals that a
-
- "gratuitous" ARP packet should cause the ISP's router to refresh their
-ARP cache (section 4.7). A gratuitous ARP is simply a host requesting the
-MAC address for its own IP; in addition to ensuring that the IP address isn't
- a duplicate...
-
- "if the host sending the gratuitous ARP has just changed its hardware
-address..., this packet causes any other host...that has an entry in its
+
(Courtesy of Bradey Honsinger) A reading of Stevens' TCP/IP
+Illustrated, Vol 1 reveals that a
+
+ "gratuitous" ARP packet should cause the ISP's router to refresh their
+ARP cache (section 4.7). A gratuitous ARP is simply a host requesting the
+MAC address for its own IP; in addition to ensuring that the IP address
+isn't a duplicate...
+
+ "if the host sending the gratuitous ARP has just changed its hardware
+address..., this packet causes any other host...that has an entry in its
cache for the old hardware address to update its ARP cache entry accordingly."
-
- Which is, of course, exactly what you want to do when you switch a host
- from being exposed to the Internet to behind Shorewall using proxy ARP (or
- static NAT for that matter). Happily enough, recent versions of Redhat's
+
+ Which is, of course, exactly what you want to do when you switch a host
+ from being exposed to the Internet to behind Shorewall using proxy ARP (or
+ static NAT for that matter). Happily enough, recent versions of Redhat's
iputils package include "arping", whose "-U" flag does just that:
-
- arping -U -I <net if> <newly
+
+ arping -U -I <net if> <newly
proxied IP>
- arping -U -I eth0 66.58.99.83 # for example
+ arping -U -I eth0 66.58.99.83 # for example
+
+ Stevens goes on to mention that not all systems respond correctly to
+gratuitous ARPs, but googling for "arping -U" seems to support the idea
+that it works most of the time.
- Stevens goes on to mention that not all systems respond correctly to gratuitous
- ARPs, but googling for "arping -U" seems to support the idea that it works
- most of the time.
-
- To use arping with Proxy ARP in the above example, you would have to:
-
- shorewall clear
- ip addr add 130.252.100.18
+ To use arping with Proxy ARP in the above example, you would have to:
+
+ shorewall clear
+ ip addr add 130.252.100.18
dev eth0
- ip addr add 130.252.100.19 dev eth0
- arping -U -I eth0 130.252.100.18
- arping -U -I eth0 130.252.100.19
- ip addr del 130.252.100.18 dev eth0
- ip addr del 130.252.100.19 dev eth0
- shorewall start
-
-
-
You can call your ISP and ask them to purge the stale ARP cache
+ ip addr add 130.252.100.19 dev eth0
+ arping -U -I eth0 130.252.100.18
+ arping -U -I eth0 130.252.100.19
+ ip addr del 130.252.100.18 dev eth0
+ ip addr del 130.252.100.19 dev eth0
+ shorewall start
+
+
+
You can call your ISP and ask them to purge the stale ARP cache
entry but many either can't or won't purge individual entries.
-
+
- You can determine if your ISP's gateway ARP cache is stale using ping
- and tcpdump. Suppose that we suspect that the gateway router has a stale
+ You can determine if your ISP's gateway ARP cache is stale using ping
+ and tcpdump. Suppose that we suspect that the gateway router has a stale
ARP cache entry for 130.252.100.19. On the firewall, run tcpdump as follows:
-
-
+
+
tcpdump -nei eth0 icmp
-
-
-
-
Now from 130.252.100.19, ping the ISP's gateway (which we
+
+
+
+
Now from 130.252.100.19, ping the ISP's gateway (which we
will assume is 130.252.100.254):
Notice that the source MAC address in the echo request is
- different from the destination MAC address in the echo reply!! In this
- case 0:4:e2:20:20:33 was the MAC of the firewall's eth0 NIC while 0:c0:a8:50:b2:57
- was the MAC address of the system on the lower left. In other words, the
- gateway's ARP cache still associates 130.252.100.19 with the NIC in that
- system rather than with the firewall's eth0.
Notice that the source MAC address in the echo request is
+ different from the destination MAC address in the echo reply!! In this
+ case 0:4:e2:20:20:33 was the MAC of the firewall's eth0 NIC while 0:c0:a8:50:b2:57
+ was the MAC address of the system on the lower left. In other words,
+the gateway's ARP cache still associates 130.252.100.19 with the NIC
+in that system rather than with the firewall's eth0.
-
- Given that I develop and support Shorewall without asking for any renumeration,
- I can hardly justify paying $200US+ a year to a Certificate Authority such
- as Thawte (A Division of VeriSign) for an X.509 certificate to prove that
- I am who I am. I have therefore established my own Certificate Authority
-(CA) and sign my own X.509 certificates. I use these certificates on my list
-server (https://lists.shorewall.net)
+
+ Given that I develop and support Shorewall without asking for any renumeration,
+ I can hardly justify paying $200US+ a year to a Certificate Authority such
+ as Thawte (A Division of VeriSign) for an X.509 certificate to prove that
+ I am who I am. I have therefore established my own Certificate Authority
+(CA) and sign my own X.509 certificates. I use these certificates on my list
+server (https://lists.shorewall.net)
which hosts parts of this web site.
-
- X.509 certificates are the basis for the Secure Socket Layer (SSL). As
-part of establishing an SSL session (URL https://...), your browser verifies
-the X.509 certificate supplied by the HTTPS server against the set of Certificate
- Authority Certificates that were shipped with your browser. It is expected
- that the server's certificate was issued by one of the authorities whose
+
+ X.509 certificates are the basis for the Secure Socket Layer (SSL). As
+part of establishing an SSL session (URL https://...), your browser verifies
+the X.509 certificate supplied by the HTTPS server against the set of Certificate
+ Authority Certificates that were shipped with your browser. It is expected
+ that the server's certificate was issued by one of the authorities whose
identities are known to your browser.
-
- This mechanism, while supposedly guaranteeing that when you connect to
-https://www.foo.bar you are REALLY connecting to www.foo.bar, means that
-the CAs literally have a license to print money -- they are selling a string
+
+ This mechanism, while supposedly guaranteeing that when you connect to
+https://www.foo.bar you are REALLY connecting to www.foo.bar, means that
+the CAs literally have a license to print money -- they are selling a string
of bits (an X.509 certificate) for $200US+ per year!!!I
-
- I wish that I had decided to become a CA rather that designing and writing
+
+ I wish that I had decided to become a CA rather that designing and writing
Shorewall.
-
- What does this mean to you? It means that the X.509 certificate that my
-server will present to your browser will not have been signed by one of the
-authorities known to your browser. If you try to connect to my server using
-SSL, your browser will frown and give you a dialog box asking if you want
+
+ What does this mean to you? It means that the X.509 certificate that my
+server will present to your browser will not have been signed by one of the
+authorities known to your browser. If you try to connect to my server using
+SSL, your browser will frown and give you a dialog box asking if you want
to accept the sleezy X.509 certificate being presented by my server.
-
- There are two things that you can do:
-
+
+ There are two things that you can do:
+
-
You can accept the mail.shorewall.net certificate when your browser
- asks -- your acceptence of the certificate can be temporary (for that access
+
You can accept the mail.shorewall.net certificate when your browser
+ asks -- your acceptence of the certificate can be temporary (for that access
only) or perminent.
You can download and install my (self-signed) CA
+certificate. This will make my Certificate Authority known to your browser
so that it will accept any certificate signed by me.
-
-
+
+
- What are the risks?
-
+ What are the risks?
+
-
If you install my CA certificate then you assume that I am trustworthy
- and that Shorewall running on your firewall won't redirect HTTPS requests
- intented to go to your bank's server to one of my systems that will present
-your browser with a bogus certificate claiming that my server is that of your
-bank.
-
If you only accept my server's certificate when prompted then the
-most that you have to loose is that when you connect to https://mail.shorewall.net,
+
If you install my CA certificate then you assume that I am trustworthy
+ and that Shorewall running on your firewall won't redirect HTTPS requests
+ intented to go to your bank's server to one of my systems that will present
+your browser with a bogus certificate claiming that my server is that of
+your bank.
+
If you only accept my server's certificate when prompted then the
+most that you have to loose is that when you connect to https://mail.shorewall.net,
the server you are connecting to might not be mine.
-
+
- I have my CA certificate loaded into all of my browsers but I certainly
+ I have my CA certificate loaded into all of my browsers but I certainly
won't be offended if you decline to load it into yours... :-)
-
+
-
- Lots of people try to download the entire Shorewall website for off-line
- browsing, including the CVS portion. In addition to being an enormous volume
- of data (HTML versions of all versions of all Shorewall files), all of
-the pages in Shorewall CVS access are cgi-generated which places a tremendous
- load on my little server. I have therefore resorted to making CVS access
- password controlled. When you are asked to log in, enter "Shorewall" (NOTE
+
+ Lots of people try to download the entire Shorewall website for off-line
+ browsing, including the CVS portion. In addition to being an enormous volume
+ of data (HTML versions of all versions of all Shorewall files), all of the
+ pages in Shorewall CVS access are cgi-generated which places a tremendous
+ load on my little server. I have therefore resorted to making CVS access
+ password controlled. When you are asked to log in, enter "Shorewall" (NOTE
THE CAPITALIZATION!!!!!) for both the user name and the password.
-
-
-
-
- This page covers Shorewall configuration to use with Squid running as a Transparent
- Proxy. If you are running Shorewall 1.3, please see this documentation.
-
-
- Please observe the following general requirements:
-
-
- In all cases, Squid should be configured
-to run as a transparent proxy as described at http://www.tldp.org/HOWTO/mini/TransparentProxy-4.html.
-
-
- The following instructions mention the files
- /etc/shorewall/start and /etc/shorewall/init -- if you don't have those
- files, siimply create them.
-
-
- When the Squid server is in the DMZ zone
- or in the local zone, that zone must be defined ONLY by its interface
--- no /etc/shorewall/hosts file entries. That is because the packets being
- routed to the Squid server still have their original destination IP addresses.
-
-
- You must have iptables installed on your
- Squid server.
-
-
- If you run a Shorewall version earlier
-than 1.4.6, you must have NAT and MANGLE enabled in your /etc/shorewall/conf
- file
-
-
-NAT_ENABLED=Yes
- MANGLE_ENABLED=Yes
-
- Three different configurations are covered:
-
-
-
- You want to redirect all local www connection requests EXCEPT
- those to your own
- http server (206.124.146.177)
- to a Squid
- transparent proxy running on the firewall and listening on port
-3128. Squid will of course require access to remote web servers.
-
- In /etc/shorewall/rules:
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
REDIRECT
-
loc
-
3128
-
tcp
-
www
-
-
-
-
!206.124.146.177
-
-
-
ACCEPT
-
fw
-
net
-
tcp
-
www
-
-
-
-
-
-
-
-
-
-
- There may be a requirement to exclude additional destination hosts
-or networks from being redirected. For example, you might also want requests
-destined for 130.252.100.0/24 to not be routed to Squid. In that case, you
-must add a manual rule in /etc/shorewall/start:
-
-
- To exclude additional hosts or networks, just add additional similar
-rules.
-
-
Squid Running in the local network
- You want to redirect all local www connection requests to a
-Squid transparent
- proxy running in your local zone at 192.168.1.3 and listening on port
- 3128. Your local interface is eth1. There may also be a web server running
- on 192.168.1.3. It is assumed that web access is already enabled from
-the local zone to the internet.
-
-
WARNING: This setup may conflict with
- other aspects of your gateway including but not limited to traffic
-shaping and route redirection. For that reason, I don't recommend
-it.
-
-
-
-
On your firewall system, issue the following command
-
-
-
-
-
-
echo 202 www.out >> /etc/iproute2/rt_tables
-
-
-
-
In /etc/shorewall/init, put:
-
-
-
-
-
-
if [ -z "`ip rule list | grep www.out`" ] ; then ip rule add fwmark 202 table www.out ip route add default via 192.168.1.3 dev eth1 table www.out ip route flush cache echo 0 > /proc/sys/net/ipv4/conf/eth1/send_redirects fi
-
-
-
-
If you are running Shorewall 1.4.1 or Shorewall 1.4.1a,
-please upgrade to Shorewall 1.4.2 or later.
-
-
-
If you are running Shorewall 1.4.2 or later, then in /etc/shorewall/interfaces:
-
-
-
-
-
-
ZONE
-
-
INTERFACE
-
-
BROADCAST
-
-
OPTIONS
-
-
-
-
loc
-
-
eth1
-
-
detect
-
-
routeback
-
-
-
-
-
-
-
-
In /etc/shorewall/rules:
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
ACCEPT
-
-
loc
-
loc
-
-
tcp
-
www
-
-
-
-
-
-
-
-
-
-
-
Alternativfely, if you are running Shorewall 1.4.0 you can have the
- following policy in place of the above rule:
-
-
-
-
-
SOURCE
-
-
DESTINATION
-
-
POLICY
-
-
LOG LEVEL
-
-
BURST PARAMETERS
-
-
-
-
loc
-
-
loc
-
-
ACCEPT
-
-
-
-
-
-
-
-
-
-
-
-
In /etc/shorewall/start add:
-
-
-
-
-
-
iptables -t mangle -A PREROUTING -i eth1 -s ! 192.168.1.3 -p tcp --dport 80 -j MARK --set-mark 202
-
-
-
-
On 192.168.1.3, arrange for the following command to be
-executed after networking has come up
-
-
- You have a single Linux system in your DMZ with IP address 192.0.2.177.
- You want to run both a web server and Squid on that system. Your DMZ
-interface is eth1 and your local interface is eth2.
-
-
-
On your firewall system, issue the following command
-
-
-
-
-
-
echo 202 www.out >> /etc/iproute2/rt_tables
-
-
-
-
In /etc/shorewall/init, put:
-
-
-
-
-
-
if [ -z "`ip rule list | grep www.out`" ] ; then ip rule add fwmark 202 table www.out ip route add default via 192.0.2.177 dev eth1 table www.out ip route flush cache fi
-
-
-
-
Do one of the following:
-
- A) In /etc/shorewall/start add
-
-
-
-
-
-
iptables -t mangle -A PREROUTING -i eth2 -p tcp --dport 80 -j MARK --set-mark 202
-
-
-
B) Set MARK_IN_FORWARD_CHAIN=No in /etc/shorewall/shorewall.conf
- and add the following entry in /etc/shorewall/tcrules:
-
- C) Run Shorewall 1.3.14 or later and add the following entry in /etc/shorewall/tcrules:
-
-
+
+
+
+
+ This page covers Shorewall configuration to use with Squid running as a Transparent
+ Proxy. If you are running Shorewall 1.3, please see this documentation.
+
+
+ Please observe the following general requirements:
+
+
+ In all cases, Squid should be configured
+ to run as a transparent proxy as described at http://www.tldp.org/HOWTO/mini/TransparentProxy-4.html.
+
+
+ The following instructions mention the
+ files /etc/shorewall/start and /etc/shorewall/init -- if you don't have
+ those files, siimply create them.
+
+
+ When the Squid server is in the DMZ
+zone or in the local zone, that zone must be defined ONLY by its interface
+ -- no /etc/shorewall/hosts file entries. That is because the packets being
+ routed to the Squid server still have their original destination IP
+addresses.
+
+
+ You must have iptables installed on
+your Squid server.
+
+
+ If you run a Shorewall version earlier
+ than 1.4.6, you must have NAT and MANGLE enabled in your /etc/shorewall/conf
+ file
+
+
+ NAT_ENABLED=Yes
+ MANGLE_ENABLED=Yes
+
+ Three different configurations are covered:
+
+
+
+ You want to redirect all local www connection requests EXCEPT
+ those to your own
+ http server (206.124.146.177)
+ to a Squid
+ transparent proxy running on the firewall and listening on port
+ 3128. Squid will of course require access to remote web servers.
+
+ In /etc/shorewall/rules:
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
REDIRECT
+
loc
+
3128
+
tcp
+
www
+
-
+
+
!206.124.146.177
+
+
+
ACCEPT
+
fw
+
net
+
tcp
+
www
+
+
+
+
+
+
+
+
+
+
+ There may be a requirement to exclude additional destination hosts
+ or networks from being redirected. For example, you might also want requests
+ destined for 130.252.100.0/24 to not be routed to Squid. In that case,
+you must add a manual rule in /etc/shorewall/start:
+
+
+ To exclude additional hosts or networks, just add additional similar
+ rules.
+
+
Squid Running in the local network
+ You want to redirect all local www connection requests to
+ a Squid transparent
+ proxy running in your local zone at 192.168.1.3 and listening on
+port 3128. Your local interface is eth1. There may also be a web server
+running on 192.168.1.3. It is assumed that web access is already enabled
+from the local zone to the internet.
+
+
WARNING: This setup may conflict with
+ other aspects of your gateway including but not limited to traffic
+shaping and route redirection. For that reason, I don't recommend
+it.
+
+
+
+
On your firewall system, issue the following command
+
+
+
+
+
+
echo 202 www.out >> /etc/iproute2/rt_tables
+
+
+
+
In /etc/shorewall/init, put:
+
+
+
+
+
+
if [ -z "`ip rule list | grep www.out`" ] ; then ip rule add fwmark 202 table www.out ip route add default via 192.168.1.3 dev eth1 table www.out ip route flush cache echo 0 > /proc/sys/net/ipv4/conf/eth1/send_redirects fi
+
+
+
+
If you are running Shorewall 1.4.1 or Shorewall 1.4.1a,
+ please upgrade to Shorewall 1.4.2 or later.
+
+
+
If you are running Shorewall 1.4.2 or later, then in /etc/shorewall/interfaces:
+
+
+
-
MARK
+
ZONE
-
SOURCE
+
INTERFACE
-
DESTINATION
+
BROADCAST
-
PROTOCOL
-
-
PORT
-
-
CLIENT PORT
+
OPTIONS
-
202:P
+
loc
-
eth2
+
eth1
-
0.0.0.0/0
+
detect
-
tcp
-
-
80
-
-
-
+
routeback
-
-
+
+
-
-
-
-
-
In /etc/shorewall/rules, you will need:
-
+
+
+
In /etc/shorewall/rules:
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
ACCEPT
+
+
loc
+
loc
+
+
tcp
+
www
+
+
+
+
+
+
+
+
+
+
+
Alternativfely, if you are running Shorewall 1.4.0 you can have
+ the following policy in place of the above rule:
+
+
+
+
+
SOURCE
+
+
DESTINATION
+
+
POLICY
+
+
LOG LEVEL
+
+
BURST PARAMETERS
+
+
+
+
loc
+
+
loc
+
+
ACCEPT
+
+
+
+
+
+
+
+
+
+
+
+
In /etc/shorewall/start add:
+
+
-
-
-
+
+
+
iptables -t mangle -A PREROUTING -i eth1 -s ! 192.168.1.3 -p tcp --dport 80 -j MARK --set-mark 202
+
+
+
+
On 192.168.1.3, arrange for the following command to
+be executed after networking has come up
+
+
+ You have a single Linux system in your DMZ with IP address
+192.0.2.177. You want to run both a web server and Squid on that system.
+Your DMZ interface is eth1 and your local interface is eth2.
+
+
+
On your firewall system, issue the following command
+
+
+
+
+
+
echo 202 www.out >> /etc/iproute2/rt_tables
+
+
+
+
In /etc/shorewall/init, put:
+
+
+
+
+
+
if [ -z "`ip rule list | grep www.out`" ] ; then ip rule add fwmark 202 table www.out ip route add default via 192.0.2.177 dev eth1 table www.out ip route flush cache fi
+
+
+
+
Do one of the following:
+
+ A) In /etc/shorewall/start add
+
+
+
+
+
+
iptables -t mangle -A PREROUTING -i eth2 -p tcp --dport 80 -j MARK --set-mark 202
+
+
+
B) Set MARK_IN_FORWARD_CHAIN=No in /etc/shorewall/shorewall.conf
+ and add the following entry in /etc/shorewall/tcrules:
+
+
+
+
+
-
ACTION
+
MARK
SOURCE
-
DEST
+
DESTINATION
-
PROTO
+
PROTOCOL
-
DEST
- PORT(S)
+
PORT
-
CLIENT
- PORT(2)
-
-
ORIGINAL
- DEST
+
CLIENT PORT
-
ACCEPT
-
-
loc
-
-
dmz
-
-
tcp
-
-
80
-
-
-
-
-
-
-
-
ACCEPT
+
202
-
dmz
+
eth2
-
net
+
0.0.0.0/0
tcp
80
-
-
-
+
-
-
-
-
-
+
+
+
-
-
-
On 192.0.2.177 (your Web/Squid server), arrange for the
-following command to be executed after networking has come up
-
-
If you are running RedHat on the server, you can simply execute
- the following commands after you have typed the iptables command above:
+ C) Run Shorewall 1.3.14 or later and add the following entry in
+/etc/shorewall/tcrules:
+
+
+
+
+
+
+
+
MARK
+
+
SOURCE
+
+
DESTINATION
+
+
PROTOCOL
+
+
PORT
+
+
CLIENT PORT
+
+
+
+
202:P
+
+
eth2
+
+
0.0.0.0/0
+
+
tcp
+
+
80
+
+
-
+
+
+
+
+
-
-
+
+
+
+
In /etc/shorewall/rules, you will need:
+
+
+
+
+
+
+
+
ACTION
+
+
SOURCE
+
+
DEST
+
+
PROTO
+
+
DEST
+ PORT(S)
+
+
CLIENT
+ PORT(2)
+
+
ORIGINAL
+ DEST
+
+
+
+
ACCEPT
+
+
loc
+
+
dmz
+
+
tcp
+
+
80
+
+
+
+
+
+
+
+
ACCEPT
+
+
dmz
+
+
net
+
+
tcp
+
+
80
+
+
+
+
+
+
+
+
+
+
+
+
+
+
On 192.0.2.177 (your Web/Squid server), arrange for
+the following command to be executed after networking has come up
+
+
- The traditional net-tools contain a program called ifconfig
-which is used to configure network devices. ifconfig introduced the concept
-of aliased or virtial interfaces. These virtual interfaces
-have names of the form interface:integer (e.g., eth0:0) and
-ifconfig treats them more or less like real interfaces.
-
- Example:
-
-
[root@gateway root]# ifconfig eth0:0 eth0:0 Link encap:Ethernet HWaddr 02:00:08:3:FA:55 inet addr:206.124.146.178 Bcast:206.124.146.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:11 Base address:0x2000 [root@gateway root]#
- The ifconfig utility is being gradually phased out in favor of the
-ip utility which is part of the iproute package. The ip
-utility does not use the concept of aliases or virtual interfaces but rather
-treats additional addresses on an interface as objects. The ip utility
-does provide for interaction with ifconfig in that it allows addresses
-to be labeled and labels may take the form of ipconfig virtual interfaces.
-
- Example:
-
-
-
[root@gateway root]# ip addr show dev eth0 2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc htb qlen 100 link/ether 02:00:08:e3:fa:55 brd ff:ff:ff:ff:ff:ff inet 206.124.146.176/24 brd 206.124.146.255 scope global eth0 inet 206.124.146.178/24 brd 206.124.146.255 scope global secondary eth0:0 [root@gateway root]#
- Note that one cannot type "ip addr show dev eth0:0" because
-"eth0:0" is a label for a particular address rather than a device name.
-
-
[root@gateway root]# ip addr show dev eth0:0 Device "eth0:0" does not exist. [root@gateway root]#
- The iptables program doesn't support virtual interfaces in either
-it's "-i" or "-o" command options; as a consequence, Shorewall does not
-allow them to be used in the /etc/shorewall/interfaces file.
-
-
-
So how do I handle more than one address on an interface?
- The answer depends on what you are trying to do with the interfaces.
- In the sub-sections that follow, we'll take a look at common scenarios.
-
-
Separate Rules
- If you need to make a rule for traffic to/from the firewall itself
-that only applies to a particular IP address, simply qualify the $FW zone
-with the IP address.
-
- Example (allow SSH from net to eth0:0 above):
-
-
-
-
-
-
-
ACTION
-
-
SOURCE
-
-
DESTINATION
-
-
PROTOCOL
-
-
PORT(S)
-
-
SOURCE PORT(S)
-
-
ORIGINAL DESTINATION
-
-
-
-
ACCEPT
-
-
net
-
-
fw:206.124.146.178
-
-
tcp
-
-
22
-
-
-
-
-
-
-
-
-
-
-
-
DNAT
- Suppose that I had set up eth0:0 as above and I wanted to port forward
- from that virtual interface to a web server running in my local zone at
- 192.168.1.3. That is accomplised by a single rule in the /etc/shorewall/rules
- file:
+
+
Background
+ The traditional net-tools contain a program called ifconfig
+ which is used to configure network devices. ifconfig introduced the concept
+ of aliased or virtial interfaces. These virtual interfaces
+ have names of the form interface:integer (e.g., eth0:0)
+and ifconfig treats them more or less like real interfaces.
+
+ Example:
+
+
[root@gateway root]# ifconfig eth0:0 eth0:0 Link encap:Ethernet HWaddr 02:00:08:3:FA:55 inet addr:206.124.146.178 Bcast:206.124.146.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:11 Base address:0x2000 [root@gateway root]#
+ The ifconfig utility is being gradually phased out in favor of the
+ip utility which is part of the iproute package. The ip utility
+does not use the concept of aliases or virtual interfaces but rather treats
+additional addresses on an interface as objects. The ip utility does provide
+for interaction with ifconfig in that it allows addresses to be labeled
+and labels may take the form of ipconfig virtual interfaces.
+
+ Example:
+
+
+
[root@gateway root]# ip addr show dev eth0 2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc htb qlen 100 link/ether 02:00:08:e3:fa:55 brd ff:ff:ff:ff:ff:ff inet 206.124.146.176/24 brd 206.124.146.255 scope global eth0 inet 206.124.146.178/24 brd 206.124.146.255 scope global secondary eth0:0 [root@gateway root]#
+ Note that one cannot type "ip addr show dev eth0:0" because
+ "eth0:0" is a label for a particular address rather than a device name.
+
+
[root@gateway root]# ip addr show dev eth0:0 Device "eth0:0" does not exist. [root@gateway root]#
+ The iptables program doesn't support virtual interfaces in either
+it's "-i" or "-o" command options; as a consequence, Shorewall does not
+allow them to be used in the /etc/shorewall/interfaces file.
+
+
+
So how do I handle more than one address on an interface?
+ The answer depends on what you are trying to do with the interfaces.
+ In the sub-sections that follow, we'll take a look at common scenarios.
+
+
Separate Rules
+ If you need to make a rule for traffic to/from the firewall itself
+that only applies to a particular IP address, simply qualify the $FW zone
+with the IP address.
-
-
+ Example (allow SSH from net to eth0:0 above):
+
+
+
-
-
-
ACTION
-
-
SOURCE
-
-
DESTINATION
-
-
PROTOCOL
-
-
PORT(S)
-
-
SOURCE PORT(S)
-
-
ORIGINAL DESTINATION
-
-
-
-
DNAT
+
+
+
ACTION
+
+
SOURCE
+
+
DESTINATION
+
+
PROTOCOL
+
+
PORT(S)
+
+
SOURCE PORT(S)
+
+
ORIGINAL DESTINATION
+
+
+
+
ACCEPT
+
+
net
+
+
fw:206.124.146.178
+
+
tcp
+
+
22
+
+
-
net
+
-
loc:192.168.1.3
-
-
tcp
-
-
80
-
-
-
-
-
206.124.146.178
-
-
-
-
+
+
+
-
+
+
DNAT
+ Suppose that I had set up eth0:0 as above and I wanted to port forward
+ from that virtual interface to a web server running in my local zone
+at 192.168.1.3. That is accomplised by a single rule in the /etc/shorewall/rules
+ file:
+
+
+
+
+
+
+
ACTION
+
+
SOURCE
+
+
DESTINATION
+
+
PROTOCOL
+
+
PORT(S)
+
+
SOURCE PORT(S)
+
+
ORIGINAL DESTINATION
+
+
+
+
DNAT
+
+
net
+
+
loc:192.168.1.3
+
+
tcp
+
+
80
+
+
-
+
+
206.124.146.178
+
+
+
+
+
+
+
+
SNAT
- If you wanted to use eth0:0 as the IP address for outbound connections
- from your local zone (eth1), then in /etc/shorewall/masq:
-
-
-
-
-
-
-
INTERFACE
-
-
SUBNET
-
-
ADDRESS
-
-
-
-
eth0
-
-
eth1
-
-
206.124.146.178
-
-
-
-
-
-
-
- Shorewall can create the alias (additional address) for you if you
-set ADD_SNAT_ALIASES=Yes in /etc/shorewall/shorewall.conf. Beginning with
-Shorewall 1.3.14, Shorewall can actually create the "label" (virtual interface)
-so that you can see the created address using ifconfig. In addition to
-setting ADD_SNAT_ALIASES=Yes, you specify the virtual interface name in
-the INTERFACE column as follows:
-
-
+ If you wanted to use eth0:0 as the IP address for outbound connections
+ from your local zone (eth1), then in /etc/shorewall/masq:
+
+
+
@@ -203,98 +173,90 @@ the INTERFACE column as follows:
-
eth0:0
+
eth0
eth1
206.124.146.178
-
-
+
+
-
-Shorewall can also set up SNAT to round-robin over a range of IP addresses.
-Do do that, you specify a range of IP addresses in the ADDRESS column. If
-you specify a label in the INTERFACE column, Shorewall will use that label
-for the first address of the range and will increment the label by one for
+
+
+ Shorewall can create the alias (additional address) for you if you
+ set ADD_SNAT_ALIASES=Yes in /etc/shorewall/shorewall.conf. Beginning
+with Shorewall 1.3.14, Shorewall can actually create the "label" (virtual
+interface) so that you can see the created address using ifconfig. In
+addition to setting ADD_SNAT_ALIASES=Yes, you specify the virtual interface
+name in the INTERFACE column as follows:
+
+
+
+
+
+
INTERFACE
+
+
SUBNET
+
+
ADDRESS
+
+
+
+
eth0:0
+
+
eth1
+
+
206.124.146.178
+
+
+
+
+
+
+ Shorewall can also set up SNAT to round-robin over a range of IP addresses.
+Do do that, you specify a range of IP addresses in the ADDRESS column. If
+you specify a label in the INTERFACE column, Shorewall will use that label
+for the first address of the range and will increment the label by one for
each subsequent label.
-
-
+
+
+
-
-
-
INTERFACE
-
-
SUBNET
-
-
ADDRESS
-
-
-
-
eth0:0
-
-
eth1
-
-
206.124.146.178-206.124.146.180
-
-
-
-
+
+
+
INTERFACE
+
+
SUBNET
+
+
ADDRESS
+
+
+
+
eth0:0
+
+
eth1
+
+
206.124.146.178-206.124.146.180
+
+
+
+
-
-The above would create three IP addresses:
-
- eth0:0 = 206.124.146.178
- eth0:1 = 206.124.146.179
- eth0:2 = 206.124.146.180
-
+
+ The above would create three IP addresses:
+
+ eth0:0 = 206.124.146.178
+ eth0:1 = 206.124.146.179
+ eth0:2 = 206.124.146.180
+
STATIC NAT
- If you wanted to use static NAT to link eth0:0 with local address
+ If you wanted to use static NAT to link eth0:0 with local address
192.168.1.3, you would have the following in /etc/shorewall/nat:
-
-
-
-
-
-
-
EXTERNAL
-
-
INTERFACE
-
-
INTERNAL
-
-
ALL INTERFACES
-
-
LOCAL
-
-
-
-
206.124.146.178
-
-
eth0
-
-
192.168.1.3
-
-
no
-
-
no
-
-
-
-
-
-
-
- Shorewall can create the alias (additional address) for you if you
-set ADD_IP_ALIASES=Yes in /etc/shorewall/shorewall.conf. Beginning with
-Shorewall 1.3.14, Shorewall can actually create the "label" (virtual interface)
-so that you can see the created address using ifconfig. In addition to
-setting ADD_IP_ALIASES=Yes, you specify the virtual interface name in the
-INTERFACE column as follows:
-
-
-
+
+
+
@@ -312,7 +274,7 @@ INTERFACE column as follows:
206.124.146.178
-
eth0:0
+
eth0
192.168.1.3
@@ -321,259 +283,119 @@ INTERFACE column as follows:
no
-
-
+
+
-
- In either case, to create rules that pertain only to this NAT pair,
-you simply qualify the local zone with the internal IP address.
-
- Example: You want to allow SSH from the net to 206.124.146.178 a.k.a.
- 192.168.1.3.
-
-
-
-
-
-
-
ACTION
-
-
SOURCE
-
-
DESTINATION
-
-
PROTOCOL
-
-
PORT(S)
-
-
SOURCE PORT(S)
-
-
ORIGINAL DESTINATION
-
-
-
-
ACCEPT
-
-
net
-
-
loc:192.168.1.3
-
-
tcp
-
-
22
-
-
-
-
-
-
-
-
-
+
+ Shorewall can create the alias (additional address) for you if you
+ set ADD_IP_ALIASES=Yes in /etc/shorewall/shorewall.conf. Beginning with
+ Shorewall 1.3.14, Shorewall can actually create the "label" (virtual
+interface) so that you can see the created address using ifconfig. In
+addition to setting ADD_IP_ALIASES=Yes, you specify the virtual interface
+name in the INTERFACE column as follows:
-
-
+
+
+
+
+
+
EXTERNAL
+
+
INTERFACE
+
+
INTERNAL
+
+
ALL INTERFACES
+
+
LOCAL
+
+
+
+
206.124.146.178
+
+
eth0:0
+
+
192.168.1.3
+
+
no
+
+
no
+
+
+
+
+
+
+
+ In either case, to create rules that pertain only to this NAT pair,
+ you simply qualify the local zone with the internal IP address.
+
+ Example: You want to allow SSH from the net to 206.124.146.178 a.k.a.
+ 192.168.1.3.
+
+
+
+
+
+
+
ACTION
+
+
SOURCE
+
+
DESTINATION
+
+
PROTOCOL
+
+
PORT(S)
+
+
SOURCE PORT(S)
+
+
ORIGINAL DESTINATION
+
+
+
+
ACCEPT
+
+
net
+
+
loc:192.168.1.3
+
+
tcp
+
+
22
+
+
+
+
+
+
+
+
+
+
+
+
MULTIPLE SUBNETS
- Sometimes multiple IP addresses are used because there are multiple
- subnetworks configured on a LAN segment. This technique does not provide
- for any security between the subnetworks if the users of the systems have
- administrative privileges because in that case, the users can simply manipulate
- their system's routing table to bypass your firewall/router. Nevertheless,
- there are cases where you simply want to consider the LAN segment itself
+ Sometimes multiple IP addresses are used because there are multiple
+ subnetworks configured on a LAN segment. This technique does not provide
+ for any security between the subnetworks if the users of the systems have
+ administrative privileges because in that case, the users can simply manipulate
+ their system's routing table to bypass your firewall/router. Nevertheless,
+ there are cases where you simply want to consider the LAN segment itself
as a zone and allow your firewall/router to route between the two subnetworks.
-
- Example 1: Local interface eth1 interfaces to 192.168.1.0/24
-and 192.168.20.0/24. The primary IP address of eth1 is 192.168.1.254 and
-eth1:0 is 192.168.20.254. You want to simply route all requests between
-the two subnetworks.
-
+
+ Example 1: Local interface eth1 interfaces to 192.168.1.0/24
+ and 192.168.20.0/24. The primary IP address of eth1 is 192.168.1.254
+and eth1:0 is 192.168.20.254. You want to simply route all requests between
+ the two subnetworks.
+
If you are running Shorewall 1.4.1 or Later
- In /etc/shorewall/interfaces:
-
-
+ In /etc/shorewall/interfaces:
+
+
-
-
-
ZONE
-
-
INTERFACE
-
-
BROADCAST
-
-
OPTIONS
-
-
-
-
-
-
-
eth1
-
-
192.168.1.255,192.168.20.255
-
-
-
-
-
-
-
-
-
- In /etc/shorewall/hosts:
-
-
-
-
-
-
ZONE
-
-
HOSTS
-
-
OPTIONS
-
-
-
-
loc
-
-
eth1:192.168.1.0/24
-
-
-
-
-
-
loc
-
-
eth1:192.168.20.0/24
-
-
-
-
-
-
-
-
-
- Note that you do NOT need any entry in /etc/shorewall/policy as Shorewall
- 1.4.1 and later releases default to allowing intra-zone traffic.
-
-
If you are running Shorewall 1.4.0 or earlier
-
- In /etc/shorewall/interfaces:
-
-
-
-
-
-
-
ZONE
-
-
INTERFACE
-
-
BROADCAST
-
-
OPTIONS
-
-
-
-
loc
-
-
eth1
-
-
192.168.1.255,192.168.20.255
-
-
Note 1:
-
-
-
-
-
-
-
- Note 1: If you are running Shorewall 1.3.10 or earlier then you must
- specify the multi option.
-
- In /etc/shorewall/policy:
-
-
-
-
-
-
-
SOURCE
-
-
DESTINATION
-
-
POLICY
-
-
LOG LEVEL
-
-
BURST:LIMIT
-
-
-
-
loc
-
-
loc
-
-
ACCEPT
-
-
-
-
-
-
-
-
-
-
-
- Example 2: Local interface eth1 interfaces to 192.168.1.0/24 and 192.168.20.0/24.
- The primary IP address of eth1 is 192.168.1.254 and eth1:0 is 192.168.20.254.
- You want to make these subnetworks into separate zones and control the
- access between them (the users of the systems do not have administrative
- privileges).
-
- In /etc/shorewall/zones:
-
-
-
-
-
-
-
ZONE
-
-
DISPLAY
-
-
DESCRIPTION
-
-
-
-
loc
-
-
Local
-
-
Local Zone 1
-
-
-
-
loc2
-
-
Local2
-
-
Local Zone 2
-
-
-
-
-
-
-
- In /etc/shorewall/interfaces:
-
-
-
-
-
+
ZONE
@@ -591,26 +413,65 @@ the two subnetworks.
192.168.1.255,192.168.20.255
-
Note 1:
+
-
-
+
+
+
+
+ In /etc/shorewall/hosts:
+
+
+
+
+
+
ZONE
+
+
HOSTS
+
+
OPTIONS
+
+
+
+
loc
+
+
eth1:192.168.1.0/24
+
+
+
+
+
+
loc
+
+
eth1:192.168.20.0/24
+
+
+
+
+
+
+
+
+
+ Note that you do NOT need any entry in /etc/shorewall/policy as Shorewall
+ 1.4.1 and later releases default to allowing intra-zone traffic.
+
+
If you are running Shorewall 1.4.0 or earlier
+
+ In /etc/shorewall/interfaces:
-
- Note 1: If you are running Shorewall 1.3.10 or earlier then you must
- specify the multi option.
-
- In /etc/shorewall/hosts:
-
-
+
+
ZONE
-
HOSTS
+
INTERFACE
+
+
BROADCAST
OPTIONS
@@ -618,33 +479,175 @@ the two subnetworks.
loc
-
eth1:192.168.1.0/24
+
eth1
+
+
192.168.1.255,192.168.20.255
+
+
Note 1:
+
+
+
+
+
+
+
+ Note 1: If you are running Shorewall 1.3.10 or earlier then you must
+ specify the multi option.
+
+ In /etc/shorewall/policy:
+
+
+
+
+
+
+
SOURCE
+
+
DESTINATION
+
+
POLICY
+
+
LOG LEVEL
+
+
BURST:LIMIT
+
+
+
+
loc
+
+
loc
+
+
ACCEPT
+
+
+
+
+
+
+
+
+ Example 2: Local interface eth1 interfaces to 192.168.1.0/24 and
+192.168.20.0/24. The primary IP address of eth1 is 192.168.1.254 and
+eth1:0 is 192.168.20.254. You want to make these subnetworks into separate
+zones and control the access between them (the users of the systems do
+not have administrative privileges).
+
+ In /etc/shorewall/zones:
+
+
+
+
+
+
+
ZONE
+
+
DISPLAY
+
+
DESCRIPTION
+
+
+
+
loc
+
+
Local
+
+
Local Zone 1
+
loc2
-
eth1:192.168.20.0/24
+
Local2
-
+
Local Zone 2
-
-
+
+
+
+
+ In /etc/shorewall/interfaces:
-
- In /etc/shorewall/rules, simply specify ACCEPT rules for the traffic
- that you want to permit.
-
-
+
+
+
+
+
+
ZONE
+
+
INTERFACE
+
+
BROADCAST
+
+
OPTIONS
+
+
+
+
-
+
+
eth1
+
+
192.168.1.255,192.168.20.255
+
+
Note 1:
+
+
+
+
+
+
+
+ Note 1: If you are running Shorewall 1.3.10 or earlier then you must
+ specify the multi option.
+
+ In /etc/shorewall/hosts:
+
+
+
+
+
+
ZONE
+
+
HOSTS
+
+
OPTIONS
+
+
+
+
loc
+
+
eth1:192.168.1.0/24
+
+
+
+
+
+
loc2
+
+
eth1:192.168.20.0/24
+
+
+
+
+
+
+
+
+
+ In /etc/shorewall/rules, simply specify ACCEPT rules for the traffic
+ that you want to permit.
+
+
It is often the case that a system behind the firewall needs to be able
-to access a remote network through Virtual Private Networking (VPN). The
-two most common means for doing this are IPSEC and PPTP. The basic setup
+
+
It is often the case that a system behind the firewall needs to be able
+to access a remote network through Virtual Private Networking (VPN). The
+two most common means for doing this are IPSEC and PPTP. The basic setup
is shown in the following diagram:
-
+
-
-
-
A system with an RFC 1918 address needs to access a remote
- network through a remote gateway. For this example, we will assume that
-the local system has IP address 192.168.1.12 and that the remote gateway
-has IP address 192.0.2.224.
-
-
If PPTP is being used, there are no firewall requirements
-beyond the default loc->net ACCEPT policy. There is one restriction however:
-Only one local system at a time can be connected to a single remote gateway
-unless you patch your kernel from the 'Patch-o-matic' patches available
-at http://www.netfilter.org.
-
-
If IPSEC is being used then only one system may connect to
-the remote gateway and there are firewall configuration requirements as
-follows:
-
-
+
+
+
A system with an RFC 1918 address needs to access a remote
+ network through a remote gateway. For this example, we will assume that the
+ local system has IP address 192.168.1.12 and that the remote gateway has
+IP address 192.0.2.224.
+
+
If PPTP is being used, there are no firewall requirements
+beyond the default loc->net ACCEPT policy. There is one restriction however:
+Only one local system at a time can be connected to a single remote gateway
+unless you patch your kernel from the 'Patch-o-matic' patches available at
+http://www.netfilter.org.
+
+
If IPSEC is being used then only one system may connect to
+the remote gateway and there are firewall configuration requirements as follows:
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
CLIENT
+ PORT
+
ORIGINAL
+ DEST
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
CLIENT
- PORT
-
ORIGINAL
- DEST
-
-
-
DNAT
-
net:192.0.2.224
-
loc:192.168.1.12
-
50
-
-
-
-
-
-
DNAT
-
net:192.0.2.224
-
loc:192.168.1.12
-
udp
-
500
-
-
-
-
-
+
DNAT
+
net:192.0.2.224
+
loc:192.168.1.12
+
50
+
+
+
+
+
+
DNAT
+
net:192.0.2.224
+
loc:192.168.1.12
+
udp
+
500
+
+
+
+
+
-
-
-
If you want to be able to give access to all of your local systems to
-the remote network, you should consider running a VPN client on your firewall.
+
+
+
If you want to be able to give access to all of your local systems to the
+ remote network, you should consider running a VPN client on your firewall.
As starting points, see http://www.shorewall.net/Documentation.htm#Tunnels
+ href="http://www.shorewall.net/Documentation.htm#Tunnels"> http://www.shorewall.net/Documentation.htm#Tunnels
or http://www.shorewall.net/PPTP.htm.
Shorewall supports two different forms of blacklisting; static and dynamic.
-
+
Static Blacklisting
-
-
Shorewall static blacklisting support has the following configuration
-parameters:
-
+
+
Shorewall static blacklisting support has the following configuration parameters:
+
-
You specify whether you want packets from blacklisted hosts dropped
- or rejected using the BLACKLIST_DISPOSITION
+
You specify whether you want packets from blacklisted hosts dropped
+ or rejected using the BLACKLIST_DISPOSITION
setting in /etc/shorewall/shorewall.conf
-
You specify whether you want packets from blacklisted hosts logged
+
You specify whether you want packets from blacklisted hosts logged
and at what syslog level using the BLACKLIST_LOGLEVEL setting in
+ href="Documentation.htm#BLLoglevel">BLACKLIST_LOGLEVEL setting in
/etc/shorewall/shorewall.conf
-
You list the IP addresses/subnets that you wish to blacklist in
- /etc/shorewall/blacklist. Beginning
- with Shorewall version 1.3.8, you may also specify PROTOCOL and Port numbers/Service
+
You list the IP addresses/subnets that you wish to blacklist in
+ /etc/shorewall/blacklist. Beginning
+ with Shorewall version 1.3.8, you may also specify PROTOCOL and Port numbers/Service
names in the blacklist file.
-
-
You specify the interfaces whose incoming packets you want checked
+
+
You specify the interfaces whose incoming packets you want checked
against the blacklist using the "blacklist" option in /etc/shorewall/interfaces.
-
The black list is refreshed from /etc/shorewall/blacklist by the
+
The black list is refreshed from /etc/shorewall/blacklist by the
"shorewall refresh" command.
-
+
-
+
Dynamic Blacklisting
-
-
Dynamic blacklisting support was added in version 1.3.2. Dynamic blacklisting
- doesn't use any configuration parameters but is rather controlled using
+
+
Dynamic blacklisting support was added in version 1.3.2. Dynamic blacklisting
+ doesn't use any configuration parameters but is rather controlled using
/sbin/shorewall commands:
-
+
-
drop <ip address list> - causes packets from the listed
+
drop <ip address list> - causes packets from the listed
IP addresses to be silently dropped by the firewall.
-
reject <ip address list> - causes packets from the
+
reject <ip address list> - causes packets from the
listed IP addresses to be rejected by the firewall.
-
allow <ip address list> - re-enables receipt of packets
+
allow <ip address list> - re-enables receipt of packets
from hosts previously blacklisted by a deny or reject command.
-
save - save the dynamic blacklisting configuration so that it will
+
save - save the dynamic blacklisting configuration so that it will
be automatically restored the next time that the firewall is restarted.
-
show dynamic - displays the dynamic blacklisting configuration.
-
+
show dynamic - displays the dynamic blacklisting configuration.
+
-Dynamic blacklisting is not dependent on the "blacklist" option in
+ Dynamic blacklisting is not dependent on the "blacklist" option in
/etc/shorewall/interfaces.
-
+
Example 1:
-
+
shorewall drop 192.0.2.124 192.0.2.125
-
+
Drops packets from hosts 192.0.2.124 and 192.0.2.125
Warning: If you copy or edit your configuration
-files on a system running Microsoft Windows, you must
- run them through dos2unix
- before you use them with Shorewall.
-
-
Files
-
-
Shorewall's configuration files are in the directory /etc/shorewall.
-
-
-
/etc/shorewall/shorewall.conf - used to set
- several firewall parameters.
-
/etc/shorewall/params - use this file to
-set shell variables that you will expand in other files.
-
/etc/shorewall/zones - partition the firewall's
- view of the world into zones.
/etc/shorewall/interfaces - describes the
-interfaces on the firewall system.
-
/etc/shorewall/hosts - allows defining zones
- in terms of individual hosts and subnetworks.
-
/etc/shorewall/masq - directs the firewall
- where to use many-to-one (dynamic) Network Address Translation
- (a.k.a. Masquerading) and Source Network Address Translation
- (SNAT).
-
/etc/shorewall/modules - directs the firewall
- to load kernel modules.
-
/etc/shorewall/rules - defines rules that
-are exceptions to the overall policies established in /etc/shorewall/policy.
-
/etc/shorewall/nat - defines static NAT rules.
-
/etc/shorewall/proxyarp - defines use of
-Proxy ARP.
-
/etc/shorewall/routestopped (Shorewall 1.3.4
- and later) - defines hosts accessible when Shorewall is stopped.
-
/etc/shorewall/tcrules - defines marking
-of packets for later use by traffic control/shaping or policy
-routing.
-
/etc/shorewall/tos - defines rules for setting
- the TOS field in packet headers.
-
/etc/shorewall/tunnels - defines IPSEC, GRE
- and IPIP tunnels with end-points on the firewall system.
/etc/shorewall/init - commands that you wish to execute at the
- beginning of a "shorewall start" or "shorewall restart".
-
/etc/shorewall/start - commands that you wish to execute at
-the completion of a "shorewall start" or "shorewall restart"
-
/etc/shorewall/stop - commands that you wish to execute at the
- beginning of a "shorewall stop".
-
/etc/shorewall/stopped - commands that you wish to execute at
- the completion of a "shorewall stop".
-
/etc/shorewall/ecn - disable Explicit Congestion Notification (ECN
- - RFC 3168) to remote hosts or networks.
-
-
-
-
-
Comments
-
-
You may place comments in configuration files by making the first non-whitespace
- character a pound sign ("#"). You may also place comments
-at the end of any line, again by delimiting the comment from
-the rest of the line with a pound sign.
-
-
Examples:
-
-
# This is a comment
-
-
ACCEPT net fw tcp www #This is an end-of-line comment
-
-
Line Continuation
-
-
You may continue lines in the configuration files using the usual backslash
- ("\") followed immediately by a new line character.
-
-
Example:
-
-
ACCEPT net fw tcp \ smtp,www,pop3,imap #Services running on the firewall
-
-
INCLUDE Directive
- Beginning with Shorewall version 1.4.2, any file may contain INCLUDE directives.
-An INCLUDE directive consists of the word INCLUDE followed by a file name
-and causes the contents of the named file to be logically included into
-the file containing the INCLUDE. File names given in an INCLUDE directive
-are assumed to reside in /etc/shorewall or in an alternate configuration
-directory if one has been specified for the command.
-
- INCLUDE's may be nested to a level of 3 -- further nested INCLUDE directives
- are ignored with a warning message.
-
- Examples:
-
-
# Shorewall 1.3 /etc/shorewall/params
- [..]
- #######################################
-
- INCLUDE params.mgmt
-
- # params unique to this host here
- #LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
-
# Shorewall version 1.3 - Rules File
- [..]
- #######################################
-
- INCLUDE rules.mgmt
-
- # rules unique to this host here
- #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
-
-
-
-
----- end rules -----
-
-
-
Using DNS Names
-
-
-
-
WARNING: I personally recommend strongly against
- using DNS names in Shorewall configuration files. If you use DNS
- names and you are called out of bed at 2:00AM because Shorewall won't
- start as a result of DNS problems then don't say that you were not
-forewarned.
-
-
-
-Tom
-
-
-
Beginning with Shorewall 1.3.9, Host addresses in Shorewall
- configuration files may be specified as either IP addresses or DNS
- Names.
-
- DNS names in iptables rules aren't nearly as useful as
- they first appear. When a DNS name appears in a rule, the iptables
- utility resolves the name to one or more IP addresses and inserts
- those addresses into the rule. So changes in the DNS->IP address
- relationship that occur after the firewall has started have absolutely
- no effect on the firewall's ruleset.
-
-
If your firewall rules include DNS names then:
-
-
-
If your /etc/resolv.conf is wrong then your firewall
- won't start.
-
If your /etc/nsswitch.conf is wrong then your firewall
- won't start.
-
If your Name Server(s) is(are) down then your firewall
- won't start.
-
If your startup scripts try to start your firewall
- before starting your DNS server then your firewall won't start.
-
-
Factors totally outside your control (your ISP's
-router is down for example), can prevent your firewall from starting.
-
You must bring up your network interfaces prior to
- starting your firewall.
-
-
-
-
-
Each DNS name much be fully qualified and include a minumum
- of two periods (although one may be trailing). This restriction
-is imposed by Shorewall to insure backward compatibility with existing
- configuration files.
-
- Examples of valid DNS names:
-
-
-
-
mail.shorewall.net
-
shorewall.net. (note the trailing period).
-
-
- Examples of invalid DNS names:
-
-
-
mail (not fully qualified)
-
shorewall.net (only one period)
-
-
- DNS names may not be used as:
-
-
-
The server address in a DNAT rule (/etc/shorewall/rules
- file)
-
In the ADDRESS column of an entry in /etc/shorewall/masq.
-
In the /etc/shorewall/nat file.
-
-
- These restrictions are not imposed by Shorewall simply
- for your inconvenience but are rather limitations of iptables.
-
-
Complementing an Address or Subnet
-
-
Where specifying an IP address, a subnet or an interface, you can precede
-the item with "!" to specify the complement of the item. For example,
-!192.168.1.4 means "any host but 192.168.1.4". There must be no white space
-following the "!".
-
-
Comma-separated Lists
-
-
Comma-separated lists are allowed in a number of contexts within the
- configuration files. A comma separated list:
-
-
-
Must not have any embedded white space.
- Valid: routefilter,dhcp,norfc1918
- Invalid: routefilter, dhcp,
-norfc1818
-
If you use line continuation to break a comma-separated
- list, the continuation line(s) must begin in column 1 (or
- there would be embedded white space)
-
Entries in a comma-separated list may appear
- in any order.
-
-
-
-
Port Numbers/Service Names
-
-
Unless otherwise specified, when giving a port number you can use either
-an integer or a service name from /etc/services.
-
-
Port Ranges
-
-
If you need to specify a range of ports, the proper syntax is <low
- port number>:<high port number>. For
-example, if you want to forward the range of tcp ports 4000 through
-4100 to local host 192.168.1.3, the entry in /etc/shorewall/rules is:
-
-
-
DNAT net loc:192.168.1.3 tcp 4000:4100
- If you omit the low port number, a value of zero is assumed; if you omit
- the high port number, a value of 65535 is assumed.
-
-
Using Shell Variables
-
-
You may use the /etc/shorewall/params file to set shell variables
- that you can then use in some of the other configuration files.
-
-
It is suggested that variable names begin with an upper case letter to distinguish them from variables used internally
- within the Shorewall programs
The result will be the same as if the record had been written
-
-
-
net eth0 130.252.100.255 routefilter,norfc1918
-
-
-
-
Variables may be used anywhere in the other configuration
- files.
-
-
Using MAC Addresses
-
-
Media Access Control (MAC) addresses can be used to specify packet
- source in several of the configuration files. To use this
-feature, your kernel must have MAC Address Match support (CONFIG_IP_NF_MATCH_MAC)
- included.
-
-
MAC addresses are 48 bits wide and each Ethernet Controller has a unique
-MAC address.
-
- In GNU/Linux, MAC addresses are usually written
-as a series of 6 hex numbers separated by colons. Example:
-
- [root@gateway root]# ifconfig eth0
- eth0 Link encap:Ethernet HWaddr 02:00:08:E3:FA:55
- inet addr:206.124.146.176 Bcast:206.124.146.255
- Mask:255.255.255.0
- UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
- RX packets:2398102 errors:0 dropped:0 overruns:0
- frame:0
- TX packets:3044698 errors:0 dropped:0 overruns:0
- carrier:0
- collisions:30394 txqueuelen:100
- RX bytes:419871805 (400.4 Mb) TX bytes:1659782221
- (1582.8 Mb)
- Interrupt:11 Base address:0x1800
-
- Because Shorewall uses colons as a separator for
- address fields, Shorewall requires MAC addresses to be written
- in another way. In Shorewall, MAC addresses begin with a tilde
- ("~") and consist of 6 hex numbers separated by hyphens. In Shorewall,
- the MAC address in the example above would be written "~02-00-08-E3-FA-55".
-
-
-
Note: It is not necessary to use the special Shorewall notation
- in the /etc/shorewall/maclist file.
-
-
-
Shorewall Configurations
-
-
Shorewall allows you to have configuration directories other than /etc/shorewall.
- The shorewall check,
-start and restart commands allow you to specify an alternate
-configuration directory and Shorewall will use the files in the alternate
-directory rather than the corresponding files in /etc/shorewall. The
-alternate directory need not contain a complete configuration; those
-files not in the alternate directory will be read from /etc/shorewall.
-
-
This facility permits you to easily create a test or temporary configuration
- by:
-
-
-
copying the files that need modification
- from /etc/shorewall to a separate directory;
-
modify those files in the separate directory;
- and
-
specifying the separate directory in a
-shorewall start or shorewall restart command (e.g., shorewall
--c /etc/testconfig restart )
-
-
-The try command
-allows you to attempt to restart using an alternate configuration and if
-an error occurs to automatically restart the standard configuration.
-
-
/etc/shorewall/interfaces - describes the
+ interfaces on the firewall system.
+
/etc/shorewall/hosts - allows defining zones
+ in terms of individual hosts and subnetworks.
+
/etc/shorewall/masq - directs the firewall
+ where to use many-to-one (dynamic) Network Address Translation
+ (a.k.a. Masquerading) and Source Network Address Translation
+ (SNAT).
+
/etc/shorewall/modules - directs the firewall
+ to load kernel modules.
+
/etc/shorewall/rules - defines rules that
+ are exceptions to the overall policies established in /etc/shorewall/policy.
+
/etc/shorewall/nat - defines static NAT
+rules.
+
/etc/shorewall/proxyarp - defines use of
+Proxy ARP.
+
/etc/shorewall/routestopped (Shorewall 1.3.4
+ and later) - defines hosts accessible when Shorewall is stopped.
+
/etc/shorewall/tcrules - defines marking
+of packets for later use by traffic control/shaping or policy
+routing.
+
/etc/shorewall/tos - defines rules for setting
+ the TOS field in packet headers.
+
/etc/shorewall/tunnels - defines IPSEC,
+GRE and IPIP tunnels with end-points on the firewall system.
/etc/shorewall/init - commands that you wish to execute at
+the beginning of a "shorewall start" or "shorewall restart".
+
/etc/shorewall/start - commands that you wish to execute at
+the completion of a "shorewall start" or "shorewall restart"
+
/etc/shorewall/stop - commands that you wish to execute at
+the beginning of a "shorewall stop".
+
/etc/shorewall/stopped - commands that you wish to execute
+at the completion of a "shorewall stop".
+
/etc/shorewall/ecn - disable Explicit Congestion Notification (ECN
+ - RFC 3168) to remote hosts or networks.
+
+
+
+
+
Comments
+
+
You may place comments in configuration files by making the first non-whitespace
+ character a pound sign ("#"). You may also place comments
+at the end of any line, again by delimiting the comment from the
+rest of the line with a pound sign.
+
+
Examples:
+
+
# This is a comment
+
+
ACCEPT net fw tcp www #This is an end-of-line comment
+
+
Line Continuation
+
+
You may continue lines in the configuration files using the usual backslash
+ ("\") followed immediately by a new line character.
+
+
Example:
+
+
ACCEPT net fw tcp \ smtp,www,pop3,imap #Services running on the firewall
+
+
INCLUDE Directive
+ Beginning with Shorewall version 1.4.2, any file may contain INCLUDE directives.
+ An INCLUDE directive consists of the word INCLUDE followed by a file name
+ and causes the contents of the named file to be logically included into
+ the file containing the INCLUDE. File names given in an INCLUDE directive
+ are assumed to reside in /etc/shorewall or in an alternate configuration
+ directory if one has been specified for the command.
+
+ INCLUDE's may be nested to a level of 3 -- further nested INCLUDE directives
+ are ignored with a warning message.
+
+ Examples:
+
+
# Shorewall 1.3 /etc/shorewall/params
+ [..]
+ #######################################
+
+ INCLUDE params.mgmt
+
+ # params unique to this host here
+ #LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
+
# Shorewall version 1.3 - Rules File
+ [..]
+ #######################################
+
+ INCLUDE rules.mgmt
+
+ # rules unique to this host here
+ #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
+
+
+
+
----- end rules -----
+
+
+
Using DNS Names
+
+
+
+
WARNING: I personally recommend strongly against
+ using DNS names in Shorewall configuration files. If you use DNS
+ names and you are called out of bed at 2:00AM because Shorewall won't
+ start as a result of DNS problems then don't say that you were not forewarned.
+
+
+
+
-Tom
+
+
+
Beginning with Shorewall 1.3.9, Host addresses in Shorewall
+ configuration files may be specified as either IP addresses or DNS
+ Names.
+
+ DNS names in iptables rules aren't nearly as useful
+as they first appear. When a DNS name appears in a rule, the iptables
+ utility resolves the name to one or more IP addresses and inserts
+ those addresses into the rule. So changes in the DNS->IP address
+ relationship that occur after the firewall has started have absolutely
+ no effect on the firewall's ruleset.
+
+
If your firewall rules include DNS names then:
+
+
+
If your /etc/resolv.conf is wrong then your firewall
+ won't start.
+
If your /etc/nsswitch.conf is wrong then your firewall
+ won't start.
+
If your Name Server(s) is(are) down then your firewall
+ won't start.
+
If your startup scripts try to start your firewall
+ before starting your DNS server then your firewall won't start.
+
+
Factors totally outside your control (your ISP's
+ router is down for example), can prevent your firewall from starting.
+
You must bring up your network interfaces prior
+to starting your firewall.
+
+
+
+
+
Each DNS name much be fully qualified and include a minumum
+ of two periods (although one may be trailing). This restriction is
+ imposed by Shorewall to insure backward compatibility with existing
+ configuration files.
+
+ Examples of valid DNS names:
+
+
+
+
mail.shorewall.net
+
shorewall.net. (note the trailing period).
+
+
+ Examples of invalid DNS names:
+
+
+
mail (not fully qualified)
+
shorewall.net (only one period)
+
+
+ DNS names may not be used as:
+
+
+
The server address in a DNAT rule (/etc/shorewall/rules
+ file)
+
In the ADDRESS column of an entry in /etc/shorewall/masq.
+
In the /etc/shorewall/nat file.
+
+
+ These restrictions are not imposed by Shorewall simply
+ for your inconvenience but are rather limitations of iptables.
+
+
Complementing an Address or Subnet
+
+
Where specifying an IP address, a subnet or an interface, you can precede
+ the item with "!" to specify the complement of the item. For example,
+ !192.168.1.4 means "any host but 192.168.1.4". There must be no white space
+ following the "!".
+
+
Comma-separated Lists
+
+
Comma-separated lists are allowed in a number of contexts within the
+ configuration files. A comma separated list:
+
+
+
Must not have any embedded white space.
+ Valid: routefilter,dhcp,norfc1918
+ Invalid: routefilter, dhcp,
+ norfc1818
+
If you use line continuation to break a
+comma-separated list, the continuation line(s) must begin
+in column 1 (or there would be embedded white space)
+
Entries in a comma-separated list may appear
+ in any order.
+
+
+
+
Port Numbers/Service Names
+
+
Unless otherwise specified, when giving a port number you can use either
+ an integer or a service name from /etc/services.
+
+
Port Ranges
+
+
If you need to specify a range of ports, the proper syntax is <low
+ port number>:<high port number>. For example,
+ if you want to forward the range of tcp ports 4000 through 4100 to
+ local host 192.168.1.3, the entry in /etc/shorewall/rules is:
+
+
+
DNAT net loc:192.168.1.3 tcp 4000:4100
+ If you omit the low port number, a value of zero is assumed; if you
+omit the high port number, a value of 65535 is assumed.
+
+
Using Shell Variables
+
+
You may use the /etc/shorewall/params file to set shell variables
+that you can then use in some of the other configuration files.
+
+
It is suggested that variable names begin with an upper case letter to distinguish them from variables used internally
+ within the Shorewall programs
The result will be the same as if the record had been written
+
+
+
net eth0 130.252.100.255 routefilter,norfc1918
+
+
+
+
Variables may be used anywhere in the other configuration
+ files.
+
+
Using MAC Addresses
+
+
Media Access Control (MAC) addresses can be used to specify packet
+ source in several of the configuration files. To use this
+ feature, your kernel must have MAC Address Match support
+(CONFIG_IP_NF_MATCH_MAC) included.
+
+
MAC addresses are 48 bits wide and each Ethernet Controller has a unique
+ MAC address.
+
+ In GNU/Linux, MAC addresses are usually written
+ as a series of 6 hex numbers separated by colons. Example:
+
+ [root@gateway root]# ifconfig eth0
+ eth0 Link encap:Ethernet HWaddr 02:00:08:E3:FA:55
+ inet addr:206.124.146.176 Bcast:206.124.146.255
+ Mask:255.255.255.0
+ UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
+ RX packets:2398102 errors:0 dropped:0 overruns:0
+ frame:0
+ TX packets:3044698 errors:0 dropped:0 overruns:0
+ carrier:0
+ collisions:30394 txqueuelen:100
+ RX bytes:419871805 (400.4 Mb) TX bytes:1659782221
+ (1582.8 Mb)
+ Interrupt:11 Base address:0x1800
+
+ Because Shorewall uses colons as a separator for
+ address fields, Shorewall requires MAC addresses to be written
+ in another way. In Shorewall, MAC addresses begin with a tilde
+ ("~") and consist of 6 hex numbers separated by hyphens. In Shorewall,
+ the MAC address in the example above would be written "~02-00-08-E3-FA-55".
+
+
+
Note: It is not necessary to use the special Shorewall notation
+ in the /etc/shorewall/maclist file.
+
+
+
Shorewall Configurations
+
+
Shorewall allows you to have configuration directories other than /etc/shorewall.
+ The shorewall check,
+start and restart commands allow you to specify an alternate
+configuration directory and Shorewall will use the files in the alternate
+directory rather than the corresponding files in /etc/shorewall. The
+alternate directory need not contain a complete configuration; those
+files not in the alternate directory will be read from /etc/shorewall.
+
+
This facility permits you to easily create a test or temporary configuration
+ by:
+
+
+
copying the files that need modification
+ from /etc/shorewall to a separate directory;
+
modify those files in the separate directory;
+ and
+
specifying the separate directory in a
+shorewall start or shorewall restart command (e.g., shorewall
+-c /etc/testconfig restart )
+
+
+ The try command
+allows you to attempt to restart using an alternate configuration and if an
+error occurs to automatically restart the standard configuration.
+
+
Permission is granted to copy, distribute and/or modify
-this document under the terms of the GNU Free Documentation License, Version
-1.1 or any later version published by the Free Software Foundation; with
-no Invariant Sections, with no Front-Cover, and with no Back-Cover Texts.
+
+
+
+
Permission is granted to copy, distribute and/or modify
+this document under the terms of the GNU Free Documentation License, Version
+1.1 or any later version published by the Free Software Foundation; with
+no Invariant Sections, with no Front-Cover, and with no Back-Cover Texts.
A copy of the license is included in the section entitled "GNU Free Documentation License".
-
Specify the "dhcp" option on each interface to be
- served by your server in the /etc/shorewall/interfaces
- file. This will generate rules that will allow DHCP to and from your
-firewall system.
-
-
-
When starting "dhcpd", you need to list those interfaces
-on the run line. On a RedHat system, this is done by modifying /etc/sysconfig/dhcpd.
+
+
Specify the "dhcp" option on each interface to be served
+by your server in the /etc/shorewall/interfaces
+ file. This will generate rules that will allow DHCP to and from your firewall
+system.
+
+
+
When starting "dhcpd", you need to list those interfaces
+on the run line. On a RedHat system, this is done by modifying /etc/sysconfig/dhcpd.
-
+
+
-
+
If a Firewall Interface gets its IP Address via DHCP
-
+
-
-
Specify the "dhcp" option for this interface in the
- /etc/shorewall/interfaces
- file. This will generate rules that will allow DHCP to and from your firewall
+
+
Specify the "dhcp" option for this interface in the
+ /etc/shorewall/interfaces
+ file. This will generate rules that will allow DHCP to and from your firewall
system.
-
-
-
If you know that the dynamic address is always going
-to be in the same subnet, you can specify the subnet address in the interface's
- entry in the /etc/shorewall/interfaces
+
+
+
If you know that the dynamic address is always going to
+be in the same subnet, you can specify the subnet address in the interface's
+ entry in the /etc/shorewall/interfaces
file.
-
-
-
If you don't know the subnet address in advance, you
-should specify "detect" for the interface's subnet address in the /etc/shorewall/interfaces file
+
+
+
If you don't know the subnet address in advance, you should
+ specify "detect" for the interface's subnet address in the /etc/shorewall/interfaces file
and start Shorewall after the interface has started.
-
-
-
In the event that the subnet address might change while
- Shorewall is started, you need to arrange for a "shorewall refresh"
-command to be executed when a new dynamic IP address gets assigned to
+
+
+
In the event that the subnet address might change while
+ Shorewall is started, you need to arrange for a "shorewall refresh"
+command to be executed when a new dynamic IP address gets assigned to
the interface. Check your DHCP client's documentation.
If you are running LRP, download the .lrp
-file (you might also want to download the .tgz so you will
+ I can mention them here. See the Installation
+ Instructions if you have problems installing the RPM.
+
If you are running LRP, download the .lrp
+ file (you might also want to download the .tgz so you will
have a copy of the documentation).
The documentation in HTML format is included in the .tgz and .rpm files
- and there is an documentation .deb that also contains the documentation. The
- .rpm will install the documentation in your default document directory
- which can be obtained using the following command:
-
-
-
+ and there is an documentation .deb that also contains the documentation. The
+ .rpm will install the documentation in your default document directory
+ which can be obtained using the following command:
+
+
+
rpm --eval '%{defaultdocdir}'
-
-
+
+
Please check the errata
- to see if there are updates that apply to the version
- that you have downloaded.
-
+ to see if there are updates that apply to the version
+ that you have downloaded.
+
WARNING - YOU CAN NOT SIMPLY INSTALL
- THE RPM AND ISSUE A "shorewall start" COMMAND. SOME CONFIGURATION
- IS REQUIRED BEFORE THE FIREWALL WILL START. Once you have completed configuration
- of your firewall, you can enable startup by removing the file /etc/shorewall/startup_disabled.
-
+ THE RPM AND ISSUE A "shorewall start" COMMAND. SOME CONFIGURATION
+ IS REQUIRED BEFORE THE FIREWALL WILL START. Once you have completed
+configuration of your firewall, you can enable startup by removing
+the file /etc/shorewall/startup_disabled.
+
The CVS repository
- at cvs.shorewall.net contains the latest snapshots of the
+ at cvs.shorewall.net contains the latest snapshots of the
each Shorewall component. There's no guarantee that what you
find there will work at all.
-
-
-
+
+
+
Shapshots:
-
-
-
+
+
+
Periodic snapshots from CVS may be found at http://shorewall.net/pub/shorewall/Snapshots
-(FTP).
-These snapshots have undergone initial testing and will have been installed
-and run at shorewall.net.
-
-
-
-
Last Updated 6/19/2003 - FTP).
+ These snapshots have undergone initial testing and will have been installed
+ and run at shorewall.net.
+
If you are installing Shorewall for the first
-time and plan to use the .tgz and install.sh script, you can untar
-the archive, replace the 'firewall' script in the untarred directory
+
+
+
+
If you are installing Shorewall for the
+first time and plan to use the .tgz and install.sh script, you can
+untar the archive, replace the 'firewall' script in the untarred directory
with the one you downloaded below, and then run install.sh.
-
-
-
-
When the instructions say to install a corrected
- firewall script in /usr/share/shorewall/firewall, you
+
+
+
+
When the instructions say to install a corrected
+ firewall script in /usr/share/shorewall/firewall, you
may rename the existing file before copying in the new file.
-
-
-
-
DO NOT INSTALL CORRECTED COMPONENTS
- ON A RELEASE EARLIER THAN THE ONE THAT THEY ARE LISTED UNDER
-BELOW. For example, do NOT install the 1.3.9a firewall script if
-you are running 1.3.7c.
-
-
-
+
+
+
+
DO NOT INSTALL CORRECTED COMPONENTS
+ ON A RELEASE EARLIER THAN THE ONE THAT THEY ARE LISTED UNDER BELOW.
+ For example, do NOT install the 1.3.9a firewall script if you are
+ running 1.3.7c.
+
The INCLUDE directive doesn't work when placed in the /etc/shorewall/zones
+ target="_top">this firewall script in /usr/share/shorewall/firewall
+as described above.
+
The INCLUDE directive doesn't work when placed in the /etc/shorewall/zones
file. This problem may be corrected by installing this functions script in /usr/share/shorewall/functions.
-
-
+ target="_top">this firewall script in /usr/share/shorewall/firewall
+as described above.
+
+
-
+
1.4.4
-
-
+
+
-
If you have zone names that are 5 characters long, you may experience
- problems starting Shorewall because the --log-prefix in a logging rule
-is too long. Upgrade to Version 1.4.4a to fix this problem..
-
+
If you have zone names that are 5 characters long, you may experience
+ problems starting Shorewall because the --log-prefix in a logging rule is
+ too long. Upgrade to Version 1.4.4a to fix this problem..
-
+ target="_top">ftp://ftp1.shorewall.net/pub/shorewall/errata/1.4.3/fireparse/.
+ See the 0README.txt file for details.
+
+
-
+
1.4.2
-
-
-
When an 'add' or 'delete' command is executed, a temporary directory
- created in /tmp is not being removed. This problem may be corrected by
-installing this firewall script in /usr/share/shorewall/firewall as
-described above.
-
-
-
-
-
1.4.1a, 1.4.1 and 1.4.0
-
Some TCP requests are rejected in the 'common' chain with an
- ICMP port-unreachable response rather than the more appropriate TCP RST
- response. This problem is corrected in this updated common.def file which may be installed in
- /etc/shorewall/common.def.
+
When an 'add' or 'delete' command is executed, a temporary
+directory created in /tmp is not being removed. This problem may be corrected
+by installing this firewall script in /usr/share/shorewall/firewall
+as described above.
-
1.4.1
+
1.4.1a, 1.4.1 and 1.4.0
-
When a "shorewall check" command is executed, each "rule"
-produces the harmless additional message:
-
- /usr/share/shorewall/firewall: line 2174: [: =: unary operator
- expected
-
- You may correct the problem by installing this corrected script in /usr/share/shorewall/firewall
- as described above.
+
Some TCP requests are rejected in the 'common' chain with
+an ICMP port-unreachable response rather than the more appropriate TCP
+RST response. This problem is corrected in this updated common.def file which may be installed in
+ /etc/shorewall/common.def.
-
1.4.0
+
1.4.1
-
When running under certain shells Shorewall will attempt
-to create ECN rules even when /etc/shorewall/ecn is empty. You may either
- just remove /etc/shorewall/ecn or you can install this
- correct script in /usr/share/shorewall/firewall as described above.
+
When a "shorewall check" command is executed, each "rule"
+produces the harmless additional message:
+
+ /usr/share/shorewall/firewall: line 2174: [: =: unary operator
+ expected
+
+ You may correct the problem by installing this corrected script in /usr/share/shorewall/firewall
+ as described above.
There are a couple of serious bugs in iptables 1.2.3 that
- prevent it from working with Shorewall. Regrettably,
- RedHat released this buggy iptables in RedHat 7.2.
Update 11/9/2001: RedHat
- has released an iptables-1.2.4 RPM of their own which you
- can download from http://www.redhat.com/support/errata/RHSA-2001-144.html.
- I have installed this RPM on my firewall and it
- works fine.
-
-
If you would like to patch iptables 1.2.3 yourself,
- the patches are available for download. This patch
- which corrects a problem with parsing of the --log-level
- specification while this patch
- corrects a problem in handling the TOS target.
-
-
To install one of the above patches:
-
-
-
cd iptables-1.2.3/extensions
-
patch -p0 < the-patch-file
-
-
-
-
-
Problems with kernels >= 2.4.18 and
-RedHat iptables
-
-
-
Users who use RedHat iptables RPMs and who upgrade to kernel 2.4.18/19
- may experience the following:
The RedHat iptables RPM is compiled with debugging enabled but the
- user-space debugging code was not updated to reflect recent changes in
- the Netfilter 'mangle' table. You can correct the problem by
- installing
- this iptables RPM. If you are already running a 1.2.5
- version of iptables, you will need to specify the --oldpackage
- option to rpm (e.g., "iptables -Uvh --oldpackage iptables-1.2.5-1.i386.rpm").
-
-
-
Problems installing/upgrading
- RPM on SuSE
-
-
If you find that rpm complains about a conflict with kernel <=
- 2.2 yet you have a 2.4 kernel installed, simply use the
-"--nodeps" option to rpm.
-
-
Installing: rpm -ivh --nodeps <shorewall rpm>
-
-
Upgrading: rpm -Uvh --nodeps <shorewall rpm>
-
-
Problems with iptables version 1.2.7 and
- MULTIPORT=Yes
-
-
The iptables 1.2.7 release of iptables has made an incompatible
- change to the syntax used to specify multiport match rules;
- as a consequence, if you install iptables 1.2.7 you must
- be running Shorewall 1.3.7a or later or:
+
1.4.0
-
set MULTIPORT=No
- in /etc/shorewall/shorewall.conf;
-or
-
if you
- are running Shorewall 1.3.6 you may
- install
- this firewall script in /var/lib/shorewall/firewall
- as described above.
-
+
When running under certain shells Shorewall will attempt
+to create ECN rules even when /etc/shorewall/ecn is empty. You may either
+ just remove /etc/shorewall/ecn or you can install this
+ correct script in /usr/share/shorewall/firewall as described above.
+
There are a couple of serious bugs in iptables 1.2.3 that
+ prevent it from working with Shorewall. Regrettably,
+ RedHat released this buggy iptables in RedHat 7.2.
Update 11/9/2001: RedHat
+ has released an iptables-1.2.4 RPM of their own which you
+ can download from http://www.redhat.com/support/errata/RHSA-2001-144.html.
+ I have installed this RPM on my firewall and it
+ works fine.
+
+
If you would like to patch iptables 1.2.3 yourself,
+ the patches are available for download. This patch
+ which corrects a problem with parsing of the --log-level
+ specification while this patch
+ corrects a problem in handling the TOS target.
+
+
To install one of the above patches:
+
+
+
cd iptables-1.2.3/extensions
+
patch -p0 < the-patch-file
+
+
+
+
+
Problems with kernels >= 2.4.18
+and RedHat iptables
+
+
+
Users who use RedHat iptables RPMs and who upgrade to kernel 2.4.18/19
+ may experience the following:
The RedHat iptables RPM is compiled with debugging enabled but the
+ user-space debugging code was not updated to reflect recent changes in
+ the Netfilter 'mangle' table. You can correct the problem by
+ installing
+ this iptables RPM. If you are already running a 1.2.5
+ version of iptables, you will need to specify the --oldpackage
+ option to rpm (e.g., "iptables -Uvh --oldpackage iptables-1.2.5-1.i386.rpm").
+
+
+
Problems installing/upgrading
+ RPM on SuSE
+
+
If you find that rpm complains about a conflict with kernel <=
+ 2.2 yet you have a 2.4 kernel installed, simply use the
+ "--nodeps" option to rpm.
+
+
Installing: rpm -ivh --nodeps <shorewall rpm>
+
+
Upgrading: rpm -Uvh --nodeps <shorewall rpm>
+
+
Problems with iptables version 1.2.7 and
+ MULTIPORT=Yes
+
+
The iptables 1.2.7 release of iptables has made an incompatible
+ change to the syntax used to specify multiport match rules;
+ as a consequence, if you install iptables 1.2.7 you
+must be running Shorewall 1.3.7a or later or:
+
+
+
set
+MULTIPORT=No in /etc/shorewall/shorewall.conf;
+or
+
if you
+ are running Shorewall 1.3.6 you may
+ install
+ this firewall script in /var/lib/shorewall/firewall
+ as described above.
+
+
+
Problems with RH Kernel 2.4.18-10 and NAT
-
- /etc/shorewall/nat entries of the following form
- will result in Shorewall being unable to start:
-
-
+
+ /etc/shorewall/nat entries of the following form
+ will result in Shorewall being unable to start:
+
+
#EXTERNAL INTERFACE INTERNAL ALL INTERFACES LOCAL 192.0.2.22 eth0 192.168.9.22 yes yes #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
- Error message is:
-
+ Error message is:
+
Setting up NAT... iptables: Invalid argument Terminated
- The solution is to put "no" in the LOCAL column.
- Kernel support for LOCAL=yes has never worked properly and 2.4.18-10
- has disabled it. The 2.4.19 kernel contains corrected support
-under a new kernel configuraiton option; see http://www.shorewall.net/Documentation.htm#NAT
-
-
-
Problems with RH Kernels after 2.4.20-9 and REJECT
-(also applies to 2.4.21-RC1)
- Beginning with errata kernel 2.4.20-13.9, "REJECT --reject-with tcp-reset"
-is broken. The symptom most commonly seen is that REJECT rules act just like
-DROP rules when dealing with TCP. A kernel patch and precompiled modules to
-fix this problem are available at
+
+
Problems with RH Kernels after 2.4.20-9 and
+REJECT (also applies to 2.4.21-RC1)
+ Beginning with errata kernel 2.4.20-13.9, "REJECT --reject-with tcp-reset"
+ is broken. The symptom most commonly seen is that REJECT rules act just
+like DROP rules when dealing with TCP. A kernel patch and precompiled modules
+to fix this problem are available at ftp://ftp1.shorewall.net/pub/shorewall/errata/kernel.
-
-
-
+
+
diff --git a/Shorewall-docs/errata_1.htm b/Shorewall-docs/errata_1.htm
index cdd1e06c3..351893bed 100644
--- a/Shorewall-docs/errata_1.htm
+++ b/Shorewall-docs/errata_1.htm
@@ -1,215 +1,196 @@
+
-
-
-
-
-
-Shorewall Errata for Version 1
+
+
+
+
+
+
+
+
+ Shorewall Errata for Version 1
-
-
-
-
-
-
-
Shorewall Errata for Version 1.1
-
-
+
+
+
+
+
+
+
Shorewall Errata for Version
+1.1
+
+
+
+
-
-
To those of you who downloaded the 1.1.13 updated firewall script prior
-to Sept 20, 2001:
-
-
-
-
Prior
-to 20:00 20 Sept 2001 GMT, the link under 1.1.13 pointed to a broken version
-of the firewall script. This has now been corrected. I apologize for any confusion
-this may have caused.
+
+
To those of you who downloaded
+the 1.1.13 updated firewall script prior to Sept 20, 2001:
+
+
+
Prior to 20:00 20 Sept 2001 GMT, the link under 1.1.13
+pointed to a broken version of the firewall script. This has now been corrected.
+I apologize for any confusion this may have caused.
+
+
+
Version 1.1.18
+
+
+
In the original .lrp, /etc/init.d/shorewall was not
+ secured for execute access. I have replaced the incorrect .lrp
+ (shorwall-1.1.18.lrp) with a corrected one (shorwall-1.1.18a.lrp).
-
-
Version 1.1.18
-
-
-
-
In the original .lrp, /etc/init.d/shorewall was not
- secured for execute access. I have replaced the incorrect .lrp
- (shorwall-1.1.18.lrp) with a corrected one (shorwall-1.1.18a.lrp).
-
-
-
-
- Version 1.1.17
-
-
-
-
In
- shorewall.conf, ADD_IP_ALIASES was incorrectly spelled
- IP_ADD_ALIASAES. There is a corrected version of the file here.
-
-
This
- problem is also corrected in version 1.1.18.
-
-
-
- Version 1.1.16
-
-
-
- The ADD_IP_ALIASES variable added in 1.1.16 was incorrectly spelled IP_ADD_ALIASES
-in the firewall script. To correct this problem, install the
- corrected firewall script
- in the location pointed to by the symbolic link /etc/shorewall/firewall.
-
-
- This problem is also corrected in version 1.1.17.
-
-
-
- Version 1.1.14-1.1.15
-
-
-
- There are no corrections for these versions.
-
-
-
- Version 1.1.13
-
-
-
- The firewall fails to start if a rule with the following format is given:
-
-
- <disposition> z1:www.xxx.yyy.zzz z2 proto p1,p2,p3
-
-
- To correct this problem, install
- this corrected firewall script
- in the location pointed to by the symbolic link /etc/shorewall/firewall.
-
-
-
- Version 1.1.12
-
-
-
- The LRP version of Shorewall 1.1.12 has the incorrect /etc/shorewall/functions
-file. This incorrect file results in many error messages of the form:
- A LAN segment attached to the firewall was served by a DHCP server
-running on the firewall.
-
-
-
-
- There were entries in /etc/shorewall/hosts that referred to the
-interface to that LAN segment.
-
-
-
-
-
- then up until now it has been necessary to include entries for 0.0.0.0
-and 255.255.255.255 for that interface in /etc/shorewall/hosts.
- This version of the firewall script
- makes those additions unnecessary provided that you simply include
-"dhcp" in the options for the interface in /etc/shorewall/interfaces.
-Install the script into the location pointed to by the symbolic link
-/etc/shorewall/firewall.
-
-
- This problem has also been corrected in version 1.1.11.
-
-
-
- Version 1.1.9
-
+
+
Version 1.1.17
+
+
+
In shorewall.conf, ADD_IP_ALIASES was incorrectly
+spelled IP_ADD_ALIASAES. There is a corrected version of the
+file here.
+
+
This problem is also corrected in version 1.1.18.
+
+
+
Version 1.1.16
+
+
+
The ADD_IP_ALIASES variable added in 1.1.16 was incorrectly
+ spelled IP_ADD_ALIASES in the firewall script. To correct this problem,
+ install the corrected
+ firewall script in the location pointed to by the symbolic link
+ /etc/shorewall/firewall.
+
+
This problem is also corrected in version 1.1.17.
+
+
+
Version 1.1.14-1.1.15
+
+
+
There are no corrections for these versions.
+
+
+
Version 1.1.13
+
+
+
The firewall fails to start if a rule with the following
+ format is given:
+
+
<disposition> z1:www.xxx.yyy.zzz z2
+ proto p1,p2,p3
+
+
To correct this problem, install this
+ corrected firewall script in the location pointed to by the symbolic
+link /etc/shorewall/firewall.
+
+
+
Version 1.1.12
+
+
+
The LRP version of Shorewall 1.1.12 has the incorrect
+ /etc/shorewall/functions file. This incorrect file results in many error
+ messages of the form:
A LAN segment attached to the firewall was served
+by a DHCP server running on the firewall.
+
+
+
There were entries in /etc/shorewall/hosts that referred
+ to the interface to that LAN segment.
+
+
+
+
+
then up until now it has been necessary to include entries
+ for 0.0.0.0 and 255.255.255.255 for that interface in /etc/shorewall/hosts.
+
+ This version of the firewall script makes those additions unnecessary
+ provided that you simply include "dhcp" in the options for the interface
+in /etc/shorewall/interfaces. Install the script into the location pointed
+to by the symbolic link /etc/shorewall/firewall.
+
+
This problem has also been corrected in version 1.1.11.
Under some circumstances, the "dhcp" option on an interface triggers
-a bug in the firewall script that results in a "chain already exists"
-error.
- This version of the firewall script
- corrects this problem. Install it into the location pointed to by
-the symbolic link /etc/shorewall/firewall.
-
- This problem is also corrected in version 1.1.9.
-
-
-
+
Under some circumstances, the "dhcp" option on an interface triggers
+a bug in the firewall script that results in a "chain already exists"
+error. This
+ version of the firewall script corrects this problem. Install
+it into the location pointed to by the symbolic link /etc/shorewall/firewall.
+
+ This problem is also corrected in version 1.1.9.
+
+
-
-
-
Version 1.1.7
-
+
+
Version 1.1.7
+
-
If the /etc/shorewall/rules template from version 1.1.7 is used, a warning
-message appears during firewall startup:
-
- Warning: Invalid Target - rule "@ icmp-unreachable packet."
+
If the /etc/shorewall/rules template from version 1.1.7 is used,
+a warning message appears during firewall startup:
+
+ Warning: Invalid Target - rule "@ icmp-unreachable packet."
ignored
-
- This warning may be eliminated by replacing the "@" in column 1 of
+
+ This warning may be eliminated by replacing the "@" in column 1 of
line 17 with "#"
-
- If you use a Windows system to download a corrected script, be sure to
-run the script through
-dos2unix
- after you have moved it to your Linux system.
-
-
-
- When the instructions say to install a corrected firewall script in
- /etc/shorewall/firewall, use the 'cp' (or 'scp') utility to overwrite the
- existing file. DO NOT REMOVE OR RENAME THE OLD /etc/shorewall/firewall
- before you do that. /etc/shorewall/firewall is a symbolic link that points
- to the 'shorewall' file used by your system initialization scripts to
- start Shorewall during boot and it is that file that must be overwritten
- with the corrected script.
Some users have reported problems installing the RPM
- on SuSE 7.3 where rpm reports a conflict with kernel <= 2.2 even
- though a 2.4 kernel RPM is installed. To get around this problem, use
- the --nodeps option to rpm (e.g., "rpm -ivh --nodeps
- shorewall-1.2-13.noarch.rpm").
-
- The problem stems from the fact that SuSE does not
- include a package named "kernel" but rather has a number of packages
- that provide the virtual package "kernel". Since virtual packages have
- no version associated with them, a conflict results. Since the
- workaround is simple, I don't intend to change the Shorewall package.
-
-
-
-
-
Shorewall accepts invalid rules of the form:
-
- ACCEPT <src> <dest>:<ip addr> all <port number> -
- <original ip address>
-
- The <port number> is ignored with the result that all
- connection requests from the <src> zone whose original destination IP
- address matches the last column are forwarded to the <dest> zone, IP
- address <ip addr>.
-
- This corrected firewall script correctly generates an error when
+
+
+
+
+
+
+
+
Shorewall 1.2 Errata
+
+
+
+
+
+
+
+ IMPORTANT
+
+
If you use a Windows system to download a
+corrected script, be sure to run the script through dos2unix
+ after you have moved it to your Linux system.
+
+
When the instructions say to install a corrected
+firewall script in /etc/shorewall/firewall, use the 'cp' (or 'scp')
+utility to overwrite the existing file. DO NOT REMOVE OR RENAME THE
+OLD /etc/shorewall/firewall before you do that. /etc/shorewall/firewall
+is a symbolic link that points to the 'shorewall' file used by your
+system initialization scripts to start Shorewall during boot and it
+is that file that must be overwritten with the corrected script.
Some users have reported problems installing the RPM
+ on SuSE 7.3 where rpm reports a conflict with kernel <= 2.2 even
+ though a 2.4 kernel RPM is installed. To get around this problem,
+use the --nodeps option to rpm (e.g., "rpm -ivh --nodeps
+ shorewall-1.2-13.noarch.rpm").
+
+ The problem stems from the fact that SuSE does not include
+a package named "kernel" but rather has a number of packages that
+provide the virtual package "kernel". Since virtual packages have
+ no version associated with them, a conflict results. Since the
+ workaround is simple, I don't intend to change the Shorewall package.
+
+
+
Shorewall accepts invalid rules of the form:
+
+ ACCEPT <src> <dest>:<ip addr>
+all <port number> - <original ip address>
+
+ The <port number> is ignored with the result that
+ all connection requests from the <src> zone whose
+original destination IP address matches the last column are forwarded
+to the <dest> zone, IP address <ip addr>.
+
+ This corrected firewall script correctly generates an error when
such a rule is encountered.
-
-
-
-
-
Version 1.2.11
-
-
-
-
-
The 'try' command is broken.
-
-
-
The usage text printed by the shorewall utility
- doesn't show the optional timeout for the 'try' command.
There have been several problems with SSH, DNS and
- ping in the two- and three-interface examples. Before reporting
- problems with these services, please verify that you have the latest
- version of the appropriate sample 'rules' file.
The shorewall.conf file and the documentation
- incorrectly refer to a parameter in /etc/shorewall/shorewall.conf
- called LOCKFILE; the correct name for the parameter is SUBSYSLOCK (see
- the corrected online documentation). Users of the rpm should
- change the name (and possibly the value) of this parameter so that
- Shorewall interacts properly with the SysV init scripts. The
- documentation on this web site has been corrected and
-
+
+
+
+
+
Version 1.2.11
+
+
+
+
The 'try' command is broken.
+
+
+
The usage text printed by the shorewall utility
+ doesn't show the optional timeout for the 'try' command.
There have been several problems with SSH, DNS and
+ ping in the two- and three-interface examples. Before reporting
+ problems with these services, please verify that you have the latest
+ version of the appropriate sample 'rules' file.
The shorewall.conf file and the documentation
+ incorrectly refer to a parameter in /etc/shorewall/shorewall.conf
+ called LOCKFILE; the correct name for the parameter is SUBSYSLOCK (see the corrected online documentation).
+Users of the rpm should change the name (and possibly the value)
+of this parameter so that Shorewall interacts properly with the
+SysV init scripts. The documentation on this web site has been
+corrected and
here's a corrected version of shorewall.conf.
-
-
-
-
-
The documentation indicates that a comma-separated
- list of IP/subnet addresses may appear in an entry in the hosts file.
- This is not the case; if you want to specify multiple addresses for a
- zone, you need to have a separate entry for each address.
-
-
-
-
-
Version 1.2.7
-
-
Version 1.2.7 is quite broken -- please install 1.2.8
-
-
If you have installed and started version 1.2.7 then before trying
- to restart under 1.2.8:
-
-
Look at your /etc/shorewall/shorewall.conf file and note the directory
- named in the STATEDIR variable. If that variable is empty, assume
- /var/state/shorewall.
-
Remove the file 'lock' in the directory determined in step 1.
-
-
You may now restart using 1.2.8.
-
-
Version 1.2.6
-
-
-
-
-
GRE and IPIP tunnels are broken.
-
-
-
The following rule results in a start error:
-
- ACCEPT z1 z2
- icmp
This version will not install "out of the box" without
- modification. Before attempting to start the
- firewall, please change the STATEDIR in /etc/shorewall/shorewall.conf to
- refer to /var/lib/shorewall. This only applies to fresh installations -- if
- you are upgrading from a previous version of Shorewall, version 1.2.4 will
- work without modification.
-
-
-
Version 1.2.3
-
-
-
-
When BLACKLIST_LOGLEVEL is set, packets from blacklisted
- hosts aren't logged. Install this
- corrected firewall script in /etc/shorewall/firewall.
-
-
-
-
Alternatively, edit /etc/shorewall/firewall and change line 1564 from:
-
-
-
run_iptables -A blacklst -d $addr -j LOG $LOGPARAMS --log-prefix \
-
-
-
to
-
-
-
run_iptables -A blacklst -s $addr -j LOG $LOGPARAMS --log-prefix \
-
-
Version 1.2.2
-
-
-
The "shorewall status" command hangs after
- it displays the chain information. Here's
- a corrected /sbin/shorewall. if you want to simply modify your copy of
- /sbin/shorewall, then at line 445 change this:
-
-
-
-
-
status)
- clear
-
-
-
-
-
to this:
-
-
-
-
-
status)
- get_config
- clear
-
-
-
-
The "shorewall monitor" command
- doesn't show the icmpdef chain - this
- corrected /sbin/shorewall fixes that problem as well as the status
- problem described above.
-
-
-
In all 1.2.x versions, the 'CLIENT PORT(S)'
- column in /etc/shorewall/tcrules is ignored. This is corrected in this
- updated firewall script. Place the script in /etc/shorewall/firewall. Thanks to Shingo Takeda for
- spotting this bug.
-
-
-
Version 1.2.1
-
-
-
The new logunclean interface option is not
- described in the help text in /etc/shorewall/interfaces. An updated
- interfaces file is available.
-
When REJECT is specified in a TCP rule, Shorewall
- correctly replies with a TCP RST packet. Previous versions of the
- firewall script are broken in the case of a REJECT policy, however; in
- REJECT policy chains, all requests are currently replied to with an
- ICMP port-unreachable packet. This
- corrected firewall script replies to TCP requests with TCP RST in
- REJECT policy chains. Place the script in /etc/shorewall/firewall.
-
-
-
Version 1.2.0
-
-
-
-
Note: If you are upgrading from one of the Beta
- RPMs to 1.2.0, you must use the "--oldpackage" option to rpm
- (e.g., rpm -Uvh --oldpackage shorewall-1.2-0.noarch.rpm).
-
-
The tunnel script released in version 1.2.0 contained
- errors -- a corrected
- script is available.
-
-
-
-
-
-
- Problem with iptables version 1.2.3
-
-
-
-
There are a couple of serious bugs in iptables 1.2.3 that
- prevent it from working with Shorewall. Regrettably,
-RedHat released this buggy iptables in RedHat 7.2.
Update
- 11/9/2001: RedHat has
- released an iptables-1.2.4 RPM of their own which you can download from
- http://www.redhat.com/support/errata/RHSA-2001-144.html.
- I have installed this RPM
- on my firewall and it works fine.
-
-
If you
- would like to patch iptables 1.2.3 yourself, the patches are available
- for download. This patch
- which corrects a problem with parsing of the --log-level specification while
- this patch
- corrects a problem in handling the TOS target.
-
-
To install one of the above patches:
-
-
cd iptables-1.2.3/extensions
-
patch -p0 < the-patch-file
-
-
-
-
-
Problems with kernel 2.4.18
- and RedHat iptables
-
-
Users who use RedHat iptables RPMs and who upgrade to kernel 2.4.18 may
- experience the following:
The documentation indicates that a comma-separated
+ list of IP/subnet addresses may appear in an entry in the hosts file.
+ This is not the case; if you want to specify multiple addresses
+for a zone, you need to have a separate entry for each address.
+
+
+
+
+
Version 1.2.7
+
+
Version 1.2.7 is quite broken -- please install 1.2.8
+
+
If you have installed and started version 1.2.7 then before trying
+ to restart under 1.2.8:
+
+
+
Look at your /etc/shorewall/shorewall.conf file and note the directory
+ named in the STATEDIR variable. If that variable is empty, assume /var/state/shorewall.
+
Remove the file 'lock' in the directory determined in step 1.
+
+
+
+
You may now restart using 1.2.8.
+
+
Version 1.2.6
+
+
+
+
GRE and IPIP tunnels are broken.
+
+
+
The following rule results in a start error:
+
+ ACCEPT z1 z2 icmp
This version will not install "out of the box" without
+ modification. Before attempting to start the firewall, please change
+the STATEDIR in /etc/shorewall/shorewall.conf to refer to /var/lib/shorewall.
+This only applies to fresh installations -- if you are upgrading from
+a previous version of Shorewall, version 1.2.4 will work without modification.
+
+
+
+
+
Version 1.2.3
+
+
+
+
When BLACKLIST_LOGLEVEL is set, packets from blacklisted
+ hosts aren't logged. Install this
+ corrected firewall script in /etc/shorewall/firewall.
+
+
+
+
+
Alternatively, edit /etc/shorewall/firewall and change line 1564 from:
-
The RedHat iptables RPM is compiled with debugging enabled but the
- user-space debugging code was not updated to reflect recent changes in the
- Netfilter 'mangle' table. You can correct the problem by installing
-
- this iptables RPM. If you are already running a 1.2.5 version of
- iptables, you will need to specify the --oldpackage option to rpm (e.g.,
- "iptables -Uvh --oldpackage iptables-1.2.5-1.i386.rpm").
The "shorewall monitor" command doesn't show the icmpdef chain
+- this corrected /sbin/shorewall
+fixes that problem as well as the status problem described above.
+
+
+
+
+
In all 1.2.x versions, the 'CLIENT PORT(S)' column in /etc/shorewall/tcrules
+is ignored. This is corrected in this updated firewall script.
+Place the script in /etc/shorewall/firewall. Thanks to Shingo Takeda for
+ spotting this bug.
+
+
+
+
Version 1.2.1
+
+
+
The new logunclean interface option is not described
+in the help text in /etc/shorewall/interfaces. An updated
+ interfaces file is available.
+
When REJECT is specified in a TCP rule, Shorewall correctly
+replies with a TCP RST packet. Previous versions of the firewall
+script are broken in the case of a REJECT policy, however; in REJECT
+policy chains, all requests are currently replied to with an ICMP
+port-unreachable packet. This
+ corrected firewall script replies to TCP requests with TCP
+RST in REJECT policy chains. Place the script in /etc/shorewall/firewall.
+
+
+
+
Version 1.2.0
+
+
+
Note: If you are upgrading from one of the Beta
+ RPMs to 1.2.0, you must use the "--oldpackage" option to rpm
+ (e.g., rpm -Uvh --oldpackage shorewall-1.2-0.noarch.rpm).
+
+
The tunnel script released in version 1.2.0 contained
+ errors -- a corrected
+ script is available.
+
+
+
+
Problem with
+iptables version 1.2.3
+
+
+
There are a couple of serious bugs in iptables 1.2.3 that
+ prevent it from working with Shorewall. Regrettably, RedHat released
+this buggy iptables in RedHat 7.2.
Update 11/9/2001: RedHat has released
+an iptables-1.2.4 RPM of their own which you can download from http://www.redhat.com/support/errata/RHSA-2001-144.html.
+ I have installed this RPM on my firewall and it works fine.
+
+
If you would like to patch iptables 1.2.3 yourself,
+the patches are available for download. This patch
+ which corrects a problem with parsing of the --log-level specification
+while this patch
+ corrects a problem in handling the TOS target.
+
+
To install one of the above patches:
+
+
+
cd iptables-1.2.3/extensions
+
patch -p0 < the-patch-file
+
+
+
+
+
Problems with kernel 2.4.18
+ and RedHat iptables
+
+
+
Users who use RedHat iptables RPMs and who upgrade to kernel 2.4.18
+may experience the following:
The RedHat iptables RPM is compiled with debugging enabled but the
+ user-space debugging code was not updated to reflect recent changes in
+the Netfilter 'mangle' table. You can correct the problem by installing
+
+ this iptables RPM. If you are already running a 1.2.5 version of
+ iptables, you will need to specify the --oldpackage option to rpm (e.g.,
+ "iptables -Uvh --oldpackage iptables-1.2.5-1.i386.rpm").
-
+
-
\ No newline at end of file
+
diff --git a/Shorewall-docs/errata_3.html b/Shorewall-docs/errata_3.html
index 59cc0fc9a..fe34058ff 100755
--- a/Shorewall-docs/errata_3.html
+++ b/Shorewall-docs/errata_3.html
@@ -1,703 +1,644 @@
-
-
+
Shorewall 1.3 Errata
-
-
-
+
-
-
+
-
-
+
-
+
-
-
-
-
-
+ bgcolor="#3366ff" height="90">
+
+
+
Shorewall Errata/Upgrade Issues
-
-
-
-
-
+
+
+
+
-
+
IMPORTANT
-
+
-
-
-
-
If you use a Windows system to download
- a corrected script, be sure to run the script through
- dos2unix after you have moved
+
+
If you use a Windows system to download
+ a corrected script, be sure to run the script through
+ dos2unix after you have moved
it to your Linux system.
-
-
-
-
-
If you are installing Shorewall for the
-first time and plan to use the .tgz and install.sh script, you can
-untar the archive, replace the 'firewall' script in the untarred directory
+
+
+
If you are installing Shorewall for the first
+time and plan to use the .tgz and install.sh script, you can untar
+the archive, replace the 'firewall' script in the untarred directory
with the one you downloaded below, and then run install.sh.
-
-
-
-
-
If you are running a Shorewall version earlier
- than 1.3.11, when the instructions say to install a corrected
-firewall script in /etc/shorewall/firewall, /usr/lib/shorewall/firewall
- or /var/lib/shorewall/firewall, use the 'cp' (or 'scp') utility to
-overwrite the existing file. DO NOT REMOVE OR RENAME THE OLD
-/etc/shorewall/firewall or /var/lib/shorewall/firewall before
-you do that. /etc/shorewall/firewall and /var/lib/shorewall/firewall
- are symbolic links that point to the 'shorewall' file used by
-your system initialization scripts to start Shorewall during
-boot. It is that file that must be overwritten with the corrected
-script. Beginning with Shorewall 1.3.11, you may rename the existing file
+
+
+
If you are running a Shorewall version earlier
+ than 1.3.11, when the instructions say to install a corrected firewall
+ script in /etc/shorewall/firewall, /usr/lib/shorewall/firewall
+ or /var/lib/shorewall/firewall, use the 'cp' (or 'scp') utility to
+overwrite the existing file. DO NOT REMOVE OR RENAME THE OLD
+/etc/shorewall/firewall or /var/lib/shorewall/firewall before
+you do that. /etc/shorewall/firewall and /var/lib/shorewall/firewall
+ are symbolic links that point to the 'shorewall' file used by your
+ system initialization scripts to start Shorewall during boot.
+It is that file that must be overwritten with the corrected
+script. Beginning with Shorewall 1.3.11, you may rename the existing file
before copying in the new file.
-
-
-
-
DO NOT INSTALL CORRECTED COMPONENTS
- ON A RELEASE EARLIER THAN THE ONE THAT THEY ARE LISTED UNDER BELOW.
- For example, do NOT install the 1.3.9a firewall script if you are running
+
+
+
DO NOT INSTALL CORRECTED COMPONENTS
+ ON A RELEASE EARLIER THAN THE ONE THAT THEY ARE LISTED UNDER BELOW.
+ For example, do NOT install the 1.3.9a firewall script if you are running
1.3.7c.
-
There is an updated
- rfc1918 file that reflects the resent allocation of 222.0.0.0/8 and
+
There is an updated
+ rfc1918 file that reflects the resent allocation of 222.0.0.0/8 and
223.0.0.0/8.
-
+
-
+
-
The documentation for the routestopped file claimed that a comma-separated
- list could appear in the second column while the code only supported a single
- host or network address.
-
Log messages produced by 'logunclean' and 'dropunclean' were not rate-limited.
-
802.11b devices with names of the form wlan<n> don't
+
The documentation for the routestopped file claimed that a comma-separated
+ list could appear in the second column while the code only supported a
+single host or network address.
+
Log messages produced by 'logunclean' and 'dropunclean' were not
+rate-limited.
+
802.11b devices with names of the form wlan<n> don't
support the 'maclist' interface option.
-
Log messages generated by RFC 1918 filtering are not rate limited.
-
The firewall fails to start in the case where you have "eth0 eth1"
+
Log messages generated by RFC 1918 filtering are not rate limited.
+
The firewall fails to start in the case where you have "eth0 eth1"
in /etc/shorewall/masq and the default route is through eth1.
-
-
+
+
- These problems have been corrected in this
- firewall script which may be installed in /usr/lib/shorewall as described
+ These problems have been corrected in this
+ firewall script which may be installed in /usr/lib/shorewall as described
above.
-
+
Version 1.3.13
-
+
-
The 'shorewall add' command produces an error message referring
+
The 'shorewall add' command produces an error message referring
to 'find_interfaces_by_maclist'.
-
The 'shorewall delete' command can leave behind undeleted rules.
-
The 'shorewall add' command can fail with "iptables: Index of insertion
- too big".
-
-
-
- All three problems are corrected by this
- firewall script which may be installed in /usr/lib/shorewall as described
- above.
-
-
-
VLAN interface names of the form "ethn.m" (e.g.,
-eth0.1) are not supported in this version or in 1.3.12. If you need such
-support, post on the users list and I can provide you with a patched version.
+
The 'shorewall delete' command can leave behind undeleted rules.
+
The 'shorewall add' command can fail with "iptables: Index of
+insertion too big".
-
+
-
-
Version 1.3.12
-
+ All three problems are corrected by this
+ firewall script which may be installed in /usr/lib/shorewall as described
+ above.
+
-
If RFC_1918_LOG_LEVEL is set to anything but ULOG, the effect
- is the same as if RFC_1918_LOG_LEVEL=info had been specified. The problem
- is corrected by this
- firewall script which may be installed in /usr/lib/shorewall as described
- above.
-
VLAN interface names of the form "ethn.m" (e.g.,
-eth0.1) are not supported in this version or in 1.3.13. If you need such
+
VLAN interface names of the form "ethn.m" (e.g.,
+eth0.1) are not supported in this version or in 1.3.12. If you need such
support, post on the users list and I can provide you with a patched version.
-
+
-
+
+
Version 1.3.12
+
+
+
If RFC_1918_LOG_LEVEL is set to anything but ULOG, the effect
+ is the same as if RFC_1918_LOG_LEVEL=info had been specified. The problem
+ is corrected by this
+ firewall script which may be installed in /usr/lib/shorewall as described
+ above.
+
VLAN interface names of the form "ethn.m" (e.g.,
+eth0.1) are not supported in this version or in 1.3.13. If you need such
+support, post on the users list and I can provide you with a patched version.
+
+
+
+
Version 1.3.12 LRP
-
+
-
The .lrp was missing the /etc/shorewall/routestopped file
--- a new lrp (shorwall-1.3.12a.lrp) has been released which corrects
-this problem.
-
When installing/upgrading using the .rpm, you may receive
+
When installing/upgrading using the .rpm, you may receive
the following warnings:
-
- user teastep does not exist - using root
- group teastep does not exist - using root
-
- These warnings are harmless and may be ignored. Users downloading
- the .rpm from shorewall.net or mirrors should no longer see these warnings
+
+ user teastep does not exist - using root
+ group teastep does not exist - using root
+
+ These warnings are harmless and may be ignored. Users downloading
+ the .rpm from shorewall.net or mirrors should no longer see these warnings
as the .rpm you will get from there has been corrected.
-
DNAT rules that exclude a source subzone (SOURCE column
-contains ! followed by a sub-zone list) result in an error message and
+
DNAT rules that exclude a source subzone (SOURCE column
+contains ! followed by a sub-zone list) result in an error message and
Shorewall fails to start.
-
- Install this
- corrected script in /usr/lib/shorewall/firewall to correct this
-problem. Thanks go to Roger Aich who analyzed this problem and provided
+
+ Install this
+ corrected script in /usr/lib/shorewall/firewall to correct this
+problem. Thanks go to Roger Aich who analyzed this problem and provided
a fix.
-
- This problem is corrected in version 1.3.11a.
-
-
+
+ This problem is corrected in version 1.3.11a.
+
+
-
+
Version 1.3.10
-
+
-
If you experience problems connecting to a PPTP server
- running on your firewall and you have a 'pptpserver' entry in /etc/shorewall/tunnels,
+
If you experience problems connecting to a PPTP server
+ running on your firewall and you have a 'pptpserver' entry in /etc/shorewall/tunnels,
this
- version of the firewall script may help. Please report any cases
- where installing this script in /usr/lib/shorewall/firewall solved
-your connection problems. Beginning with version 1.3.10, it is safe
-to save the old version of /usr/lib/shorewall/firewall before copying
-in the new one since /usr/lib/shorewall/firewall is the real script
-now and not just a symbolic link to the real script.
-
-
+ href="http://www.shorewall.net/pub/shorewall/errata/1.3.10/firewall">this
+ version of the firewall script may help. Please report any cases
+ where installing this script in /usr/lib/shorewall/firewall solved your
+ connection problems. Beginning with version 1.3.10, it is safe to save
+ the old version of /usr/lib/shorewall/firewall before copying in the
+ new one since /usr/lib/shorewall/firewall is the real script now and
+not just a symbolic link to the real script.
+
+
-
+
Version 1.3.9a
-
+
-
If entries are used in /etc/shorewall/hosts and MERGE_HOSTS=No
+
If entries are used in /etc/shorewall/hosts and MERGE_HOSTS=No
then the following message appears during "shorewall [re]start":
-
+
-
+
recalculate_interfacess: command not found
-
+
The updated firewall script at ftp://www.shorewall.net/pub/shorewall/errata/1.3.9/firewall
- corrects this problem.Copy the script to /usr/lib/shorewall/firewall
+ target="_top">ftp://www.shorewall.net/pub/shorewall/errata/1.3.9/firewall
+ corrects this problem.Copy the script to /usr/lib/shorewall/firewall
as described above.
-
-
-
Alternatively, edit /usr/lob/shorewall/firewall and change the
- single occurence (line 483 in version 1.3.9a) of 'recalculate_interefacess'
+
+
+
Alternatively, edit /usr/lob/shorewall/firewall and change the
+ single occurence (line 483 in version 1.3.9a) of 'recalculate_interefacess'
to 'recalculate_interface'.
-
-
+
+
-
The installer (install.sh) issues a misleading message
- "Common functions installed in /var/lib/shorewall/functions" whereas
- the file is installed in /usr/lib/shorewall/functions. The installer
- also performs incorrectly when updating old configurations that had the
+
- TUNNELS Broken in 1.3.9!!! There is an updated
+ TUNNELS Broken in 1.3.9!!! There is an updated
firewall script at ftp://www.shorewall.net/pub/shorewall/errata/1.3.9/firewall
+ target="_top">ftp://www.shorewall.net/pub/shorewall/errata/1.3.9/firewall
-- copy that file to /usr/lib/shorewall/firewall as described above.
-
- Version 1.3.8
+
+ Version 1.3.8
-
Use of shell variables in the LOG LEVEL or SYNPARMS
+
Use of shell variables in the LOG LEVEL or SYNPARMS
columns of the policy file doesn't work.
-
A DNAT rule with the same original and new IP
-addresses but with different port numbers doesn't work (e.g., "DNAT
+
A DNAT rule with the same original and new IP
+addresses but with different port numbers doesn't work (e.g., "DNAT
loc dmz:10.1.1.1:24 tcp 25 - 10.1.1.1")
-
DNAT rules where the source zone is 'fw' ($FW)
- result in an error message. Installing
-
- this corrected firewall script in /var/lib/shorewall/firewall
- as described above corrects this
+
+
DNAT rules where the source zone is 'fw' ($FW) result in an error
+message. Installing
+ this corrected firewall script in /var/lib/shorewall/firewall
+ as described above corrects this
problem.
-
-
+
Version 1.3.7a
-
-
-
"shorewall refresh" is not creating the proper
- rule for FORWARDPING=Yes. Consequently, after
- "shorewall refresh", the firewall will not forward
- icmp echo-request (ping) packets. Installing
+
+
"shorewall refresh" is not creating the proper rule for FORWARDPING=Yes.
+Consequently, after "shorewall refresh", the firewall will not
+forward icmp echo-request (ping) packets. Installing
- this corrected firewall script in /var/lib/shorewall/firewall
- as described above corrects this
+ href="http://www.shorewall.net/pub/shorewall/errata/1.3.7/firewall">
+ this corrected firewall script in /var/lib/shorewall/firewall
+ as described above corrects this
problem.
-
-
+
Version <= 1.3.7a
-
-
-
If "norfc1918" and "dhcp" are both specified as
- options on a given interface then RFC 1918
- checking is occurring before DHCP checking. This
- means that if a DHCP client broadcasts using an
- RFC 1918 source address, then the firewall will
- reject the broadcast (usually logging it). This
+
+
If "norfc1918" and "dhcp" are both specified as options on a
+given interface then RFC 1918 checking is occurring before DHCP
+checking. This means that if a DHCP client broadcasts using
+an RFC 1918 source address, then the firewall will
+ reject the broadcast (usually logging it). This
has two problems:
-
-
+
-
If the firewall
- is running a DHCP server, the
-client won't be able to obtain an IP address
- lease from that server.
-
With this order
- of checking, the "dhcp" option
-cannot be used as a noise-reduction
- measure where there are both dynamic and static
- clients on a LAN segment.
-
+
If the firewall
+ is running a DHCP server, the client
+ won't be able to obtain an IP address lease from
+that server.
+
With this order
+ of checking, the "dhcp" option
+cannot be used as a noise-reduction measure where there are both
+dynamic and static clients on a LAN segment.
-
-
+ href="http://www.shorewall.net/pub/shorewall/errata/1.3.7/firewall">
+ This version of the 1.3.7a firewall script
+ corrects the problem. It must be installed
+ in /var/lib/shorewall as described
+ above.
+
Version 1.3.7
-
-
-
Version 1.3.7 dead on arrival -- please use
- version 1.3.7a and check your version against
- these md5sums -- if there's a difference, please
+
+
Version 1.3.7 dead on arrival -- please use version 1.3.7a and check
+your version against these md5sums -- if there's a difference, please
download again.
In other words, type "md5sum <whatever package you downloaded>
+
+
In other words, type "md5sum <whatever package you downloaded>
and compare the result with what you see above.
-
-
I'm embarrassed to report that 1.2.7 was also DOA -- maybe I'll skip the
+
+
I'm embarrassed to report that 1.2.7 was also DOA -- maybe I'll skip the
.7 version in each sequence from now on.
-
+
Version 1.3.6
-
+
-
-
-
-
If ADD_SNAT_ALIASES=Yes is specified in /etc/shorewall/shorewall.conf,
- an error occurs when the firewall script attempts to
+
+
If ADD_SNAT_ALIASES=Yes is specified in /etc/shorewall/shorewall.conf,
+ an error occurs when the firewall script attempts to
add an SNAT alias.
-
-
-
-
-
The logunclean and dropunclean options
- cause errors during startup when Shorewall is run with iptables
+
+
+
The logunclean and dropunclean options
+ cause errors during startup when Shorewall is run with iptables
1.2.7.
-
-
+
+
-
+
These problems are fixed in
- this correct firewall script which must be installed in
- /var/lib/shorewall/ as described above. These problems are also
- corrected in version 1.3.7.
-
+ href="http://www.shorewall.net/pub/shorewall/errata/1.3.6/firewall">
+ this correct firewall script which must be installed in /var/lib/shorewall/
+as described above. These problems are also corrected in version 1.3.7.
+
A line was inadvertently deleted from the "interfaces
- file" -- this line should be added back in if the version that you
- downloaded is missing it:
-
+
+
A line was inadvertently deleted from the "interfaces
+ file" -- this line should be added back in if the version that you
+ downloaded is missing it:
+
net eth0 detect routefilter,dhcp,norfc1918
-
-
If you downloaded two-interfaces-a.tgz then the above
- line should already be in the file.
-
+
+
If you downloaded two-interfaces-a.tgz then the above
+ line should already be in the file.
+
Version 1.3.5-1.3.5b
-
-
The new 'proxyarp' interface option doesn't work :-(
- This is fixed in
- this corrected firewall script which must be installed in
- /var/lib/shorewall/ as described above.
-
+
+
The new 'proxyarp' interface option doesn't work :-(
+ This is fixed in
+ this corrected firewall script which must be installed in
+/var/lib/shorewall/ as described above.
+
Versions 1.3.4-1.3.5a
-
-
Prior to version 1.3.4, host file entries such as the
- following were allowed:
-
-
+
+
Prior to version 1.3.4, host file entries such as the
+ following were allowed:
+
+
adm eth0:1.2.4.5,eth0:5.6.7.8
-
-
-
-
That capability was lost in version 1.3.4 so that it is only
- possible to include a single host specification on each line.
+
+
+
+
That capability was lost in version 1.3.4 so that it is only
+ possible to include a single host specification on each line.
This problem is corrected by this
- modified 1.3.5a firewall script. Install the script in
+ href="http://www.shorewall.net/pub/shorewall/errata/1.3.5a/firewall">this
+ modified 1.3.5a firewall script. Install the script in
/var/lib/pub/shorewall/firewall as instructed above.
-
-
-
+
+
+
This problem is corrected in version 1.3.5b.
-
-
+
+
Version 1.3.5
-
-
REDIRECT rules are broken in this version. Install
-
- this corrected firewall script in /var/lib/pub/shorewall/firewall
- as instructed above. This problem is corrected in version
+
+
REDIRECT rules are broken in this version. Install
+ this corrected firewall script in /var/lib/pub/shorewall/firewall
+ as instructed above. This problem is corrected in version
1.3.5a.
-
+
Version 1.3.n, n < 4
-
-
The "shorewall start" and "shorewall restart" commands
- to not verify that the zones named in the /etc/shorewall/policy
-file have been previously defined in the /etc/shorewall/zones
-file. The "shorewall check" command does perform this verification
-so it's a good idea to run that command after you have made configuration
+
+
The "shorewall start" and "shorewall restart" commands
+ to not verify that the zones named in the /etc/shorewall/policy file
+ have been previously defined in the /etc/shorewall/zones file.
+The "shorewall check" command does perform this verification so
+it's a good idea to run that command after you have made configuration
changes.
-
+
Version 1.3.n, n < 3
-
-
If you have upgraded from Shorewall 1.2 and after
- "Activating rules..." you see the message: "iptables: No chains/target/match
- by that name" then you probably have an entry in /etc/shorewall/hosts
- that specifies an interface that you didn't include
-in /etc/shorewall/interfaces. To correct this problem, you
- must add an entry to /etc/shorewall/interfaces. Shorewall 1.3.3
- and later versions produce a clearer error message in
-this case.
-
+
+
If you have upgraded from Shorewall 1.2 and after "Activating
+rules..." you see the message: "iptables: No chains/target/match
+ by that name" then you probably have an entry in /etc/shorewall/hosts
+ that specifies an interface that you didn't include
+in /etc/shorewall/interfaces. To correct this problem, you
+ must add an entry to /etc/shorewall/interfaces. Shorewall 1.3.3
+and later versions produce a clearer error message in this
+ case.
+
Version 1.3.2
-
-
Until approximately 2130 GMT on 17 June 2002, the
- download sites contained an incorrect version of the .lrp file. That
- file can be identified by its size (56284 bytes). The correct
-version has a size of 38126 bytes.
-
+
+
Until approximately 2130 GMT on 17 June 2002, the download
+sites contained an incorrect version of the .lrp file. That file
+can be identified by its size (56284 bytes). The correct version
+ has a size of 38126 bytes.
+
-
The code to detect a duplicate interface
- entry in /etc/shorewall/interfaces contained a typo that
+
The code to detect a duplicate interface
+ entry in /etc/shorewall/interfaces contained a typo that
prevented it from working correctly.
-
"NAT_BEFORE_RULES=No" was broken;
+
"NAT_BEFORE_RULES=No" was broken;
it behaved just like "NAT_BEFORE_RULES=Yes".
-
+
-
+
Both problems are corrected in
- this script which should be installed in /var/lib/shorewall
+ href="http://www.shorewall.net/pub/shorewall/errata/1.3.2/firewall">
+ this script which should be installed in /var/lib/shorewall
as described above.
-
+
-
-
-
-
The IANA have just announced the allocation of subnet
+
+
The IANA have just announced the allocation of subnet
221.0.0.0/8. This
- updated rfc1918 file reflects that allocation.
TCP SYN packets may be double counted
- when LIMIT:BURST is included in a CONTINUE or ACCEPT policy
+
TCP SYN packets may be double counted
+ when LIMIT:BURST is included in a CONTINUE or ACCEPT policy
(i.e., each packet is sent through the limit chain twice).
-
An unnecessary jump to the policy
+
An unnecessary jump to the policy
chain is sometimes generated for a CONTINUE policy.
-
When an option is given for more than
- one interface in /etc/shorewall/interfaces then depending
- on the option, Shorewall may ignore all but the first
- appearence of the option. For example:
-
- net eth0 dhcp
- loc eth1 dhcp
-
- Shorewall will ignore the 'dhcp' on eth1.
-
Update 17 June 2002 - The bug described
- in the prior bullet affects the following options:
-dhcp, dropunclean, logunclean, norfc1918, routefilter,
-multi, filterping and noping. An additional bug has been
+
When an option is given for more
+than one interface in /etc/shorewall/interfaces then
+depending on the option, Shorewall may ignore all but
+the first appearence of the option. For example:
+
+ net eth0 dhcp
+ loc eth1 dhcp
+
+ Shorewall will ignore the 'dhcp' on eth1.
+
Update 17 June 2002 - The bug described
+ in the prior bullet affects the following options:
+dhcp, dropunclean, logunclean, norfc1918, routefilter,
+multi, filterping and noping. An additional bug has been
found that affects only the 'routestopped' option.
-
- Users who downloaded the corrected script
- prior to 1850 GMT today should download and install
- the corrected script again to ensure that this second
+
+ Users who downloaded the corrected script
+ prior to 1850 GMT today should download and install
+ the corrected script again to ensure that this second
problem is corrected.
-
+
-
+
These problems are corrected in
- this firewall script which should be installed in /etc/shorewall/firewall
+ href="http://www.shorewall.net/pub/shorewall/errata/1.3.1/firewall">
+ this firewall script which should be installed in /etc/shorewall/firewall
as described above.
-
+
Version 1.3.0
-
+
-
Folks who downloaded 1.3.0 from the
- links on the download page before 23:40 GMT, 29 May
- 2002 may have downloaded 1.2.13 rather than 1.3.0.
-The "shorewall version" command will tell you which version
- that you have installed.
-
The documentation NAT.htm file uses
- non-existent wallpaper and bullet graphic files. The
-
- corrected version is here.
-
+
Folks who downloaded 1.3.0 from the
+ links on the download page before 23:40 GMT, 29 May
+ 2002 may have downloaded 1.2.13 rather than 1.3.0.
+The "shorewall version" command will tell you which version
+ that you have installed.
+
The documentation NAT.htm file uses
+ non-existent wallpaper and bullet graphic files. The
+
+ corrected version is here.
There are a couple of serious bugs in iptables 1.2.3 that
- prevent it from working with Shorewall. Regrettably, RedHat
- released this buggy iptables in RedHat 7.2.
-
-
+
+
+
There are a couple of serious bugs in iptables 1.2.3 that
+ prevent it from working with Shorewall. Regrettably,
+RedHat released this buggy iptables in RedHat 7.2.
+
I have built a
- corrected 1.2.3 rpm which you can download here and I have
+ href="ftp://ftp.shorewall.net/pub/shorewall/errata/iptables-1.2.3-3.i386.rpm">
+ corrected 1.2.3 rpm which you can download here and I have
also built an
-iptables-1.2.4 rpm which you can download here. If you are currently
- running RedHat 7.1, you can install either of these RPMs
- beforeyou upgrade to RedHat 7.2.
-
-
-
Update 11/9/2001: RedHat
- has released an iptables-1.2.4 RPM of their own which you can
+ href="ftp://ftp.shorewall.net/pub/shorewall/iptables-1.2.4-1.i386.rpm"> iptables-1.2.4
+ rpm which you can download here. If you are currently running
+RedHat 7.1, you can install either of these RPMs before
+ you upgrade to RedHat 7.2.
+
+
Update 11/9/2001: RedHat
+ has released an iptables-1.2.4 RPM of their own which you can
download from http://www.redhat.com/support/errata/RHSA-2001-144.html.
- I have installed this RPM on my firewall and it works
+ href="http://www.redhat.com/support/errata/RHSA-2001-144.html">http://www.redhat.com/support/errata/RHSA-2001-144.html.
+
I have installed this RPM on my firewall and it works
fine.
-
-
-
If you would like to patch iptables 1.2.3 yourself,
+
+
If you would like to patch iptables 1.2.3 yourself,
the patches are available for download. This patch
- which corrects a problem with parsing of the --log-level specification
+ href="ftp://ftp.shorewall.net/pub/shorewall/errata/iptables-1.2.3/loglevel.patch">patch
+ which corrects a problem with parsing of the --log-level specification
while this patch
+ href="ftp://ftp.shorewall.net/pub/shorewall/errata/iptables-1.2.3/tos.patch">patch
corrects a problem in handling the TOS target.
-
-
+
To install one of the above patches:
-
-
+
-
cd iptables-1.2.3/extensions
-
patch -p0 < the-patch-file
-
-
+
cd iptables-1.2.3/extensions
+
patch -p0 < the-patch-file
+
-
-
-
-
Problems with kernels >= 2.4.18
- and RedHat iptables
-
-
-
-
Users who use RedHat iptables RPMs and who upgrade to kernel 2.4.18/19
+
+
+
Problems with kernels >= 2.4.18
+ and RedHat iptables
+
+
+
Users who use RedHat iptables RPMs and who upgrade to kernel 2.4.18/19
may experience the following:
The RedHat iptables RPM is compiled with debugging enabled but the
- user-space debugging code was not updated to reflect recent changes in
- the Netfilter 'mangle' table. You can correct the problem
-by installing
- this iptables RPM. If you are already running a 1.2.5 version
- of iptables, you will need to specify the --oldpackage option
+
+
+
The RedHat iptables RPM is compiled with debugging enabled but the
+ user-space debugging code was not updated to reflect recent changes in
+ the Netfilter 'mangle' table. You can correct the problem by
+ installing
+ this iptables RPM. If you are already running a 1.2.5 version
+ of iptables, you will need to specify the --oldpackage option
to rpm (e.g., "iptables -Uvh --oldpackage iptables-1.2.5-1.i386.rpm").
-
-
-
-
Problems installing/upgrading
+
+
+
Problems installing/upgrading
RPM on SuSE
-
-
-
If you find that rpm complains about a conflict
- with kernel <= 2.2 yet you have a 2.4 kernel
- installed, simply use the "--nodeps" option to
- rpm.
-
-
+
+
If you find that rpm complains about a conflict with kernel <=
+2.2 yet you have a 2.4 kernel installed, simply use the "--nodeps"
+option to rpm.
+
Installing: rpm -ivh --nodeps <shorewall rpm>
-
-
+
Upgrading: rpm -Uvh --nodeps <shorewall rpm>
-
-
-
Problems with
- iptables version 1.2.7 and MULTIPORT=Yes
-
-
-
The iptables 1.2.7 release of iptables has made
- an incompatible change to the syntax used to
- specify multiport match rules; as a consequence,
- if you install iptables 1.2.7 you must be running
- Shorewall 1.3.7a or later or:
-
-
+
+
Problems with iptables version 1.2.7 and
+MULTIPORT=Yes
+
+
The iptables 1.2.7 release of iptables has made an incompatible
+change to the syntax used to specify multiport match rules; as
+a consequence, if you install iptables 1.2.7 you must
+be running Shorewall 1.3.7a or later or:
+
-
set MULTIPORT=No
+
set MULTIPORT=No
in /etc/shorewall/shorewall.conf; or
-
if you are running
- Shorewall 1.3.6 you may install
+
if you are running
+ Shorewall 1.3.6 you may install
- this firewall script in /var/lib/shorewall/firewall
+ href="http://www.shorewall.net/pub/shorewall/errata/1.3.6/firewall">
+ this firewall script in /var/lib/shorewall/firewall
as described above.
-
+
-
+
Problems with RH Kernel 2.4.18-10 and NAT
-
- /etc/shorewall/nat entries of the following form will result
- in Shorewall being unable to start:
-
-
+
+ /etc/shorewall/nat entries of the following form will
+result in Shorewall being unable to start:
+
+
#EXTERNAL INTERFACE INTERNAL ALL INTERFACES LOCAL 192.0.2.22 eth0 192.168.9.22 yes yes #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
- Error message is:
-
+ Error message is:
+
Setting up NAT... iptables: Invalid argument Terminated
- The solution is to put "no" in the LOCAL column. Kernel
-support for LOCAL=yes has never worked properly and 2.4.18-10 has
-disabled it. The 2.4.19 kernel contains corrected support under a new
+ The solution is to put "no" in the LOCAL column. Kernel
+support for LOCAL=yes has never worked properly and 2.4.18-10 has
+disabled it. The 2.4.19 kernel contains corrected support under a new
kernel configuraiton option; see http://www.shorewall.net/Documentation.htm#NAT
-
-
Falling Back to the Previous Version of Shorewall
using the Fallback Script
-
-
If you install Shorewall and discover that
-it doesn't work for you, you can fall back to your previously
-installed version. To do that:
-
+
+
If you install Shorewall and discover that it doesn't work for you, you
+can fall back to your previously installed version. To do that:
+
-
cd to the distribution directory for the version
- of Seattle Firewall that you are
- currently running (NOT the version
- that you want to fall back to).
-
Type "./fallback.sh"
+
cd to the distribution directory for the version of Seattle
+Firewall that you are currently running (NOT the version
+ that you want to fall back to).
+
Type "./fallback.sh"
+
-
-
Warning: The fallback script
-will replace /etc/shorewall/policy, /etc/shorewall/rules, /etc/shorewall/interfaces,
-/etc/shorewall/nat, /etc/shorewall/proxyarp and /etc/shorewall/masq with the version of
-these files from before the current version was installed. Any
-changes to any of these files will be lost.
-
-
Falling Back to the Previous Version of Shorewall using
+
+
Warning: The fallback script will replace /etc/shorewall/policy,
+/etc/shorewall/rules, /etc/shorewall/interfaces, /etc/shorewall/nat, /etc/shorewall/proxyarp
+and /etc/shorewall/masq with the version of these files from before the current
+version was installed. Any changes to any of these files will be lost.
+
+
Falling Back to the Previous Version of Shorewall using
rpm
-
-
If your previous version of Shorewall was
-installed using RPM, you may fall back to that version by typing
-"rpm -Uvh --force <old rpm>" at a root shell
-prompt (Example: "rpm -Uvh --force /downloads/shorewall-3.1=0noarch.rpm" would fall back to the 3.1-0
-version of Shorewall).
-
+
+
If your previous version of Shorewall was installed using RPM, you may
+fall back to that version by typing "rpm -Uvh --force <old rpm>" at
+a root shell prompt (Example: "rpm -Uvh --force /downloads/shorewall-3.1=0noarch.rpm"
+would fall back to the 3.1-0 version of Shorewall).
+
Uninstalling Shorewall
-
-
If you no longer wish to use Shorewall, you
-may remove it by:
-
+
+
If you no longer wish to use Shorewall, you may remove it by:
+
-
cd to the distribution directory for the version
- of Shorewall that you have installed.
-
type "./uninstall.sh"
+
cd to the distribution directory for the version of Shorewall
+that you have installed.
+
type "./uninstall.sh"
+
-
-
If you installed using an rpm, at a root shell prompt
-type "rpm -e shorewall".
GNU Mailman/Postfix the Easy
+ id="AutoNumber1" bgcolor="#3366ff" height="90">
+
+
+
+
GNU Mailman/Postfix the Easy
Way
-
-
-
-
+
+
+
+
-
+
-
-
The following was posted on the Postfix mailing list on 5/4/2002 by Michael
+
+
The following was posted on the Postfix mailing list on 5/4/2002 by Michael
Tokarev as a suggested addition to the Postfix FAQ.
-
+
Q: Mailman does not work with Postfix, complaining about GID mismatch
-
- A: Mailman uses a setgid wrapper that is designed to be used in system-wide
- aliases file so that rest of mailman's mail handling processes will run
-with proper uid/gid. Postfix has an ability to run a command specified in
-an alias as owner of that alias, thus mailman's wrapper is not needed here.
- The best method to invoke mailman's mail handling via aliases is to use
-separate alias file especially for mailman, and made it owned by mailman
+
+ A: Mailman uses a setgid wrapper that is designed to be used in system-wide
+ aliases file so that rest of mailman's mail handling processes will run
+with proper uid/gid. Postfix has an ability to run a command specified in
+an alias as owner of that alias, thus mailman's wrapper is not needed here.
+ The best method to invoke mailman's mail handling via aliases is to use
+separate alias file especially for mailman, and made it owned by mailman
and group mailman. Like:
-
- alias_maps = hash:/etc/postfix/aliases, hash:/var/mailman/aliases
-
- Make sure that /var/mailman/aliases.db is owned by mailman user (this
+
+ alias_maps = hash:/etc/postfix/aliases, hash:/var/mailman/aliases
+
+ Make sure that /var/mailman/aliases.db is owned by mailman user (this
may be done by executing postalias as mailman userid).
-
- Next, instead of using mailman-suggested aliases entries with wrapper,
+
+ Next, instead of using mailman-suggested aliases entries with wrapper,
use the following:
-
- instead of
- mailinglist: /var/mailman/mail/wrapper post mailinglist
- mailinglist-admin: /var/mailman/mail/wrapper mailowner mailinglist
- mailinglist-request: /var/mailman/mail/wrapper mailcmd mailinglist
- ...
-
- use
- mailinglist: /var/mailman/scripts/post mailinglist
- mailinglist-admin: /var/mailman/scripts/mailowner mailinglist
- mailinglist-request: /var/mailman/scripts/mailcmd mailinglist
- ...
-
-
The above tip works with Mailman 2.0; Mailman 2.1 has adopted something
-very similar so that no workaround is necessary. See the README.POSTFIX file
+
+ instead of
+ mailinglist: /var/mailman/mail/wrapper post mailinglist
+ mailinglist-admin: /var/mailman/mail/wrapper mailowner mailinglist
+ mailinglist-request: /var/mailman/mail/wrapper mailcmd mailinglist
+ ...
+
+ use
+ mailinglist: /var/mailman/scripts/post mailinglist
+ mailinglist-admin: /var/mailman/scripts/mailowner mailinglist
+ mailinglist-request: /var/mailman/scripts/mailcmd mailinglist
+ ...
+
+
The above tip works with Mailman 2.0; Mailman 2.1 has adopted something
+very similar so that no workaround is necessary. See the README.POSTFIX file
included with Mailman-2.1.
Here's a screen shot of my Network Options Configuration:
-
-
-
-
While not all of the options that I've selected are required, they should be
-sufficient for most applications. Here's an excerpt from the corresponding .config
-file (Note: If you are running a kernel older than 2.4.17, be sure to select
-CONFIG_NETLINK and CONFIG_RTNETLINK):
-
-
-
+
+
+
+
+
+
+
While not all of the options that I've selected are required, they should
+be sufficient for most applications. Here's an excerpt from the corresponding
+.config file (Note: If you are running a kernel older than 2.4.17, be sure
+to select CONFIG_NETLINK and CONFIG_RTNETLINK):
+
+
#
- # Networking options
- #
- CONFIG_PACKET=y
- # CONFIG_PACKET_MMAP is not set
- # CONFIG_NETLINK_DEV is not set
- CONFIG_NETFILTER=y
- CONFIG_NETFILTER_DEBUG=y
- CONFIG_FILTER=y
- CONFIG_UNIX=y
- CONFIG_INET=y
- CONFIG_IP_MULTICAST=y
- CONFIG_IP_ADVANCED_ROUTER=y
- CONFIG_IP_MULTIPLE_TABLES=y
- CONFIG_IP_ROUTE_FWMARK=y
- CONFIG_IP_ROUTE_NAT=y
- CONFIG_IP_ROUTE_MULTIPATH=y
- CONFIG_IP_ROUTE_TOS=y
- CONFIG_IP_ROUTE_VERBOSE=y
- # CONFIG_IP_ROUTE_LARGE_TABLES is not set
- # CONFIG_IP_PNP is not set
- CONFIG_NET_IPIP=m
- CONFIG_NET_IPGRE=m
- # CONFIG_NET_IPGRE_GROADCAST is not set
- # CONFIG_IP_MROUTE is not set
- # CONFIG_ARPD is not set
- CONFIG_INET_ECN=y
- CONFIG_SYN_COOKIES=y
-
-
-
+ # Networking options
+ #
+ CONFIG_PACKET=y
+ # CONFIG_PACKET_MMAP is not set
+ # CONFIG_NETLINK_DEV is not set
+ CONFIG_NETFILTER=y
+ CONFIG_NETFILTER_DEBUG=y
+ CONFIG_FILTER=y
+ CONFIG_UNIX=y
+ CONFIG_INET=y
+ CONFIG_IP_MULTICAST=y
+ CONFIG_IP_ADVANCED_ROUTER=y
+ CONFIG_IP_MULTIPLE_TABLES=y
+ CONFIG_IP_ROUTE_FWMARK=y
+ CONFIG_IP_ROUTE_NAT=y
+ CONFIG_IP_ROUTE_MULTIPATH=y
+ CONFIG_IP_ROUTE_TOS=y
+ CONFIG_IP_ROUTE_VERBOSE=y
+ # CONFIG_IP_ROUTE_LARGE_TABLES is not set
+ # CONFIG_IP_PNP is not set
+ CONFIG_NET_IPIP=m
+ CONFIG_NET_IPGRE=m
+ # CONFIG_NET_IPGRE_GROADCAST is not set
+ # CONFIG_IP_MROUTE is not set
+ # CONFIG_ARPD is not set
+ CONFIG_INET_ECN=y
+ CONFIG_SYN_COOKIES=y
+
+
Here's a screen shot of my Netfilter configuration:
-
-
-
-
-
+
+
+
+
+
+
Here's an excerpt from the corresponding .config file.
-
+
+
#
- # IP: Netfilter Configuration
- #
- CONFIG_IP_NF_CONNTRACK=y
- CONFIG_IP_NF_FTP=m
- # CONFIG_IP_NF_QUEUE is not set
- CONFIG_IP_NF_IPTABLES=y
- CONFIG_IP_NF_MATCH_LIMIT=y
- CONFIG_IP_NF_MATCH_MAC=y
- CONFIG_IP_NF_MATCH_MARK=y
- CONFIG_IP_NF_MATCH_MULTIPORT=y
- CONFIG_IP_NF_MATCH_TOS=y
- # CONFIG_IP_NF_MATCH_TCPMSS is not set
- CONFIG_IP_NF_MATCH_STATE=y
- # CONFIG_IP_NF_MATCH_UNCLEAN is not set
- # CONFIG_IP_NF_MATCH_OWNER is not set
- CONFIG_IP_NF_FILTER=y
- CONFIG_IP_NF_TARGET_REJECT=y
- # CONFIG_IP_NF_TARGET_MIRROR is not set
- CONFIG_IP_NF_NAT=y
- CONFIG_IP_NF_NAT_NEEDED=y
- CONFIG_IP_NF_TARGET_MASQUERADE=y
- CONFIG_IP_NF_TARGET_REDIRECT=y
- CONFIG_IP_NF_NAT_FTP=m
- CONFIG_IP_NF_MANGLE=y
- CONFIG_IP_NF_TARGET_TOS=y
- CONFIG_IP_NF_TARGET_MARK=y
- CONFIG_IP_NF_TARGET_LOG=y
- CONFIG_IP_NF_TARGET_TCPMSS=y
- # CONFIG_IPV6 is not set
-
-
-
Note that I have built everything I need into the kernel except for the FTP
-connection tracking and NAT modules. I have also run successfully with all of
-the options selected above built as modules:
-
-
-
-
+ # IP: Netfilter Configuration
+ #
+ CONFIG_IP_NF_CONNTRACK=y
+ CONFIG_IP_NF_FTP=m
+ # CONFIG_IP_NF_QUEUE is not set
+ CONFIG_IP_NF_IPTABLES=y
+ CONFIG_IP_NF_MATCH_LIMIT=y
+ CONFIG_IP_NF_MATCH_MAC=y
+ CONFIG_IP_NF_MATCH_MARK=y
+ CONFIG_IP_NF_MATCH_MULTIPORT=y
+ CONFIG_IP_NF_MATCH_TOS=y
+ # CONFIG_IP_NF_MATCH_TCPMSS is not set
+ CONFIG_IP_NF_MATCH_STATE=y
+ # CONFIG_IP_NF_MATCH_UNCLEAN is not set
+ # CONFIG_IP_NF_MATCH_OWNER is not set
+ CONFIG_IP_NF_FILTER=y
+ CONFIG_IP_NF_TARGET_REJECT=y
+ # CONFIG_IP_NF_TARGET_MIRROR is not set
+ CONFIG_IP_NF_NAT=y
+ CONFIG_IP_NF_NAT_NEEDED=y
+ CONFIG_IP_NF_TARGET_MASQUERADE=y
+ CONFIG_IP_NF_TARGET_REDIRECT=y
+ CONFIG_IP_NF_NAT_FTP=m
+ CONFIG_IP_NF_MANGLE=y
+ CONFIG_IP_NF_TARGET_TOS=y
+ CONFIG_IP_NF_TARGET_MARK=y
+ CONFIG_IP_NF_TARGET_LOG=y
+ CONFIG_IP_NF_TARGET_TCPMSS=y
+ # CONFIG_IPV6 is not set
+
+
+
+
Note that I have built everything I need into the kernel except for the
+FTP connection tracking and NAT modules. I have also run successfully with
+all of the options selected above built as modules:
+
+
+
+
+
#
- # IP: Netfilter Configuration
- #
- CONFIG_IP_NF_CONNTRACK=m
- CONFIG_IP_NF_FTP=m
- # CONFIG_IP_NF_QUEUE is not set
- CONFIG_IP_NF_IPTABLES=m
- CONFIG_IP_NF_MATCH_LIMIT=m
- CONFIG_IP_NF_MATCH_MAC=m
- CONFIG_IP_NF_MATCH_MARK=m
- CONFIG_IP_NF_MATCH_MULTIPORT=m
- CONFIG_IP_NF_MATCH_TOS=m
- # CONFIG_IP_NF_MATCH_TCPMSS is not set
- CONFIG_IP_NF_MATCH_STATE=m
- # CONFIG_IP_NF_MATCH_UNCLEAN is not set
- # CONFIG_IP_NF_MATCH_OWNER is not set
- CONFIG_IP_NF_FILTER=m
- CONFIG_IP_NF_TARGET_REJECT=m
- # CONFIG_IP_NF_TARGET_MIRROR is not set
- CONFIG_IP_NF_NAT=m
- CONFIG_IP_NF_NAT_NEEDED=m
- CONFIG_IP_NF_TARGET_MASQUERADE=m
- CONFIG_IP_NF_TARGET_REDIRECT=m
- CONFIG_IP_NF_NAT_FTP=m
- CONFIG_IP_NF_MANGLE=m
- CONFIG_IP_NF_TARGET_TOS=m
- CONFIG_IP_NF_TARGET_MARK=m
- CONFIG_IP_NF_TARGET_LOG=m
- CONFIG_IP_NF_TARGET_TCPMSS=m
- # CONFIG_IPV6 is not set
-
to ensure that the sender address is fully
- qualified.
-
to verify that the sender's domain has an
- A or MX record in DNS.
-
to ensure that the host name in the HELO/EHLO
+
+
to ensure that the sender address is fully
+ qualified.
+
to verify that the sender's domain has
+an A or MX record in DNS.
+
to ensure that the host name in the HELO/EHLO
command is a valid fully-qualified DNS name that resolves.
-
+
-
+
Please post in plain text
- A growing number of MTAs serving list subscribers are
- rejecting all HTML traffic. At least one MTA has gone so far as
-to blacklist shorewall.net "for continuous abuse" because it has been
+ A growing number of MTAs serving list subscribers are
+ rejecting all HTML traffic. At least one MTA has gone so far as to
+ blacklist shorewall.net "for continuous abuse" because it has been
my policy to allow HTML in list posts!!
-
- I think that blocking all HTML is a Draconian way to
-control spam and that the ultimate losers here are not the spammers
-but the list subscribers whose MTAs are bouncing all shorewall.net
-mail. As one list subscriber wrote to me privately "These e-mail admin's
-need to get a (explitive deleted) life instead of trying to rid
-the planet of HTML based e-mail". Nevertheless, to allow subscribers to
-receive list posts as must as possible, I have now configured the list
-server at shorewall.net to strip all HTML from outgoing posts. This
-means that HTML-only posts will be bounced by the list server.
-
+
+ I think that blocking all HTML is a Draconian way to
+ control spam and that the ultimate losers here are not the spammers
+ but the list subscribers whose MTAs are bouncing all shorewall.net
+ mail. As one list subscriber wrote to me privately "These e-mail admin's
+ need to get a (explitive deleted) life instead of trying to rid
+ the planet of HTML based e-mail". Nevertheless, to allow subscribers
+to receive list posts as must as possible, I have now configured the
+list server at shorewall.net to strip all HTML from outgoing posts.
+This means that HTML-only posts will be bounced by the list server.
+
Note: The list server limits posts to 120kb.
-
-
+
+
Other Mail Delivery Problems
- If you find that you are missing an occasional list post,
- your e-mail admin may be blocking mail whose Received: headers
- contain the names of certain ISPs. Again, I believe that such policies
- hurt more than they help but I'm not prepared to go so far as to start
+ If you find that you are missing an occasional list post,
+ your e-mail admin may be blocking mail whose Received: headers
+ contain the names of certain ISPs. Again, I believe that such policies
+ hurt more than they help but I'm not prepared to go so far as to start
stripping Received: headers to circumvent those policies.
-
+
Mailing Lists Archive Search
-
-
+
+
Please do not try to download the entire
+Archive -- it is 75MB (and growing daily) and my slow DSL line simply won't
+stand the traffic. If I catch you, you will be blacklisted.
+
+
Shorewall CA Certificate
- If you want to trust X.509 certificates issued
- by Shoreline Firewall (such as the one used on my web site), you
- may download and install my CA certificate
- in your browser. If you don't wish to trust my certificates
-then you can either use unencrypted access when subscribing to Shorewall
- mailing lists or you can use secure access (SSL) and accept the
-server's certificate when prompted by your browser.
-
+ If you want to trust X.509 certificates issued
+ by Shoreline Firewall (such as the one used on my web site),
+you may download and install my CA certificate
+ in your browser. If you don't wish to trust my certificates
+ then you can either use unencrypted access when subscribing to
+Shorewall mailing lists or you can use secure access (SSL) and
+accept the server's certificate when prompted by your browser.
+
Shorewall Users Mailing List
-
-
The Shorewall Users Mailing list provides a way for users
- to get answers to questions and to report problems. Information
- of general interest to the Shorewall user community is also posted
- to this list.
The Shorewall Development Mailing list provides a forum for
- the exchange of ideas about the future of Shorewall and for
- coordinating ongoing Shorewall Development.
-
+
+
The Shorewall Users Mailing list provides a way for users
+ to get answers to questions and to report problems. Information
+ of general interest to the Shorewall user community is also
+posted to this list.
The Shorewall Development Mailing list provides a forum for
+ the exchange of ideas about the future of Shorewall and for
+ coordinating ongoing Shorewall Development.
How to Unsubscribe from one of
- the Mailing Lists
-
-
There seems to be near-universal confusion about unsubscribing
- from Mailman-managed lists although Mailman 2.1 has attempted
- to make this less confusing. To unsubscribe:
-
+
+
How to Unsubscribe from one of
+ the Mailing Lists
+
+
There seems to be near-universal confusion about unsubscribing
+ from Mailman-managed lists although Mailman 2.1 has attempted
+ to make this less confusing. To unsubscribe:
+
-
-
-
Follow the same link above that you used to subscribe
- to the list.
-
-
-
-
Down at the bottom of that page is the following text:
- " To unsubscribe from <list name>, get
- a password reminder, or change your subscription options enter
- your subscription email address:". Enter your email address
- in the box and click on the "Unsubscribe or edit options"
- button.
-
-
-
-
There will now be a box where you can enter your password
- and click on "Unsubscribe"; if you have forgotten your password,
- there is another button that will cause your password to be
-emailed to you.
-
-
+
+
+
Follow the same link above that you used to subscribe
+ to the list.
+
+
+
+
Down at the bottom of that page is the following text:
+ " To unsubscribe from <list name>, get
+ a password reminder, or change your subscription options
+enter your subscription email address:". Enter your email
+ address in the box and click on the "Unsubscribe or edit
+options" button.
+
+
+
+
There will now be a box where you can enter your password
+ and click on "Unsubscribe"; if you have forgotten your password,
+ there is another button that will cause your password to be
+ emailed to you.
+
+
-
-
+
+
Frustrated by having to Rebuild Mailman to use it with Postfix?
Warning 1: I
- use a combination of Static NAT and Proxy ARP, neither of which are
- relevant to a simple configuration with a single public IP address.
- If you have just a single public IP address, most of what you see
-here won't apply to your setup so beware of copying parts of this configuration
- and expecting them to work for you. What you copy may or may not work
+
+
+
Warning 1: I
+ use a combination of Static NAT and Proxy ARP, neither of which are
+ relevant to a simple configuration with a single public IP address.
+ If you have just a single public IP address, most of what you see here
+ won't apply to your setup so beware of copying parts of this configuration
+ and expecting them to work for you. What you copy may or may not work
in your configuration.
-
-
-
Warning 2: The
-configuration shown here corresponds to Snapshot 1.4.5_20030629 plus a couple
+
+
+
Warning 2: The
+configuration shown here corresponds to Snapshot 1.4.5_20030629 plus a couple
of patches.
-
-
-
I have DSL service and have 5 static IP addresses (206.124.146.176-180).
- My DSL "modem" (Fujitsu
-Speedport) is connected to eth0. I have a local network connected
-to eth2 (subnet 192.168.1.0/24), a DMZ connected to eth1 (192.168.2.0/24)
+
+
+
I have DSL service and have 5 static IP addresses (206.124.146.176-180).
+ My DSL "modem" (Fujitsu
+Speedport) is connected to eth0. I have a local network connected
+to eth2 (subnet 192.168.1.0/24), a DMZ connected to eth1 (192.168.2.0/24)
and a Wireless network connected to eth3 (192.168.3.0/24).
-
+
I use:
-
-
+
+
-
Static NAT for Ursa (my XP System) - Internal
+
Static NAT for Ursa (my XP System) - Internal
address 192.168.1.5 and external address 206.124.146.178.
-
Static NAT for Wookie (my Linux System). Internal
+
Static NAT for Wookie (my Linux System). Internal
address 192.168.1.3 and external address 206.124.146.179.
-
Static NAT for EastepLaptop (My work system). Internal address
+
Static NAT for EastepLaptop (My work system). Internal address
192.168.1.7 and external address 206.124.146.180.
-
-
SNAT through the primary gateway address (206.124.146.176)
- for my Wife's system (Tarry) and our laptop (Tipper) which connects
- through the Wireless Access Point (wap) via a Wireless Bridge (bridge).
-
-
- Note: While the distance between the WAP and where I usually
-use the laptop isn't very far (25 feet or so), using a WAC11 (CardBus
-wireless card) has proved very unsatisfactory (lots of lost connections).
-By replacing the WAC11 with the WET11 wireless bridge, I have virtually
-eliminated these problems (Being an old radio tinkerer (K7JPV), I was
-also able to eliminate the disconnects by hanging a piece of aluminum foil
-on the family room wall. Needless to say, my wife Tarry rejected that as
-a permanent solution :-).
-
+
+
SNAT through the primary gateway address (206.124.146.176)
+ for my Wife's system (Tarry) and our laptop (Tipper) which connects
+ through the Wireless Access Point (wap) via a Wireless Bridge (bridge).
+
+
+ Note: While the distance between the WAP and where I usually
+use the laptop isn't very far (25 feet or so), using a WAC11 (CardBus
+wireless card) has proved very unsatisfactory (lots of lost connections).
+By replacing the WAC11 with the WET11 wireless bridge, I have virtually
+eliminated these problems (Being an old radio tinkerer (K7JPV), I was also
+able to eliminate the disconnects by hanging a piece of aluminum foil on
+the family room wall. Needless to say, my wife Tarry rejected that as a
+permanent solution :-).
+
-
+
The firewall runs on a 256MB PII/233 with RH9.0.
-
-
Wookie and the Firewall both run Samba and the Firewall acts as a
-WINS server.
-
-
-
Wookie is in its own 'whitelist' zone called 'me' which is
-embedded in the local zone.
-
-
The wireless network connects to eth3 via a LinkSys WAP11. In additional
- to using the rather weak WEP 40-bit encryption (64-bit with the 24-bit
-prefix), I use MAC verification. This
-is still a weak combination and if I lived near a wireless "hot spot", I
+
+
Wookie and the Firewall both run Samba and the Firewall acts as a WINS
+server.
+
+
+
Wookie is in its own 'whitelist' zone called 'me' which is embedded
+in the local zone.
+
+
The wireless network connects to eth3 via a LinkSys WAP11. In additional
+ to using the rather weak WEP 40-bit encryption (64-bit with the 24-bit
+prefix), I use MAC verification. This
+is still a weak combination and if I lived near a wireless "hot spot", I
would probably add IPSEC or something similar to my WiFi->local connections.
-
-
-
The single system in the DMZ (address 206.124.146.177) runs postfix,
- Courier IMAP (imaps and pop3), DNS, a Web server (Apache) and
-an FTP server (Pure-ftpd). The system also runs fetchmail to fetch
-our email from our old and current ISPs. That server is managed through
+
+
+
The single system in the DMZ (address 206.124.146.177) runs postfix,
+ Courier IMAP (imaps and pop3), DNS, a Web server (Apache) and an
+ FTP server (Pure-ftpd). The system also runs fetchmail to fetch
+our email from our old and current ISPs. That server is managed through
Proxy ARP.
-
-
The firewall system itself runs a DHCP server that serves the local
- network. It also runs Postfix which is configured as a Virus
-and Spam filter with all incoming mail then being forwarded to the MTA
-in the DMZ.
-
-
All administration and publishing is done using ssh/scp. I have X installed
- on the firewall but no X server or desktop is installed. X applications
- tunnel through SSH to XWin.exe running on Ursa. The server does have a desktop
- environment installed and that desktop environment is available via XDMCP
- from the local zone. For the most part though, X tunneled through SSH is
-used for server administration and the server runs at run level 3 (multi-user
-console mode on RedHat).
-
+
+
The firewall system itself runs a DHCP server that serves the local
+ network. It also runs Postfix which is configured as a Virus and
+ Spam filter with all incoming mail then being forwarded to the MTA in
+the DMZ.
+
+
All administration and publishing is done using ssh/scp. I have X installed
+ on the firewall but no X server or desktop is installed. X applications
+ tunnel through SSH to XWin.exe running on Ursa. The server does have a
+desktop environment installed and that desktop environment is available
+via XDMCP from the local zone. For the most part though, X tunneled through
+SSH is used for server administration and the server runs at run level 3
+(multi-user console mode on RedHat).
+
I run an SNMP server on my firewall to serve MRTG running
+ href="http://www.ee.ethz.ch/%7Eoetiker/webtools/mrtg/"> MRTG running
in the DMZ.
-
+
-
-
+
+
-
-
The ethernet interface in the Server is configured with IP address
- 206.124.146.177, netmask 255.255.255.0. The server's default gateway
- is 206.124.146.254 (Router at my ISP. This is the same default
- gateway used by the firewall itself). On the firewall,
- Shorewall automatically adds a host route to
- 206.124.146.177 through eth1 (192.168.2.1) because of
- the entry in /etc/shorewall/proxyarp (see below).
-
-
Ursa (192.168.1.5 AKA 206.124.146.178) runs a PPTP server for Road Warrior
+
+
The ethernet interface in the Server is configured with IP address
+ 206.124.146.177, netmask 255.255.255.0. The server's default gateway
+ is 206.124.146.254 (Router at my ISP. This is the same
+default gateway used by the firewall itself). On the firewall,
+ Shorewall automatically adds a host route to
+ 206.124.146.177 through eth1 (192.168.2.1) because
+ of the entry in /etc/shorewall/proxyarp (see
+ below).
+
+
Ursa (192.168.1.5 AKA 206.124.146.178) runs a PPTP server for Road Warrior
access.
-
MIRRORS=<list of shorewall mirror ip addresses> NTPSERVERS=<list of the NTP servers I sync with>
TEXAS=<ip address of gateway in Dallas> LOG=info
-
-
+
+
Zones File
-
-
+
+
#ZONE DISPLAY COMMENTS net Internet Internet WiFi Wireless Wireless Network on eth3 me Wookie My Linux Workstation dmz DMZ Demilitarized zone loc Local Local networks tx Texas Peer Network in Dallas #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
-
-
+
+
Interfaces File:
-
-
-
This is set up so that I can start the firewall before bringing up my
-Ethernet interfaces.
-
-
-
+
+
+
This is set up so that I can start the firewall before bringing up
+my Ethernet interfaces.
+
+
+
#ZONE INERFACE BROADCAST OPTIONS net eth0 206.124.146.255 dhcp,norfc1918,routefilter,blacklist,tcpflags loc eth2 192.168.1.255 dhcp dmz eth1 192.168.2.255 WiFi eth3 192.168.3.255 dhcp,maclist - texas 192.168.9.255 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
-
-
+
+
Hosts File:
-
-
+
+
#ZONE HOST(S) OPTIONS me eth2:192.168.1.3 tx texas:192.168.8.0/22 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
-
-
+
+
Routestopped File:
-
-
+
+
#INTERFACQ HOST(S) eth1 206.124.146.177 eth2 - eth3 192.168.3.8 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
-
-
+
+
Policy File:
-
-
+
+
#SOURCE DESTINATION POLICY LOG LEVEL BURST:LIMIT me loc NONE me all ACCEPT tx me ACCEPT WiFi loc ACCEPT loc WiFi ACCEPT loc me NONE all me CONTINUE - 2/sec:5 loc net ACCEPT $FW loc ACCEPT $FW tx ACCEPT loc tx ACCEPT loc fw REJECT $LOG WiFi net ACCEPT net all DROP $LOG 10/sec:40 all all REJECT $LOG #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
-
-
+
+
Masq File:
-
-
-
Although most of our internal systems use static NAT, my wife's system
- (192.168.1.4) uses IP Masquerading (actually SNAT) as do visitors
- with laptops. Also, I masquerade systems connected through the wireless
- network.
-
-
-
+
+
+
Although most of our internal systems use static NAT, my wife's system
+ (192.168.1.4) uses IP Masquerading (actually SNAT) as do visitors
+ with laptops. Also, I masquerade systems connected through the wireless
+ network.
+
+
+
#INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 eth0 eth3 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
-
-
+
+
NAT File:
-
-
+
+
#EXTERNAL INTERFACE INTERNAL ALL INTERFACES LOCAL 206.124.146.178 eth0:0 192.168.1.5 No No 206.124.146.179 eth0:1 192.168.1.3 No No 206.124.146.180 eth0:2 192.168.1.7 No No 192.168.1.193 eth2:0 206.124.146.177 No No #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE\
-
-
+
+
Proxy ARP File:
-
-
+
+
#ADDRESS INTERFACE EXTERNAL HAVEROUTE 206.124.146.177 eth1 eth0 No #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
-
-
+
+
Tunnels File (Shell variable TEXAS set in /etc/shorewall/params):
-
-
+
+
#TYPE ZONE GATEWAY GATEWAY ZONE PORT gre net $TEXAS #LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
-
-
+
+
-
+
Rules File (The shell variables are set in /etc/shorewall/params):
-
-
+
+
################################################################################################################################################################ #RESULT CLIENT(S) SERVER(S) PROTO PORT(S) CLIENT ORIGINAL DEST:SNAT ################################################################################################################################################################ # Local Network to Internet - Reject attempts by Trojans to call home # REJECT:$LOG loc net tcp 6667 # # Stop NETBIOS crap since our policy is ACCEPT # REJECT loc net tcp 137,445 REJECT loc net udp 137:139 ################################################################################################################################################################ # Local Network to Firewall # DROP loc:!192.168.1.0/24 fw ACCEPT loc fw tcp ssh,time,10000,smtp,swat,137,139,445 ACCEPT loc fw udp snmp,ntp,445 ACCEPT loc fw udp 137:139 ACCEPT loc fw udp 1024: 137 ################################################################################################################################################################ # Local Network to DMZ # ACCEPT loc dmz udp domain,xdmcp ACCEPT loc dmz tcp www,smtp,domain,ssh,imap,https,imaps,cvspserver,ftp,10000,8080,pop3 - ################################################################################################################################################################ # Internet to DMZ # ACCEPT net dmz tcp www,ftp,imaps,domain,cvspserver,https - ACCEPT net dmz udp domain ACCEPT net:$MIRRORS dmz tcp rsync ACCEPT:$LOG net dmz tcp 32768:61000 20 DROP net dmz tcp 1433 ################################################################################################################################################################ # # Net to Local # # When I'm "on the road", the following two rules allow me VPN access back home. # ACCEPT net loc:192.168.1.5 tcp 1723 ACCEPT net loc:192.168.1.5 gre # # ICQ # ACCEPT net loc:192.168.1.5 tcp 4000:4100 # # Real Audio # ACCEPT net loc:192.168.1.5 udp 6790 ################################################################################################################################################################ # Net to me # ACCEPT net loc:192.168.1.3 tcp 4000:4100 ################################################################################################################################################################ # DMZ to Internet # ACCEPT dmz net tcp smtp,domain,www,https,whois,echo,2702,21,2703,ssh ACCEPT dmz net udp domain #ACCEPT dmz net:$POPSERVERS tcp pop3 #ACCEPT dmz net:206.191.151.2 tcp pop3 #ACCEPT dmz net:66.216.26.115 tcp pop3 # # Something is wrong with the FTP connection tracking code or there is some client out there # that is sending a PORT command which that code doesn't understand. Either way, # the following works around the problem. # ACCEPT:$LOG dmz net tcp 1024: 20 ################################################################################################################################################################ # DMZ to Firewall -- ntp & snmp, Silently reject Auth # ACCEPT dmz fw udp ntp ntp ACCEPT dmz fw tcp snmp,ssh ACCEPT dmz fw udp snmp REJECT dmz fw tcp auth ################################################################################################################################################################ # # DMZ to Local Network # ACCEPT dmz loc tcp smtp,6001:6010 ################################################################################################################################################################ # # DMZ to Me -- NFS # ACCEPT dmz me tcp 111 ACCEPT dmz me udp 111 ACCEPT dmz me udp 2049 ACCEPT dmz me udp 32700: ################################################################################################################################################################ # Internet to Firewall # REDIRECT- net 25 tcp smtp - 206.124.146.177 ACCEPT net fw tcp smtp REJECT net fw tcp www DROP net fw tcp 1433 ################################################################################################################################################################ # WiFi to Firewall (SMB and NTP) # ACCEPT WiFi fw tcp ssh,137,139,445 ACCEPT WiFi fw udp 137:139,445 ACCEPT WiFi fw udp 1024: 137 ACCEPT WiFi fw udp ntp ntp ################################################################################################################################################################ # Firewall to WiFi (SMB) # ACCEPT fw WiFi tcp 137,139,445 ACCEPT fw WiFi udp 137:139,445 ACCEPT fw WiFi udp 1024: 137 ############################################################################################################################################################### # WiFi to DMZ # DNAT- WiFi dmz:206.124.146.177 all - - 192.168.1.193 ACCEPT WiFi dmz tcp smtp,www,ftp,imaps,domain,https,ssh - ACCEPT WiFi dmz udp domain ################################################################################################################################################################ # Firewall to Internet # ACCEPT fw net:$NTPSERVERS udp ntp ntp ACCEPT fw net:$POPSERVERS tcp pop3 ACCEPT fw net udp domain ACCEPT fw net tcp domain,www,https,ssh,1723,whois,1863,smtp,ftp,2702,2703,7 ACCEPT fw net udp 33435:33535 ACCEPT fw net icmp 8 ################################################################################################################################################################ # Firewall to DMZ # ACCEPT fw dmz tcp www,ftp,ssh,smtp ACCEPT fw dmz udp domain ACCEPT fw dmz icmp 8 REJECT fw dmz udp 137:139
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
-
- Shorewall 'Ping' management has evolved over time with the latest change
- coming in Shorewall version 1.4.0. To find out which version of Shorewall
-you are running, at a shell prompt type "/sbin/shorewall
-version". If that command gives you an error, it's time to upgrade
+
+ Shorewall 'Ping' management has evolved over time with the latest
+change coming in Shorewall version 1.4.0. To find out which version of
+Shorewall you are running, at a shell prompt type "/sbin/shorewall
+version". If that command gives you an error, it's time to upgrade
since you have a very old version of Shorewall installed (1.2.4 or earlier).
-
+
Shorewall Versions >= 1.4.0
- In Shoreall 1.4.0 and later version, ICMP echo-request's are treated just
-like any other connection request.
-
- In order to accept ping requests from zone z1 to zone z2 where the policy
- for z1 to z2 is not ACCEPT, you need a rule in /etc/shoreall/rules of the
+ In Shoreall 1.4.0 and later version, ICMP echo-request's are treated just
+ like any other connection request.
+
+ In order to accept ping requests from zone z1 to zone z2 where the policy
+ for z1 to z2 is not ACCEPT, you need a rule in /etc/shoreall/rules of the
form:
-
-
ACCEPT z1 z2
+
+
ACCEPT z1 z2
icmp 8
-
- Example:
-
- To permit ping from the local zone to the firewall:
-
-
ACCEPT loc fw
+
+ Example:
+
+ To permit ping from the local zone to the firewall:
+
+
ACCEPT loc fw
icmp 8
-
- If you would like to accept 'ping' by default even when the relevant
- policy is DROP or REJECT, create /etc/shorewall/icmpdef if it doesn't
+
+ If you would like to accept 'ping' by default even when the relevant
+ policy is DROP or REJECT, create /etc/shorewall/icmpdef if it doesn't
already exist and in that file place the following command:
-
-
+
+
run_iptables -A icmpdef -p icmp --icmp-type 8 -j ACCEPT
-
- With that rule in place, if you want to ignore 'ping' from z1 to z2
+
+ With that rule in place, if you want to ignore 'ping' from z1 to z2
then you need a rule of the form:
-
-
DROP z1 z2
+
+
DROP z1 z2
icmp 8
-
- Example:
-
- To drop ping from the internet, you would need this rule in /etc/shorewall/rules:
-
-
-
DROP net fw
+
+ Example:
+
+ To drop ping from the internet, you would need this rule in /etc/shorewall/rules:
+
+
+
DROP net fw
icmp 8
-
-
-
Shorewall Versions >= 1.3.14 and < 1.4.0 with OLD_PING_HANDLING=No
-in /etc/shorewall/shorewall.conf
- In 1.3.14, Ping handling was put under control of the rules and policies
- just like any other connection request. In order to accept ping requests
- from zone z1 to zone z2 where the policy for z1 to z2 is not ACCEPT, you
-need a rule in /etc/shoreall/rules of the form:
-
-
ACCEPT z1 z2
+
+
+
Shorewall Versions >= 1.3.14 and < 1.4.0 with OLD_PING_HANDLING=No
+ in /etc/shorewall/shorewall.conf
+ In 1.3.14, Ping handling was put under control of the rules and policies
+ just like any other connection request. In order to accept ping requests
+ from zone z1 to zone z2 where the policy for z1 to z2 is not ACCEPT, you
+ need a rule in /etc/shoreall/rules of the form:
+
+
ACCEPT z1 z2
icmp 8
-
- Example:
-
- To permit ping from the local zone to the firewall:
-
-
ACCEPT loc fw
+
+ Example:
+
+ To permit ping from the local zone to the firewall:
+
+
ACCEPT loc fw
icmp 8
-
- If you would like to accept 'ping' by default even when the relevant
- policy is DROP or REJECT, create /etc/shorewall/icmpdef if it doesn't
+
+ If you would like to accept 'ping' by default even when the relevant
+ policy is DROP or REJECT, create /etc/shorewall/icmpdef if it doesn't
already exist and in that file place the following command:
-
-
+
+
run_iptables -A icmpdef -p icmp --icmp-type 8 -j ACCEPT
-
- With that rule in place, if you want to ignore 'ping' from z1 to z2
+
+ With that rule in place, if you want to ignore 'ping' from z1 to z2
then you need a rule of the form:
-
-
DROP z1 z2
+
+
DROP z1 z2
icmp 8
-
- Example:
-
- To drop ping from the internet, you would need this rule in /etc/shorewall/rules:
-
-
DROP net fw
+
+ Example:
+
+ To drop ping from the internet, you would need this rule in /etc/shorewall/rules:
+
+
DROP net fw
icmp 8
-
-
+
+
-
+
Shorewall Versions < 1.3.14 or with OLD_PING_HANDLING=Yes in /etc/shorewall/shorewall.conf
-
- There are several aspects to the old Shorewall Ping management:
-
+
+ There are several aspects to the old Shorewall Ping management:
+
-
+
- There are two cases to consider:
-
+ There are two cases to consider:
+
-
Ping requests addressed to the firewall itself; and
-
Ping requests being forwarded to another system. Included here
- are all cases of packet forwarding including NAT, DNAT rule, Proxy ARP
+
Ping requests addressed to the firewall itself; and
+
Ping requests being forwarded to another system. Included here
+ are all cases of packet forwarding including NAT, DNAT rule, Proxy ARP
and simple routing.
-
+
- These cases will be covered separately.
-
+ These cases will be covered separately.
+
Ping Requests Addressed to the Firewall Itself
- For ping requests addressed to the firewall, the sequence is as follows:
-
+ For ping requests addressed to the firewall, the sequence is as follows:
+
-
If neither noping nor filterping are specified
-for the interface that receives the ping request then the request will
+
If neither noping nor filterping are specified
+for the interface that receives the ping request then the request will
be responded to with an ICMP echo-reply.
-
If noping is specified for the interface that receives
-the ping request then the request is ignored.
-
If filterping is specified for the interface then the
+
If noping is specified for the interface that receives
+ the ping request then the request is ignored.
+
If filterping is specified for the interface then the
request is passed to the rules/policy evaluation.
-
+
-
+
Ping Requests Forwarded by the Firewall
- These requests are always passed to rules/policy evaluation.
-
+ These requests are always passed to rules/policy evaluation.
+
Rules Evaluation
- Ping requests are ICMP type 8. So the general rule format is:
-
- Target Source
+ Ping requests are ICMP type 8. So the general rule format is:
+
+ Target Source
Destination icmp 8
-
- Example 1. Accept pings from the net to the dmz (pings are responded
+
+ Example 1. Accept pings from the net to the dmz (pings are responded
to with an ICMP echo-reply):
-
- ACCEPT net dmz
+
+ ACCEPT net
+dmz icmp 8
+
+ Example 2. Drop pings from the net to the firewall
+
+ DROP net fw
icmp 8
-
- Example 2. Drop pings from the net to the firewall
-
- DROP net fw
- icmp 8
-
+
Policy Evaluation
- If no applicable rule is found, then the policy for the source to the
- destination is applied.
-
+ If no applicable rule is found, then the policy for the source to
+the destination is applied.
+
-
If the relevant policy is ACCEPT then the request is responded
+
If the relevant policy is ACCEPT then the request is responded
to with an ICMP echo-reply.
-
If FORWARDPING is set to Yes in /etc/shorewall/shorewall.conf
+
If FORWARDPING is set to Yes in /etc/shorewall/shorewall.conf
then the request is responded to with an ICMP echo-reply.
-
Otherwise, the relevant REJECT or DROP policy is used and the
-request is either rejected or simply ignored.
-
+
Otherwise, the relevant REJECT or DROP policy is used and the
+ request is either rejected or simply ignored.
Ports required for Various
- Services/Applications
-
-
-
-
+ Services/Applications
+
+
+
+
-
+
In addition to those applications described in the /etc/shorewall/rules documentation, here
- are some other services/applications that you may need to configure your
- firewall to accommodate.
-
+ are some other services/applications that you may need to configure your
+ firewall to accommodate.
+
NTP (Network Time Protocol)
-
-
+
+
UDP Port 123
-
-
+
+
rdate
-
-
+
+
TCP Port 37
-
-
+
+
UseNet (NNTP)
-
-
+
+
TCP Port 119
-
-
+
+
DNS
-
-
+
+
UDP Port 53. If you are configuring a DNS client, you will probably want
to open TCP Port 53 as well.
- If you are configuring a server, only open TCP Port 53 if you will
- return long replies to queries or if you need to enable ZONE transfers. In
- the latter case, be sure that your server is properly configured.
-
-
+ If you are configuring a server, only open TCP Port 53 if you
+will return long replies to queries or if you need to enable ZONE transfers. In
+ the latter case, be sure that your server is properly configured.
+
+
ICQ
-
-
+
+
UDP Port 4000. You will also need to open a range of TCP ports which
- you can specify to your ICQ client. By default, clients use 4000-4100.
-
-
+ you can specify to your ICQ client. By default, clients use 4000-4100.
+
For a client, you must open outbound TCP port 21 and be sure that your
- kernel is compiled to support FTP connection tracking. If you build this
- support as a module, Shorewall will automatically load the module from
- /var/lib/<kernel version>/kernel/net/ipv4/netfilter.
-
-
-
If you run an FTP server on a nonstandard port or you need to access
- such a server, then you must specify that port in /etc/shorewall/modules.
- For example, if you run an FTP server that listens on port 49 then you would
- have:
-
-
-
-
loadmodule ip_conntrack_ftp ports=21,49
- loadmodule ip_nat_ftp ports=21,49
+ kernel is compiled to support FTP connection tracking. If you build
+this support as a module, Shorewall will automatically load the module
+from /var/lib/<kernel version>/kernel/net/ipv4/netfilter.
-
-
+
+
If you run an FTP server on a nonstandard port or you need to access
+ such a server, then you must specify that port in /etc/shorewall/modules.
+ For example, if you run an FTP server that listens on port 49 then you
+would have:
+
IMPORTANT: Once you have made these changes to /etc/shorewall/modules
- and/or /etc/modules.conf, you must either:
-
-
-
-
Unload the modules and restart shorewall: (rmmod ip_nat_ftp; rmmod ip_conntrack_ftp; shorewall restart);
- or
-
Reboot
-
-
-
-
-
-
-
-
-
-
SMB/NMB (Samba/Windows Browsing/File Sharing)
-
-
-
-
-
TCP Ports 137, 139 and 445.
- UDP Ports 137-139.
-
- Also, see this page.
-
-
-
Traceroute
-
-
-
UDP ports 33434 through 33434+<max number of hops>-1
-
-
-
NFS
-
-
-
-
I personally use the following rules for opening access from zone z1
- to a server with IP address a.b.c.d in zone z2:
+ and/or /etc/modules.conf, you must either:
-
+
+
+
Unload the modules and restart shorewall: (rmmod ip_nat_ftp; rmmod ip_conntrack_ftp; shorewall restart);
+ or
+
Reboot
+
+
+
+
+
+
+
+
+
+
SMB/NMB (Samba/Windows Browsing/File Sharing)
+
+
+
+
+
TCP Ports 137, 139 and 445.
+ UDP Ports 137-139.
+
+ Also, see this page.
+
+
+
Traceroute
+
+
+
UDP ports 33434 through 33434+<max number of hops>-1
+ICMP type 8 ('ping')
+
+
+
+
NFS
+
+
+
+
I personally use the following rules for opening access from zone z1
+ to a server with IP address a.b.c.d in zone z2:
+
- "I have fought with IPtables for untold hours. First I tried
-the SuSE firewall, which worked for 80% of what I needed. Then gShield, which
-also worked for 80%. Then I set out to write my own IPtables parser in shell
-and awk, which was a lot of fun but never got me past the "hey, cool" stage.
-Then I discovered Shorewall. After about an hour, everything just worked.
-I am stunned, and very grateful" -- ES, Phoenix AZ, USA.
-
"The configuration is intuitive and flexible, and much easier than any
-of the other iptables-based firewall programs out there. After sifting through
-many other scripts, it is obvious that yours is the most well thought-out
-and complete one available." -- BC, USA
+ "I have fought with IPtables for untold hours. First I
+tried the SuSE firewall, which worked for 80% of what I needed. Then gShield,
+which also worked for 80%. Then I set out to write my own IPtables parser
+in shell and awk, which was a lot of fun but never got me past the "hey,
+cool" stage. Then I discovered Shorewall. After about an hour, everything
+just worked. I am stunned, and very grateful" -- ES, Phoenix AZ, USA.
-
"I just installed Shorewall after weeks of messing with ipchains/iptables
- and I had it up and running in under 20 minutes!" -- JL, Ohio
-
- "My case was almost like [the one above]. Well. instead of 'weeks' it
-was 'months' for me, and I think I needed two minutes more:
-
-
-
One to see that I had no Internet access from the firewall itself.
-
Other to see that this was the default configuration, and it was
-enough to uncomment a line in /etc/shorewall/policy.
-
-
-
- Minutes instead of months! Congratulations and thanks for such a simple
-and well documented thing for something as huge as iptables." -- JV, Spain.
-
-
"I downloaded Shorewall 1.2.0 and installed it on Mandrake 8.1 without
- any problems. Your documentation is great and I really appreciate your
-network configuration info. That really helped me out alot. THANKS!!!"
- -- MM.
-
-
"[Shorewall is a] great, great project. I've used/tested may firewall
- scripts but this one is till now the best." -- B.R, Netherlands
-
-
-
"Never in my +12 year career as a sys admin have I witnessed someone
- so relentless in developing a secure, state of the art, safe and useful
- product as the Shorewall firewall package for no cost or obligation involved."
--- Mario Kerecki, Toronto
-
-
"one time more to report, that your great shorewall in the latest release
- 1.2.9 is working fine for me with SuSE Linux 7.3! I now have 7 machines
-up and running with shorewall on several versions - starting with 1.2.2
-up to the new 1.2.9 and I never have encountered any problems!" --
-SM, Germany
-
-
"You have the best support of any other package I've ever used."
- -- SE, US
-
-
"Because our company has information which has been classified by the
-national government as secret, our security doesn't stop by putting a fence
- around our company. Information security is a hot issue. We also make use
- of checkpoint firewalls, but not all of the internet servers are guarded
- by checkpoint, some of them are running....Shorewall." -- Name withheld
-by request, Europe
-
-
"thanx for all your efforts you put into shorewall - this product stands
- out against a lot of commercial stuff i´ve been working with in terms of
- flexibillity, quality & support" -- RM, Austria
-
-
"I have never seen such a complete firewall package that is so easy to
- configure. I searched the Debian package system for firewall scripts and
- Shorewall won hands down." -- RG, Toronto
-
-
"My respects... I've just found and installed Shorewall 1.3.3-1 and it
- is a wonderful piece of software. I've just sent out an email to about 30
- people recommending it. :-)
- While I had previously taken the time (maybe 40 hours) to really understand
- ipchains, then spent at least an hour per server customizing and carefully
- scrutinizing firewall rules, I've got shorewall running on my home firewall,
- with rulesets and policies that I know make sense, in under 20 minutes."
- -- RP, Guatamala
-
-
"The configuration is intuitive and flexible, and much easier than any
+ of the other iptables-based firewall programs out there. After sifting through
+ many other scripts, it is obvious that yours is the most well thought-out
+ and complete one available." -- BC, USA
+
+
"I just installed Shorewall after weeks of messing with ipchains/iptables
+ and I had it up and running in under 20 minutes!" -- JL, Ohio
+ "My case was almost like [the one above]. Well. instead of 'weeks' it
+was 'months' for me, and I think I needed two minutes more:
+
+
+
One to see that I had no Internet access from the firewall itself.
+
Other to see that this was the default configuration, and it was
+ enough to uncomment a line in /etc/shorewall/policy.
+
+
+
+ Minutes instead of months! Congratulations and thanks for such a simple
+ and well documented thing for something as huge as iptables." -- JV, Spain.
+
+
"I downloaded Shorewall 1.2.0 and installed it on Mandrake 8.1 without
+ any problems. Your documentation is great and I really appreciate your
+ network configuration info. That really helped me out alot. THANKS!!!"
+ -- MM.
+
+
"[Shorewall is a] great, great project. I've used/tested may firewall
+ scripts but this one is till now the best." -- B.R, Netherlands
+
+
+
"Never in my +12 year career as a sys admin have I witnessed someone
+ so relentless in developing a secure, state of the art, safe and
+useful product as the Shorewall firewall package for no cost or obligation
+ involved." -- Mario Kerecki, Toronto
+
+
"one time more to report, that your great shorewall in the latest release
+ 1.2.9 is working fine for me with SuSE Linux 7.3! I now have 7 machines
+up and running with shorewall on several versions - starting with 1.2.2
+up to the new 1.2.9 and I never have encountered any problems!" -- SM,
+Germany
+
+
"You have the best support of any other package I've ever used."
+ -- SE, US
+
+
"Because our company has information which has been classified by the
+ national government as secret, our security doesn't stop by putting a fence
+ around our company. Information security is a hot issue. We also make
+use of checkpoint firewalls, but not all of the internet servers are guarded
+ by checkpoint, some of them are running....Shorewall." -- Name withheld
+ by request, Europe
+
+
"thanx for all your efforts you put into shorewall - this product stands
+ out against a lot of commercial stuff i´ve been working with in terms
+of flexibillity, quality & support" -- RM, Austria
+
+
"I have never seen such a complete firewall package that is so easy to
+ configure. I searched the Debian package system for firewall scripts and
+ Shorewall won hands down." -- RG, Toronto
+
+
"My respects... I've just found and installed Shorewall 1.3.3-1 and it
+ is a wonderful piece of software. I've just sent out an email to about
+30 people recommending it. :-)
+ While I had previously taken the time (maybe 40 hours) to really understand
+ ipchains, then spent at least an hour per server customizing and carefully
+ scrutinizing firewall rules, I've got shorewall running on my home firewall,
+ with rulesets and policies that I know make sense, in under 20 minutes."
+ -- RP, Guatamala
The Shoreline Firewall, more commonly known as "Shorewall", is a
Netfilter (iptables) based firewall
that can be used on a dedicated firewall system, a multi-function
@@ -79,35 +96,37 @@
-
+
+
This program is free software; you can redistribute it and/or modify
- it under the terms of Version 2 of the GNU
General Public License as published by the Free Software
Foundation.
-
+
- This program is distributed in
- the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even
-the implied warranty of MERCHANTABILITY
- or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
+ This program is distributed
+ in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even
+ the implied warranty of MERCHANTABILITY
+ or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
-
+
- You should have received a copy
- of the GNU General Public License
- along with this program; if not, write
- to the Free Software Foundation,
-Inc., 675 Mass Ave, Cambridge, MA 02139, USA
+ You should have received a copy
+ of the GNU General Public License
+ along with this program; if not, write
+ to the Free Software Foundation,
+ Inc., 675 Mass Ave, Cambridge, MA 02139, USA
-
+
+
- New to Shorewall? Start by selecting the
- QuickStart Guide that
-most closely match your environment and follow the step by
- step instructions.
-
+ New to Shorewall? Start by selecting
+the QuickStart Guide
+that most closely match your environment and follow the step
+by step instructions.
+
Looking for Information?
- The Documentation
- Index is a good place to start as is the Quick Search to your right.
-
+ The Documentation
+ Index is a good place to start as is the Quick Search to your right.
+
Running Shorewall on Mandrake with a two-interface setup?
- If so, the documentationon this site will not
- apply directly to your setup. If you want to use the documentation
- that you find here, you will want to consider uninstalling what you have
- and installing a setup that matches the documentation on this site.
- See the Two-interface QuickStart Guide
- for details.
-
+ If so, the documentationon this site will
+ not apply directly to your setup. If you want to use the documentation
+ that you find here, you will want to consider uninstalling what you have
+ and installing a setup that matches the documentation on this site.
+ See the Two-interface QuickStart Guide
+ for details.
+
A problem seen on RH7.3 systems where Shorewall encountered
-start errors when started using the "service" mechanism has been worked
-around.
-
-
-
Where a list of IP addresses appears in the DEST column of a
-DNAT[-] rule, Shorewall incorrectly created multiple DNAT rules in the nat
-table (one for each element in the list). Shorewall now correctly creates
-a single DNAT rule with multiple "--to-destination" clauses.
-
-
-
Corrected a problem in Beta 1 where DNS names containing a "-"
-were mis-handled when they appeared in the DEST column of a rule.
+
A problem seen on RH7.3 systems where Shorewall encountered
+ start errors when started using the "service" mechanism has been worked
+ around.
+
+
+
Where a list of IP addresses appears in the DEST column
+of a DNAT[-] rule, Shorewall incorrectly created multiple DNAT rules in
+the nat table (one for each element in the list). Shorewall now correctly
+creates a single DNAT rule with multiple "--to-destination" clauses.
+
+
+
Corrected a problem in Beta 1 where DNS names containing
+a "-" were mis-handled when they appeared in the DEST column of a rule.
+
+
+
A number of problems with rule parsing have been corrected.
+ Corrections involve the handling of "z1!z2" in the SOURCE column as well
+as lists in the ORIGINAL DESTINATION column.
+
+
+
+
+
Migration Issues:
+
+
+
+
In earlier versions, an undocumented feature allowed entries
+ in the host file as follows:
+
+ z eth1:192.168.1.0/24,eth2:192.168.2.0/24
+
+ This capability was never documented and has been removed in 1.4.6
+to allow entries of the following format:
+
+ z eth1:192.168.1.0/24,192.168.2.0/24
-
A number of problems with rule parsing have been corrected. Corrections
-involve the handling of "z1!z2" in the SOURCE column as well as lists in
-the ORIGINAL DESTINATION column.
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have
+ been removed from /etc/shorewall/shorewall.conf. These capabilities are
+now automatically detected by Shorewall (see below).
-
+
-
-
Migration Issues:
-
-
-
-
In earlier versions, an undocumented feature allowed entries
-in the host file as follows:
-
- z eth1:192.168.1.0/24,eth2:192.168.2.0/24
-
- This capability was never documented and has been removed in 1.4.6 to allow
-entries of the following format:
-
- z eth1:192.168.1.0/24,192.168.2.0/24
-
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have been
-removed from /etc/shorewall/shorewall.conf. These capabilities are now automatically
- detected by Shorewall (see below).
-
-
-
-
+
New Features:
-
-
+
+
-
A 'newnotsyn' interface option has been added. This option may
-be specified in /etc/shorewall/interfaces and overrides the setting NEWNOTSYN=No
- for packets arriving on the associated interface.
-
-
-
The means for specifying a range of IP addresses in /etc/shorewall/masq
- to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for address
- ranges.
-
-
-
Shorewall can now add IP addresses to subnets other than the
-first one on an interface.
-
-
-
DNAT[-] rules may now be used to load balance (round-robin)
-over a set of servers. Servers may be specified in a range of addresses
- given as <first address>-<last address>.
-
- Example:
-
- DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
-
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration
-options have been removed and have been replaced by code that detects whether
-these capabilities are present in the current kernel. The output of the
-start, restart and check commands have been enhanced to report the outcome:
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Verifying Configuration...
-
-
-
Support for the Connection Tracking Match Extension has been
-added. This extension is available in recent kernel/iptables releases and
-allows for rules which match against elements in netfilter's connection tracking
- table. Shorewall automatically detects the availability of this extension
- and reports its availability in the output of the start, restart and check
- commands.
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Connection Tracking Match: Available
- Verifying Configuration...
-
- If this extension is available, the ruleset generated by Shorewall is
-changed in the following ways:
-
+
A 'newnotsyn' interface option has been added. This option
+ may be specified in /etc/shorewall/interfaces and overrides the setting
+NEWNOTSYN=No for packets arriving on the associated interface.
+
+
+
The means for specifying a range of IP addresses in /etc/shorewall/masq
+ to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for
+address ranges.
+
+
+
Shorewall can now add IP addresses to subnets other than
+the first one on an interface.
+
+
+
DNAT[-] rules may now be used to load balance (round-robin)
+ over a set of servers. Servers may be specified in a range of addresses
+ given as <first address>-<last address>.
+
+ Example:
+
+ DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
+
+
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration
+ options have been removed and have been replaced by code that detects
+whether these capabilities are present in the current kernel. The output
+of the start, restart and check commands have been enhanced to report the
+outcome:
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Verifying Configuration...
+
+
+
Support for the Connection Tracking Match Extension has
+been added. This extension is available in recent kernel/iptables releases
+and allows for rules which match against elements in netfilter's connection
+ tracking table. Shorewall automatically detects the availability of this
+ extension and reports its availability in the output of the start, restart
+ and check commands.
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Connection Tracking Match: Available
+ Verifying Configuration...
+
+ If this extension is available, the ruleset generated by Shorewall
+is changed in the following ways:
+
-
To handle 'norfc1918' filtering, Shorewall will not create
-chains in the mangle table but will rather do all 'norfc1918' filtering in
-the filter table (rfc1918 chain).
-
Recall that Shorewall DNAT rules generate two netfilter rules;
-one in the nat table and one in the filter table. If the Connection Tracking
-Match Extension is available, the rule in the filter table is extended to
-check that the original destination address was the same as specified (or
-defaulted to) in the DNAT rule.
-
-
-
-
-
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
- may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
-
-
-
An 'ipcalc' command has been added to /sbin/shorewall.
-
- ipcalc [ <address> <netmask> | <address>/<vlsm>
-]
-
- Examples:
-
- [root@wookie root]# shorewall ipcalc 192.168.1.0/24
- CIDR=192.168.1.0/24
- NETMASK=255.255.255.0
- NETWORK=192.168.1.0
- BROADCAST=192.168.1.255
- [root@wookie root]#
-
- [root@wookie root]# shorewall ipcalc 192.168.1.0 255.255.255.0
- CIDR=192.168.1.0/24
- NETMASK=255.255.255.0
- NETWORK=192.168.1.0
- BROADCAST=192.168.1.255
- [root@wookie root]#
-
- Warning:
-
- If your shell only supports 32-bit signed arithmatic (ash or dash), then
- the ipcalc command produces incorrect information for IP addresses 128.0.0.0-1
- and for /1 networks. Bash should produce correct information for all valid
- IP addresses.
-
-
-
An 'iprange' command has been added to /sbin/shorewall.
-
- iprange <address>-<address>
-
- This command decomposes a range of IP addressses into a list of network
-and host addresses. The command can be useful if you need to construct an
-efficient set of rules that accept connections from a range of network addresses.
-
- Note: If your shell only supports 32-bit signed arithmetic (ash or dash)
-then the range may not span 128.0.0.0.
-
- Example:
-
- [root@gateway root]# shorewall iprange 192.168.1.4-192.168.12.9
- 192.168.1.4/30
- 192.168.1.8/29
- 192.168.1.16/28
- 192.168.1.32/27
- 192.168.1.64/26
- 192.168.1.128/25
- 192.168.2.0/23
- 192.168.4.0/22
- 192.168.8.0/22
- 192.168.12.0/29
- 192.168.12.8/31
- [root@gateway root]#
-
-
-
A list of host/net addresses is now allowed in an entry in /etc/shorewall/hosts.
-
- Example:
-
- foo eth1:192.168.1.0/24,192.168.2.0/24
-
-
-
-
-
6/17/2003 - Shorewall-1.4.5
-
-
Problems Corrected:
-
-
-
-
The command "shorewall debug try <directory>" now
- correctly traces the attempt.
-
The INCLUDE directive now works properly in the zones
-file; previously, INCLUDE in that file was ignored.
-
/etc/shorewall/routestopped records with an empty second
- column are no longer ignored.
+
To handle 'norfc1918' filtering, Shorewall will not create
+ chains in the mangle table but will rather do all 'norfc1918' filtering
+ in the filter table (rfc1918 chain).
+
Recall that Shorewall DNAT rules generate two netfilter
+ rules; one in the nat table and one in the filter table. If the Connection
+ Tracking Match Extension is available, the rule in the filter table is
+extended to check that the original destination address was the same as
+specified (or defaulted to) in the DNAT rule.
+
-
+
+
+
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
+ may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
+
+
+
An 'ipcalc' command has been added to /sbin/shorewall.
+
+ ipcalc [ <address> <netmask> | <address>/<vlsm>
+ ]
+
+ Examples:
+
+ [root@wookie root]# shorewall ipcalc 192.168.1.0/24
+ CIDR=192.168.1.0/24
+ NETMASK=255.255.255.0
+ NETWORK=192.168.1.0
+ BROADCAST=192.168.1.255
+ [root@wookie root]#
+
+ [root@wookie root]# shorewall ipcalc 192.168.1.0 255.255.255.0
+ CIDR=192.168.1.0/24
+ NETMASK=255.255.255.0
+ NETWORK=192.168.1.0
+ BROADCAST=192.168.1.255
+ [root@wookie root]#
+
+ Warning:
+
+ If your shell only supports 32-bit signed arithmatic (ash or dash),
+then the ipcalc command produces incorrect information for IP addresses
+128.0.0.0-1 and for /1 networks. Bash should produce correct information
+for all valid IP addresses.
+
+
+
An 'iprange' command has been added to /sbin/shorewall.
+
+
+ iprange <address>-<address>
+
+ This command decomposes a range of IP addressses into a list of network
+ and host addresses. The command can be useful if you need to construct an
+ efficient set of rules that accept connections from a range of network addresses.
+
+ Note: If your shell only supports 32-bit signed arithmetic (ash or
+dash) then the range may not span 128.0.0.0.
+
+ Example:
+
+ [root@gateway root]# shorewall iprange 192.168.1.4-192.168.12.9
+ 192.168.1.4/30
+ 192.168.1.8/29
+ 192.168.1.16/28
+ 192.168.1.32/27
+ 192.168.1.64/26
+ 192.168.1.128/25
+ 192.168.2.0/23
+ 192.168.4.0/22
+ 192.168.8.0/22
+ 192.168.12.0/29
+ 192.168.12.8/31
+ [root@gateway root]#
+
+
+
A list of host/net addresses is now allowed in an entry
+in /etc/shorewall/hosts.
+
+ Example:
+
+ foo eth1:192.168.1.0/24,192.168.2.0/24
+
+
-
-
New Features:
-
-
+
+
6/17/2003 - Shorewall-1.4.5
+
+
+
Problems Corrected:
+
+
+
-
The ORIGINAL DEST column in a DNAT[-] or REDIRECT[-]
-rule may now contain a list of addresses. If the list begins with "!'
-then the rule will take effect only if the original destination address
-in the connection request does not match any of the addresses listed.
-
+
The command "shorewall debug try <directory>"
+ now correctly traces the attempt.
+
The INCLUDE directive now works properly in the zones
+ file; previously, INCLUDE in that file was ignored.
+
/etc/shorewall/routestopped records with an empty
+second column are no longer ignored.
+
+
+
-
+
+
+
New Features:
+
+
+
+
+
The ORIGINAL DEST column in a DNAT[-] or REDIRECT[-]
+ rule may now contain a list of addresses. If the list begins with "!'
+ then the rule will take effect only if the original destination address
+ in the connection request does not match any of the addresses listed.
+
+
+
+
+
6/15/2003 - Shorewall, Kernel 2.4.21 and iptables 1.2.8
-
+
+
The firewall at shorewall.net has been upgraded to the 2.4.21 kernel
- and iptables 1.2.8 (using the "official" RPM from netfilter.org). No problems
- have been encountered with this set of software. The Shorewall version
- is 1.4.4b plus the accumulated changes for 1.4.5.
-
+ and iptables 1.2.8 (using the "official" RPM from netfilter.org). No
+ problems have been encountered with this set of software. The Shorewall
+ version is 1.4.4b plus the accumulated changes for 1.4.5.
+
+
6/8/2003 - Updated Samples
-
+
Thanks to Francesca Smith, the samples have been updated to Shorewall
- version 1.4.4.
- Jacques Nilo and Eric Wolzak
- have a LEAF (router/firewall/gateway
- on a floppy, CD or compact flash) distribution
- called Bering that features
- Shorewall-1.4.2 and Kernel-2.4.20. You
- can find their work at: http://leaf.sourceforge.net/devel/jnilo
+ Jacques Nilo and Eric
+ Wolzak have a LEAF (router/firewall/gateway
+ on a floppy, CD or compact flash) distribution
+ called Bering that
+ features Shorewall-1.4.2 and Kernel-2.4.20.
+ You can find their work at:
+ http://leaf.sourceforge.net/devel/jnilo
-
+
- Congratulations to Jacques and Eric on the
-recent release of Bering 1.2!!!
+ Congratulations to Jacques and Eric on
+the recent release of Bering 1.2!!!
-
+
I am currently a member of the design team for the next-generation operating
+
+
I am currently a member of the design team for the next-generation operating
system from the NonStop Enterprise Division of HP.
-
-
I became interested in Internet Security when I established a home office
- in 1999 and had DSL service installed in our home. I investigated
- ipchains and developed the scripts which are now collectively known
- as Seattle Firewall.
- Expanding on what I learned from Seattle Firewall, I then
- designed and wrote Shorewall.
-
+
+
I became interested in Internet Security when I established a home office
+ in 1999 and had DSL service installed in our home. I investigated
+ ipchains and developed the scripts which are now collectively
+known as Seattle Firewall.
+ Expanding on what I learned from Seattle Firewall, I then
+ designed and wrote Shorewall.
-
+ href="http://www.cityofshoreline.com">Shoreline, Washington where
+I live with my wife Tarry.
+
Our current home network consists of:
-
+
-
1.2Gz Athlon, Windows XP Pro, 320MB RAM,
-40GB & 20GB IDE HDs and LNE100TX (Tulip) NIC - My personal
- Windows system. Serves as a PPTP server for Road Warrior access. Dual
+
1.2Gz Athlon, Windows XP Pro, 320MB RAM,
+ 40GB & 20GB IDE HDs and LNE100TX (Tulip) NIC - My personal
+ Windows system. Serves as a PPTP server for Road Warrior access. Dual
boots Mandrake 9.0.
-
Celeron 1.4Gz, RH8.0, 384MB RAM, 60GB HD,
- LNE100TX(Tulip) NIC - My personal Linux System which runs
-Samba. This system also has VMware
- installed and can run both Debian
- Woody and SuSE 8.1 in virtual
+
Celeron 1.4Gz, RH8.0, 384MB RAM, 60GB HD,
+ LNE100TX(Tulip) NIC - My personal Linux System which runs
+Samba. This system also has VMware
+ installed and can run both Debian
+ Woody and SuSE 8.1 in virtual
machines.
-
K6-2/350, RH8.0, 384MB RAM, 8GB IDE HD,
-EEPRO100 NIC - Email (Postfix, Courier-IMAP and Mailman), HTTP (Apache),
-FTP (Pure_ftpd), DNS server (Bind 9).
-
PII/233, RH8.0, 256MB MB RAM, 2GB SCSI
-HD - 3 LNE100TX (Tulip) and 1 TLAN NICs - Firewall running Shorewall
- 1.4.6Beta1, a DHCP server and Samba configured as a WINS server..
-
Duron 750, Win ME, 192MB RAM, 20GB HD, RTL8139
- NIC - My wife's personal system.
-
PII/400 Laptop, WinXP SP1, 224MB RAM, 12GB
- HD, built-in EEPRO100, EEPRO100 in expansion base - My work system.
-
XP 2200 Laptop, WinXP SP1, 512MB RAM, 40GB HD, built-in NIC and
- LinkSys WET11 - Our Laptop.
-
-
+
K6-2/350, RH8.0, 384MB RAM, 8GB IDE HD,
+EEPRO100 NIC - Email (Postfix, Courier-IMAP and Mailman), HTTP (Apache),
+ FTP (Pure_ftpd), DNS server (Bind 9).
+
PII/233, RH8.0, 256MB MB RAM, 2GB SCSI
+ HD - 3 LNE100TX (Tulip) and 1 TLAN NICs - Firewall running Shorewall
+ 1.4.6Beta1, a DHCP server and Samba configured as a WINS server..
+
Duron 750, Win ME, 192MB RAM, 20GB HD,
+RTL8139 NIC - My wife's personal system.
+
PII/400 Laptop, WinXP SP1, 224MB RAM, 12GB
+ HD, built-in EEPRO100, EEPRO100 in expansion base - My work system.
+
XP 2200 Laptop, WinXP SP1, 512MB RAM, 40GB HD, built-in NIC
+and LinkSys WET11 - Our Laptop.
+
Extension scripts are user-provided scripts that are invoked at various
- points during firewall start, restart, stop and clear. The scripts are
- placed in /etc/shorewall and are processed using the Bourne shell "source"
+
+
Extension scripts are user-provided scripts that are invoked at various
+ points during firewall start, restart, stop and clear. The scripts are
+ placed in /etc/shorewall and are processed using the Bourne shell "source"
mechanism.
-
-
Caution:
-
-
-
-
Be sure that you actually need to use an extension
-script to do what you want. Shorewall has a wide range of features that cover
-most requirements.
-
DO NOT SIMPLY COPY RULES THAT YOU FIND ON
-THE NET INTO AN EXTENSION SCRIPT AND EXPECT THEM TO WORK AND TO NOT BREAK
-SHOREWALL. TO USE SHOREWALL EXTENSION SCRIPTS YOU MUST KNOW WHAT YOU ARE DOING
-WITH RESPECT TO iptables/Netfilter
-
-
The following scripts can be supplied:
-
-
-
init -- invoked early in "shorewall start" and "shorewall
- restart"
-
start -- invoked after the firewall has been started or restarted.
-
stop -- invoked as a first step when the firewall is being stopped.
-
stopped -- invoked after the firewall has been stopped.
-
clear -- invoked after the firewall has been cleared.
-
refresh -- invoked while the firewall is being refreshed but before
- the common and/or blacklst chains have been rebuilt.
-
newnotsyn (added in version 1.3.6) -- invoked after the 'newnotsyn'
- chain has been created but before any rules have been added to it.
-
-
-
-
If your version of Shorewall doesn't have the file that you want
- to use from the above list, you can simply create the file yourself.
-
-
You can also supply a script with the same name as any of the filter
- chains in the firewall and the script will be invoked after the /etc/shorewall/rules
- file has been processed but before the /etc/shorewall/policy file has
- been processed.
-
-
The /etc/shorewall/common file receives special treatment. If this file
- is present, the rules that it defines will totally replace the default
- rules in the common chain. These default rules are contained in
-the file /etc/shorewall/common.def which may be used as a starting
-point for making your own customized file.
-
-
Rather than running iptables directly, you should run it using the
- function run_iptables. Similarly, rather than running "ip" directly, you
-should use run_ip. These functions accept the same arguments as the underlying
-command but cause the firewall to be stopped if an error occurs during processing
-of the command.
-
-
If you decide to create /etc/shorewall/common it is a good idea to use
-the following technique
-
-
/etc/shorewall/common:
-
-
-
. /etc/shorewall/common.def <add your rules here>
-
-
-
If you need to supercede a rule in the released common.def file, you can
- add the superceding rule before the '.' command. Using this technique
-allows you to add new rules while still getting the benefit of the latest
-common.def file.
-
-
Remember that /etc/shorewall/common defines rules that are only applied
- if the applicable policy is DROP or REJECT. These rules are NOT applied
- if the policy is ACCEPT or CONTINUE
-
+
Caution:
+
+
+
+
Be sure that you actually need to use an
+extension script to do what you want. Shorewall has a wide range of features
+that cover most requirements.
+
DO NOT SIMPLY COPY RULES THAT YOU FIND ON
+THE NET INTO AN EXTENSION SCRIPT AND EXPECT THEM TO WORK AND TO NOT BREAK
+ SHOREWALL. TO USE SHOREWALL EXTENSION SCRIPTS YOU MUST KNOW WHAT YOU ARE
+DOING WITH RESPECT TO iptables/Netfilter
+
+
+
+
The following scripts can be supplied:
+
+
init -- invoked early in "shorewall start" and "shorewall
+ restart"
+
start -- invoked after the firewall has been started or restarted.
+
stop -- invoked as a first step when the firewall is being stopped.
+
stopped -- invoked after the firewall has been stopped.
+
clear -- invoked after the firewall has been cleared.
+
refresh -- invoked while the firewall is being refreshed but
+before the common and/or blacklst chains have been rebuilt.
+
newnotsyn (added in version 1.3.6) -- invoked after the 'newnotsyn'
+ chain has been created but before any rules have been added to it.
+
+
+
+
If your version of Shorewall doesn't have the file that you want
+ to use from the above list, you can simply create the file yourself.
+
+
You can also supply a script with the same name as any of the filter
+ chains in the firewall and the script will be invoked after the /etc/shorewall/rules
+ file has been processed but before the /etc/shorewall/policy file has
+ been processed.
+
+
The /etc/shorewall/common file receives special treatment. If this file
+ is present, the rules that it defines will totally replace the default
+ rules in the common chain. These default rules are contained in the
+ file /etc/shorewall/common.def which may be used as a starting point
+ for making your own customized file.
+
+
Rather than running iptables directly, you should run it using the
+function run_iptables. Similarly, rather than running "ip" directly, you
+ should use run_ip. These functions accept the same arguments as the underlying
+ command but cause the firewall to be stopped if an error occurs during
+processing of the command.
+
+
If you decide to create /etc/shorewall/common it is a good idea to
+use the following technique
+
+
/etc/shorewall/common:
+
+
+
. /etc/shorewall/common.def <add your rules here>
+
+
+
If you need to supercede a rule in the released common.def file, you can
+ add the superceding rule before the '.' command. Using this technique allows
+ you to add new rules while still getting the benefit of the latest common.def
+ file.
+
+
Remember that /etc/shorewall/common defines rules that are only applied
+ if the applicable policy is DROP or REJECT. These rules are NOT applied
+ if the policy is ACCEPT or CONTINUE
+
Shorewall views the network in which it is running as a set of
+ zones. Shorewall itself defines exactly one zone called "fw" which
+ refers to the firewall system itself . The /etc/shorewall/zones file
+is used to define additional zones and the example file provided with
+Shorewall defines the zones:
+
+
+
net -- the (untrusted) internet.
+
dmz - systems that must be accessible from the internet
+ and from the local network. These systems cannot be trusted completely
+since their servers may have been compromised through a security exploit.
+
loc - systems in your local network(s). These systems
+ must be protected from the internet and from the DMZ and in some
+cases, from each other.
It can't be stressed enough that with the exception of the firewall zone,
+ Shorewall itself attaches no meaning to zone names. Zone names are simply
+ labels used to refer to a collection of network hosts.
+
+
While zones are normally disjoint (no two zones have a host in common),
+ there are cases where nested or overlapping zone definitions are appropriate.
+
+
Netfilter has the concept of tables and chains. For the purpose
+of this document, we will consider Netfilter to have three tables:
+
+
+
Filter table -- this is the main table for packet filtering and
+can be displayed with the command "shorewall show".
+
Nat table -- used for all forms of Network Address Translation (NAT);
+ SNAT, DNAT and MASQUERADE.
+
Mangle table -- used to modify fields in the packet header.
+
+
+
+
+
Netfilter defines a number of inbuilt chains: PREROUTING, INPUT, OUTPUT,
+ FORWARD and POSTROUTING. Not all inbuilt chains are present in all tables
+ as shown in this table.
+
+
+
+
+
-
-
Firewall Structure
-
-
-
+
CHAIN
+
+
Filter
+
+
Nat
+
+
Mangle
+
+
+
+
PREROUTING
+
+
+
+
X
+
+
X
+
+
+
+
INPUT
+
+
X
+
+
+
+
X
+
+
+
+
OUTPUT
+
+
X
+
+
X
+
+
X
+
+
+
+
FORWARD
+
+
X
+
+
+
+
X
+
+
+
+
POSTROUTING
+
+
+
+
X
+
+
X
+
+
+
-
-
Shorewall views the network in which it is running as a set of
- zones. Shorewall itself defines exactly one zone called "fw" which
- refers to the firewall system itself . The /etc/shorewall/zones file is
- used to define additional zones and the example file provided with Shorewall
- defines the zones:
-
-
-
net -- the (untrusted) internet.
-
dmz - systems that must be accessible from the internet
- and from the local network. These systems cannot be trusted completely since
- their servers may have been compromised through a security exploit.
-
loc - systems in your local network(s). These systems
- must be protected from the internet and from the DMZ and in some cases,
- from each other.
It can't be stressed enough that with the exception of the firewall zone,
- Shorewall itself attaches no meaning to zone names. Zone names are simply
- labels used to refer to a collection of network hosts.
-
-
While zones are normally disjoint (no two zones have a host in common),
- there are cases where nested or overlapping zone definitions are appropriate.
-
-
Netfilter has the concept of tables and chains. For the
-purpose of this document, we will consider Netfilter to have three tables:
-
-
-
Filter table -- this is the main table for packet filtering and can
- be displayed with the command "shorewall show".
-
Nat table -- used for all forms of Network Address Translation (NAT);
- SNAT, DNAT and MASQUERADE.
-
Mangle table -- used to modify fields in the packet header.
-
-
-
-
-
Netfilter defines a number of inbuilt chains: PREROUTING, INPUT, OUTPUT,
- FORWARD and POSTROUTING. Not all inbuilt chains are present in all tables
- as shown in this table.
-
-
-
-
-
-
-
CHAIN
-
-
Filter
-
-
Nat
-
-
Mangle
-
-
-
-
PREROUTING
-
-
-
-
X
-
-
X
-
-
-
-
INPUT
-
-
X
-
-
-
-
X
-
-
-
-
OUTPUT
-
-
X
-
-
X
-
-
X
-
-
-
-
FORWARD
-
-
X
-
-
-
-
X
-
-
-
-
POSTROUTING
-
-
-
-
X
-
-
X
-
-
-
-
-
-
-
-
Shorewall doesn't create rules in all of the builtin chains. In the large
- diagram below are boxes such as shown below. This box represents in INPUT
- chain and shows that packets first flow through the INPUT chain in the Mangle
- table followed by the INPUT chain in the Filter table. The parentheses around
- "Mangle" indicate that while the packets will flow through the INPUT chain
+
+
+
Shorewall doesn't create rules in all of the builtin chains. In the large
+ diagram below are boxes such as shown below. This box represents in INPUT
+ chain and shows that packets first flow through the INPUT chain in the Mangle
+ table followed by the INPUT chain in the Filter table. The parentheses around
+ "Mangle" indicate that while the packets will flow through the INPUT chain
in the Mangle table, Shorewall does not create any rules in that chain.
-
-
+
+
-
-
-
-
-
-
Here is a picture of how packets traverse the various chains and tables
- in Netfilter. In that diagram, "Local Process" refers to a process running
- on the Firewall itself (in the 'fw' zone).
+
+
+
+
+
Here is a picture of how packets traverse the various chains and tables
+ in Netfilter. In that diagram, "Local Process" refers to a process running
+ on the Firewall itself (in the 'fw' zone).
+
-
-
-
-
- In the text that follows, the paragraph numbers correspond to the box number
- in the diagram above.
-
-
-
-
Packets entering the firewall first pass through the mangle table's
- PREROUTING chain (you can see the mangle table by typing "shorewall show
- mangle"). If the packet entered through an interface that has the norfc1918
- option and if iptables/netfilter doesn't support the connection tracking
-match extension, then the packet is sent down the man1918 chain which
-will drop the packet if its destination IP address is reserved (as specified
-in the /etc/shorewall/rfc1918 file). Next the packet passes through the
-pretos chain to set its TOS field as specified in the /etc/shorewall/tos
-file. Finally, if traffic control/shaping is being used, the packet is sent
-through the tcpre chain to be marked for later use in policy routing
-or traffic control.
-
- Next, if the packet isn't part of an established connection, it passes
- through the nat table's PREROUTING chain (you can see the nat table
- by typing "shorewall show nat"). If you are doing both static nat and port
- forwarding, the order in which chains are traversed is dependent on the
- setting of NAT_BEFORE_RULES in shorewall.conf. If NAT_BEFORE_RULES is on
-then packets will ender a chain calledinterface_in where
- interface is the name of the interface on which the packet entered.
-Here it's destination IP is compared to each of the EXTERNAL IP addresses
-from /etc/shorewall/nat that correspond to this interface; if there is
-a match, DNAT is applied and the packet header is modified to the IP in
-the INTERNAL column of the nat file record. If the destination address
-doesn't match any of the rules in the interface_in chain then
-the packet enters a chain called sourcezone_dnat where sourcezone
-is the source zone of the packet. There it is compared for a match against
-each of the DNAT records in the rules file that specify sourcezone
- as the source zone. If a match is found, the destination IP address
-(and possibly the destination port) is modified based on the rule matched.
-If NAT_BEFORE_RULES is off, then the order of traversal of the interface_in
-and sourcezone_dnat is reversed.
-
-
-
Depending on whether the packet is destined for the firewall itself
- or for another system, it follows either the left or the right path. Traffic
- going to the firewall goes through chain called INPUT in the mangle table.
- Shorewall doesn't add any rules to that chain.
-
-
-
Traffic that is to be forwarded to another host goes through the chains
-called FORWARD in the mangle table. If MARK_IN_FORWARD=Yes in shorewall.conf,
-all rules in /etc/shorewall/tcrules that do not specify Prerouting (:P) are
-processed in a chain called
-
-
-
-
-
-
Traffic is next sent to an interface chain in the main Netfilter
- table (called 'filter'). If the traffic is destined for the firewall itself,
- the name of the interface chain is formed by appending "_in" to the interface
- name. So traffic on eth0 destined for the firewall will enter a chain called
- eth0_in. The interface chain for traffic that will be routed
-to another system is formed by appending "_fwd" to the interface name.
-So traffic from eth1 that is going to be forwarded enters a chain called
-eth1_fwd. Interfaces described with the wild-card character ("+")
-in /etc/shorewall/interfaces, share input chains. if ppp+ appears
-in /etc/shorewall/interfaces then all PPP interfaces (ppp0, ppp1, ...) will
-share the interface chains ppp_in and ppp_fwd. In other words,
-"+" is deleted from the name before forming the input chain names.
-
-While the use of interfacechains may seem wasteful in simple environments,
- in complex setups it substantially reduces the number of rules that each
- packet must traverse.
-
-
-
-
Traffic directed from a zone to the firewall itself is sent through a
-chain named <zone name>2fw. For example, traffic inbound from
- the internet and addressed to the firewall is sent through a chain named
- net2fw. Similarly, traffic originating in the firewall and being sent
-to a host in a given zone is sent through a chain named fw2<zone
-name>. For example, traffic originating in the firewall and
-destined for a host in the local network is sent through a chain named
-fw2loc.
-
-
Traffic being forwarded between two zones (or from one interface to a
-zone to another interface to that zone) is sent through a chain named
- <source zone>2 <destination zone>. So for example,
- traffic originating in a local system and destined for a remote web server
- is sent through chain loc2net. This chain is referred to
-as the canonical chain from <source zone> to <destination
- zone>. Any destination NAT will have occurred before the packet
- traverses one of these chains so rules in /etc/shorewall/rules should
-be expressed in terms of the destination system's real IP address as opposed
- to its apparent external address. Similarly, source NAT will occur after
- the packet has traversed the appropriate forwarding chain so the rules
- again will be expressed using the source system's real IP address.
-
-
For each record in the /etc/shorewall/policy file, a chain is created.
- Policies in that file are expressed in terms of a source zone and destination
- zone where these zones may be a zone defined in /etc/shorewall/zones, "fw"
- or "all". Policies specifying the pseudo-zone "all" matches all defined
- zones and "fw". These chains are referred to as Policy Chains. Notice
- that for an ordered pair of zones (za,zb), the canonical chain (za2zb)
-may also be the policy chain for the pair or the policy chain may be a
-different chain (za2all, for example). Packets from one zone to another
-will traverse chains as follows:
-
-
-
If the canonical chain exists, packets first traverse that
- chain.
-
If the canonical chain and policy chain are different and
- the packet does not match a rule in the canonical chain, it then is sent
- to the policy chain.
-
If the canonical chain does not exist, packets are sent
-immediately to the policy chain.
-
-
-
-
The canonical chain from zone za to zone zb will be created only if there
-are exception rules defined in /etc/shorewall/rules for packets going from
-za to zb.
-
-
Shorewall is built on top of the Netfilter kernel facility. Netfilter
- implements connection tracking function that allow what is often referred
- to as "statefull inspection" of packets. This statefull property allows
- firewall rules to be defined in terms of "connections" rather than
-in terms of "packets". With Shorewall, you:
-
-
-
Identify the client's zone.
-
Identify the server's zone.
-
If the POLICY from the client's zone to the server's zone
- is what you want for this client/server pair, you need do nothing further.
-
If the POLICY is not what you want, then you must add a
-rule. That rule is expressed in terms of the client's zone and the
-server's zone.
-
-
-
-
Just because connections of a particular type are allowed between zone
- A and the firewall and are also allowed between the firewall and zone B
- DOES NOT mean that these connections are
- allowed between zone A and zone B. It rather means that
- you can have a proxy running on the firewall that accepts a connection
-from zone A and then establishes its own separate connection from the firewall
- to zone B.
-
-
If you adopt the default policy of ACCEPT from the local zone to the
- internet zone and you are having problems connecting from a local client
- to an internet server, adding a rule won't
- help (see point 3 above).
+ In the text that follows, the paragraph numbers correspond to the box
+number in the diagram above.
+
+
+
+
Packets entering the firewall first pass through the mangle table's
+ PREROUTING chain (you can see the mangle table by typing "shorewall show
+ mangle"). If the packet entered through an interface that has the norfc1918
+ option and if iptables/netfilter doesn't support the connection tracking
+match extension, then the packet is sent down the man1918 chain which
+will drop the packet if its destination IP address is reserved (as specified
+ in the /etc/shorewall/rfc1918 file). Next the packet passes through the
+ pretos chain to set its TOS field as specified in the /etc/shorewall/tos
+ file. Finally, if traffic control/shaping is being used, the packet is
+sent through the tcpre chain to be marked for later use in policy
+routing or traffic control.
+
+ Next, if the packet isn't part of an established connection, it passes
+ through the nat table's PREROUTING chain (you can see the nat table
+ by typing "shorewall show nat"). If you are doing both static nat and
+ port forwarding, the order in which chains are traversed is dependent on
+the setting of NAT_BEFORE_RULES in shorewall.conf. If NAT_BEFORE_RULES is
+on then packets will ender a chain calledinterface_in where
+ interface is the name of the interface on which the packet entered.
+ Here it's destination IP is compared to each of the EXTERNAL IP
+addresses from /etc/shorewall/nat that correspond to this interface; if
+there is a match, DNAT is applied and the packet header is modified to
+the IP in the INTERNAL column of the nat file record. If the destination
+address doesn't match any of the rules in the interface_in
+chain then the packet enters a chain called sourcezone_dnat
+ where sourcezone is the source zone of the packet. There it is compared
+ for a match against each of the DNAT records in the rules file that specify
+ sourcezone as the source zone. If a match is found, the
+destination IP address (and possibly the destination port) is modified based
+on the rule matched. If NAT_BEFORE_RULES is off, then the order of traversal
+of the interface_in and sourcezone_dnat is
+reversed.
+
+
+
Depending on whether the packet is destined for the firewall itself
+ or for another system, it follows either the left or the right path. Traffic
+ going to the firewall goes through chain called INPUT in the mangle table.
+ Shorewall doesn't add any rules to that chain.
+
+
+
Traffic that is to be forwarded to another host goes through the chains
+called FORWARD in the mangle table. If MARK_IN_FORWARD=Yes in shorewall.conf,
+all rules in /etc/shorewall/tcrules that do not specify Prerouting (:P) are
+processed in a chain called
+
+
+
+
+
+
+
Traffic is next sent to an interface chain in the main Netfilter
+ table (called 'filter'). If the traffic is destined for the firewall
+itself, the name of the interface chain is formed by appending "_in" to
+ the interface name. So traffic on eth0 destined for the firewall will
+enter a chain called eth0_in. The interface chain for traffic
+that will be routed to another system is formed by appending "_fwd" to
+the interface name. So traffic from eth1 that is going to be forwarded
+enters a chain called eth1_fwd. Interfaces described with the wild-card
+character ("+") in /etc/shorewall/interfaces, share input chains. if ppp+
+ appears in /etc/shorewall/interfaces then all PPP interfaces (ppp0,
+ppp1, ...) will share the interface chains ppp_in and ppp_fwd.
+In other words, "+" is deleted from the name before forming the input chain
+names.
+
+ While the use of interfacechains may seem wasteful in simple environments,
+ in complex setups it substantially reduces the number of rules that each
+ packet must traverse.
+
+
+
+
Traffic directed from a zone to the firewall itself is sent through
+a chain named <zone name>2fw. For example, traffic inbound from
+ the internet and addressed to the firewall is sent through a chain named
+ net2fw. Similarly, traffic originating in the firewall and being sent
+to a host in a given zone is sent through a chain named fw2<zone
+name>. For example, traffic originating in the firewall and
+destined for a host in the local network is sent through a chain named
+fw2loc.
+
+
Traffic being forwarded between two zones (or from one interface to
+a zone to another interface to that zone) is sent through a chain named
+ <source zone>2 <destination zone>. So for example,
+ traffic originating in a local system and destined for a remote web server
+ is sent through chain loc2net. This chain is referred to
+as the canonical chain from <source zone> to <destination
+ zone>. Any destination NAT will have occurred before the packet
+ traverses one of these chains so rules in /etc/shorewall/rules should
+be expressed in terms of the destination system's real IP address as opposed
+ to its apparent external address. Similarly, source NAT will occur after
+ the packet has traversed the appropriate forwarding chain so the rules
+ again will be expressed using the source system's real IP address.
+
+
For each record in the /etc/shorewall/policy file, a chain is created.
+ Policies in that file are expressed in terms of a source zone and destination
+ zone where these zones may be a zone defined in /etc/shorewall/zones,
+"fw" or "all". Policies specifying the pseudo-zone "all" matches all defined
+ zones and "fw". These chains are referred to as Policy Chains. Notice
+ that for an ordered pair of zones (za,zb), the canonical chain (za2zb)
+ may also be the policy chain for the pair or the policy chain may be
+a different chain (za2all, for example). Packets from one zone to another
+ will traverse chains as follows:
+
+
+
If the canonical chain exists, packets first traverse
+that chain.
+
If the canonical chain and policy chain are different
+and the packet does not match a rule in the canonical chain, it then
+is sent to the policy chain.
+
If the canonical chain does not exist, packets are sent
+ immediately to the policy chain.
+
+
+
+
The canonical chain from zone za to zone zb will be created only if
+there are exception rules defined in /etc/shorewall/rules for packets going
+from za to zb.
+
+
Shorewall is built on top of the Netfilter kernel facility. Netfilter
+ implements connection tracking function that allow what is often referred
+ to as "statefull inspection" of packets. This statefull property allows
+ firewall rules to be defined in terms of "connections" rather than in
+ terms of "packets". With Shorewall, you:
+
+
+
Identify the client's zone.
+
Identify the server's zone.
+
If the POLICY from the client's zone to the server's zone
+ is what you want for this client/server pair, you need do nothing further.
+
If the POLICY is not what you want, then you must add
+a rule. That rule is expressed in terms of the client's zone and
+the server's zone.
+
+
+
+
Just because connections of a particular type are allowed between zone
+ A and the firewall and are also allowed between the firewall and zone
+B DOES NOT mean that these connections
+are allowed between zone A and zone B. It rather means
+that you can have a proxy running on the firewall that accepts a connection
+ from zone A and then establishes its own separate connection from the
+firewall to zone B.
+
+
If you adopt the default policy of ACCEPT from the local zone to the
+ internet zone and you are having problems connecting from a local client
+ to an internet server, adding a rule won't
+ help (see point 3 above).
-
- By default, Shorewall directs NetFilter to log using syslog (8). Syslog
- classifies log messages by a facility and a priority (using
+
+ By default, Shorewall directs NetFilter to log using syslog (8). Syslog
+ classifies log messages by a facility and a priority (using
the notation facility.priority).
-
- The facilities defined by syslog are auth, authpriv, cron, daemon,
- kern, lpr, mail, mark, news, syslog, user, uucp and local0 through
+
+ The facilities defined by syslog are auth, authpriv, cron, daemon,
+ kern, lpr, mail, mark, news, syslog, user, uucp and local0 through
local7.
-
- Throughout the Shorewall documentation, I will use the term level
- rather than priority since level is the term used by NetFilter.
+
+ Throughout the Shorewall documentation, I will use the term level
+ rather than priority since level is the term used by NetFilter.
The syslog documentation uses the term priority.
-
+
Syslog Levels
-
- Syslog levels are a method of describing to syslog (8) the importance
- of a message and a number of Shorewall parameters have a syslog level
+
+ Syslog levels are a method of describing to syslog (8) the importance
+ of a message and a number of Shorewall parameters have a syslog level
as their value.
-
- Valid levels are:
-
- 7
+
+ Valid levels are:
+
+ 7
debug
- 6
+ 6
info
- 5
+ 5
notice
- 4
+ 4
warning
- 3
+ 3
err
- 2
+ 2
crit
- 1
+ 1
alert
- 0
+ 0
emerg
-
- For most Shorewall logging, a level of 6 (info) is appropriate.
-Shorewall log messages are generated by NetFilter and are logged using
-the kern facility and the level that you specify. If you are unsure
-of the level to choose, 6 (info) is a safe bet. You may specify levels
+
+ For most Shorewall logging, a level of 6 (info) is appropriate.
+Shorewall log messages are generated by NetFilter and are logged using
+the kern facility and the level that you specify. If you are unsure
+of the level to choose, 6 (info) is a safe bet. You may specify levels
by name or by number.
-
- Syslogd writes log messages to files (typically in /var/log/*) based
- on their facility and level. The mapping of these facility/level pairs
-to log files is done in /etc/syslog.conf (5). If you make changes to this
+
+ Syslogd writes log messages to files (typically in /var/log/*) based
+ on their facility and level. The mapping of these facility/level pairs
+to log files is done in /etc/syslog.conf (5). If you make changes to this
file, you must restart syslogd before the changes can take effect.
-
+
Configuring a Separate Log for Shorewall Messages
- There are a couple of limitations to syslogd-based logging:
-
+ There are a couple of limitations to syslogd-based logging:
+
-
If you give, for example, kern.info it's own log destination then
- that destination will also receive all kernel messages of levels 5 (notice)
+
If you give, for example, kern.info it's own log destination then
+ that destination will also receive all kernel messages of levels 5 (notice)
through 0 (emerg).
-
All kernel.info messages will go to that destination and not just
+
All kernel.info messages will go to that destination and not just
those from NetFilter.
-
-
+
+
- Beginning with Shorewall version 1.3.12, if your kernel has ULOG
-target support (and most vendor-supplied kernels do), you may also specify
-a log level of ULOG (must be all caps). When ULOG is used, Shorewall will
-direct netfilter to log the related messages via the ULOG target which will
-send them to a process called 'ulogd'. The ulogd program is available from
-http://www.gnumonks.org/projects/ulogd and can be configured to log all
-Shorewall message to their own log file.
-
- Note: The ULOG logging mechanism is completely separate from
-syslog. Once you switch to ULOG, the settings in /etc/syslog.conf have absolutely
-no effect on your Shorewall logging (except for Shorewall status messages
+ Beginning with Shorewall version 1.3.12, if your kernel has ULOG
+target support (and most vendor-supplied kernels do), you may also specify
+a log level of ULOG (must be all caps). When ULOG is used, Shorewall will
+direct netfilter to log the related messages via the ULOG target which
+will send them to a process called 'ulogd'. The ulogd program is available
+from http://www.gnumonks.org/projects/ulogd and can be configured to log
+all Shorewall message to their own log file.
+
+ Note: The ULOG logging mechanism is completely separate from
+syslog. Once you switch to ULOG, the settings in /etc/syslog.conf have absolutely
+no effect on your Shorewall logging (except for Shorewall status messages
which still go to syslog).
-
-You will need to have the kernel source available to compile ulogd.
-
-Download the ulod tar file and:
-
-
-
Be sure that /usr/src/linux is linked to your kernel source tree
-
-
cd /usr/local/src (or wherever you do your builds)
-
tar -zxf source-tarball-that-you-downloaded
-
cd ulogd-version
-
-
./configure
-
make
-
make install
-
-
-
- If you are like me and don't have a development environment on your firewall,
- you can do the first six steps on another system then either NFS mount
-your /usr/local/src directory or tar up the /usr/local/src/ulogd-version
- directory and move it to your firewall system.
-
- Now on the firewall system, edit /usr/local/etc/ulogd.conf and set:
-
-
-
syslogfile <file that you wish to log to>
-
syslogsync 1
-
-
- I also copied the file /usr/local/src/ulogd-version/ulogd.init
-to /etc/init.d/ulogd. I had to edit the line that read "daemon /usr/local/sbin/ulogd"
- to read daemon /usr/local/sbin/ulogd -d". On a RedHat system, a simple
-"chkconfig --level 3 ulogd on" starts ulogd during boot up. Your init system
-may need something else done to activate the script.
+
+ You will need to have the kernel source available to compile ulogd.
- You will need to change all instances of log levels (usually 'info') in
-your configuration files to 'ULOG' - this includes entries in the policy,
+ Download the ulod tar file and:
+
+
+
Be sure that /usr/src/linux is linked to your kernel source tree
+
+
cd /usr/local/src (or wherever you do your builds)
+
tar -zxf source-tarball-that-you-downloaded
+
cd ulogd-version
+
+
./configure
+
make
+
make install
+
+
+
+ If you are like me and don't have a development environment on your
+firewall, you can do the first six steps on another system then either
+NFS mount your /usr/local/src directory or tar up the /usr/local/src/ulogd-version
+ directory and move it to your firewall system.
+
+ Now on the firewall system, edit /usr/local/etc/ulogd.conf and set:
+
+
+
syslogfile <file that you wish to log to>
+
syslogsync 1
+
+
+ I also copied the file /usr/local/src/ulogd-version/ulogd.init
+to /etc/init.d/ulogd. I had to edit the line that read "daemon /usr/local/sbin/ulogd"
+ to read daemon /usr/local/sbin/ulogd -d". On a RedHat system, a simple "chkconfig
+ --level 3 ulogd on" starts ulogd during boot up. Your init system may need
+ something else done to activate the script.
+
+ You will need to change all instances of log levels (usually 'info') in
+your configuration files to 'ULOG' - this includes entries in the policy,
rules and shorewall.conf files. Here's what I have:
-
+
[root@gateway shorewall]# grep ULOG * policy:loc fw REJECT ULOG policy:net all DROP ULOG 10/sec:40 policy:all all REJECT ULOG rules:REJECT:ULOG loc net tcp 6667 shorewall.conf:TCP_FLAGS_LOG_LEVEL=ULOG shorewall.conf:RFC1918_LOG_LEVEL=ULOG [root@gateway shorewall]#
- Finally edit /etc/shorewall/shorewall.conf and set LOGFILE=<file
- that you wish to log to>. This tells the /sbin/shorewall program
-where to look for the log when processing its "show log", "logwatch" and
-"monitor" commands.
-
-
Updated 1/11/2003 - Tom Eastep
+ Finally edit /etc/shorewall/shorewall.conf and set LOGFILE=<file
+ that you wish to log to>. This tells the /sbin/shorewall program
+where to look for the log when processing its "show log", "logwatch" and "monitor"
+ commands.
+
+
Remember that updates to the mirrors are often delayed
- for 6-12 hours after an update to the primary rsync site. For HTML content,
- the main web site (http://shorewall.sf.net)
- is updated at the same time as the rsync site.
-
+ for 6-12 hours after an update to the primary rsync site. For HTML content,
+ the main web site (http://shorewall.sf.net)
+ is updated at the same time as the rsync site.
+
The main Shorewall Web Site is http://shorewall.sf.net
- and is located in California, USA. It is mirrored at:
-
+ and is located in California, USA. It is mirrored at:
+
iptables 1.2 or later but beware version 1.2.3 -- see the
- Errata. WARNING:
- The buggy iptables version 1.2.3 is included in RedHat
-7.2 and you should upgrade to iptables 1.2.4 prior to installing Shorewall.
+
iptables 1.2 or later but beware version 1.2.3 -- see the
+ Errata. WARNING:
+ The buggy iptables version 1.2.3 is included in RedHat
+7.2 and you should upgrade to iptables 1.2.4 prior to installing Shorewall.
Version 1.2.4 is available from RedHat
- and in the Shorewall Errata.
-
Iproute ("ip" utility). The iproute package is included
- with most distributions but may not be installed by default. The official
- download site is ftp://ftp.inr.ac.ru/ip-routing.
-
-
A Bourne shell or derivative such as bash or ash. This shell
- must have correct support for variable expansion formats ${variable%pattern
- }, ${variable%%pattern}, ${variable#pattern
- } and ${variable##pattern}.
-
Your shell must produce a sensible result when a number n (128 <=
-n <= 255) is left shifted by 24 bits. You can check this at a shell prompt
+ href="http://www.redhat.com/support/errata/RHSA-2001-144.html">from RedHat
+ and in the Shorewall Errata.
+
Iproute ("ip" utility). The iproute package is included
+ with most distributions but may not be installed by default. The official
+ download site is ftp://ftp.inr.ac.ru/ip-routing.
+
+
A Bourne shell or derivative such as bash or ash. This shell
+ must have correct support for variable expansion formats ${variable%pattern
+ }, ${variable%%pattern}, ${variable#pattern
+ } and ${variable##pattern}.
+
Your shell must produce a sensible result when a number n (128 <=
+n <= 255) is left shifted by 24 bits. You can check this at a shell prompt
by:
-
+
-
echo $((128 << 24))
-
-
The result must be either 2147483648 or -2147483648.
-
-
+
echo $((128 << 24))
+
+
The result must be either 2147483648 or -2147483648.
+
+
-
The firewall monitoring display is greatly improved if you
+
The firewall monitoring display is greatly improved if you
have awk (gawk) installed.
With thanks to Richard who reminded me once again that
we must all first walk before we can run.
- The French Translations are courtesy of Patrice Vetsel
-
-
+ The French Translations are courtesy of Patrice Vetsel
+
+
The Guides
-
+
These guides provide step-by-step instructions for configuring Shorewall
- in common firewall setups.
-
+ in common firewall setups.
+
The following guides are for users who have a single public IP address:
The above guides are designed to get your first firewall up and running
- quickly in the three most common Shorewall configurations.
-
+ quickly in the three most common Shorewall configurations.
+
The Shorewall Setup Guide (See
- Index Below) outlines the steps necessary to set up a firewall
- where there are multiple public IP addresses involved or
- if you want to learn more about Shorewall than is explained in
- the single-address guides above.
-
+ Index Below) outlines the steps necessary to set up a firewall
+ where there are multiple public IP addresses involved
+or if you want to learn more about Shorewall than is explained
+in the single-address guides above.
+
-
+
-
+
Documentation Index
-
+
The following documentation covers a variety of topics and supplements
- the QuickStart Guides
- described above. Please review the appropriate guide before
- trying to use this documentation directly.
-
+ the QuickStart
+Guides described above. Please review the appropriate
+guide before trying to use this documentation directly.
+
Extension Scripts
(How to extend Shorewall without modifying Shorewall code through the
- use of files in /etc/shorewall -- /etc/shorewall/start, /etc/shorewall/stopped,
- etc.)
This guide is intended for users who are setting up Shorewall in an environment
- where a set of public IP addresses must be managed or who want to know
- more about Shorewall than is contained in the single-address guides. Because
- the range of possible applications is so broad, the Guide will give
+
+
This guide is intended for users who are setting up Shorewall in an environment
+ where a set of public IP addresses must be managed or who want to
+ know more about Shorewall than is contained in the single-address guides. Because
+ the range of possible applications is so broad, the Guide will give
you general guidelines and will point you to other resources as necessary.
-
+
- If you run LEAF Bering, your Shorewall configuration is
- NOT what I release -- I suggest that you consider installing a stock
+ If you run LEAF Bering, your Shorewall configuration
+is NOT what I release -- I suggest that you consider installing a stock
Shorewall lrp from the shorewall.net site before you proceed.
-
-
Shorewall requires that the iproute/iproute2 package be installed (on
- RedHat, the package is called iproute). You can tell if
- this package is installed by the presence of an ip program on your
- firewall system. As root, you can use the 'which' command to check for
- this program:
-
+
+
Shorewall requires that the iproute/iproute2 package be installed (on
+ RedHat, the package is called iproute). You can tell
+if this package is installed by the presence of an ip program
+on your firewall system. As root, you can use the 'which' command to
+check for this program:
+
[root@gateway root]# which ip /sbin/ip [root@gateway root]#
-
-
I recommend that you first read through the guide to familiarize yourself
- with what's involved then go back through it again making your configuration
- changes. Points at which configuration changes are recommended are
-flagged with I recommend that you first read through the guide to familiarize yourself
+ with what's involved then go back through it again making your configuration
+ changes. Points at which configuration changes are recommended are
+ flagged with
- .
-
+ .
+
- If you edit your configuration files on a Windows system,
- you must save them as Unix files if your editor supports that option
- or you must run them through dos2unix before trying to use them with
-Shorewall. Similarly, if you copy a configuration file from your Windows
-hard drive to a floppy disk, you must run dos2unix against the copy
-before using it with Shorewall.
-
+ If you edit your configuration files on a Windows system,
+ you must save them as Unix files if your editor supports that option
+ or you must run them through dos2unix before trying to use them with Shorewall.
+ Similarly, if you copy a configuration file from your Windows hard
+drive to a floppy disk, you must run dos2unix against the copy before
+using it with Shorewall.
+
As each file is introduced, I suggest that you look through the actual
- file on your system -- each file contains detailed configuration instructions
- and some contain default entries.
-
-
Shorewall views the network where it is running as being composed of a
- set of zones. In the default installation, the following zone
- names are used:
-
+
+
As each file is introduced, I suggest that you look through the actual
+ file on your system -- each file contains detailed configuration
+instructions and some contain default entries.
+
+
Shorewall views the network where it is running as being composed of a
+ set of zones. In the default installation, the following zone
+ names are used:
Shorewall also recognizes the firewall system as its own zone - by default,
- the firewall itself is known as fw but that may be changed in
- the /etc/shorewall/shorewall.conf
- file. In this guide, the default name (fw) will be used.
-
-
With the exception of fw, Shorewall attaches absolutely no meaning
- to zone names. Zones are entirely what YOU make of them. That means
- that you should not expect Shorewall to do something special "because
+
+
Shorewall also recognizes the firewall system as its own zone - by default,
+ the firewall itself is known as fw but that may be changed
+in the /etc/shorewall/shorewall.conf
+ file. In this guide, the default name (fw) will be used.
+
+
With the exception of fw, Shorewall attaches absolutely no meaning
+ to zone names. Zones are entirely what YOU make of them. That means
+ that you should not expect Shorewall to do something special "because
this is the internet zone" or "because that is the DMZ".
-
+
- Edit the /etc/shorewall/zones file and make any changes
+ Edit the /etc/shorewall/zones file and make any changes
necessary.
-
-
Rules about what traffic to allow and what traffic to deny are expressed
- in terms of zones.
-
+
+
Rules about what traffic to allow and what traffic to deny are expressed
+ in terms of zones.
Shorewall is built on top of the Netfilter
- kernel facility. Netfilter implements a connection
- tracking function that allows what is often referred to as stateful
- inspection of packets. This stateful property allows firewall
-rules to be defined in terms of connections rather than in terms
-of packets. With Shorewall, you:
-
+
+
Shorewall is built on top of the Netfilter
+ kernel facility. Netfilter implements a connection
+ tracking function that allows what is often referred to as stateful
+ inspection of packets. This stateful property allows firewall
+ rules to be defined in terms of connections rather than in
+terms of packets. With Shorewall, you:
+
-
Identify the source zone.
-
Identify the destination zone.
-
If the POLICY from the client's zone to the
-server's zone is what you want for this client/server pair, you
+
Identify the source zone.
+
Identify the destination zone.
+
If the POLICY from the client's zone to the
+server's zone is what you want for this client/server pair, you
need do nothing further.
-
If the POLICY is not what you want, then you
-must add a rule. That rule is expressed in terms of the client's
-zone and the server's zone.
-
+
If the POLICY is not what you want, then you
+ must add a rule. That rule is expressed in terms of the client's
+ zone and the server's zone.
+
-
-
Just because connections of a particular type are allowed from zone
-A to the firewall and are also allowed from the firewall to zone B DOES NOT mean that these connections are allowed
- from zone A to zone B. It rather means that you can
- have a proxy running on the firewall that accepts a connection from
- zone A and then establishes its own separate connection from the firewall
- to zone B.
-
-
For each connection request entering the firewall, the request is first
- checked against the /etc/shorewall/rules file. If no rule in that file
- matches the connection request then the first policy in /etc/shorewall/policy
- that matches the request is applied. If that policy is REJECT or DROP
- the request is first checked against the rules in /etc/shorewall/common.def.
-
+
+
Just because connections of a particular type are allowed from zone A
+to the firewall and are also allowed from the firewall to zone B DOES NOT mean that these connections are allowed
+ from zone A to zone B. It rather means that you
+can have a proxy running on the firewall that accepts a connection
+from zone A and then establishes its own separate connection from the
+firewall to zone B.
+
+
For each connection request entering the firewall, the request is first
+ checked against the /etc/shorewall/rules file. If no rule in that
+file matches the connection request then the first policy in /etc/shorewall/policy
+ that matches the request is applied. If that policy is REJECT or DROP
+ the request is first checked against the rules in /etc/shorewall/common.def.
+
The default /etc/shorewall/policy file has the following policies:
-
-
+
+
-
+
+
+
Source Zone
+
Destination Zone
+
Policy
+
Log Level
+
Limit:Burst
+
-
Source Zone
-
Destination Zone
-
Policy
-
Log Level
-
Limit:Burst
-
-
-
loc
-
net
-
ACCEPT
-
-
-
-
-
net
-
all
-
DROP
-
info
-
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
+
loc
+
net
+
ACCEPT
+
+
+
+
+
net
+
all
+
DROP
+
info
+
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
-
-
+
+
The above policy will:
-
+
-
allow all connection requests from your local network
+
allow all connection requests from your local network
to the internet
-
drop (ignore) all connection requests from the internet
- to your firewall or local network and log a message at the info
- level (here is a description of log
- levels).
-
reject all other connection requests and log a message
- at the info level. When a request is rejected, the firewall
- will return an RST (if the protocol is TCP) or an ICMP port-unreachable
- packet for other protocols.
-
+
drop (ignore) all connection requests from the internet
+ to your firewall or local network and log a message at the info
+ level (here is a description of
+log levels).
+
reject all other connection requests and log a message
+ at the info level. When a request is rejected, the firewall
+ will return an RST (if the protocol is TCP) or an ICMP port-unreachable
+ packet for other protocols.
+
-
+
- At this point, edit your /etc/shorewall/policy and make
-any changes that you wish.
-
+ At this point, edit your /etc/shorewall/policy and make
+ any changes that you wish.
+
3.0 Network Interfaces
-
-
For the remainder of this guide, we'll refer to the following
- diagram. While it may not look like your own network, it can be used
- to illustrate the important aspects of Shorewall configuration.
-
+
+
For the remainder of this guide, we'll refer to the following
+ diagram. While it may not look like your own network, it can be used
+ to illustrate the important aspects of Shorewall configuration.
+
In this diagram:
-
+
-
The DMZ Zone consists of systems DMZ 1 and DMZ 2. A
-DMZ is used to isolate your internet-accessible servers from your
-local systems so that if one of those servers is compromised, you still
-have the firewall between the compromised system and your local systems.
-
-
The Local Zone consists of systems Local 1, Local 2
+
The DMZ Zone consists of systems DMZ 1 and DMZ 2. A
+DMZ is used to isolate your internet-accessible servers from your local
+ systems so that if one of those servers is compromised, you still have
+ the firewall between the compromised system and your local systems.
+
+
The Local Zone consists of systems Local 1, Local 2
and Local 3.
-
All systems from the ISP outward comprise the Internet
- Zone.
-
+
All systems from the ISP outward comprise the Internet
+ Zone.
+
-
+
-
-
-
The simplest way to define zones is to simply associate the
- zone name (previously defined in /etc/shorewall/zones) with a network
- interface. This is done in the
+
+
The firewall illustrated above has three network interfaces.
- Where Internet connectivity is through a cable or DSL "Modem", the
-External Interface will be the Ethernet adapter that is connected
-to that "Modem" (e.g., eth0) unless you connect via Point-to-Point
- Protocol over Ethernet (PPPoE) or Point-to-Point
- Tunneling Protocol (PPTP) in which case the External
- Interface will be a ppp interface (e.g., ppp0). If you connect
- via a regular modem, your External Interface will also be ppp0.
- If you connect using ISDN, you external interface will be ippp0.
-
+
+
The firewall illustrated above has three network interfaces.
+ Where Internet connectivity is through a cable or DSL "Modem", the
+ External Interface will be the Ethernet adapter that is connected
+ to that "Modem" (e.g., eth0) unless you connect via
+Point-to-Point Protocol over Ethernet
+(PPPoE) or Point-to-Point Tunneling Protocol
+(PPTP) in which case the External Interface will be a ppp interface
+(e.g., ppp0). If you connect via a regular modem, your External
+ Interface will also be ppp0. If you connect using ISDN, you external
+ interface will be ippp0.
+
- If your external interface is ppp0 or ippp0
+ If your external interface is ppp0 or ippp0
then you will want to set CLAMPMSS=yes in /etc/shorewall/shorewall.conf.
-
-
Your Local Interface will be an Ethernet adapter (eth0,
- eth1 or eth2) and will be connected to a hub or switch. Your local
-computers will be connected to the same switch (note: If you have only
-a single local system, you can connect the firewall directly to the computer
-using a cross-over cable).
-
-
Your DMZ Interface will also be an Ethernet adapter
- (eth0, eth1 or eth2) and will be connected to a hub or switch. Your
- DMZ computers will be connected to the same switch (note: If you have
- only a single DMZ system, you can connect the firewall directly to the
+
+
Your Local Interface will be an Ethernet adapter (eth0,
+ eth1 or eth2) and will be connected to a hub or switch. Your local
+ computers will be connected to the same switch (note: If you have
+only a single local system, you can connect the firewall directly to
+the computer using a cross-over cable).
+
+
Your DMZ Interface will also be an Ethernet adapter
+ (eth0, eth1 or eth2) and will be connected to a hub or switch. Your
+ DMZ computers will be connected to the same switch (note: If you have
+ only a single DMZ system, you can connect the firewall directly to the
computer using a cross-over cable).
-
+
- Do not connect more than one interface to the same
-hub or switch (even for testing). It won't work the way that you expect
- it to and you will end up confused and believing that Linux networking
- doesn't work at all.
-
+ Do not connect more than one interface to the same
+ hub or switch (even for testing). It won't work the way that you
+expect it to and you will end up confused and believing that Linux networking
+ doesn't work at all.
+
For the remainder of this Guide, we will assume that:
-
+
-
+
The external interface is eth0.
-
-
+
+
The Local interface is eth1.
-
-
+
+
The DMZ interface is eth2.
-
-
+
+
-
-
The Shorewall default configuration does not define the contents
- of any zone. To define the above configuration using the /etc/shorewall/interfaces
- file, that file would might contain:
-
-
+
+
The Shorewall default configuration does not define the contents
+ of any zone. To define the above configuration using the /etc/shorewall/interfaces
+ file, that file would might contain:
+
+
-
+
+
+
Zone
+
Interface
+
Broadcast
+
Options
+
-
Zone
-
Interface
-
Broadcast
-
Options
-
-
-
net
-
eth0
-
detect
-
norfc1918
-
-
-
loc
-
eth1
-
detect
-
-
-
-
dmz
-
eth2
-
detect
-
-
-
-
+
net
+
eth0
+
detect
+
norfc1918
+
+
+
loc
+
eth1
+
detect
+
+
+
+
dmz
+
eth2
+
detect
+
+
+
+
-
-
+
+
- Edit the /etc/shorewall/interfaces file and define the
-network interfaces on your firewall and associate each interface with
-a zone. If you have a zone that is interfaced through more than one interface,
- simply include one entry for each interface and repeat the zone name
-as many times as necessary.
-
+ Edit the /etc/shorewall/interfaces file and define the
+ network interfaces on your firewall and associate each interface
+with a zone. If you have a zone that is interfaced through more than
+one interface, simply include one entry for each interface and repeat
+the zone name as many times as necessary.
+
Example:
-
-
+
+
-
+
+
+
Zone
+
Interface
+
Broadcast
+
Options
+
-
Zone
-
Interface
-
Broadcast
-
Options
-
-
-
net
-
eth0
-
detect
-
norfc1918
-
-
-
loc
-
eth1
-
detect
-
-
-
-
loc
-
eth2
-
detect
-
dhcp
-
-
-
+
net
+
eth0
+
detect
+
norfc1918
+
+
+
loc
+
eth1
+
detect
+
+
+
+
loc
+
eth2
+
detect
+
dhcp
+
+
+
-
-
-
-
When you have more than one interface to a zone, you will
- usually want a policy that permits intra-zone traffic:
-
-
-
-
+
+
+
+
When you have more than one interface to a zone, you will
+ usually want a policy that permits intra-zone traffic:
+
+
+
+
-
-
-
Source Zone
-
Destination Zone
-
Policy
-
Log Level
-
Limit:Burst
-
+
-
loc
-
loc
-
ACCEPT
-
-
-
-
-
+
Source Zone
+
Destination Zone
+
Policy
+
Log Level
+
Limit:Burst
+
+
+
loc
+
loc
+
ACCEPT
+
+
+
+
+
-
-
-
+
+
+
- You may define more complicated zones using the /etc/shorewall/hosts file but in most
- cases, that isn't necessary.
-
+ You may define more complicated zones using the /etc/shorewall/hosts file but in most
+ cases, that isn't necessary.
+
4.0 Addressing, Subnets and Routing
-
-
Normally, your ISP will assign you a set of Public
- IP addresses. You will configure your firewall's external interface
-to use one of those addresses permanently and you will then have to decide
- how you are going to use the rest of your addresses. Before we tackle
-that question though, some background is in order.
-
-
If you are thoroughly familiar with IP addressing and routing,
- you may go to the next section.
-
-
The following discussion barely scratches the surface of
-addressing and routing. If you are interested in learning more about this
-subject, I highly recommend "IP Fundamentals: What Everyone Needs to
-Know about Addressing & Routing", Thomas A. Maufer, Prentice-Hall,
- 1999, ISBN 0-13-975483-0.
-
+
+
Normally, your ISP will assign you a set of Public
+ IP addresses. You will configure your firewall's external interface
+ to use one of those addresses permanently and you will then have to
+decide how you are going to use the rest of your addresses. Before we
+tackle that question though, some background is in order.
+
+
If you are thoroughly familiar with IP addressing and routing,
+ you may go to the next section.
+
+
The following discussion barely scratches the surface of addressing
+and routing. If you are interested in learning more about this subject,
+I highly recommend "IP Fundamentals: What Everyone Needs to Know about
+Addressing & Routing", Thomas A. Maufer, Prentice-Hall, 1999, ISBN
+0-13-975483-0.
+
4.1 IP Addresses
-
-
IP version 4 (IPv4) addresses are 32-bit numbers.
- The notation w.x.y.z refers to an address where the high-order byte
-has value "w", the next byte has value "x", etc. If we take the address
-192.0.2.14 and express it in hexadecimal, we get:
-
-
+
+
IP version 4 (IPv4) addresses are 32-bit numbers.
+ The notation w.x.y.z refers to an address where the high-order byte
+ has value "w", the next byte has value "x", etc. If we take the address
+ 192.0.2.14 and express it in hexadecimal, we get:
+
+
C0.00.02.0E
-
-
+
+
or looking at it as a 32-bit integer
-
-
+
+
C000020E
-
-
+
+
4.2 Subnets
-
-
You will still hear the terms "Class A network", "Class B
- network" and "Class C network". In the early days of IP, networks
-only came in three sizes (there were also Class D networks but they were
-used differently):
-
-
+
+
You will still hear the terms "Class A network", "Class B
+ network" and "Class C network". In the early days of IP, networks
+ only came in three sizes (there were also Class D networks but they
+were used differently):
+
+
Class A - netmask 255.0.0.0, size = 2 ** 24
-
+
Class B - netmask 255.255.0.0, size = 2 ** 16
-
+
Class C - netmask 255.255.255.0, size = 256
-
-
-
The class of a network was uniquely determined by the value
- of the high order byte of its address so you could look at an IP address
- and immediately determine the associated netmask. The netmask
- is a number that when logically ANDed with an address isolates the network
- number; the remainder of the address is the host number.
- For example, in the Class C address 192.0.2.14, the network number
-is hex C00002 and the host number is hex 0E.
-
-
As the internet grew, it became clear that such a gross partitioning
- of the 32-bit address space was going to be very limiting (early on, large
- corporations and universities were assigned their own class A network!).
- After some false starts, the current technique of subnetting these
- networks into smaller subnetworks evolved; that technique is referred
- to as Classless InterDomain Routing (CIDR). Today, any system that
- you are likely to work with will understand CIDR and Class-based networking
- is largely a thing of the past.
-
-
A subnetwork (often referred to as a subnet) is
- a contiguous set of IP addresses such that:
-
+
+
+
The class of a network was uniquely determined by the value
+ of the high order byte of its address so you could look at an IP
+address and immediately determine the associated netmask.
+The netmask is a number that when logically ANDed with an address isolates
+the network number; the remainder of the address is the host
+number. For example, in the Class C address 192.0.2.14, the network
+number is hex C00002 and the host number is hex 0E.
+
+
As the internet grew, it became clear that such a gross partitioning
+ of the 32-bit address space was going to be very limiting (early on, large
+ corporations and universities were assigned their own class A network!).
+ After some false starts, the current technique of subnetting these
+ networks into smaller subnetworks evolved; that technique is referred
+ to as Classless InterDomain Routing (CIDR). Today, any system that
+ you are likely to work with will understand CIDR and Class-based networking
+ is largely a thing of the past.
+
+
A subnetwork (often referred to as a subnet) is
+ a contiguous set of IP addresses such that:
+
-
+
The number of addresses in the set is a power of 2; and
-
-
-
The first address in the set is a multiple of the set
- size.
-
-
-
The first address in the subnet is reserved and is referred
- to as the subnet address.
-
-
-
The last address in the subnet is reserved as the subnet's
- broadcast address.
-
-
+
+
+
The first address in the set is a multiple of the set
+ size.
+
+
+
The first address in the subnet is reserved and is referred
+ to as the subnet address.
+
+
+
The last address in the subnet is reserved as the subnet's
+ broadcast address.
+
+
-
-
As you can see by this definition, in each subnet of size
- n there are (n - 2) usable addresses (addresses that
- can be assigned to hosts). The first and last address in the subnet
- are used for the subnet address and subnet broadcast address respectively.
- Consequently, small subnetworks are more wasteful of IP addresses
-than are large ones.
-
-
Since n is a power of two, we can easily calculate
- the Natural Logarithm (log2) of n. For the more
- common subnet sizes, the size and its natural logarithm are given in
-the following table:
-
-
+
+
As you can see by this definition, in each subnet of size
+ n there are (n - 2) usable addresses (addresses that
+ can be assigned to hosts). The first and last address in the subnet
+ are used for the subnet address and subnet broadcast address respectively.
+ Consequently, small subnetworks are more wasteful of IP addresses
+ than are large ones.
+
+
Since n is a power of two, we can easily calculate
+ the Natural Logarithm (log2) of n. For the
+more common subnet sizes, the size and its natural logarithm are given
+in the following table:
+
+
-
+
+
+
n
+
log2 n
+
(32 - log2 n)
+
-
n
-
log2 n
-
(32 - log2 n)
-
-
-
8
-
3
-
29
-
-
-
16
-
4
-
28
-
-
-
32
-
5
-
27
-
-
-
64
-
6
-
26
-
-
-
128
-
7
-
25
-
-
-
256
-
8
-
24
-
-
-
512
-
9
-
23
-
-
-
1024
-
10
-
22
-
-
-
2048
-
11
-
21
-
-
-
4096
-
12
-
20
-
-
-
8192
-
13
-
19
-
-
-
16384
-
14
-
18
-
-
-
32768
-
15
-
17
-
-
-
65536
-
16
-
16
-
-
-
+
8
+
3
+
29
+
+
+
16
+
4
+
28
+
+
+
32
+
5
+
27
+
+
+
64
+
6
+
26
+
+
+
128
+
7
+
25
+
+
+
256
+
8
+
24
+
+
+
512
+
9
+
23
+
+
+
1024
+
10
+
22
+
+
+
2048
+
11
+
21
+
+
+
4096
+
12
+
20
+
+
+
8192
+
13
+
19
+
+
+
16384
+
14
+
18
+
+
+
32768
+
15
+
17
+
+
+
65536
+
16
+
16
+
+
+
-
-
-
You will notice that the above table also contains a column
- for (32 - log2 n). That number is the Variable Length Subnet
- Mask for a network of size n. From the above table, we
- can derive the following one which is a little easier to use.
-
-
+
+
+
You will notice that the above table also contains a column
+ for (32 - log2 n). That number is the Variable Length
+Subnet Mask for a network of size n. From the above table,
+we can derive the following one which is a little easier to use.
+
+
-
+
+
+
Size of Subnet
+
VLSM
+
Subnet Mask
+
-
Size of Subnet
-
VLSM
-
Subnet Mask
-
-
-
8
-
/29
-
255.255.255.248
-
-
-
16
-
/28
-
255.255.255.240
-
-
-
32
-
/27
-
255.255.255.224
-
-
-
64
-
/26
-
255.255.255.192
-
-
-
128
-
/25
-
255.255.255.128
-
-
-
256
-
/24
-
255.255.255.0
-
-
-
512
-
/23
-
255.255.254.0
-
-
-
1024
-
/22
-
255.255.252.0
-
-
-
2048
-
/21
-
255.255.248.0
-
-
-
4096
-
/20
-
255.255.240.0
-
-
-
8192
-
/19
-
255.255.224.0
-
-
-
16384
-
/18
-
255.255.192.0
-
-
-
32768
-
/17
-
255.255.128.0
-
-
-
65536
-
/16
-
255.255.0.0
-
-
-
2 ** 24
-
/8
-
255.0.0.0
-
-
-
+
8
+
/29
+
255.255.255.248
+
+
+
16
+
/28
+
255.255.255.240
+
+
+
32
+
/27
+
255.255.255.224
+
+
+
64
+
/26
+
255.255.255.192
+
+
+
128
+
/25
+
255.255.255.128
+
+
+
256
+
/24
+
255.255.255.0
+
+
+
512
+
/23
+
255.255.254.0
+
+
+
1024
+
/22
+
255.255.252.0
+
+
+
2048
+
/21
+
255.255.248.0
+
+
+
4096
+
/20
+
255.255.240.0
+
+
+
8192
+
/19
+
255.255.224.0
+
+
+
16384
+
/18
+
255.255.192.0
+
+
+
32768
+
/17
+
255.255.128.0
+
+
+
65536
+
/16
+
255.255.0.0
+
+
+
2 ** 24
+
/8
+
255.0.0.0
+
+
+
-
-
-
Notice that the VLSM is written with a slash ("/") -- you
- will often hear a subnet of size 64 referred to as a "slash 26" subnet
- and one of size 8 referred to as a "slash 29".
-
-
The subnet's mask (also referred to as its netmask) is
- simply a 32-bit number with the first "VLSM" bits set to one and
-the remaining bits set to zero. For example, for a subnet of size 64,
-the subnet mask has 26 leading one bits:
The subnet mask has the property that if you logically AND
- the subnet mask with an address in the subnet, the result is the
-subnet address. Just as important, if you logically AND the subnet
-mask with an address outside the subnet, the result is NOT the subnet
-address. As we will see below, this property of subnet masks is very
-useful in routing.
-
-
For a subnetwork whose address is a.b.c.d and whose
- Variable Length Subnet Mask is /v, we denote the subnetwork
- as "a.b.c.d/v" using CIDRNotation.
-
+
+
+
Notice that the VLSM is written with a slash ("/") -- you
+ will often hear a subnet of size 64 referred to as a "slash 26"
+subnet and one of size 8 referred to as a "slash 29".
+
+
The subnet's mask (also referred to as its netmask) is
+ simply a 32-bit number with the first "VLSM" bits set to one and
+ the remaining bits set to zero. For example, for a subnet of size
+64, the subnet mask has 26 leading one bits:
The subnet mask has the property that if you logically AND
+ the subnet mask with an address in the subnet, the result is the
+ subnet address. Just as important, if you logically AND the subnet
+ mask with an address outside the subnet, the result is NOT the subnet
+ address. As we will see below, this property of subnet masks is very
+ useful in routing.
+
+
For a subnetwork whose address is a.b.c.d and whose
+ Variable Length Subnet Mask is /v, we denote the subnetwork
+ as "a.b.c.d/v" using CIDRNotation.
+
Example:
-
-
+
+
-
-
-
Subnet:
-
10.10.10.0 - 10.10.10.127
-
+
-
Subnet Size:
-
128
-
-
-
Subnet Address:
-
10.10.10.0
-
-
-
Broadcast Address:
-
10.10.10.127
-
-
-
CIDR Notation:
-
10.10.10.0/25
-
-
-
+
Subnet:
+
10.10.10.0 - 10.10.10.127
+
+
+
Subnet Size:
+
128
+
+
+
Subnet Address:
+
10.10.10.0
+
+
+
Broadcast Address:
+
10.10.10.127
+
+
+
CIDR Notation:
+
10.10.10.0/25
+
+
+
-
-
-
There are two degenerate subnets that need mentioning; namely,
- the subnet with one member and the subnet with 2 ** 32 members.
-
-
+
+
+
There are two degenerate subnets that need mentioning; namely,
+ the subnet with one member and the subnet with 2 ** 32 members.
+
+
-
+
+
+
Size of Subnetwork
+
VLSM Length
+
Subnet Mask
+
CIDR Notation
+
-
Size of Subnetwork
-
VLSM Length
-
Subnet Mask
-
CIDR Notation
-
-
-
1
-
32
-
255.255.255.255
-
a.b.c.d/32
-
-
-
2 ** 32
-
0
-
0.0.0.0
-
0.0.0.0/0
-
-
-
+
1
+
32
+
255.255.255.255
+
a.b.c.d/32
+
+
+
2 ** 32
+
0
+
0.0.0.0
+
0.0.0.0/0
+
+
+
-
-
-
So any address a.b.c.d may also be written a.b.c.d/32
- and the set of all possible IP addresses is written 0.0.0.0/0.
-
-
Later in this guide, you will see the notation a.b.c.d/v
- used to describe the ip configuration of a network interface (the 'ip'
- utility also uses this syntax). This simply means that the interface
- is configured with ip address a.b.c.d and with the netmask that
+
+
+
So any address a.b.c.d may also be written a.b.c.d/32
+ and the set of all possible IP addresses is written 0.0.0.0/0.
+
+
Later in this guide, you will see the notation a.b.c.d/v
+ used to describe the ip configuration of a network interface (the
+'ip' utility also uses this syntax). This simply means that the interface
+ is configured with ip address a.b.c.d and with the netmask that
corresponds to VLSM /v.
-
+
Example: 192.0.2.65/29
-
-
The interface is configured with IP address 192.0.2.65
- and netmask 255.255.255.248.
-
-
Beginning with Shorewall 1.4.6, /sbin/shorewall supports
-an ipcalc command that automatically calculates information about
-a [sub]network.
-
+
+
The interface is configured with IP address 192.0.2.65
+ and netmask 255.255.255.248.
+
+
+
Beginning with Shorewall 1.4.6, /sbin/shorewall supports an
+ipcalc command that automatically calculates information about a [sub]network.
+
The device texas is a GRE tunnel to a peer site in
- the Dallas, Texas area.
-
- The first three routes are host routes since they indicate
- how to get to a single host. In the 'netstat' output this can be seen
- by the "Genmask" (Subnet Mask) of 255.255.255.255 and the "H" in the
- Flags column. The remainder are 'net' routes since they tell the kernel
- how to route packets to a subnetwork. The last route is the default
- route and the gateway mentioned in that route is called the default
- gateway.
-
-
When the kernel is trying to send a packet to IP address
-A, it starts at the top of the routing table and:
-
+
+
+
+
The device texas is a GRE tunnel to a peer site in
+ the Dallas, Texas area.
+
+ The first three routes are host routes since they
+indicate how to get to a single host. In the 'netstat' output this
+can be seen by the "Genmask" (Subnet Mask) of 255.255.255.255 and
+the "H" in the Flags column. The remainder are 'net' routes since they
+tell the kernel how to route packets to a subnetwork. The last route
+is the default route and the gateway mentioned in that route is
+called the default gateway.
+
+
When the kernel is trying to send a packet to IP address A,
+ it starts at the top of the routing table and:
+
-
-
A is logically ANDed with the 'Genmask' value
-in the table entry.
-
-
-
The result is compared with the 'Destination' value in
- the table entry.
-
-
-
If the result and the 'Destination' value are the same,
- then:
-
+
+
A is logically ANDed with the 'Genmask' value in
+the table entry.
+
+
+
The result is compared with the 'Destination' value in
+ the table entry.
+
+
+
If the result and the 'Destination' value are the same,
+ then:
+
-
-
If the 'Gateway' column is non-zero, the packet is
- sent to the gateway over the interface named in the 'Iface' column.
-
-
-
Otherwise, the packet is sent directly to A over
- the interface named in the 'iface' column.
-
-
+
+
+
If the 'Gateway' column is non-zero, the packet is
+ sent to the gateway over the interface named in the 'Iface' column.
+
+
+
+
Otherwise, the packet is sent directly to A over
+ the interface named in the 'iface' column.
+
+
-
-
-
Otherwise, the above steps are repeated on the next entry
- in the table.
-
-
+
+
+
Otherwise, the above steps are repeated on the next entry
+ in the table.
+
+
-
-
Since the default route matches any IP address (A
-land 0.0.0.0 = 0.0.0.0), packets that don't match any of the other routing
-table entries are sent to the default gateway which is usually a
-router at your ISP.
-
-
Lets take an example. Suppose that we want to route a packet
- to 192.168.1.5. That address clearly doesn't match any of the host
-routes in the table but if we logically and that address with 255.255.255.0,
- the result is 192.168.1.0 which matches this routing table entry:
-
-
-
+
+
Since the default route matches any IP address (A land
+ 0.0.0.0 = 0.0.0.0), packets that don't match any of the other routing table
+ entries are sent to the default gateway which is usually a router
+at your ISP.
+
+
Lets take an example. Suppose that we want to route a packet
+ to 192.168.1.5. That address clearly doesn't match any of the host
+ routes in the table but if we logically and that address with 255.255.255.0,
+ the result is 192.168.1.0 which matches this routing table entry:
+
+
+
192.168.1.0 0.0.0.0 255.255.255.0 U 40 0 0 eth2
-
-
-
So to route a packet to 192.168.1.5, the packet is sent directly over
-eth2.
-
-
-
One more thing needs to be emphasized -- all outgoing packet
- are sent using the routing table and reply packets are not a special
- case. There seems to be a common mis-conception whereby people think
- that request packets are like salmon and contain a genetic code that
- is magically transferred to reply packets so that the replies follow
-the reverse route taken by the request. That isn't the case; the replies
-may take a totally different route back to the client than was taken by
+
+
+
So to route a packet to 192.168.1.5, the packet is sent directly over eth2.
+
+
+
One more thing needs to be emphasized -- all outgoing packet
+ are sent using the routing table and reply packets are not a special
+ case. There seems to be a common mis-conception whereby people think
+ that request packets are like salmon and contain a genetic code that
+ is magically transferred to reply packets so that the replies follow
+the reverse route taken by the request. That isn't the case; the replies
+may take a totally different route back to the client than was taken by
the requests -- they are totally independent.
-
+
4.4 Address Resolution Protocol (ARP)
-
-
When sending packets over Ethernet, IP addresses aren't used.
- Rather Ethernet addressing is based on Media Access Control
-(MAC) addresses. Each Ethernet device has it's own unique MAC address
-which is burned into a PROM on the device during manufacture. You can
-obtain the MAC of an Ethernet device using the 'ip' utility:
-
-
-
+
+
When sending packets over Ethernet, IP addresses aren't used.
+ Rather Ethernet addressing is based on Media Access Control
+ (MAC) addresses. Each Ethernet device has it's own unique MAC address
+ which is burned into a PROM on the device during manufacture. You can
+ obtain the MAC of an Ethernet device using the 'ip' utility:
+
+
+
[root@gateway root]# ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc htb qlen 100 link/ether 02:00:08:e3:fa:55 brd ff:ff:ff:ff:ff:ff inet 206.124.146.176/24 brd 206.124.146.255 scope global eth0 inet 206.124.146.178/24 brd 206.124.146.255 scope global secondary eth0 inet 206.124.146.179/24 brd 206.124.146.255 scope global secondary eth0 [root@gateway root]#
-
-
-
-
-
As you can see from the above output, the MAC is 6 bytes
-(48 bits) wide. A card's MAC is usually also printed on a label attached
-to the card itself.
-
-
-
-
Because IP uses IP addresses and Ethernet uses MAC addresses,
- a mechanism is required to translate an IP address into a MAC address;
- that is the purpose of the Address Resolution Protocol (ARP).
- Here is ARP in action:
-
-
-
-
-
+
+
+
+
+
As you can see from the above output, the MAC is 6 bytes (48
+ bits) wide. A card's MAC is usually also printed on a label attached to
+the card itself.
+
+
+
+
Because IP uses IP addresses and Ethernet uses MAC addresses,
+ a mechanism is required to translate an IP address into a MAC address;
+ that is the purpose of the Address Resolution Protocol (ARP).
+ Here is ARP in action:
2 packets received by filter 0 packets dropped by kernel [root@gateway root]#
-
-
-
-
-
In this exchange, 192.168.1.254 (MAC 2:0:8:e3:4c:48) wants
- to know the MAC of the device with IP address 192.168.1.19. The system
- having that IP address is responding that the MAC address of the device
- with IP address 192.168.1.19 is 0:6:25:aa:8a:f0.
-
-
In order to avoid having to exchange ARP information each
- time that an IP packet is to be sent, systems maintain an ARP cache
- of IP<->MAC correspondences. You can see the ARP cache on your
- system (including your Windows system) using the 'arp' command:
-
-
-
+
+
+
+
+
In this exchange, 192.168.1.254 (MAC 2:0:8:e3:4c:48) wants
+ to know the MAC of the device with IP address 192.168.1.19. The system
+ having that IP address is responding that the MAC address of the device
+ with IP address 192.168.1.19 is 0:6:25:aa:8a:f0.
+
+
In order to avoid having to exchange ARP information each
+ time that an IP packet is to be sent, systems maintain an ARP
+cache of IP<->MAC correspondences. You can see the ARP
+cache on your system (including your Windows system) using the 'arp'
+command:
+
+
+
[root@gateway root]# arp -na ? (206.124.146.177) at 00:A0:C9:15:39:78 [ether] on eth1 ? (192.168.1.3) at 00:A0:CC:63:66:89 [ether] on eth2 ? (192.168.1.5) at 00:A0:CC:DB:31:C4 [ether] on eth2 ? (206.124.146.254) at 00:03:6C:8A:18:38 [ether] on eth0 ? (192.168.1.19) at 00:06:25:AA:8A:F0 [ether] on eth2
-
-
-
-
The leading question marks are a result of my having specified
- the 'n' option (Windows 'arp' doesn't allow that option) which causes
- the 'arp' program to forego IP->DNS name translation. Had I not given
- that option, the question marks would have been replaced with the FQDN
- corresponding to each IP address. Notice that the last entry in the
-table records the information we saw using tcpdump above.
-
+
+
+
+
The leading question marks are a result of my having specified
+ the 'n' option (Windows 'arp' doesn't allow that option) which causes
+ the 'arp' program to forego IP->DNS name translation. Had I not
+given that option, the question marks would have been replaced with
+the FQDN corresponding to each IP address. Notice that the last entry
+in the table records the information we saw using tcpdump above.
+
4.5 RFC 1918
-
+
IP addresses are allocated by the Internet Assigned Number Authority(IANA)
- who delegates allocations on a geographic basis to Regional Internet
- Registries (RIRs). For example, allocation for the Americas and
-for sub-Sahara Africa is delegated to the American Registry for Internet Numbers
- (ARIN). These RIRs may in turn delegate to national registries.
-Most of us don't deal with these registrars but rather get our IP addresses
- from our ISP.
-
-
It's a fact of life that most of us can't afford as many
-Public IP addresses as we have devices to assign them to so we end up making
-use of Private IP addresses. RFC 1918 reserves several IP address
-ranges for this purpose:
-
-
+ href="http://www.iana.org">Internet Assigned Number Authority (IANA)
+ who delegates allocations on a geographic basis to Regional Internet
+ Registries (RIRs). For example, allocation for the Americas and
+ for sub-Sahara Africa is delegated to the American Registry for Internet Numbers
+ (ARIN). These RIRs may in turn delegate to national registries.
+ Most of us don't deal with these registrars but rather get our IP addresses
+ from our ISP.
+
+
It's a fact of life that most of us can't afford as many Public
+ IP addresses as we have devices to assign them to so we end up making use
+of Private IP addresses. RFC 1918 reserves several IP address ranges
+for this purpose:
The addresses reserved by RFC 1918 are sometimes referred
+ to as non-routable because the Internet backbone routers
+don't forward packets which have an RFC-1918 destination address.
+This is understandable given that anyone can select any of these
+addresses for their private use.
-
-
-
The addresses reserved by RFC 1918 are sometimes referred
- to as non-routable because the Internet backbone routers don't
- forward packets which have an RFC-1918 destination address. This
-is understandable given that anyone can select any of these addresses
- for their private use.
-
-
-
-
When selecting addresses from these ranges, there's a couple
- of things to keep in mind:
-
-
-
+
+
+
When selecting addresses from these ranges, there's a couple
+ of things to keep in mind:
+
+
+
-
-
As the IPv4 address space becomes depleted, more and
-more organizations (including ISPs) are beginning to use RFC 1918 addresses
- in their infrastructure.
-
-
-
You don't want to use addresses that are being used by
- your ISP or by another organization with whom you want to establish
- a VPN relationship.
-
-
+
+
As the IPv4 address space becomes depleted, more and more
+ organizations (including ISPs) are beginning to use RFC 1918 addresses
+ in their infrastructure.
+
+
+
You don't want to use addresses that are being used by
+ your ISP or by another organization with whom you want to establish
+ a VPN relationship.
+
+
+
+
+
+
So it's a good idea to check with your ISP to see if they
+ are using (or are planning to use) private addresses before you
+decide the addresses that you are going to use.
-
-
-
So it's a good idea to check with your ISP to see if they
- are using (or are planning to use) private addresses before you decide
- the addresses that you are going to use.
-
-
-
+
+
5.0 Setting up your Network
-
-
-
-
The choice of how to set up your network depends primarily
- on how many Public IP addresses you have vs. how many addressable
- entities you have in your network. Regardless of how many addresses
- you have, your ISP will handle that set of addresses in one of two
+
+
+
+
The choice of how to set up your network depends primarily
+ on how many Public IP addresses you have vs. how many addressable
+ entities you have in your network. Regardless of how many addresses
+ you have, your ISP will handle that set of addresses in one of two
ways:
-
-
-
-
-
-
Routed - Traffic to any of your addresses will
- be routed through a single gateway address. This will generally
- only be done if your ISP has assigned you a complete subnet (/29
-or larger). In this case, you will assign the gateway address as the
-IP address of your firewall/router's external interface.
-
-
-
Non-routed - Your ISP will send traffic to each
- of your addresses directly.
-
-
-
-
-
-
In the subsections that follow, we'll look at each of these
- separately.
-
-
+
+
+
+
+
Routed - Traffic to any of your addresses will
+ be routed through a single gateway address. This will generally
+ only be done if your ISP has assigned you a complete subnet (/29
+ or larger). In this case, you will assign the gateway address as
+the IP address of your firewall/router's external interface.
+
+
+
+
Non-routed - Your ISP will send traffic to each
+ of your addresses directly.
+
+
+
+
+
+
+
In the subsections that follow, we'll look at each of these
+ separately.
+
+
Before we begin, there is one thing for you to check:
-
+
- If you are using the Debian package, please check your shorewall.conf
- file to ensure that the following are set correctly; if they are not,
- change them appropriately:
-
-
+ If you are using the Debian package, please check your
+shorewall.conf file to ensure that the following are set correctly;
+if they are not, change them appropriately:
+
+
-
NAT_ENABLED=Yes (Shorewall versions earlier than 1.4.6)
-
IP_FORWARDING=On
-
-
+
NAT_ENABLED=Yes (Shorewall versions earlier than 1.4.6)
+
IP_FORWARDING=On
+
+
-
-
-
-
5.1 Routed
-
-
-
Let's assume that your ISP has assigned you the subnet 192.0.2.64/28
- routed through 192.0.2.65. That means that you have IP addresses
- 192.0.2.64 - 192.0.2.79 and that your firewall's external IP address
-is 192.0.2.65. Your ISP has also told you that you should use a netmask
- of 255.255.255.0 (so your /28 is part of a larger /24). With this
-many IP addresses, you are able to subnet your /28 into two /29's
-and set up your network as shown in the following diagram.
-
-
-
+
+
+
5.1 Routed
+
+
+
+
Let's assume that your ISP has assigned you the subnet 192.0.2.64/28
+ routed through 192.0.2.65. That means that you have IP addresses
+192.0.2.64 - 192.0.2.79 and that your firewall's external IP address is
+ 192.0.2.65. Your ISP has also told you that you should use a netmask
+ of 255.255.255.0 (so your /28 is part of a larger /24). With this many
+ IP addresses, you are able to subnet your /28 into two /29's and set
+ up your network as shown in the following diagram.
+
+
+
-
-
-
-
-
Here, the DMZ comprises the subnet 192.0.2.64/29 and the
-Local network is 192.0.2.72/29. The default gateway for hosts in the DMZ
-would be configured to 192.0.2.66 and the default gateway for hosts in
-the local network would be 192.0.2.73.
-
-
-
-
Notice that this arrangement is rather wasteful of public
- IP addresses since it is using 192.0.2.64 and 192.0.2.72 for subnet
- addresses, 192.0.2.71 and 192.0.2.79 for subnet broadcast addresses
- and 192.0.2.66 and 168.0.2.73 for internal addresses on the firewall/router.
- Nevertheless, it shows how subnetting can work and if we were dealing
- with a /24 rather than a /28 network, the use of 6 IP addresses out
- of 256 would be justified because of the simplicity of the setup.
-
-
-
-
The astute reader may have noticed that the Firewall/Router's
- external interface is actually part of the DMZ subnet (192.0.2.64/29).
- What if DMZ 1 (192.0.2.67) tries to communicate with 192.0.2.65?
-The routing table on DMZ 1 will look like this:
-
-
-
-
+
+
+
+
+
Here, the DMZ comprises the subnet 192.0.2.64/29 and the Local
+ network is 192.0.2.72/29. The default gateway for hosts in the DMZ would
+be configured to 192.0.2.66 and the default gateway for hosts in the local
+ network would be 192.0.2.73.
+
+
+
+
Notice that this arrangement is rather wasteful of public
+ IP addresses since it is using 192.0.2.64 and 192.0.2.72 for subnet
+ addresses, 192.0.2.71 and 192.0.2.79 for subnet broadcast addresses
+ and 192.0.2.66 and 168.0.2.73 for internal addresses on the firewall/router.
+ Nevertheless, it shows how subnetting can work and if we were dealing
+ with a /24 rather than a /28 network, the use of 6 IP addresses
+out of 256 would be justified because of the simplicity of the setup.
+
+
+
+
The astute reader may have noticed that the Firewall/Router's
+ external interface is actually part of the DMZ subnet (192.0.2.64/29).
+ What if DMZ 1 (192.0.2.67) tries to communicate with 192.0.2.65?
+ The routing table on DMZ 1 will look like this:
+
+
+
+
Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 192.0.2.64 0.0.0.0 255.255.255.248 U 40 0 0 eth0 0.0.0.0 192.0.2.66 0.0.0.0 UG 40 0 0 eth0
-
+
+
+
+
+
This means that DMZ 1 will send an ARP "who-has 192.0.2.65"
+ request and no device on the DMZ Ethernet segment has that IP address.
+ Oddly enough, the firewall will respond to the request with the
+MAC address of its DMZ Interface!! DMZ 1 can then send Ethernet
+ frames addressed to that MAC address and the frames will be received
+ (correctly) by the firewall/router.
-
-
-
This means that DMZ 1 will send an ARP "who-has 192.0.2.65"
- request and no device on the DMZ Ethernet segment has that IP address.
- Oddly enough, the firewall will respond to the request with the MAC
- address of its DMZ Interface!! DMZ 1 can then send Ethernet
-frames addressed to that MAC address and the frames will be received
-(correctly) by the firewall/router.
-
-
-
-
It is this rather unexpected ARP behavior on the part of
-the Linux Kernel that prompts the warning earlier in this guide regarding
-the connecting of multiple firewall/router interfaces to the same hub
-or switch. When an ARP request for one of the firewall/router's IP addresses
-is sent by another system connected to the hub/switch, all of the firewall's
- interfaces that connect to the hub/switch can respond! It is then
+
+
+
It is this rather unexpected ARP behavior on the part of the
+ Linux Kernel that prompts the warning earlier in this guide regarding the
+ connecting of multiple firewall/router interfaces to the same hub or switch.
+ When an ARP request for one of the firewall/router's IP addresses is sent
+by another system connected to the hub/switch, all of the firewall's
+ interfaces that connect to the hub/switch can respond! It is then
a race as to which "here-is" response reaches the sender first.
-
-
-
+
+
+
5.2 Non-routed
+
+
+
+
If you have the above situation but it is non-routed, you
+can configure your network exactly as described above with one additional
+ twist; simply specify the "proxyarp" option on all three firewall
+ interfaces in the /etc/shorewall/interfaces file.
-
-
-
If you have the above situation but it is non-routed,
-you can configure your network exactly as described above with one additional
- twist; simply specify the "proxyarp" option on all three firewall
- interfaces in the /etc/shorewall/interfaces file.
-
-
-
-
Most of us don't have the luxury of having enough public
-IP addresses to set up our networks as shown in the preceding example
-(even if the setup is routed).
-
-
-
-
For the remainder of this section, assume that your ISP
- has assigned you IP addresses 192.0.2.176-180 and has told you to
- use netmask 255.255.255.0 and default gateway 192.0.2.254.
-
-
-
-
Clearly, that set of addresses doesn't comprise a subnetwork
- and there aren't enough addresses for all of the network interfaces.
- There are four different techniques that can be used to work around
- this problem.
-
-
-
+
+
+
Most of us don't have the luxury of having enough public IP
+ addresses to set up our networks as shown in the preceding example (even
+if the setup is routed).
+
+
+
+
For the remainder of this section, assume that your ISP
+ has assigned you IP addresses 192.0.2.176-180 and has told you
+to use netmask 255.255.255.0 and default gateway 192.0.2.254.
+
+
+
+
Clearly, that set of addresses doesn't comprise a subnetwork
+ and there aren't enough addresses for all of the network interfaces.
+ There are four different techniques that can be used to work around
+ this problem.
+
+
+
-
-
Source Network Address Translation (SNAT).
-
-
-
-
Destination Network Address Translation (DNAT)
- also known as Port Forwarding.
-
-
+
+
Source Network Address Translation (SNAT).
+
+
+
+
Destination Network Address Translation (DNAT)
+ also known as Port Forwarding.
+
+
Proxy ARP.
-
-
-
Network Address Translation (NAT) also referred
- to as Static NAT.
-
-
+
+
+
Network Address Translation (NAT) also referred
+ to as Static NAT.
+
+
+
+
+
+
Often a combination of these techniques is used. Each of these
+ will be discussed in the sections that follow.
-
-
-
Often a combination of these techniques is used. Each of
-these will be discussed in the sections that follow.
-
-
-
+
+
5.2.1 SNAT
-
-
-
-
With SNAT, an internal LAN segment is configured using RFC
- 1918 addresses. When a host A on this internal segment initiates
- a connection to host B on the internet, the firewall/router
- rewrites the IP header in the request to use one of your public IP
- addresses as the source address. When B responds and the response
- is received by the firewall, the firewall changes the destination
-address back to the RFC 1918 address of A and forwards the response
+
+
+
+
With SNAT, an internal LAN segment is configured using RFC
+ 1918 addresses. When a host A on this internal segment initiates
+ a connection to host B on the internet, the firewall/router
+ rewrites the IP header in the request to use one of your public
+IP addresses as the source address. When B responds and the
+response is received by the firewall, the firewall changes the destination
+address back to the RFC 1918 address of A and forwards the response
back to A.
-
-
-
-
Let's suppose that you decide to use SNAT on your local zone
- and use public address 192.0.2.176 as both your firewall's external
- IP address and the source IP address of internet requests sent from
- that zone.
-
-
-
+
+
+
+
Let's suppose that you decide to use SNAT on your local zone
+ and use public address 192.0.2.176 as both your firewall's external
+ IP address and the source IP address of internet requests sent from
+ that zone.
+
+
+
-
-
-
-
The local zone has been subnetted as 192.168.201.0/29
- (netmask 255.255.255.248).
-
+
+
+
+
The local zone has been subnetted as 192.168.201.0/29
+ (netmask 255.255.255.248).
+
-
+
- The systems in the local zone would be configured with
- a default gateway of 192.168.201.1 (the IP address of the firewall's
- local interface).
-
+ The systems in the local zone would be configured with
+ a default gateway of 192.168.201.1 (the IP address of the firewall's
+ local interface).
This example used the normal technique of assigning the same
+ public IP address for the firewall external interface and for SNAT.
+ If you wanted to use a different IP address, you would either have
+ to use your distributions network configuration tools to add that
+IP address to the external interface or you could set ADD_SNAT_ALIASES=Yes
+ in /etc/shorewall/shorewall.conf and Shorewall will add the address for
+ you.
-
-
-
This example used the normal technique of assigning the same
- public IP address for the firewall external interface and for SNAT.
- If you wanted to use a different IP address, you would either have
- to use your distributions network configuration tools to add that
-IP address to the external interface or you could set ADD_SNAT_ALIASES=Yes
- in /etc/shorewall/shorewall.conf and Shorewall will add the address
-for you.
-
-
-
+
+
5.2.2 DNAT
+
+
+
+
When SNAT is used, it is impossible for hosts on the internet
+ to initiate a connection to one of the internal systems since those
+ systems do not have a public IP address. DNAT provides a way to
+allow selected connections from the internet.
-
-
-
When SNAT is used, it is impossible for hosts on the internet
- to initiate a connection to one of the internal systems since those
- systems do not have a public IP address. DNAT provides a way to allow
- selected connections from the internet.
-
-
-
+
+
- Suppose that your daughter wants to run a web server
- on her system "Local 3". You could allow connections to the internet
- to her server by adding the following entry in /etc/shorewall/rules:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL DESTINATION
-
+
-
DNAT
-
net
-
loc:192.168.201.4
-
tcp
-
www
-
-
-
192.0.2.176
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL DESTINATION
+
+
+
DNAT
+
net
+
loc:192.168.201.4
+
tcp
+
www
+
-
+
192.0.2.176
+
+
+
-
-
-
-
-
If one of your daughter's friends at address A wants
- to access your daughter's server, she can connect to http://192.0.2.176 (the firewall's external
- IP address) and the firewall will rewrite the destination IP address
- to 192.168.201.4 (your daughter's system) and forward the request.
- When your daughter's server responds, the firewall will rewrite the
+
+
+
+
+
If one of your daughter's friends at address A wants
+ to access your daughter's server, she can connect to http://192.0.2.176 (the firewall's external
+ IP address) and the firewall will rewrite the destination IP address
+ to 192.168.201.4 (your daughter's system) and forward the request.
+ When your daughter's server responds, the firewall will rewrite the
source address back to 192.0.2.176 and send the response back to A.
-
-
-
-
This example used the firewall's external IP address for
-DNAT. You can use another of your public IP addresses but Shorewall will
-not add that address to the firewall's external interface for you.
-
-
-
+
+
+
+
This example used the firewall's external IP address for DNAT.
+ You can use another of your public IP addresses but Shorewall will not
+add that address to the firewall's external interface for you.
+
+
+
5.2.3 Proxy ARP
-
-
-
+
+
+
The idea behind proxy ARP is that:
-
-
-
-
-
-
A host H behind your firewall is assigned one
-of your public IP addresses (A) and is assigned the same netmask
- (M) as the firewall's external interface.
-
-
-
The firewall responds to ARP "who has" requests for A.
-
-
-
-
When H issues an ARP "who has" request for an
-address in the subnetwork defined by A and M, the firewall
-will respond (with the MAC if the firewall interface to H).
-
-
-
-
-
-
Let suppose that we decide to use Proxy ARP on the DMZ in
- our example network.
-
-
-
+
+
+
+
+
A host H behind your firewall is assigned one of
+your public IP addresses (A) and is assigned the same netmask
+ (M) as the firewall's external interface.
+
+
+
The firewall responds to ARP "who has" requests for A.
+
+
+
+
When H issues an ARP "who has" request for an address
+ in the subnetwork defined by A and M, the firewall will
+respond (with the MAC if the firewall interface to H).
+
+
+
+
+
+
+
Let suppose that we decide to use Proxy ARP on the DMZ in
+ our example network.
+
+
+
-
-
-
-
Here, we've assigned the IP addresses 192.0.2.177 to
- system DMZ 1 and 192.0.2.178 to DMZ 2. Notice that we've just assigned
- an arbitrary RFC 1918 IP address and subnet mask to the DMZ interface
- on the firewall. That address and netmask isn't relevant - just be
- sure it doesn't overlap another subnet that you've defined.
-
+
+
+
+
Here, we've assigned the IP addresses 192.0.2.177 to
+ system DMZ 1 and 192.0.2.178 to DMZ 2. Notice that we've just assigned
+ an arbitrary RFC 1918 IP address and subnet mask to the DMZ interface
+ on the firewall. That address and netmask isn't relevant - just
+be sure it doesn't overlap another subnet that you've defined.
+
-
+
- The Shorewall configuration of Proxy ARP is done using
- the /etc/shorewall/proxyarp
-file.
-
-
-
+ The Shorewall configuration of Proxy ARP is done using
+ the /etc/shorewall/proxyarp
+ file.
+
+
+
-
-
-
ADDRESS
-
INTERFACE
-
EXTERNAL
-
HAVE ROUTE
-
+
-
192.0.2.177
-
eth2
-
eth0
-
No
-
-
-
192.0.2.178
-
eth2
-
eth0
-
No
-
-
-
+
ADDRESS
+
INTERFACE
+
EXTERNAL
+
HAVE ROUTE
+
+
+
192.0.2.177
+
eth2
+
eth0
+
No
+
+
+
192.0.2.178
+
eth2
+
eth0
+
No
+
+
+
-
-
-
-
-
Because the HAVE ROUTE column contains No, Shorewall will
- add host routes thru eth2 to 192.0.2.177 and 192.0.2.178.
-
-
-
The ethernet interfaces on DMZ 1 and DMZ 2 should be configured
- to have the IP addresses shown but should have the same default gateway
- as the firewall itself -- namely 192.0.2.254. In other words, they should
- be configured just like they would be if they were parallel to the firewall
- rather than behind it.
-
-
-
NOTE: Do not add the Proxy ARP'ed address(es)
- (192.0.2.177 and 192.0.2.178 in the above example) to the external interface
- (eth0 in this example) of the firewall.
-
-
+
+
+
+
+
Because the HAVE ROUTE column contains No, Shorewall will
+ add host routes thru eth2 to 192.0.2.177 and 192.0.2.178.
+
+
+
The ethernet interfaces on DMZ 1 and DMZ 2 should be configured
+ to have the IP addresses shown but should have the same default gateway
+ as the firewall itself -- namely 192.0.2.254. In other words, they should
+ be configured just like they would be if they were parallel to the firewall
+ rather than behind it.
+
+
+
NOTE: Do not add the Proxy ARP'ed address(es)
+ (192.0.2.177 and 192.0.2.178 in the above example) to the external interface
+ (eth0 in this example) of the firewall.
+
+
-
-
-
+
+
+
-
-
-
-
-
A word of warning is in order here. ISPs typically configure
- their routers with a long ARP cache timeout. If you move a system
-from parallel to your firewall to behind your firewall with Proxy ARP,
-it will probably be HOURS before that system can communicate with the
-internet. There are a couple of things that you can try:
-
-
+
+
+
+
+
A word of warning is in order here. ISPs typically configure
+ their routers with a long ARP cache timeout. If you move a system
+ from parallel to your firewall to behind your firewall with Proxy
+ARP, it will probably be HOURS before that system can communicate with
+the internet. There are a couple of things that you can try:
+
+
-
(Courtesy of Bradey Honsinger) A reading of Stevens' TCP/IP
- Illustrated, Vol 1 reveals that a
-
- "gratuitous" ARP packet should cause the ISP's router to refresh
- their ARP cache (section 4.7). A gratuitous ARP is simply a host requesting
- the MAC address for its own IP; in addition to ensuring that the IP address
- isn't a duplicate,...
+
(Courtesy of Bradey Honsinger) A reading of Stevens' TCP/IP
+ Illustrated, Vol 1 reveals that a
- "if the host sending the gratuitous ARP has just changed its
-hardware address..., this packet causes any other host...that has an
-entry in its cache for the old hardware address to update its ARP cache
+ "gratuitous" ARP packet should cause the ISP's router to refresh
+ their ARP cache (section 4.7). A gratuitous ARP is simply a host requesting
+ the MAC address for its own IP; in addition to ensuring that the IP
+address isn't a duplicate,...
+
+ "if the host sending the gratuitous ARP has just changed its
+hardware address..., this packet causes any other host...that has an
+entry in its cache for the old hardware address to update its ARP cache
entry accordingly."
-
- Which is, of course, exactly what you want to do when you switch
- a host from being exposed to the Internet to behind Shorewall using proxy
- ARP (or static NAT for that matter). Happily enough, recent versions of
- Redhat's iputils package include "arping", whose "-U" flag does just that:
-
- arping -U -I <net if> <newly
- proxied IP>
- arping -U -I eth0 66.58.99.83 #
+
+ Which is, of course, exactly what you want to do when you switch
+ a host from being exposed to the Internet to behind Shorewall using proxy
+ ARP (or static NAT for that matter). Happily enough, recent versions
+of Redhat's iputils package include "arping", whose "-U" flag does just
+that:
+
+ arping -U -I <net if> <newly
+ proxied IP>
+ arping -U -I eth0 66.58.99.83 #
for example
-
- Stevens goes on to mention that not all systems respond correctly
- to gratuitous ARPs, but googling for "arping -U" seems to support the
- idea that it works most of the time.
-
-
-
You can call your ISP and ask them to purge the stale
-ARP cache entry but many either can't or won't purge individual entries.
-
+
+ Stevens goes on to mention that not all systems respond correctly
+ to gratuitous ARPs, but googling for "arping -U" seems to support the
+ idea that it works most of the time.
+
+
+
You can call your ISP and ask them to purge the stale
+ ARP cache entry but many either can't or won't purge individual
+entries.
+
- You can determine if your ISP's gateway ARP cache is stale
-using ping and tcpdump. Suppose that we suspect that the gateway router
-has a stale ARP cache entry for 192.0.2.177. On the firewall, run
-tcpdump as follows:
-
-
+ You can determine if your ISP's gateway ARP cache is stale
+ using ping and tcpdump. Suppose that we suspect that the gateway
+router has a stale ARP cache entry for 192.0.2.177. On the firewall,
+run tcpdump as follows:
+
+
tcpdump -nei eth0 icmp
+
+
+
+
Now from 192.0.2.177, ping the ISP's gateway (which we
+ will assume is 192.0.2.254):
-
-
-
Now from 192.0.2.177, ping the ISP's gateway (which we
- will assume is 192.0.2.254):
Notice that the source MAC address in the echo request is
+ different from the destination MAC address in the echo reply!!
+In this case 0:4:e2:20:20:33 was the MAC of the firewall's eth0
+NIC while 0:c0:a8:50:b2:57 was the MAC address of DMZ 1. In other
+words, the gateway's ARP cache still associates 192.0.2.177 with
+the NIC in DMZ 1 rather than with the firewall's eth0.
-
-
-
Notice that the source MAC address in the echo request is
- different from the destination MAC address in the echo reply!! In
- this case 0:4:e2:20:20:33 was the MAC of the firewall's eth0 NIC
-while 0:c0:a8:50:b2:57 was the MAC address of DMZ 1. In other words,
-the gateway's ARP cache still associates 192.0.2.177 with the NIC
-in DMZ 1 rather than with the firewall's eth0.
-
-
-
+
+
5.2.4 Static NAT
+
+
+
+
With static NAT, you assign local systems RFC 1918 addresses
+ then establish a one-to-one mapping between those addresses and
+public IP addresses. For outgoing connections SNAT (Source Network
+Address Translation) occurs and on incoming connections DNAT (Destination
+ Network Address Translation) occurs. Let's go back to our earlier example
+ involving your daughter's web server running on system Local 3.
-
-
-
With static NAT, you assign local systems RFC 1918 addresses
- then establish a one-to-one mapping between those addresses and public
- IP addresses. For outgoing connections SNAT (Source Network Address
- Translation) occurs and on incoming connections DNAT (Destination
- Network Address Translation) occurs. Let's go back to our earlier example
- involving your daughter's web server running on system Local 3.
-
-
-
+
+
-
-
-
-
-
Recall that in this setup, the local network is using SNAT
- and is sharing the firewall external IP (192.0.2.176) for outbound
- connections. This is done with the following entry in /etc/shorewall/masq:
-
-
-
-
+
+
+
+
+
Recall that in this setup, the local network is using SNAT
+ and is sharing the firewall external IP (192.0.2.176) for outbound
+ connections. This is done with the following entry in /etc/shorewall/masq:
+
+
+
+
-
-
-
INTERFACE
-
SUBNET
-
ADDRESS
-
+
-
eth0
-
192.168.201.0/29
-
192.0.2.176
-
-
-
+
INTERFACE
+
SUBNET
+
ADDRESS
+
+
+
eth0
+
192.168.201.0/29
+
192.0.2.176
+
+
+
-
-
-
-
+
+
+
+
- Suppose now that you have decided to give your daughter
- her own IP address (192.0.2.179) for both inbound and outbound connections.
- You would do that by adding an entry in /etc/shorewall/nat.
-
-
-
-
+
+
+
+
-
-
-
EXTERNAL
-
INTERFACE
-
INTERNAL
-
ALL INTERFACES
-
LOCAL
-
+
-
192.0.2.179
-
eth0
-
192.168.201.4
-
No
-
No
-
-
-
+
EXTERNAL
+
INTERFACE
+
INTERNAL
+
ALL INTERFACES
+
LOCAL
+
+
+
192.0.2.179
+
eth0
+
192.168.201.4
+
No
+
No
+
+
+
-
+
+
+
+
+
With this entry in place, you daughter has her own IP address
+ and the other two local systems share the firewall's IP address.
-
-
-
With this entry in place, you daughter has her own IP address
- and the other two local systems share the firewall's IP address.
-
-
-
+
+
- Once the relationship between 192.0.2.179 and 192.168.201.4
- is established by the nat file entry above, it is no longer appropriate
- to use a DNAT rule for you daughter's web server -- you would rather
- just use an ACCEPT rule:
-
-
-
-
+ Once the relationship between 192.0.2.179 and 192.168.201.4
+ is established by the nat file entry above, it is no longer appropriate
+ to use a DNAT rule for you daughter's web server -- you would rather
+ just use an ACCEPT rule:
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL DESTINATION
-
+
-
ACCEPT
-
net
-
loc:192.168.201.4
-
tcp
-
www
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL DESTINATION
+
+
+
ACCEPT
+
net
+
loc:192.168.201.4
+
tcp
+
www
+
+
+
+
+
-
-
-
-
-
-
-
A word of warning is in order here. ISPs typically configure
- their routers with a long ARP cache timeout. If you move a system
-from parallel to your firewall to behind your firewall with static
-NAT, it will probably be HOURS before that system can communicate with
-the internet. There are a couple of things that you can try:
-
-
+
+
+
+
+
+
+
A word of warning is in order here. ISPs typically configure
+ their routers with a long ARP cache timeout. If you move a system
+ from parallel to your firewall to behind your firewall with static
+ NAT, it will probably be HOURS before that system can communicate
+with the internet. There are a couple of things that you can try:
+
+
-
(Courtesy of Bradey Honsinger) A reading of Stevens' TCP/IP
-Illustrated, Vol 1 reveals that a
-
- "gratuitous" ARP packet should cause the ISP's router to refresh
- their ARP cache (section 4.7). A gratuitous ARP is simply a host requesting
- the MAC address for its own IP; in addition to ensuring that the IP address
- isn't a duplicate,...
+
(Courtesy of Bradey Honsinger) A reading of Stevens' TCP/IP
+ Illustrated, Vol 1 reveals that a
- "if the host sending the gratuitous ARP has just changed its
-hardware address..., this packet causes any other host...that has an
-entry in its cache for the old hardware address to update its ARP cache
+ "gratuitous" ARP packet should cause the ISP's router to refresh
+ their ARP cache (section 4.7). A gratuitous ARP is simply a host requesting
+ the MAC address for its own IP; in addition to ensuring that the IP
+address isn't a duplicate,...
+
+ "if the host sending the gratuitous ARP has just changed its
+hardware address..., this packet causes any other host...that has an
+entry in its cache for the old hardware address to update its ARP cache
entry accordingly."
-
- Which is, of course, exactly what you want to do when you switch
- a host from being exposed to the Internet to behind Shorewall using proxy
- ARP (or static NAT for that matter). Happily enough, recent versions of
- Redhat's iputils package include "arping", whose "-U" flag does just that:
-
- arping -U -I <net if> <newly
- proxied IP>
- arping -U -I eth0 66.58.99.83 #
+
+ Which is, of course, exactly what you want to do when you switch
+ a host from being exposed to the Internet to behind Shorewall using proxy
+ ARP (or static NAT for that matter). Happily enough, recent versions
+of Redhat's iputils package include "arping", whose "-U" flag does just
+that:
+
+ arping -U -I <net if> <newly
+ proxied IP>
+ arping -U -I eth0 66.58.99.83 #
for example
-
- Stevens goes on to mention that not all systems respond correctly
- to gratuitous ARPs, but googling for "arping -U" seems to support the
- idea that it works most of the time.
-
-
-
You can call your ISP and ask them to purge the stale ARP cache
+
+ Stevens goes on to mention that not all systems respond correctly
+ to gratuitous ARPs, but googling for "arping -U" seems to support the
+ idea that it works most of the time.
+
+
+
You can call your ISP and ask them to purge the stale ARP cache
entry but many either can't or won't purge individual entries.
-
+
- You can determine if your ISP's gateway ARP cache is stale
-using ping and tcpdump. Suppose that we suspect that the gateway router
-has a stale ARP cache entry for 209.0.2.179. On the firewall, run
-tcpdump as follows:
-
-
+ You can determine if your ISP's gateway ARP cache is stale
+ using ping and tcpdump. Suppose that we suspect that the gateway
+router has a stale ARP cache entry for 209.0.2.179. On the firewall,
+run tcpdump as follows:
+
+
tcpdump -nei eth0 icmp
-
-
-
-
Now from the 192.168.201.4, ping the ISP's gateway (which
+
+
+
+
Now from the 192.168.201.4, ping the ISP's gateway (which
we will assume is 192.0.2.254):
Notice that the source MAC address in the echo request is
+ different from the destination MAC address in the echo reply!!
+In this case 0:4:e2:20:20:33 was the MAC of the firewall's eth0
+NIC while 0:c0:a8:50:b2:57 was the MAC address of DMZ 1. In other
+words, the gateway's ARP cache still associates 192.0.2.179 with
+the NIC in the local zone rather than with the firewall's eth0.
-
-
-
Notice that the source MAC address in the echo request is
- different from the destination MAC address in the echo reply!! In
- this case 0:4:e2:20:20:33 was the MAC of the firewall's eth0 NIC
-while 0:c0:a8:50:b2:57 was the MAC address of DMZ 1. In other words,
-the gateway's ARP cache still associates 192.0.2.179 with the NIC
-in the local zone rather than with the firewall's eth0.
-
-
+
5.3 Rules
-
-
-
+
+
+
- With the default policies, your local systems (Local
-1-3) can access any servers on the internet and the DMZ can't access
-any other host (including the firewall). With the exception of DNAT rules which cause address translation and allow
- the translated connection request to pass through the firewall, the
- way to allow connection requests through your firewall is to use ACCEPT
- rules.
-
-
-
-
NOTE: Since the SOURCE PORT and ORIG. DEST. Columns aren't
- used in this section, they won't be shown
-
-
-
+ With the default policies, your local systems (Local
+ 1-3) can access any servers on the internet and the DMZ can't access
+ any other host (including the firewall). With the exception of
+DNAT rules which cause address translation and allow
+ the translated connection request to pass through the firewall,
+the way to allow connection requests through your firewall is to
+use ACCEPT rules.
+
+
+
+
NOTE: Since the SOURCE PORT and ORIG. DEST. Columns aren't
+ used in this section, they won't be shown
+
+
+
You probably want to allow ping between your zones:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
+
-
ACCEPT
-
net
-
dmz
-
icmp
-
echo-request
-
-
-
ACCEPT
-
net
-
loc
-
icmp
-
echo-request
-
-
-
ACCEPT
-
dmz
-
loc
-
icmp
-
echo-request
-
-
-
ACCEPT
-
loc
-
dmz
-
icmp
-
echo-request
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
+
+
ACCEPT
+
net
+
dmz
+
icmp
+
echo-request
+
+
+
ACCEPT
+
net
+
loc
+
icmp
+
echo-request
+
+
+
ACCEPT
+
dmz
+
loc
+
icmp
+
echo-request
+
+
+
ACCEPT
+
loc
+
dmz
+
icmp
+
echo-request
+
+
+
-
+
+
+
+
+
Let's suppose that you run mail and pop3 servers on DMZ 2
+ and a Web Server on DMZ 1. The rules that you would need are:
-
-
-
Let's suppose that you run mail and pop3 servers on DMZ 2
- and a Web Server on DMZ 1. The rules that you would need are:
-
-
-
-
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
COMMENTS
-
+
-
ACCEPT
-
net
-
dmz:192.0.2.178
-
tcp
-
smtp
-
# Mail from the Internet
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.178
-
tcp
-
pop3
-
# Pop3 from the Internet
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.178
-
tcp
-
smtp
-
# Mail from the Local Network
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.178
-
tcp
-
pop3
-
# Pop3 from the Local Network
-
-
-
ACCEPT
-
fw
-
dmz:192.0.2.178
-
tcp
-
smtp
-
# Mail from the Firewall
-
-
-
ACCEPT
-
dmz:192.0.2.178
-
net
-
tcp
-
smtp
-
# Mail to the Internet
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.177
-
tcp
-
http
-
# WWW from the Net
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.177
-
tcp
-
https
-
# Secure HTTP from the Net
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.177
-
tcp
-
https
-
# Secure HTTP from the Local Net
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
COMMENTS
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.178
+
tcp
+
smtp
+
# Mail from the Internet
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.178
+
tcp
+
pop3
+
# Pop3 from the Internet
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.178
+
tcp
+
smtp
+
# Mail from the Local Network
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.178
+
tcp
+
pop3
+
# Pop3 from the Local Network
+
+
+
ACCEPT
+
fw
+
dmz:192.0.2.178
+
tcp
+
smtp
+
# Mail from the Firewall
+
+
+
ACCEPT
+
dmz:192.0.2.178
+
net
+
tcp
+
smtp
+
# Mail to the Internet
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.177
+
tcp
+
http
+
# WWW from the Net
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.177
+
tcp
+
https
+
# Secure HTTP from the Net
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.177
+
tcp
+
https
+
# Secure HTTP from the Local Net
+
+
+
-
+
+
+
+
+
If you run a public DNS server on 192.0.2.177, you would need
+ to add the following rules:
-
-
-
If you run a public DNS server on 192.0.2.177, you would
-need to add the following rules:
-
-
-
-
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
COMMENTS
-
+
-
ACCEPT
-
net
-
dmz:192.0.2.177
-
udp
-
domain
-
# UDP DNS from the Internet
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.177
-
tcp
-
domain
-
# TCP DNS from the internet
-
-
-
ACCEPT
-
fw
-
dmz:192.0.2.177
-
udp
-
domain
-
# UDP DNS from firewall
-
-
-
ACCEPT
-
fw
-
dmz:192.0.2.177
-
tcp
-
domain
-
# TCP DNS from firewall
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.177
-
udp
-
domain
-
# UDP DNS from the local Net
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.177
-
tcp
-
domain
-
# TCP DNS from the local Net
-
-
-
ACCEPT
-
dmz:192.0.2.177
-
net
-
udp
-
domain
-
# UDP DNS to the Internet
-
-
-
ACCEPT
-
dmz:192.0.2.177
-
net
-
tcp
-
domain
-
# TCP DNS to the Internet
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
COMMENTS
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.177
+
udp
+
domain
+
# UDP DNS from the Internet
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.177
+
tcp
+
domain
+
# TCP DNS from the internet
+
+
+
ACCEPT
+
fw
+
dmz:192.0.2.177
+
udp
+
domain
+
# UDP DNS from firewall
+
+
+
ACCEPT
+
fw
+
dmz:192.0.2.177
+
tcp
+
domain
+
# TCP DNS from firewall
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.177
+
udp
+
domain
+
# UDP DNS from the local Net
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.177
+
tcp
+
domain
+
# TCP DNS from the local Net
+
+
+
ACCEPT
+
dmz:192.0.2.177
+
net
+
udp
+
domain
+
# UDP DNS to the Internet
+
+
+
ACCEPT
+
dmz:192.0.2.177
+
net
+
tcp
+
domain
+
# TCP DNS to the Internet
+
+
+
-
+
+
+
+
+
You probably want some way to communicate with your firewall
+ and DMZ systems from the local network -- I recommend SSH which
+through its scp utility can also do publishing and software update
+distribution.
-
-
-
You probably want some way to communicate with your firewall
- and DMZ systems from the local network -- I recommend SSH which through
- its scp utility can also do publishing and software update distribution.
-
-
-
-
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
COMMENTS
-
+
-
ACCEPT
-
loc
-
dmz
-
tcp
-
ssh
-
# SSH to the DMZ
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
ssh
-
# SSH to the Firewall
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
COMMENTS
+
+
+
ACCEPT
+
loc
+
dmz
+
tcp
+
ssh
+
# SSH to the DMZ
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
ssh
+
# SSH to the Firewall
+
+
+
-
-
-
-
+
+
+
+
5.4 Odds and Ends
+
+
+
+
The above discussion reflects my personal preference for using
+ Proxy ARP for my servers in my DMZ and SNAT/NAT for my local systems. I
+prefer to use NAT only in cases where a system that is part of an RFC 1918
+subnet needs to have it's own public IP.
-
-
-
The above discussion reflects my personal preference for
-using Proxy ARP for my servers in my DMZ and SNAT/NAT for my local systems.
-I prefer to use NAT only in cases where a system that is part of an RFC
-1918 subnet needs to have it's own public IP.
-
-
-
+
+
- If you haven't already, it would be a good idea to browse
- through /etc/shorewall/shorewall.conf
- just to see if there is anything there that might be of interest.
- You might also want to look at the other configuration files that
- you haven't touched yet just to get a feel for the other things that
+ If you haven't already, it would be a good idea to
+browse through /etc/shorewall/shorewall.conf
+ just to see if there is anything there that might be of interest.
+ You might also want to look at the other configuration files that
+ you haven't touched yet just to get a feel for the other things that
Shorewall can do.
-
-
-
-
In case you haven't been keeping score, here's the final
-set of configuration files for our sample network. Only those that were
-modified from the original installation are shown.
-
-
-
-
/etc/shorewall/interfaces (The "options" will be very
-site-specific).
-
-
-
-
+
+
+
+
In case you haven't been keeping score, here's the final set
+ of configuration files for our sample network. Only those that were modified
+ from the original installation are shown.
+
+
+
+
/etc/shorewall/interfaces (The "options" will be very site-specific).
+
+
+
+
-
+
+
+
Zone
+
Interface
+
Broadcast
+
Options
+
-
Zone
-
Interface
-
Broadcast
-
Options
-
-
-
net
-
eth0
-
detect
-
norfc1918,routefilter
-
-
-
loc
-
eth1
-
detect
-
-
-
-
dmz
-
eth2
-
detect
-
-
-
-
+
net
+
eth0
+
detect
+
norfc1918,routefilter
+
+
+
loc
+
eth1
+
detect
+
+
+
+
dmz
+
eth2
+
detect
+
+
+
+
-
+
+
+
+
+
The setup described here requires that your network interfaces
+ be brought up before Shorewall can start. This opens a short window
+ during which you have no firewall protection. If you replace 'detect'
+ with the actual broadcast addresses in the entries above, you can
+ bring up Shorewall before you bring up your network interfaces.
-
-
-
The setup described here requires that your network interfaces
- be brought up before Shorewall can start. This opens a short window
- during which you have no firewall protection. If you replace 'detect'
- with the actual broadcast addresses in the entries above, you can
-bring up Shorewall before you bring up your network interfaces.
-
-
-
-
+
+
+
-
+
+
+
Zone
+
Interface
+
Broadcast
+
Options
+
-
Zone
-
Interface
-
Broadcast
-
Options
-
-
-
net
-
eth0
-
192.0.2.255
-
norfc1918,routefilter
-
-
-
loc
-
eth1
-
192.168.201.7
-
-
-
-
dmz
-
eth2
-
192.168.202.7
-
-
-
-
+
net
+
eth0
+
192.0.2.255
+
norfc1918,routefilter
+
+
+
loc
+
eth1
+
192.168.201.7
+
+
+
+
dmz
+
eth2
+
192.168.202.7
+
+
+
+
-
-
-
-
+
+
+
+
/etc/shorewall/masq - Local subnet
-
-
-
-
+
+
+
+
-
-
-
INTERFACE
-
SUBNET
-
ADDRESS
-
+
-
eth0
-
192.168.201.0/29
-
192.0.2.176
-
-
-
+
INTERFACE
+
SUBNET
+
ADDRESS
+
+
+
eth0
+
192.168.201.0/29
+
192.0.2.176
+
+
+
-
-
-
-
+
+
+
+
/etc/shorewall/proxyarp - DMZ
-
-
-
-
+
+
+
+
-
-
-
ADDRESS
-
INTERFACE
-
EXTERNAL
-
HAVE ROUTE
-
+
-
192.0.2.177
-
eth2
-
eth0
-
No
-
-
-
192.0.2.178
-
eth2
-
eth0
-
No
-
-
-
+
ADDRESS
+
INTERFACE
+
EXTERNAL
+
HAVE ROUTE
+
+
+
192.0.2.177
+
eth2
+
eth0
+
No
+
+
+
192.0.2.178
+
eth2
+
eth0
+
No
+
+
+
-
-
-
-
+
+
+
+
/etc/shorewall/nat- Daughter's System
-
-
-
-
+
+
+
+
-
-
-
EXTERNAL
-
INTERFACE
-
INTERNAL
-
ALL INTERFACES
-
LOCAL
-
+
-
192.0.2.179
-
eth0
-
192.168.201.4
-
No
-
No
-
-
-
+
EXTERNAL
+
INTERFACE
+
INTERNAL
+
ALL INTERFACES
+
LOCAL
+
+
+
192.0.2.179
+
eth0
+
192.168.201.4
+
No
+
No
+
+
+
-
-
-
-
+
+
+
+
/etc/shorewall/rules
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
COMMENTS
-
+
-
ACCEPT
-
net
-
dmz:192.0.2.178
-
tcp
-
smtp
-
# Mail from the Internet
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.178
-
tcp
-
pop3
-
# Pop3 from the Internet
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.178
-
tcp
-
smtp
-
# Mail from the Local Network
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.178
-
tcp
-
pop3
-
# Pop3 from the Local Network
-
-
-
ACCEPT
-
fw
-
dmz:192.0.2.178
-
tcp
-
smtp
-
# Mail from the Firewall
-
-
-
ACCEPT
-
dmz:192.0.2.178
-
net
-
tcp
-
smtp
-
# Mail to the Internet
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.178
-
tcp
-
http
-
# WWW from the Net
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.178
-
tcp
-
https
-
# Secure HTTP from the Net
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.178
-
tcp
-
https
-
# Secure HTTP from the Local Net
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.177
-
udp
-
domain
-
# UDP DNS from the Internet
-
-
-
ACCEPT
-
net
-
dmz:192.0.2.177
-
tcp
-
domain
-
# TCP DNS from the internet
-
-
-
ACCEPT
-
fw
-
dmz:192.0.2.177
-
udp
-
domain
-
# UDP DNS from firewall
-
-
-
ACCEPT
-
fw
-
dmz:192.0.2.177
-
tcp
-
domain
-
# TCP DNS from firewall
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.177
-
udp
-
domain
-
# UDP DNS from the local Net
-
-
-
ACCEPT
-
loc
-
dmz:192.0.2.177
-
tcp
-
domain
-
# TCP DNS from the local Net
-
-
-
ACCEPT
-
dmz:192.0.2.177
-
net
-
udp
-
domain
-
# UDP DNS to the Internet
-
-
-
ACCEPT
-
dmz:192.0.2.177
-
net
-
tcp
-
domain
-
# TCP DNS to the Internet
-
-
-
ACCEPT
-
net
-
dmz
-
icmp
-
echo-request
-
# Ping
-
-
-
ACCEPT
-
net
-
loc
-
icmp
-
echo-request
-
# "
-
-
-
ACCEPT
-
dmz
-
loc
-
icmp
-
echo-request
-
# "
-
-
-
ACCEPT
-
loc
-
dmz
-
icmp
-
echo-request
-
# "
-
-
-
ACCEPT
-
loc
-
dmz
-
tcp
-
ssh
-
# SSH to the DMZ
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
ssh
-
# SSH to the Firewall
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
COMMENTS
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.178
+
tcp
+
smtp
+
# Mail from the Internet
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.178
+
tcp
+
pop3
+
# Pop3 from the Internet
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.178
+
tcp
+
smtp
+
# Mail from the Local Network
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.178
+
tcp
+
pop3
+
# Pop3 from the Local Network
+
+
+
ACCEPT
+
fw
+
dmz:192.0.2.178
+
tcp
+
smtp
+
# Mail from the Firewall
+
+
+
ACCEPT
+
dmz:192.0.2.178
+
net
+
tcp
+
smtp
+
# Mail to the Internet
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.178
+
tcp
+
http
+
# WWW from the Net
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.178
+
tcp
+
https
+
# Secure HTTP from the Net
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.178
+
tcp
+
https
+
# Secure HTTP from the Local Net
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.177
+
udp
+
domain
+
# UDP DNS from the Internet
+
+
+
ACCEPT
+
net
+
dmz:192.0.2.177
+
tcp
+
domain
+
# TCP DNS from the internet
+
+
+
ACCEPT
+
fw
+
dmz:192.0.2.177
+
udp
+
domain
+
# UDP DNS from firewall
+
+
+
ACCEPT
+
fw
+
dmz:192.0.2.177
+
tcp
+
domain
+
# TCP DNS from firewall
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.177
+
udp
+
domain
+
# UDP DNS from the local Net
+
+
+
ACCEPT
+
loc
+
dmz:192.0.2.177
+
tcp
+
domain
+
# TCP DNS from the local Net
+
+
+
ACCEPT
+
dmz:192.0.2.177
+
net
+
udp
+
domain
+
# UDP DNS to the Internet
+
+
+
ACCEPT
+
dmz:192.0.2.177
+
net
+
tcp
+
domain
+
# TCP DNS to the Internet
+
+
+
ACCEPT
+
net
+
dmz
+
icmp
+
echo-request
+
# Ping
+
+
+
ACCEPT
+
net
+
loc
+
icmp
+
echo-request
+
# "
+
+
+
ACCEPT
+
dmz
+
loc
+
icmp
+
echo-request
+
# "
+
+
+
ACCEPT
+
loc
+
dmz
+
icmp
+
echo-request
+
# "
+
+
+
ACCEPT
+
loc
+
dmz
+
tcp
+
ssh
+
# SSH to the DMZ
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
ssh
+
# SSH to the Firewall
+
+
+
-
-
-
-
+
+
+
+
6.0 DNS
-
-
-
-
Given the collection of RFC 1918 and public addresses in
-this setup, it only makes sense to have separate internal and external
-DNS servers. You can combine the two into a single BIND 9 server using
-Views. If you are not interested in Bind 9 views, you can
+
+
Suppose that your domain is foobar.net and you want the two
- DMZ systems named www.foobar.net and mail.foobar.net and you want
- the three local systems named "winken.foobar.net, blinken.foobar.net
- and nod.foobar.net. You want your firewall to be known as firewall.foobar.net
- externally and it's interface to the local network to be know as gateway.foobar.net
- and its interface to the dmz as dmz.foobar.net. Let's have the DNS
- server on 192.0.2.177 which will also be known by the name ns1.foobar.net.
-
-
-
+
+
+
+
Suppose that your domain is foobar.net and you want the two
+ DMZ systems named www.foobar.net and mail.foobar.net and you want
+ the three local systems named "winken.foobar.net, blinken.foobar.net
+ and nod.foobar.net. You want your firewall to be known as firewall.foobar.net
+ externally and it's interface to the local network to be know as
+gateway.foobar.net and its interface to the dmz as dmz.foobar.net.
+Let's have the DNS server on 192.0.2.177 which will also be known
+by the name ns1.foobar.net.
# # This is the view presented to our internal systems #
view "internal" { # # These are the clients that see this view # match-clients { 192.168.201.0/29; 192.168.202.0/29; 127.0.0.0/8; 192.0.2.176/32; 192.0.2.178/32; 192.0.2.179/32; 192.0.2.180/32; }; # # If this server can't complete the request, it should use outside # servers to do so # recursion yes;
zone "." in { type hint; file "int/root.cache"; };
zone "foobar.net" in { type master; notify no; allow-update { none; }; file "int/db.foobar"; };
zone "0.0.127.in-addr.arpa" in { type master; notify no; allow-update { none; }; file "int/db.127.0.0"; };
zone "201.168.192.in-addr.arpa" in { type master; notify no; allow-update { none; }; file "int/db.192.168.201"; };
zone "202.168.192.in-addr.arpa" in { type master; notify no; allow-update { none; }; file "int/db.192.168.202"; };
zone "176.2.0.192.in-addr.arpa" in { type master; notify no; allow-update { none; }; file "db.192.0.2.176"; }; (or status NAT for that matter) zone "177.2.0.192.in-addr.arpa" in { type master; notify no; allow-update { none; }; file "db.192.0.2.177"; };
zone "178.2.0.192.in-addr.arpa" in { type master; notify no; allow-update { none; }; file "db.192.0.2.178"; };
zone "179.2.0.192.in-addr.arpa" in { type master; notify no; allow-update { none; }; file "db.206.124.146.179"; };
}; # # This is the view that we present to the outside world # view "external" { match-clients { any; }; # # If we can't answer the query, we tell the client so # recursion no;
zone "foobar.net" in { type master; notify yes; allow-update {none; }; allow-transfer { <secondary NS IP>; }; file "ext/db.foobar"; };
zone "176.2.0.192.in-addr.arpa" in { type master; notify yes; allow-update { none; }; allow-transfer { <secondary NS IP>; }; file "db.192.0.2.176"; };
zone "177.2.0.192.in-addr.arpa" in { type master; notify yes; allow-update { none; }; allow-transfer { <secondary NS IP>; }; file "db.192.0.2.177"; };
zone "178.2.0.192.in-addr.arpa" in { type master; notify yes; allow-update { none; }; allow-transfer { <secondary NS IP>; }; file "db.192.0.2.178"; };
zone "179.2.0.192.in-addr.arpa" in { type master; notify yes; allow-update { none; }; allow-transfer { <secondary NS IP>; }; file "db.192.0.2.179"; }; };
-
-
-
-
-
-
Here are the files in /var/named (those not shown are usually
- included in your bind disbribution).
-
-
db.192.0.2.176 - This is the reverse zone for the firewall's
- external interface
-
-
+
+
+
+
+
+
Here are the files in /var/named (those not shown are usually
+ included in your bind disbribution).
+
+
db.192.0.2.176 - This is the reverse zone for the firewall's
+ external interface
+
+
; ############################################################ ; Start of Authority (Inverse Address Arpa) for 192.0.2.176/32 ; Filename: db.192.0.2.176 ; ############################################################ @ 604800 IN SOA ns1.foobar.net. netadmin.foobar.net. ( 2001102303 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ) ; minimum (1 day) ; ; ############################################################ ; Specify Name Servers for all Reverse Lookups (IN-ADDR.ARPA) ; ############################################################ @ 604800 IN NS ns1.foobar.net. @ 604800 IN NS <name of secondary ns>. ; ; ############################################################ ; Iverse Address Arpa Records (PTR's) ; ############################################################ 176.2.0.192.in-addr.arpa. 86400 IN PTR firewall.foobar.net.
-
-
-
-
-
db.192.0.2.177 - This is the reverse zone for the www/DNS
- server
-
+
+
+
+
+
db.192.0.2.177 - This is the reverse zone for the www/DNS
+ server
+
; ############################################################ ; Start of Authority (Inverse Address Arpa) for 192.0.2.177/32 ; Filename: db.192.0.2.177 ; ############################################################ @ 604800 IN SOA ns1.foobar.net. netadmin.foobar.net. ( 2001102303 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ) ; minimum (1 day) ; ; ############################################################ ; Specify Name Servers for all Reverse Lookups (IN-ADDR.ARPA) ; ############################################################ @ 604800 IN NS ns1.foobar.net. @ 604800 IN NS <name of secondary ns>. ; ; ############################################################ ; Iverse Address Arpa Records (PTR's) ; ############################################################ 177.2.0.192.in-addr.arpa. 86400 IN PTR www.foobar.net.
-
-
-
-
-
-
db.192.0.2.178 - This is the reverse zone for the mail
- server
-
+
+
+
+
+
+
db.192.0.2.178 - This is the reverse zone for the mail
+ server
+
; ############################################################ ; Start of Authority (Inverse Address Arpa) for 192.0.2.178/32 ; Filename: db.192.0.2.178 ; ############################################################ @ 604800 IN SOA ns1.foobar.net. netadmin.foobar.net. ( 2001102303 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ) ; minimum (1 day) ; ; ############################################################ ; Specify Name Servers for all Reverse Lookups (IN-ADDR.ARPA) ; ############################################################ @ 604800 IN NS ns1.foobar.net. @ 604800 IN NS <name of secondary ns>. ; ; ############################################################ ; Iverse Address Arpa Records (PTR's) ; ############################################################ 178.2.0.192.in-addr.arpa. 86400 IN PTR mail.foobar.net.
-
-
-
-
-
-
db.192.0.2.179 - This is the reverse zone for daughter's
- web server's public IP
-
+
+
+
+
+
+
db.192.0.2.179 - This is the reverse zone for daughter's
+ web server's public IP
+
; ############################################################ ; Start of Authority (Inverse Address Arpa) for 192.0.2.179/32 ; Filename: db.192.0.2.179 ; ############################################################ @ 604800 IN SOA ns1.foobar.net. netadmin.foobar.net. ( 2001102303 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ) ; minimum (1 day) ; ; ############################################################ ; Specify Name Servers for all Reverse Lookups (IN-ADDR.ARPA) ; ############################################################ @ 604800 IN NS ns1.foobar.net. @ 604800 IN NS <name of secondary ns>. ; ; ############################################################ ; Iverse Address Arpa Records (PTR's) ; ############################################################ 179.2.0.192.in-addr.arpa. 86400 IN PTR nod.foobar.net.
-
-
-
-
-
+
+
+
+
+
int/db.127.0.0 - The reverse zone for localhost
-
-
-
-
+
+
+
+
; ############################################################ ; Start of Authority (Inverse Address Arpa) for 127.0.0.0/8 ; Filename: db.127.0.0 ; ############################################################ @ 604800 IN SOA ns1.foobar.net. netadmin.foobar.net. ( 2001092901 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ) ; minimum (1 day) ; ############################################################ ; Specify Name Servers for all Reverse Lookups (IN-ADDR.ARPA) ; ############################################################ @ 604800 IN NS ns1.foobar.net.
; ############################################################ ; Iverse Address Arpa Records (PTR's) ; ############################################################ 1 86400 IN PTR localhost.foobar.net.
-
+
+
+
+
+
int/db.192.168.201 - Reverse zone for the local net. This
+ is only shown to internal clients
-
-
-
int/db.192.168.201 - Reverse zone for the local net. This
- is only shown to internal clients
-
-
-
-
+
+
+
; ############################################################ ; Start of Authority (Inverse Address Arpa) for 192.168.201.0/29 ; Filename: db.192.168.201 ; ############################################################ @ 604800 IN SOA ns1.foobar.net netadmin.foobar.net. ( 2002032501 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ) ; minimum (1 day)
; ############################################################ ; Specify Name Servers for all Reverse Lookups (IN-ADDR.ARPA) ; ############################################################ @ 604800 IN NS ns1.foobar.net.
; ############################################################ ; Iverse Address Arpa Records (PTR's) ; ############################################################ 1 86400 IN PTR gateway.foobar.net. 2 86400 IN PTR winken.foobar.net. 3 86400 IN PTR blinken.foobar.net. 4 86400 IN PTR nod.foobar.net.
-
+
+
+
+
+
int/db.192.168.202 - Reverse zone for the firewall's DMZ
+ interface
-
-
-
int/db.192.168.202 - Reverse zone for the firewall's DMZ
- interface
-
-
-
-
-
+
+
+
+
; ############################################################ ; Start of Authority (Inverse Address Arpa) for 192.168.202.0/29 ; Filename: db.192.168.202 ; ############################################################ @ 604800 IN SOA ns1.foobar.net netadmin.foobar.net. ( 2002032501 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ) ; minimum (1 day)
; ############################################################ ; Specify Name Servers for all Reverse Lookups (IN-ADDR.ARPA) ; ############################################################ @ 604800 IN NS ns1.foobar.net.
; ############################################################ ; Iverse Address Arpa Records (PTR's) ; ############################################################ 1 86400 IN PTR dmz.foobar.net.
-
-
-
-
-
+
+
+
+
+
int/db.foobar - Forward zone for use by internal clients.
-
-
-
-
+
+
+
+
;############################################################## ; Start of Authority for foobar.net. ; Filename: db.foobar ;############################################################## @ 604800 IN SOA ns1.foobar.net. netadmin.foobar.net. ( 2002071501 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ); minimum (1 day) ;############################################################ ; foobar.net Nameserver Records (NS) ;############################################################ @ 604800 IN NS ns1.foobar.net.
;############################################################ ; Foobar.net Office Records (ADDRESS) ;############################################################ localhost 86400 IN A 127.0.0.1
firewall 86400 IN A 192.0.2.176 www 86400 IN A 192.0.2.177 ns1 86400 IN A 192.0.2.177 www 86400 IN A 192.0.2.177
gateway 86400 IN A 192.168.201.1 winken 86400 IN A 192.168.201.2 blinken 86400 IN A 192.168.201.3 nod 86400 IN A 192.168.201.4
-
-
-
-
+
+
+
+
ext/db.foobar - Forward zone for external clients
-
-
-
-
-
+
+
+
+
+
;############################################################## ; Start of Authority for foobar.net. ; Filename: db.foobar ;############################################################## @ 86400 IN SOA ns1.foobar.net. netadmin.foobar.net. ( 2002052901 ; serial 10800 ; refresh (3 hour) 3600 ; retry (1 hour) 604800 ; expire (7 days) 86400 ); minimum (1 day) ;############################################################ ; Foobar.net Nameserver Records (NS) ;############################################################ @ 86400 IN NS ns1.foobar.net. @ 86400 IN NS <secondary NS>. ;############################################################ ; Foobar.net Foobar Wa Office Records (ADDRESS) ;############################################################ localhost 86400 IN A 127.0.0.1 ; ; The firewall itself ; firewall 86400 IN A 192.0.2.176 ; ; The DMZ ; ns1 86400 IN A 192.0.2.177 www 86400 IN A 192.0.2.177 mail 86400 IN A 192.0.2.178 ; ; The Local Network ; nod 86400 IN A 192.0.2.179
;############################################################ ; Current Aliases for foobar.net (CNAME) ;############################################################
;############################################################ ; foobar.net MX Records (MAIL EXCHANGER) ;############################################################ foobar.net. 86400 IN A 192.0.2.177 86400 IN MX 0 mail.foobar.net. 86400 IN MX 1 <backup MX>.
The firewall is started using the "shorewall start" command
- and stopped using "shorewall stop". When the firewall is stopped,
+
+
+
The firewall is started using the "shorewall start" command
+ and stopped using "shorewall stop". When the firewall is stopped,
routing is enabled on those hosts that have an entry in /etc/shorewall/routestopped. A
- running firewall may be restarted using the "shorewall restart" command.
- If you want to totally remove any trace of Shorewall from your Netfilter
- configuration, use "shorewall clear".
-
-
-
+ href="Documentation.htm#Routestopped">/etc/shorewall/routestopped. A
+ running firewall may be restarted using the "shorewall restart"
+command. If you want to totally remove any trace of Shorewall from
+your Netfilter configuration, use "shorewall clear".
+
+
+
- Edit the /etc/shorewall/routestopped file and configure
- those systems that you want to be able to access the firewall when
+ Edit the /etc/shorewall/routestopped file and configure
+ those systems that you want to be able to access the firewall when
it is stopped.
-
-
-
-
WARNING: If you are connected to your firewall from
- the internet, do not issue a "shorewall stop" command unless you
-have added an entry for the IP address that you are connected from
-to /etc/shorewall/routestopped.
- Also, I don't recommend using "shorewall restart"; it is better to create
- an alternate configuration
- and test it using the "shorewall
- try" command.
-
-
+
+
+
+
WARNING: If you are connected to your firewall from
+ the internet, do not issue a "shorewall stop" command unless you
+ have added an entry for the IP address that you are connected from
+ to /etc/shorewall/routestopped.
+ Also, I don't recommend using "shorewall restart"; it is better to create
+ an alternate configuration
+ and test it using the "shorewall
+ try" command.
The Shoreline Firewall, more commonly known as "Shorewall", is
- a Netfilter (iptables)
- based firewall that can be used on a dedicated
- firewall system, a multi-function gateway/router/server
- or on a standalone GNU/Linux system.
+
+
The Shoreline Firewall, more commonly known as "Shorewall", is
+ a Netfilter (iptables)
+ based firewall that can be used on a dedicated
+ firewall system, a multi-function gateway/router/server
+ or on a standalone GNU/Linux system.
-
-
This program is free software; you can redistribute it and/or modify
-
+
+
This program is free software; you can redistribute it and/or modify
+
it under the terms of Version 2 of the
-GNU General Public License as published by the Free Software
- Foundation.
+ href="http://www.gnu.org/licenses/gpl.html">Version 2 of the GNU
+General Public License as published by the Free Software
+ Foundation.
-
+
- This program is distributed in
- the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the
- implied warranty of MERCHANTABILITY or
- FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
+ This program is distributed
+ in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even
+ the implied warranty of MERCHANTABILITY
+ or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
-
+
- You should have received a copy
- of the GNU General Public License
- along with this program; if not, write
- to the Free Software Foundation,
+ You should have received a copy
+ of the GNU General Public License
+ along with this program; if not, write
+ to the Free Software Foundation,
Inc., 675 Mass Ave, Cambridge, MA 02139, USA
- New to Shorewall? Start by selecting the
- QuickStart
- Guide that most closely match your environment and follow
- the step by step instructions.
-
+ New to Shorewall? Start by selecting the
+ QuickStart
+ Guide that most closely match your environment and follow
+ the step by step instructions.
+
Looking for Information?
- The Documentation
- Index is a good place to start as is the Quick Search to your right.
-
+ The Documentation
+ Index is a good place to start as is the Quick Search to your right.
+
Running Shorewall on Mandrake with a two-interface setup?
- If so, the documentationon this site will
-not apply directly to your setup. If you want to use the documentation
- that you find here, you will want to consider uninstalling what you have
- and installing a setup that matches the documentation on this site.
- See the Two-interface QuickStart Guide
- for details.
+ If so, the documentationon this site will
+ not apply directly to your setup. If you want to use the documentation
+ that you find here, you will want to consider uninstalling what you have
+ and installing a setup that matches the documentation on this site.
+ See the Two-interface QuickStart Guide
+ for details.
-
+
+
A problem seen on RH7.3 systems where Shorewall encountered
-start errors when started using the "service" mechanism has been worked
+
A problem seen on RH7.3 systems where Shorewall encountered
+ start errors when started using the "service" mechanism has been worked
around.
-
-
-
Where a list of IP addresses appears in the DEST column of a
-DNAT[-] rule, Shorewall incorrectly created multiple DNAT rules in the nat
-table (one for each element in the list). Shorewall now correctly creates
-a single DNAT rule with multiple "--to-destination" clauses.
-
-
-
Corrected a problem in Beta 1 where DNS names containing a "-"
-were mis-handled when they appeared in the DEST column of a rule.
-
A number of problems with rule parsing have been corrected.
-Corrections involve the handling of "z1!z2" in the SOURCE column as well
-as lists in the ORIGINAL DESTINATION column.
-
-
+
Where a list of IP addresses appears in the DEST column of
+ a DNAT[-] rule, Shorewall incorrectly created multiple DNAT rules in the
+ nat table (one for each element in the list). Shorewall now correctly creates
+ a single DNAT rule with multiple "--to-destination" clauses.
+
+
+
Corrected a problem in Beta 1 where DNS names containing
+a "-" were mis-handled when they appeared in the DEST column of a rule.
+
+
+
A number of problems with rule parsing have been
+corrected. Corrections involve the handling of "z1!z2" in the SOURCE column
+as well as lists in the ORIGINAL DESTINATION column.
+
+
-
+
Migration Issues:
-
-
+
+
-
In earlier versions, an undocumented feature allowed entries
-in the host file as follows:
-
- z eth1:192.168.1.0/24,eth2:192.168.2.0/24
-
- This capability was never documented and has been removed in 1.4.6 to allow
-entries of the following format:
-
- z eth1:192.168.1.0/24,192.168.2.0/24
-
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have been
-removed from /etc/shorewall/shorewall.conf. These capabilities are now automatically
- detected by Shorewall (see below).
-
-
-
-
-
New Features:
-
-
-
-
A 'newnotsyn' interface option has been added. This option may
-be specified in /etc/shorewall/interfaces and overrides the setting NEWNOTSYN=No
- for packets arriving on the associated interface.
-
-
-
The means for specifying a range of IP addresses in /etc/shorewall/masq
- to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for address
- ranges.
-
-
-
Shorewall can now add IP addresses to subnets other than the
-first one on an interface.
-
-
-
DNAT[-] rules may now be used to load balance (round-robin)
-over a set of servers. Servers may be specified in a range of addresses
- given as <first address>-<last address>.
-
- Example:
-
- DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
-
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration
-options have been removed and have been replaced by code that detects whether
-these capabilities are present in the current kernel. The output of the
-start, restart and check commands have been enhanced to report the outcome:
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Verifying Configuration...
-
-
-
Support for the Connection Tracking Match Extension has been
-added. This extension is available in recent kernel/iptables releases and
-allows for rules which match against elements in netfilter's connection tracking
- table. Shorewall automatically detects the availability of this extension
- and reports its availability in the output of the start, restart and check
- commands.
-
- Shorewall has detected the following iptables/netfilter capabilities:
- NAT: Available
- Packet Mangling: Available
- Multi-port Match: Available
- Connection Tracking Match: Available
- Verifying Configuration...
-
- If this extension is available, the ruleset generated by Shorewall is
-changed in the following ways:
-
-
-
To handle 'norfc1918' filtering, Shorewall will not create
-chains in the mangle table but will rather do all 'norfc1918' filtering in
-the filter table (rfc1918 chain).
-
Recall that Shorewall DNAT rules generate two netfilter rules;
-one in the nat table and one in the filter table. If the Connection Tracking
-Match Extension is available, the rule in the filter table is extended to
-check that the original destination address was the same as specified (or
-defaulted to) in the DNAT rule.
+
In earlier versions, an undocumented feature allowed entries
+ in the host file as follows:
+
+ z eth1:192.168.1.0/24,eth2:192.168.2.0/24
+
+ This capability was never documented and has been removed in 1.4.6 to
+ allow entries of the following format:
+
+ z eth1:192.168.1.0/24,192.168.2.0/24
-
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have
+ been removed from /etc/shorewall/shorewall.conf. These capabilities are
+now automatically detected by Shorewall (see below).
+
+
+
+
+
New Features:
+
+
+
+
A 'newnotsyn' interface option has been added. This option
+ may be specified in /etc/shorewall/interfaces and overrides the setting
+NEWNOTSYN=No for packets arriving on the associated interface.
+
+
+
The means for specifying a range of IP addresses in /etc/shorewall/masq
+ to use for SNAT is now documented. ADD_SNAT_ALIASES=Yes is enabled for
+address ranges.
+
+
+
Shorewall can now add IP addresses to subnets other than
+the first one on an interface.
+
+
+
DNAT[-] rules may now be used to load balance (round-robin)
+ over a set of servers. Servers may be specified in a range of addresses
+ given as <first address>-<last address>.
+
+ Example:
+
+ DNAT net loc:192.168.10.2-192.168.10.5 tcp 80
+
+
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT configuration
+ options have been removed and have been replaced by code that detects whether
+ these capabilities are present in the current kernel. The output of the
+start, restart and check commands have been enhanced to report the outcome:
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Verifying Configuration...
+
+
+
Support for the Connection Tracking Match Extension has been
+ added. This extension is available in recent kernel/iptables releases
+and allows for rules which match against elements in netfilter's connection
+ tracking table. Shorewall automatically detects the availability of this
+ extension and reports its availability in the output of the start, restart
+ and check commands.
+
+ Shorewall has detected the following iptables/netfilter capabilities:
+ NAT: Available
+ Packet Mangling: Available
+ Multi-port Match: Available
+ Connection Tracking Match: Available
+ Verifying Configuration...
+
+ If this extension is available, the ruleset generated by Shorewall
+is changed in the following ways:
+
+
+
To handle 'norfc1918' filtering, Shorewall will not create
+ chains in the mangle table but will rather do all 'norfc1918' filtering
+ in the filter table (rfc1918 chain).
+
Recall that Shorewall DNAT rules generate two netfilter
+rules; one in the nat table and one in the filter table. If the Connection
+Tracking Match Extension is available, the rule in the filter table is extended
+to check that the original destination address was the same as specified
+(or defaulted to) in the DNAT rule.
+
+
+
-
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
- may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
-
-
-
An 'ipcalc' command has been added to /sbin/shorewall.
-
- ipcalc [ <address> <netmask> | <address>/<vlsm>
-]
-
- Examples:
-
- [root@wookie root]# shorewall ipcalc 192.168.1.0/24
- CIDR=192.168.1.0/24
- NETMASK=255.255.255.0
- NETWORK=192.168.1.0
- BROADCAST=192.168.1.255
- [root@wookie root]#
-
- [root@wookie root]# shorewall ipcalc 192.168.1.0 255.255.255.0
- CIDR=192.168.1.0/24
- NETMASK=255.255.255.0
- NETWORK=192.168.1.0
- BROADCAST=192.168.1.255
- [root@wookie root]#
-
- Warning:
-
- If your shell only supports 32-bit signed arithmatic (ash or dash), then
- the ipcalc command produces incorrect information for IP addresses 128.0.0.0-1
- and for /1 networks. Bash should produce correct information for all valid
- IP addresses.
-
-
-
An 'iprange' command has been added to /sbin/shorewall.
-
- iprange <address>-<address>
-
- This command decomposes a range of IP addressses into a list of network
-and host addresses. The command can be useful if you need to construct an
-efficient set of rules that accept connections from a range of network addresses.
-
- Note: If your shell only supports 32-bit signed arithmetic (ash or dash)
-then the range may not span 128.0.0.0.
-
- Example:
-
- [root@gateway root]# shorewall iprange 192.168.1.4-192.168.12.9
- 192.168.1.4/30
- 192.168.1.8/29
- 192.168.1.16/28
- 192.168.1.32/27
- 192.168.1.64/26
- 192.168.1.128/25
- 192.168.2.0/23
- 192.168.4.0/22
- 192.168.8.0/22
- 192.168.12.0/29
- 192.168.12.8/31
- [root@gateway root]#
-
-
-
A list of host/net addresses is now allowed in an entry in /etc/shorewall/hosts.
-
- Example:
-
- foo eth1:192.168.1.0/24,192.168.2.0/24
-
+
The shell used to interpret the firewall script (/usr/share/shorewall/firewall)
+ may now be specified using the SHOREWALL_SHELL parameter in shorewall.conf.
+
+
+
An 'ipcalc' command has been added to /sbin/shorewall.
+
+ ipcalc [ <address> <netmask> | <address>/<vlsm>
+ ]
+
+ Examples:
+
+ [root@wookie root]# shorewall ipcalc 192.168.1.0/24
+ CIDR=192.168.1.0/24
+ NETMASK=255.255.255.0
+ NETWORK=192.168.1.0
+ BROADCAST=192.168.1.255
+ [root@wookie root]#
+
+ [root@wookie root]# shorewall ipcalc 192.168.1.0 255.255.255.0
+ CIDR=192.168.1.0/24
+ NETMASK=255.255.255.0
+ NETWORK=192.168.1.0
+ BROADCAST=192.168.1.255
+ [root@wookie root]#
+
+ Warning:
+
+ If your shell only supports 32-bit signed arithmatic (ash or dash),
+then the ipcalc command produces incorrect information for IP addresses
+128.0.0.0-1 and for /1 networks. Bash should produce correct information
+for all valid IP addresses.
+
+
+
An 'iprange' command has been added to /sbin/shorewall.
+
+ iprange <address>-<address>
+
+ This command decomposes a range of IP addressses into a list of network
+ and host addresses. The command can be useful if you need to construct
+an efficient set of rules that accept connections from a range of network
+addresses.
+
+ Note: If your shell only supports 32-bit signed arithmetic (ash or dash)
+ then the range may not span 128.0.0.0.
+
+ Example:
+
+ [root@gateway root]# shorewall iprange 192.168.1.4-192.168.12.9
+ 192.168.1.4/30
+ 192.168.1.8/29
+ 192.168.1.16/28
+ 192.168.1.32/27
+ 192.168.1.64/26
+ 192.168.1.128/25
+ 192.168.2.0/23
+ 192.168.4.0/22
+ 192.168.8.0/22
+ 192.168.12.0/29
+ 192.168.12.8/31
+ [root@gateway root]#
+
+
+
A list of host/net addresses is now allowed in an entry in
+ /etc/shorewall/hosts.
+
+ Example:
+
+ foo eth1:192.168.1.0/24,192.168.2.0/24
+
-
+
-
+
-
+
6/17/2003 - Shorewall-1.4.5
-
+
+
Problems Corrected:
-
-
+
+
+
-
The command "shorewall debug try <directory>" now
- correctly traces the attempt.
-
The INCLUDE directive now works properly in the zones
-file; previously, INCLUDE in that file was ignored.
-
/etc/shorewall/routestopped records with an empty second
- column are no longer ignored.
-
-
+
The command "shorewall debug try <directory>"
+ now correctly traces the attempt.
+
The INCLUDE directive now works properly in the zones
+ file; previously, INCLUDE in that file was ignored.
+
/etc/shorewall/routestopped records with an empty
+second column are no longer ignored.
+
+
+
-
+
+
New Features:
-
-
+
+
+
-
The ORIGINAL DEST column in a DNAT[-] or REDIRECT[-]
-rule may now contain a list of addresses. If the list begins with "!'
-then the rule will take effect only if the original destination address
+
The ORIGINAL DEST column in a DNAT[-] or REDIRECT[-]
+ rule may now contain a list of addresses. If the list begins with "!'
+then the rule will take effect only if the original destination address
in the connection request does not match any of the addresses listed.
-
+
+
-
-
6/15/2003 - Shorewall, Kernel 2.4.21 and iptables 1.2.8
-
- The firewall at shorewall.net has been upgraded to the 2.4.21
-kernel and iptables 1.2.8 (using the "official" RPM from netfilter.org).
-No problems have been encountered with this set of software. The Shorewall
-version is 1.4.4b plus the accumulated changes for 1.4.5.
-
+
+
+
6/15/2003 - Shorewall, Kernel 2.4.21 and iptables 1.2.8
+
+ The firewall at shorewall.net has been upgraded to the 2.4.21
+ kernel and iptables 1.2.8 (using the "official" RPM from netfilter.org).
+ No problems have been encountered with this set of software. The Shorewall
+ version is 1.4.4b plus the accumulated changes for 1.4.5.
+
6/8/2003 - Updated Samples
-
-
Thanks to Francesca Smith, the samples have been updated to Shorewall
- version 1.4.4.
-
-
+
+
Thanks to Francesca Smith, the samples have been updated to Shorewall
+ version 1.4.4.
- Jacques Nilo and Eric Wolzak
- have a LEAF (router/firewall/gateway
- on a floppy, CD or compact flash) distribution
- called Bering that features
- Shorewall-1.4.2 and Kernel-2.4.20.
-You can find their work at: http://leaf.sourceforge.net/devel/jnilo
+ Jacques Nilo and Eric
+ Wolzak have a LEAF (router/firewall/gateway
+ on a floppy, CD or compact flash) distribution
+ called Bering that
+ features Shorewall-1.4.2 and Kernel-2.4.20.
+ You can find their work at:
+ http://leaf.sourceforge.net/devel/jnilo
- Congratulations to Jacques
- and Eric on the recent release of Bering 1.2!!!
-
+ Congratulations to Jacques
+ and Eric on the recent release of Bering
+ 1.2!!!
-
+
Setting up Shorewall on a standalone Linux system is very
+
+
Setting up Shorewall on a standalone Linux system is very
easy if you understand the basics and follow the documentation.
-
-
This guide doesn't attempt to acquaint you with all of the features of
- Shorewall. It rather focuses on what is required to configure Shorewall
+
+
This guide doesn't attempt to acquaint you with all of the features of
+ Shorewall. It rather focuses on what is required to configure Shorewall
in one of its most common configurations:
-
+
-
Linux system
-
Single external IP address
-
Connection through Cable Modem, DSL, ISDN, Frame Relay, dial-up...
-
+
Linux system
+
Single external IP address
+
Connection through Cable Modem, DSL, ISDN, Frame Relay, dial-up...
+
-
-
Shorewall requires that you have the iproute/iproute2 package installed
- (on RedHat, the package is called iproute). You can tell
- if this package is installed by the presence of an ip program
-on your firewall system. As root, you can use the 'which' command to
-check for this program:
-
+
+
Shorewall requires that you have the iproute/iproute2 package installed
+ (on RedHat, the package is called iproute). You can tell
+ if this package is installed by the presence of an ip program on
+ your firewall system. As root, you can use the 'which' command to check
+ for this program:
+
[root@gateway root]# which ip /sbin/ip [root@gateway root]#
-
-
I recommend that you read through the guide first to familiarize yourself
- with what's involved then go back through it again making your configuration
- changes. Points at which configuration changes are recommended are
-flagged with I recommend that you read through the guide first to familiarize yourself
+ with what's involved then go back through it again making your configuration
+ changes. Points at which configuration changes are recommended are flagged
+ with
- .
-
+ .
+
- If you edit your configuration files on a Windows system, you
- must save them as Unix files if your editor supports that option or you
- must run them through dos2unix before trying to use them. Similarly, if
- you copy a configuration file from your Windows hard drive to a floppy
+ If you edit your configuration files on a Windows system, you
+ must save them as Unix files if your editor supports that option or you
+ must run them through dos2unix before trying to use them. Similarly, if
+ you copy a configuration file from your Windows hard drive to a floppy
disk, you must run dos2unix against the copy before using it with Shorewall.
- The configuration files for Shorewall are contained in the directory
- /etc/shorewall -- for simple setups, you only need to deal with a few
+ The configuration files for Shorewall are contained in the directory
+ /etc/shorewall -- for simple setups, you only need to deal with a few
of these as described in this guide. After you have installed Shorewall, download the one-interface sample,
- un-tar it (tar -zxvf one-interface.tgz) and and copy the files to /etc/shorewall
- (they will replace files with the same names that were placed in /etc/shorewall
+ href="http://www1.shorewall.net/pub/shorewall/Samples/">one-interface sample,
+ un-tar it (tar -zxvf one-interface.tgz) and and copy the files to /etc/shorewall
+ (they will replace files with the same names that were placed in /etc/shorewall
during Shorewall installation).
-
-
As each file is introduced, I suggest that you look through the actual
- file on your system -- each file contains detailed configuration instructions
+
+
As each file is introduced, I suggest that you look through the actual
+ file on your system -- each file contains detailed configuration instructions
and default entries.
-
-
Shorewall views the network where it is running as being composed of a
- set of zones. In the one-interface sample configuration, only
+
+
Shorewall views the network where it is running as being composed of a
+ set of zones. In the one-interface sample configuration, only
one zone is defined:
For each connection request entering the firewall, the request is first
- checked against the /etc/shorewall/rules file. If no rule in that file
- matches the connection request then the first policy in /etc/shorewall/policy
- that matches the request is applied. If that policy is REJECT or DROP
- the request is first checked against the rules in /etc/shorewall/common
+
+
For each connection request entering the firewall, the request is first
+ checked against the /etc/shorewall/rules file. If no rule in that file
+ matches the connection request then the first policy in /etc/shorewall/policy
+ that matches the request is applied. If that policy is REJECT or DROP
+ the request is first checked against the rules in /etc/shorewall/common
(the samples provide that file for you).
-
-
The /etc/shorewall/policy file included with the one-interface sample
-has the following policies:
-
-
+
+
The /etc/shorewall/policy file included with the one-interface sample has
+the following policies:
+
+
-
+
+
+
SOURCE ZONE
+
DESTINATION ZONE
+
POLICY
+
LOG LEVEL
+
LIMIT:BURST
+
-
SOURCE ZONE
-
DESTINATION ZONE
-
POLICY
-
LOG LEVEL
-
LIMIT:BURST
-
-
-
fw
-
net
-
ACCEPT
-
-
-
-
-
net
-
all
-
-
DROP
-
info
-
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
+
fw
+
net
+
ACCEPT
+
+
+
+
+
net
+
all
+
+
DROP
+
info
+
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
-
-
+
+
The above policy will:
-
+
-
allow all connection requests from the firewall to the internet
-
drop (ignore) all connection requests from the internet to
-your firewall
-
reject all other connection requests (Shorewall requires this
- catchall policy).
-
+
allow all connection requests from the firewall to the internet
+
drop (ignore) all connection requests from the internet to
+ your firewall
+
reject all other connection requests (Shorewall requires
+this catchall policy).
+
-
-
At this point, edit your /etc/shorewall/policy and make any changes that
+
+
At this point, edit your /etc/shorewall/policy and make any changes that
you wish.
-
+
External Interface
-
-
The firewall has a single network interface. Where Internet
- connectivity is through a cable or DSL "Modem", the External Interface
- will be the ethernet adapter (eth0) that is connected to that
-"Modem" unless you connect via Point-to-Point
-Protocol over Ethernet (PPPoE) or Point-to-Point
-Tunneling Protocol (PPTP) in which case the External
-Interface will be a ppp0. If you connect via a regular modem, your
-External Interface will also be ppp0. If you connect using ISDN,
+
+
The firewall has a single network interface. Where Internet
+ connectivity is through a cable or DSL "Modem", the External Interface
+ will be the ethernet adapter (eth0) that is connected to that
+"Modem" unless you connect via Point-to-Point
+Protocol over Ethernet (PPPoE) or Point-to-Point
+Tunneling Protocol (PPTP) in which case the External
+Interface will be a ppp0. If you connect via a regular modem, your
+External Interface will also be ppp0. If you connect using ISDN,
your external interface will be ippp0.
-
+
- The Shorewall one-interface sample configuration assumes that
-the external interface is eth0. If your configuration is different,
- you will have to modify the sample /etc/shorewall/interfaces file accordingly.
- While you are there, you may wish to review the list of options that
+ The Shorewall one-interface sample configuration assumes that
+the external interface is eth0. If your configuration is different,
+ you will have to modify the sample /etc/shorewall/interfaces file accordingly.
+ While you are there, you may wish to review the list of options that
are specified for the interface. Some hints:
-
+
-
-
If your external interface is ppp0 or ippp0,
+
+
If your external interface is ppp0 or ippp0,
you can replace the "detect" in the second column with "-".
-
-
-
If your external interface is ppp0 or ippp0
- or if you have a static IP address, you can remove "dhcp" from the
+
+
+
If your external interface is ppp0 or ippp0
+ or if you have a static IP address, you can remove "dhcp" from the
option list.
-
-
+
+
-
-
+
+
IP Addresses
-
-
-
-
RFC 1918 reserves several Private IP address ranges
+
+
+
+
RFC 1918 reserves several Private IP address ranges
for use in private networks:
These addresses are sometimes referred to as non-routable
- because the Internet backbone routers will not forward a packet whose
- destination address is reserved by RFC 1918. In some cases though,
-ISPs are assigning these addresses then using Network Address Translation
+
+
+
These addresses are sometimes referred to as non-routable
+ because the Internet backbone routers will not forward a packet whose
+ destination address is reserved by RFC 1918. In some cases though, ISPs
+ are assigning these addresses then using Network Address Translation
to rewrite packet headers when forwarding to/from the internet.
-
+
- Before starting Shorewall, you should look at the IP address
- of your external interface and if it is one of the above ranges, you
+ Before starting Shorewall, you should look at the IP address
+ of your external interface and if it is one of the above ranges, you
should remove the 'norfc1918' option from the entry in /etc/shorewall/interfaces.
-
-
-
-
Enabling other Connections
-
-
-
If you wish to enable connections from the internet to your
+
+
+
Enabling other Connections
+
+
+
+
If you wish to enable connections from the internet to your
firewall, the general format is:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
net
-
fw
-
<protocol>
-
<port>
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
<protocol>
+
<port>
+
+
+
+
+
-
+
+
+
+
+
Example - You want to run a Web Server and a POP3 Server on
+your firewall system:
-
-
-
Example - You want to run a Web Server and a POP3 Server
-on your firewall system:
-
-
-
-
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
net
-
fw
-
tcp
-
80
-
-
-
-
-
ACCEPT
-
net
-
fw
-
tcp
-
110
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
80
+
+
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
110
+
+
+
+
+
-
+
+
+
+
+
If you don't know what port and protocol a particular application
+ uses, see here.
-
-
-
If you don't know what port and protocol a particular application
-uses, see here.
-
-
-
-
Important: I don't recommend enabling telnet to/from
- the internet because it uses clear text (even for login!). If you
-want shell access to your firewall from the internet, use SSH:
-
-
-
-
+
+
+
Important: I don't recommend enabling telnet to/from
+ the internet because it uses clear text (even for login!). If you want
+ shell access to your firewall from the internet, use SSH:
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
net
-
fw
-
tcp
-
22
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
22
+
+
+
+
+
-
-
-
-
+
+
+
+
- At this point, edit /etc/shorewall/rules to add other connections
+ At this point, edit /etc/shorewall/rules to add other connections
as desired.
-
-
-
-
Starting and Stopping Your Firewall
-
-
+
+
+
Starting and Stopping Your Firewall
+
+
+
- The installation procedure configures
- your system to start Shorewall at system boot but beginning with Shorewall
- version 1.3.9 startup is disabled so that your system won't try to start
- Shorewall before configuration is complete. Once you have completed configuration
- of your firewall, you can enable Shorewall startup by removing the file
-/etc/shorewall/startup_disabled.
-
-
-
IMPORTANT: Users of the .deb
+ The installation procedure configures
+ your system to start Shorewall at system boot but beginning with Shorewall
+ version 1.3.9 startup is disabled so that your system won't try to start
+ Shorewall before configuration is complete. Once you have completed configuration
+ of your firewall, you can enable Shorewall startup by removing the file
+ /etc/shorewall/startup_disabled.
+
+
+
IMPORTANT: Users of the .deb
package must edit /etc/default/shorewall and set 'startup=1'.
-
-
-
-
-
The firewall is started using the "shorewall start" command
- and stopped using "shorewall stop". When the firewall is stopped,
-routing is enabled on those hosts that have an entry in /etc/shorewall/routestopped. A
- running firewall may be restarted using the "shorewall restart" command.
- If you want to totally remove any trace of Shorewall from your Netfilter
+
+
+
+
+
The firewall is started using the "shorewall start" command
+ and stopped using "shorewall stop". When the firewall is stopped, routing
+ is enabled on those hosts that have an entry in /etc/shorewall/routestopped. A
+ running firewall may be restarted using the "shorewall restart" command.
+ If you want to totally remove any trace of Shorewall from your Netfilter
configuration, use "shorewall clear".
-
-
-
-
WARNING: If you are connected to your firewall from
- the internet, do not issue a "shorewall stop" command unless you have
- added an entry for the IP address that you are connected from to
-/etc/shorewall/routestopped.
- Also, I don't recommend using "shorewall restart"; it is better to create
- an alternate configuration
+
+
+
+
WARNING: If you are connected to your firewall from
+ the internet, do not issue a "shorewall stop" command unless you have
+ added an entry for the IP address that you are connected from to /etc/shorewall/routestopped.
+Also, I don't recommend using "shorewall restart"; it is better to create
+ an alternate configuration
and test it using the "shorewall try" command.
Notes du traducteur :
- Je ne prétends pas être un vrai traducteur dans le sens ou mon travail
-n'est pas des plus précis (loin de là...). Je ne me suis pas attaché à une
-traduction exacte du texte, mais plutôt à en faire une version française
-intelligible par tous (et par moi). Les termes techniques sont la plupart
-du temps conservés sous leur forme originale et mis entre parenthèses car
-vous pouvez les retrouver dans le reste des documentations ainsi que dans
-les fichiers de configuration. N?hésitez pas à me contacter afin d?améliorer
-ce document VETSEL Patrice
-(merci à JMM pour sa relecture et ses commentaires pertinents, ainsi qu'à
-Tom EASTEP pour son formidable outil et sa disponibilité).
-
-
Mettre en place un système Linux en tant que firewall (écluse)
-pour un petit réseau est une chose assez simple, si vous comprenez les bases
-et suivez la documentation.
-
-
Ce guide ne veut pas vous apprendre tous les rouages de Shorewall. Il se
-focalise sur ce qui est nécessaire pour configurer Shorewall, dans son utilisation
-la plus courante :
-
+ Je ne prétends pas être un vrai traducteur dans le sens ou mon travail
+n'est pas des plus précis (loin de là...). Je ne me suis pas attaché à une
+traduction exacte du texte, mais plutôt à en faire une version française intelligible
+par tous (et par moi). Les termes techniques sont la plupart du temps conservés
+sous leur forme originale et mis entre parenthèses car vous pouvez les retrouver
+dans le reste des documentations ainsi que dans les fichiers de configuration.
+N?hésitez pas à me contacter afin d?améliorer ce document VETSEL Patrice (merci à JMM
+pour sa relecture et ses commentaires pertinents, ainsi qu'à Tom EASTEP pour
+son formidable outil et sa disponibilité).
+
+
Mettre en place un système Linux en tant que firewall (écluse)
+ pour un petit réseau est une chose assez simple, si vous comprenez les bases
+ et suivez la documentation.
+
+
Ce guide ne veut pas vous apprendre tous les rouages de Shorewall. Il
+se focalise sur ce qui est nécessaire pour configurer Shorewall, dans son
+utilisation la plus courante :
+
-
Un système Linux
-
Une seule adresse IP externe
-
Une connexion passant par un modem câble, ADSL, ISDN, Frame Relay,
-rtc...
-
+
Un système Linux
+
Une seule adresse IP externe
+
Une connexion passant par un modem câble, ADSL, ISDN, Frame Relay,
+ rtc...
+
-
-
Ce guide suppose que vous avez le paquet iproute/iproute2 d'installé. Vous
-pouvez voir si le paquet est installé en vérifiant la présence du programme
-ip sur votre système de firewall. Sous root, utilisez la commande 'which'
-pour rechercher le programme :
-
+
+
Ce guide suppose que vous avez le paquet iproute/iproute2 d'installé.
+Vous pouvez voir si le paquet est installé en vérifiant la présence du programme
+ ip sur votre système de firewall. Sous root, utilisez la commande 'which'
+ pour rechercher le programme :
+
[root@gateway root]# which ip /sbin/ip [root@gateway root]#
-
-
Je vous recommande dans un premier temps de parcourir tout le guide pour
-vous familiariser avec ce qu'il va se passer, et de revenir au début en effectuant
-le changements dans votre configuration. Les points, où les changements dans
-la configuration sont recommandées, sont signalés par une Je vous recommande dans un premier temps de parcourir tout le guide pour
+ vous familiariser avec ce qu'il va se passer, et de revenir au début en
+effectuant le changements dans votre configuration. Les points, où les changements
+dans la configuration sont recommandées, sont signalés par une
- .
-
+ .
+
- Si vous éditez vos fichiers de configuration sur un système Windows, vous
- devez les sauver comme des fichiers Unix si votre éditeur supporte cette
-option sinon vous devez les faire passer par dos2unix avant d'essayer de
-les utiliser. De la même manière, si vous copiez un fichier de configuration
-depuis votre disque dur Windows vers une disquette, vous devez lancer dos2unix
-sur la copie avant de l'utiliser avec Shorewall.
-
+ Si vous éditez vos fichiers de configuration sur un système Windows, vous
+ devez les sauver comme des fichiers Unix si votre éditeur supporte cette
+option sinon vous devez les faire passer par dos2unix avant d'essayer de les
+utiliser. De la même manière, si vous copiez un fichier de configuration depuis
+votre disque dur Windows vers une disquette, vous devez lancer dos2unix sur
+la copie avant de l'utiliser avec Shorewall.
+
- Les fichiers de configuration pour Shorewall sont situés dans le répertoire
- /etc/shorewall -- pour de simples paramétrages, vous n'avez à faire qu'avec
-quelques un d'entre eux comme décris dans ce guide. Après avoir installé Shorewall, téléchargez le one-interface sample,
-un-tarez le (tar -zxvf one-interface.tgz) et copiez les fichiers vers /etc/shorewall
- (Ils remplaceront les fichiers de même nom déjà existant dans /etc/shorewall
+ href="http://www1.shorewall.net/pub/shorewall/Samples/">one-interface sample,
+un-tarez le (tar -zxvf one-interface.tgz) et copiez les fichiers vers /etc/shorewall
+ (Ils remplaceront les fichiers de même nom déjà existant dans /etc/shorewall
installés lors de l'installation de Shorewall).
-
-
Parallèlement à la description, je vous suggère de jeter un oeil à ceux
-physiquement présents sur votre système -- chacun des fichiers contient des
-instructions de configuration détaillées et des entrées par défaut.
-
-
Shorewall voit le réseau où il tourne comme composé par un ensemble de
-zones. Dans les fichiers de configuration fournis pour une unique interface,
-une seule zone est définie :
-
+
+
Parallèlement à la description, je vous suggère de jeter un oeil à ceux
+ physiquement présents sur votre système -- chacun des fichiers contient
+des instructions de configuration détaillées et des entrées par défaut.
+
+
Shorewall voit le réseau où il tourne comme composé par un ensemble de
+ zones. Dans les fichiers de configuration fournis pour une unique
+interface, une seule zone est définie :
Shorewall reconnaît aussi le système de firewall comme sa propre zone -
-par défaut, le firewall lui-même est connu en tant que fw.
-
-
Les règles concernant le trafic à autoriser ou à interdire sont exprimées
-en utilisant les termes de zones.
-
+
+
Shorewall reconnaît aussi le système de firewall comme sa propre zone
+- par défaut, le firewall lui-même est connu en tant que fw.
+
+
Les règles concernant le trafic à autoriser ou à interdire sont exprimées
+ en utilisant les termes de zones.
+
-
Vous exprimez les politiques par défaut pour les connexions d'une
-zone à une autre dans le fichier /etc/shorewall/policy
- .
-
Vous définissez les exceptions à ces règles de politiques par défaut
-dans le fichier /etc/shorewall/rules.
-
+
Vous exprimez les politiques par défaut pour les connexions d'une
+zone à une autre dans le fichier /etc/shorewall/policy
+ .
+
Vous définissez les exceptions à ces règles de politiques par défaut
+ dans le fichier /etc/shorewall/rules.
+
-
-
Pour chacune des demandes de connexion entrantes dans le firewall, les
-demandes sont en premier lieu comparées par rapport au fichier /etc/shorewall/rules.
-Si aucune des règles dans ce fichier ne correspondent, alors la première politique
-dans /etc/shorewall/policy qui y correspond est appliquée. Si cette politique
-est REJECT ou DROP la requête est alors comparée par rapport aux règles contenues
-dans /etc/shorewall/common (l'archive d'exemple vous fournit ce fichier).
-
-
Le fichier /etc/shorewall/policy d'exemple contenu dans l'archive one-interface
-a les politiques suivantes :
-
-
+
+
Pour chacune des demandes de connexion entrantes dans le firewall, les
+ demandes sont en premier lieu comparées par rapport au fichier /etc/shorewall/rules.
+ Si aucune des règles dans ce fichier ne correspondent, alors la première
+politique dans /etc/shorewall/policy qui y correspond est appliquée. Si cette
+politique est REJECT ou DROP la requête est alors comparée par rapport aux
+règles contenues dans /etc/shorewall/common (l'archive d'exemple vous fournit
+ce fichier).
+
+
Le fichier /etc/shorewall/policy d'exemple contenu dans l'archive one-interface
+ a les politiques suivantes :
+
+
-
-
-
SOURCE ZONE
-
DESTINATION ZONE
-
POLICY
-
LOG LEVEL
-
LIMIT:BURST
-
-
-
fw
-
net
-
ACCEPT
-
-
-
-
-
-
-
net
-
all
-
-
DROP
-
info
-
-
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
-
+
+
+
SOURCE ZONE
+
DESTINATION ZONE
+
POLICY
+
LOG LEVEL
+
LIMIT:BURST
+
+
+
fw
+
net
+
ACCEPT
+
+
+
+
+
+
+
net
+
all
+
+
DROP
+
info
+
+
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
+
-
-
+
+
- Ces politiques vont :
+ Ces politiques vont :
-
permettre toutes demandes de connexion depuis le firewall vers l'Internet
-
drop (ignorer) toutes les demandes de connexion depuis l'Internet
+
permettre toutes demandes de connexion depuis le firewall vers l'Internet
+
drop (ignorer) toutes les demandes de connexion depuis l'Internet
vers votre firewall
-
rejeter toutes les autres requêtes de connexion (Shorewall à besoin
-de cette politique).
-
+
rejeter toutes les autres requêtes de connexion (Shorewall à besoin
+ de cette politique).
+
-
-
A ce point, éditez votre /etc/shorewall/policy et faites y les changements
-que vous désirez.
-
+
+
A ce point, éditez votre /etc/shorewall/policy et faites y les changements
+ que vous désirez.
+
Interface Externe
-
-
Le firewall possède une seule interface réseau. Lorsque la
-connexion Internet passe par un modem câble ou par un routeur ADSL (pas un
-simple modem), l'External Interface (interface externe) sera l'adaptateur
-ethernet (eth0) qui y est connecté à moins que vous vous connectiez
-par Point-to-Point Protocol over Ethernet
-(PPPoE) ou Point-to-Point TunnelingProtocol(PPTP)
- dans ce cas l'interface externe sera ppp0. Si vous vous connectez
-par un simple modem (RTC), votre interface externe sera aussi ppp0.
- Si vous vous connectez en utilisant l'ISDN (numéris), votre interface externe
-sera ippp0.
-
+
+
Le firewall possède une seule interface réseau. Lorsque la
+ connexion Internet passe par un modem câble ou par un routeur ADSL (pas
+un simple modem), l'External Interface (interface externe) sera l'adaptateur
+ ethernet (eth0) qui y est connecté à moins que vous vous connectiez
+ par Point-to-Point Protocol over Ethernet
+ (PPPoE) ou Point-to-Point TunnelingProtocol(PPTP)
+ dans ce cas l'interface externe sera ppp0. Si vous vous connectez
+ par un simple modem (RTC), votre interface externe sera aussi ppp0.
+ Si vous vous connectez en utilisant l'ISDN (numéris), votre interface externe
+ sera ippp0.
+
- L'exemple de configuration de Shorewall pour une interface suppose que
-votre interface externe est eth0. Si votre configuration est différente,
-vous devrez modifier le fichier d'exemple /etc/shorewall/interfaces en conséquence.
- Puisque vous y êtes, vous pourriez parcourir la liste d'options qui sont
-spécifiées pour l'interface. Quelques astuces :
-
+ L'exemple de configuration de Shorewall pour une interface suppose que
+votre interface externe est eth0. Si votre configuration est différente,
+ vous devrez modifier le fichier d'exemple /etc/shorewall/interfaces en conséquence.
+ Puisque vous y êtes, vous pourriez parcourir la liste d'options qui sont
+ spécifiées pour l'interface. Quelques astuces :
+
-
-
Si votre interface externe est ppp0 ou ippp0,
- vous pouvez remplacer le "detect" dans la seconde colonne par un "-".
-
-
-
-
Si votre interface externe est ppp0 ou ippp0
- ou bien si vous avez une adresse IP statique, vous pouvez enlever le "dhcp"
-de la liste d'option.
-
-
+
+
Si votre interface externe est ppp0 ou ippp0,
+ vous pouvez remplacer le "detect" dans la seconde colonne par un "-".
+
+
+
+
Si votre interface externe est ppp0 ou ippp0
+ ou bien si vous avez une adresse IP statique, vous pouvez enlever le "dhcp"
+ de la liste d'option.
+
+
-
-
+
+
Adresse IP
-
-
-
-
La RFC 1918 définie plusieurs plage d'adresses IP privée (PrivateIP)
-pour l'utilisation dans des réseaux privés :
-
-
+
+
+
+
La RFC 1918 définie plusieurs plage d'adresses IP privée
+(PrivateIP) pour l'utilisation dans des réseaux privés :
Ces adresses sont parfois désignées comme étant non-routables
- car les routeurs sur les backbones Internet ne font pas passer les paquets
-dont les adresses de destinations sont définies dans la RFC 1918. Dans certains
-cas, les fournisseurs (provider ou ISP) utilisent ces adresses et utilisent
-le Network Address Translation afin de récrire les entêtes des paquets
-lorsqu'ils les font circuler depuis ou vers l'Internet.
-
+
+
+
Ces adresses sont parfois désignées comme étant non-routables
+ car les routeurs sur les backbones Internet ne font pas passer les paquets
+ dont les adresses de destinations sont définies dans la RFC 1918. Dans certains
+ cas, les fournisseurs (provider ou ISP) utilisent ces adresses et utilisent
+ le Network Address Translation afin de récrire les entêtes des paquets
+ lorsqu'ils les font circuler depuis ou vers l'Internet.
+
- Avant de lancer Shorewall, vous devriez regarder l'adresse de votre interface
-externe et si elle est comprise dans une des plages précédentes, vous devriez
-enlever l'option 'norfc1918' dans le fichier /etc/shorewall/interfaces.
-
-
-
+ Avant de lancer Shorewall, vous devriez regarder l'adresse de votre interface
+ externe et si elle est comprise dans une des plages précédentes, vous devriez
+ enlever l'option 'norfc1918' dans le fichier /etc/shorewall/interfaces.
+
+
+
Permettre d'autres connexions
-
-
-
-
Si vous désirez autoriser d'autres connexions depuis l'Internet
-vers votre firewall, le format général est :
-
-
-
-
+
+
+
+
Si vous désirez autoriser d'autres connexions depuis l'Internet
+ vers votre firewall, le format général est :
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
net
-
fw
-
<protocol>
-
<port>
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
<protocol>
+
<port>
+
+
+
+
+
+
+
-
-
-
-
-
Exemple - Vous voulez faire tourner un serveur Web et un serveur
-POP3 sur votre système de firewall :
-
-
-
-
+
+
+
+
+
Exemple - Vous voulez faire tourner un serveur Web et un
+serveur POP3 sur votre système de firewall :
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
net
-
fw
-
tcp
-
80
-
-
-
-
-
-
-
ACCEPT
-
net
-
fw
-
tcp
-
110
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
80
+
+
+
+
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
110
+
+
+
+
+
+
+
-
-
-
-
-
Si vous ne savez pas quel port ou protocole une application
-particulière utilise, regardez ici.
-
-
-
-
Important: Je ne vous recommande pas d'autoriser le
-telnet depuis ou vers l'Internet car il utilise du texte en clair (même pour
-le login et le mot de passe !). Si vous voulez avoir un accès au shell de
-votre firewall depuis Internet, utilisez SSH :
-
-
-
-
+
+
+
+
+
Si vous ne savez pas quel port ou protocole une application
+ particulière utilise, regardez ici.
+
+
+
+
Important: Je ne vous recommande pas d'autoriser le
+ telnet depuis ou vers l'Internet car il utilise du texte en clair (même
+pour le login et le mot de passe !). Si vous voulez avoir un accès au shell
+de votre firewall depuis Internet, utilisez SSH :
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
net
-
fw
-
tcp
-
22
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
22
+
+
+
+
+
+
+
-
-
-
-
+
+
+
+
ACCEPT net fw tcp 22
-
-
-
+
+
+
- A ce point, éditez /etc/shorewall/rules pour rajouter les autres connexions
-désirées.
-
-
-
+ A ce point, éditez /etc/shorewall/rules pour rajouter les autres connexions
+ désirées.
+
+
+
Lancer et Arrêter son Firewall
-
-
-
+
+
+
- La procédure d'installation configure votre
-système pour lancer Shorewall au boot du système, mais au début avec la version
-1.3.9 de Shorewall le lancement est désactivé, n'essayer pas de lancer Shorewall
-avec que la configuration soit finie. Une fois que vous en aurez fini avec
-la configuration du firewall, vous pouvez permettre le lancement de Shorewall
-en supprimant le fichier /etc/shorewall/startup_disabled.
-
-
-
IMPORTANT: Les utilisateurs des
-paquets .deb doivent éditer /etc/default/shorewall et mettre 'startup=1'.
-
-
-
-
-
Le firewall est activé en utilisant la commande "shorewall
-start" et arrêté avec "shorewall stop". Lorsque le firewall est stoppé, le
-routage est autorisé sur les hôtes qui possèdent une entrée dans /etc/shorewall/routestopped. Un
-firewall qui tourne peut être relancé en utilisant la commande "shorewall
-restart". Si vous voulez enlever toutes traces de Shorewall sur votre configuration
-de Netfilter, utilisez "shorewall clear".
-
-
-
-
ATTENTION: Si vous êtes connecté à votre firewall depuis
-Internet, n'essayez pas une commande "shorewall stop" tant que vous n'avez
-pas ajouté une entrée pour votre adresse IP (celle à partir de laquelle vous
-êtes connectée) dans /etc/shorewall/routestopped.
- De la même manière, je ne vous recommande pas d'utiliser "shorewall restart";
-il est plus intéressant de créer une configuration alternative
+ La procédure d'installation configure votre
+système pour lancer Shorewall au boot du système, mais au début avec la version
+1.3.9 de Shorewall le lancement est désactivé, n'essayer pas de lancer Shorewall
+ avec que la configuration soit finie. Une fois que vous en aurez fini avec
+ la configuration du firewall, vous pouvez permettre le lancement de Shorewall
+ en supprimant le fichier /etc/shorewall/startup_disabled.
+
+
+
IMPORTANT: Les utilisateurs
+des paquets .deb doivent éditer /etc/default/shorewall et mettre 'startup=1'.
+
+
+
+
+
Le firewall est activé en utilisant la commande "shorewall
+ start" et arrêté avec "shorewall stop". Lorsque le firewall est stoppé,
+le routage est autorisé sur les hôtes qui possèdent une entrée dans /etc/shorewall/routestopped. Un
+ firewall qui tourne peut être relancé en utilisant la commande "shorewall
+ restart". Si vous voulez enlever toutes traces de Shorewall sur votre
+configuration de Netfilter, utilisez "shorewall clear".
+
+
+
+
ATTENTION: Si vous êtes connecté à votre firewall
+depuis Internet, n'essayez pas une commande "shorewall stop" tant que vous
+n'avez pas ajouté une entrée pour votre adresse IP (celle à partir de laquelle
+vous êtes connectée) dans /etc/shorewall/routestopped.
+ De la même manière, je ne vous recommande pas d'utiliser "shorewall restart";
+ il est plus intéressant de créer une configuration alternative
et de la tester en utilisant la commande "shorewall try".
If you have a permanent internet connection such as DSL or Cable,
- I recommend that you start the firewall automatically at boot.
-Once you have installed "firewall" in your init.d directory, simply
-type "chkconfig --add firewall". This will start the firewall
-in run levels 2-5 and stop it in run levels 1 and 6. If you want to
-configure your firewall differently from this default, you can use
-the "--level" option in chkconfig (see "man chkconfig") or using your
- favorite graphical run-level editor.
If you have a permanent internet connection such as DSL or Cable,
+ I recommend that you start the firewall automatically at boot.
+ Once you have installed "firewall" in your init.d directory, simply
+ type "chkconfig --add firewall". This will start the firewall
+ in run levels 2-5 and stop it in run levels 1 and 6. If you want
+to configure your firewall differently from this default, you can
+use the "--level" option in chkconfig (see "man chkconfig") or using
+your favorite graphical run-level editor.
+
Important Notes:
-
-
+
+
-
Shorewall startup is disabled by default. Once you have
-configured your firewall, you can enable startup by removing the file
-/etc/shorewall/startup_disabled. Note: Users of the .deb package must
-edit /etc/default/shorewall and set 'startup=1'.
-
-
If you use dialup, you may want to start the firewall
- in your /etc/ppp/ip-up.local script. I recommend just placing "shorewall
+
Shorewall startup is disabled by default. Once you have
+ configured your firewall, you can enable startup by removing the file
+ /etc/shorewall/startup_disabled. Note: Users of the .deb package must
+ edit /etc/default/shorewall and set 'startup=1'.
+
+
If you use dialup, you may want to start the firewall
+ in your /etc/ppp/ip-up.local script. I recommend just placing "shorewall
restart" in that script.
-
+
-
+
+
+
You can manually start and stop Shoreline Firewall using the "shorewall"
+ shell program:
-
You can manually start and stop Shoreline Firewall using the "shorewall"
- shell program:
-
-
shorewall start - starts the firewall
-
shorewall stop - stops the firewall
-
shorewall restart - stops the firewall (if it's
- running) and then starts it again
-
shorewall reset - reset the packet and byte counters
- in the firewall
-
shorewall clear - remove all rules and chains installed
- by Shoreline Firewall
-
shorewall refresh - refresh the rules involving the
+
shorewall start - starts the firewall
+
shorewall stop - stops the firewall
+
shorewall restart - stops the firewall (if it's
+ running) and then starts it again
+
shorewall reset - reset the packet and byte counters
+ in the firewall
+
shorewall clear - remove all rules and chains
+installed by Shoreline Firewall
The "shorewall" program may also be used to monitor the firewall.
-
-
-
shorewall status - produce a verbose report about the
-firewall (iptables -L -n -v)
-
shorewall show chain - produce a verbose report
- about chain (iptables -L chain -n -v)
-
shorewall show nat - produce a verbose report about
-the nat table (iptables -t nat -L -n -v)
-
shorewall show tos - produce a verbose report about
-the mangle table (iptables -t mangle -L -n -v)
-
shorewall show log - display the last 20 packet log
-entries.
-
shorewall show connections - displays the IP connections
- currently being tracked by the firewall.
-
shorewall show
- tc - displays
- information about the traffic control/shaping configuration.
-
shorewall monitor [ delay ] - Continuously display the
- firewall status, last 20 log entries and nat. When the log
-entry display changes, an audible alarm is sounded.
-
shorewall hits - Produces several reports about the
-Shorewall packet log messages in the current /var/log/messages
-file.
-
shorewall version - Displays the installed version
- number.
-
shorewall check - Performs a cursory validation of the
- zones, interfaces, hosts, rules and policy files.
-
- The "check" command is totally unsuppored
-and does not parse and validate the generated iptables commands.
-Even though the "check" command completes successfully, the configuration
-may fail to start. Problem reports that complain about errors that the 'check'
-command does not detect will not be accepted.
-
- See the recommended way to make configuration changes described below.
-
-
-
shorewall try configuration-directory [ timeout
- ] - Restart shorewall using the specified configuration and if
-an error occurs or if the timeout option is given and the
-new configuration has been up for that many seconds then shorewall
-is restarted using the standard configuration.
-
shorewall deny, shorewall reject, shorewall accept and
- shorewall save implement dynamic
- blacklisting.
-
shorewall logwatch (added in version 1.3.2) - Monitors
- the LOGFILE and produces an audible alarm when
- new Shorewall messages are logged.
-
-
-Beginning with Shorewall 1.4.6, /sbin/shorewall supports a couple of commands
-for dealing with IP addresses and IP address ranges:
-
-
shorewall ipcalc [ address mask | address/vlsm ] - displays
-the network address, broadcast address, network in CIDR notation and netmask
-corresponding to the input[s].
-
shorewall iprange address1-address2 - Decomposes the specified
-range of IP addresses into the equivalent list of network/host addresses.
-
-
-
-Finally, the "shorewall" program may be used to dynamically alter the
-contents of a zone.
-
-
-
shorewall add interface[:host]zone -
- Adds the specified interface (and host if included) to the specified zone.
-
shorewall delete interface[:host]zone
- - Deletes the specified interface (and host if included) from
-the specified zone.
-
-
-
-
Examples:
-
shorewall add ipsec0:192.0.2.24 vpn1
- -- adds the address 192.0.2.24 from interface ipsec0 to the zone vpn1
- shorewall delete ipsec0:192.0.2.24
-vpn1 -- deletes the address 192.0.2.24 from interface ipsec0
-from zone vpn1
-
-
-
-
The shorewall start, shorewall restart, shorewall check, and
- shorewall try commands allow you to specify which Shorewall configuration
- to use:
-
-
+
+ If you include the keyword debug as the first argument,
+then a shell trace of the command is produced as in:
+
+
shorewall debug start 2> /tmp/trace
+
+
The above command would trace the 'start' command and place the trace
+information in the file /tmp/trace
+
The "shorewall" program may also be used to monitor the firewall.
+
+
+
shorewall status - produce a verbose report about the
+ firewall (iptables -L -n -v)
+
shorewall show chain - produce a verbose report
+ about chain (iptables -L chain -n -v)
+
shorewall show nat - produce a verbose report about
+the nat table (iptables -t nat -L -n -v)
+
shorewall show tos - produce a verbose report about
+the mangle table (iptables -t mangle -L -n -v)
+
shorewall show log - display the last 20 packet log
+entries.
+
shorewall show connections - displays the IP connections
+ currently being tracked by the firewall.
+
shorewall
+show tc - displays
+ information about the traffic control/shaping configuration.
+
shorewall monitor [ delay ] - Continuously display
+the firewall status, last 20 log entries and nat. When the
+log entry display changes, an audible alarm is sounded.
+
shorewall hits - Produces several reports about the
+Shorewall packet log messages in the current /var/log/messages
+file.
+
shorewall version - Displays the installed version
+ number.
+
shorewall check - Performs a cursory validation of
+the zones, interfaces, hosts, rules and policy files.
+
+ The "check" command is totally unsuppored
+ and does not parse and validate the generated iptables commands.
+Even though the "check" command completes successfully, the configuration
+ may fail to start. Problem reports that complain about errors that the 'check'
+ command does not detect will not be accepted.
+
+ See the recommended way to make configuration changes described
+below.
+
+
+
shorewall try configuration-directory [ timeout
+ ] - Restart shorewall using the specified configuration and if
+an error occurs or if the timeout option is given and the new
+configuration has been up for that many seconds then shorewall is
+restarted using the standard configuration.
shorewall logwatch (added in version 1.3.2) - Monitors
+ the LOGFILE and produces an audible alarm
+when new Shorewall messages are logged.
+
+
+ Beginning with Shorewall 1.4.6, /sbin/shorewall supports a couple of commands
+for dealing with IP addresses and IP address ranges:
+
+
+
shorewall ipcalc [ address mask | address/vlsm ] - displays
+the network address, broadcast address, network in CIDR notation and netmask
+corresponding to the input[s].
+
shorewall iprange address1-address2 - Decomposes the specified
+range of IP addresses into the equivalent list of network/host addresses.
+
+
+
+
+ Finally, the "shorewall" program may be used to dynamically alter the
+ contents of a zone.
+
+
+
shorewall add interface[:host]zone -
+ Adds the specified interface (and host if included) to the specified
+zone.
+
shorewall delete interface[:host]zone
+ - Deletes the specified interface (and host if included) from
+the specified zone.
+
+
+
+
Examples:
+
+
shorewall add ipsec0:192.0.2.24 vpn1
+ -- adds the address 192.0.2.24 from interface ipsec0 to the zone vpn1
+ shorewall delete ipsec0:192.0.2.24
+ vpn1 -- deletes the address 192.0.2.24 from interface ipsec0
+ from zone vpn1
+
+
+
+
The shorewall start, shorewall restart, shorewall check, and
+ shorewall try commands allow you to specify which Shorewall configuration
+ to use:
If a configuration-directory is specified, each time that Shorewall
- is going to use a file in /etc/shorewall it will first look in the
-configuration-directory . If the file is present in the configuration-directory,
-that file will be used; otherwise, the file in /etc/shorewall will be
-used.
-
-
When changing the configuration of a production firewall, I recommend
- the following:
+ shorewall try configuration-directory
+
+
If a configuration-directory is specified, each time that Shorewall
+ is going to use a file in /etc/shorewall it will first look in the
+ configuration-directory . If the file is present in the configuration-directory,
+ that file will be used; otherwise, the file in /etc/shorewall will
+be used.
+
+
When changing the configuration of a production firewall, I recommend
+ the following:
+
-
mkdir /etc/test
-
cd /etc/test
-
<copy any files that you need to change
+
mkdir /etc/test
+
cd /etc/test
+
<copy any files that you need to change
from /etc/shorewall to . and change them here>
-
shorewall -c . check
-
<correct any errors found by check and check again>
-
shorewall -c . check
+
<correct any errors found by check and check again>
+
/sbin/shorewall try .
-
+
-
-
If the configuration starts but doesn't work, just "shorewall restart"
- to restore the old configuration. If the new configuration fails to
- start, the "try" command will automatically start the old one for you.
+
If the configuration starts but doesn't work, just "shorewall restart"
+ to restore the old configuration. If the new configuration fails
+to start, the "try" command will automatically start the old one for
+you.
+
When the new configuration works then just
-
+
-
cp * /etc/shorewall
-
cd
-
rm -rf /etc/test
-
+
cp * /etc/shorewall
+
cd
+
rm -rf /etc/test
+
-
+
The Shorewall State Diargram is depicted below.
-
-
+
+
-
-
-
+
+
+
-
- You will note that the commands that result in state transitions
-use the word "firewall" rather than "shorewall". That is because the actual
- transitions are done by /usr/lib/shorewall/firewall (/usr/share/shorewall/firewall
- on Debian); /sbin/shorewall runs 'firewall" according to the following
+
+ You will note that the commands that result in state transitions
+ use the word "firewall" rather than "shorewall". That is because the
+actual transitions are done by /usr/lib/shorewall/firewall (/usr/share/shorewall/firewall
+ on Debian); /sbin/shorewall runs 'firewall" according to the following
table:
-
-
+
+
-
-
-
shorewall start
-
-
firewall start
-
-
-
-
shorewall stop
-
-
firewall stop
-
-
-
-
shorewall restart
-
-
firewall restart
-
-
-
-
shorewall add
-
-
firewall add
-
-
-
-
shorewall delete
-
-
firewall delete
-
-
-
-
shorewall refresh
-
-
firewall refresh
-
-
-
-
shorewall try
-
-
firewall -c <new configuration> restart
- If unsuccessful then firewall start (standard configuration)
- If timeout then firewall restart (standard configuration)
-
-
-
-
+
+
+
shorewall start
+
+
firewall start
+
+
+
+
shorewall stop
+
+
firewall stop
+
+
+
+
shorewall restart
+
+
firewall restart
+
+
+
+
shorewall add
+
+
firewall add
+
+
+
+
shorewall delete
+
+
firewall delete
+
+
+
+
shorewall refresh
+
+
firewall refresh
+
+
+
+
shorewall try
+
+
firewall -c <new configuration> restart
+ If unsuccessful then firewall start (standard configuration)
+ If timeout then firewall restart (standard configuration)
+
+
-There are a number of sources of Shorewall information. Please
- try these before you post.
+ There are a number of sources of Shorewall information. Please
+ try these before you post.
-
Shorewall versions
-earlier that 1.3.0 are no longer supported.
-
-
More than half of the questions posted on the support
- list have answers directly accessible from the Documentation
+
- The FAQ
- has solutions to more than 20 common problems.
-
+
+
+ The FAQ
+ has solutions to more than 20 common problems.
+
+
+ The Troubleshooting
+ Information contains a number of tips to
+ help you solve common problems.
- The Troubleshooting
- Information contains a number of tips to
-help you solve common problems.
-
-The Errata
+ The Errata
has links to download updated components.
-
- The Site and Mailing List Archives search facility can
-locate documents and posts about similar problems:
-
-
+
+ The Site and Mailing List Archives search facility can
+ locate documents and posts about similar problems:
+
+
-
+
Site and Mailing List Archive Search
-
-
+
+
-
-
+
+
+
Problem Reporting Guidelines
-
-
+
+
-
Please remember we only know
- what is posted in your message. Do not leave out any information
- that appears to be correct, or was mentioned in a previous
- post. There have been countless posts by people who were sure
- that some part of their configuration was correct when it actually
- contained a small error. We tend to be skeptics where detail
- is lacking.
-
-
-
Please keep in mind that
-you're asking for free technical
- support. Any help we offer is an act of generosity, not an obligation.
- Try to make it easy for us to help you. Follow good, courteous
- practices in writing and formatting your e-mail. Provide details that
- we need if you expect good answers. Exact quoting of
-error messages, log entries, command output, and other output is better
- than a paraphrase or summary.
-
-
-
- Please don't describe your environment and then
-ask us to send you custom configuration files.
- We're here to answer your questions but we can't
+
Please remember we only
+know what is posted in your message. Do not leave out any
+information that appears to be correct, or was mentioned
+ in a previous post. There have been countless posts by people
+ who were sure that some part of their configuration was correct
+ when it actually contained a small error. We tend to be skeptics
+where detail is lacking.
+
+
+
Please keep in mind that
+you're asking for free technical
+support. Any help we offer is an act of generosity, not an obligation.
+ Try to make it easy for us to help you. Follow good, courteous
+ practices in writing and formatting your e-mail. Provide details
+that we need if you expect good answers. Exact quoting
+ of error messages, log entries, command output, and other output is
+better than a paraphrase or summary.
+
+
+
+ Please don't describe your environment and then
+ ask us to send you custom configuration files.
+ We're here to answer your questions but we can't
do your job for you.
-
-
-
When reporting a problem,
- ALWAYS include this information:
-
+
+
+
When reporting a problem,
+ ALWAYS include this information:
+
-
+
-
+
-
the exact version of Shorewall
+
the exact version of Shorewall
you are running.
-
- shorewall
- version
-
-
-
+
+ shorewall version
+
+
+
-
+
-
+
-
+
-
the complete, exact output
+
the complete, exact output
of
-
- ip
- addr show
-
-
-
+
+ ip
+ addr show
+
+
+
-
+
-
the complete, exact output
+
the complete, exact output
of
-
- ip
- route show
-
-
+
+ ip
+ route show
+
+
-
+
-
+
-
+
-
+
-
+
-
THIS IS
-IMPORTANT! If your problem
-is that some type of connection to/from or through your firewall isn't working
+
THIS IS
+IMPORTANT! If your problem is
+that some type of connection to/from or through your firewall isn't working
then please perform the following four steps:
-
- 1. /sbin/shorewall reset
-
- 2. Try making the connection that is failing.
-
- 3. /sbin/shorewall
+
+ 1. /sbin/shorewall reset
+
+ 2. Try making the connection that is failing.
+
+ 3. /sbin/shorewall
status > /tmp/status.txt
-
- 4. Post the /tmp/status.txt file as an attachment
+
+ 4. Post the /tmp/status.txt file as an attachment
(you may compress it if you like).
-
-
-
the exact wording of any
+
+
the exact wording of any ping failure responses
-
-
-
If you installed Shorewall using one of the QuickStart
- Guides, please indicate which one.
-
-
-
If you are running Shorewall under Mandrake using
- the Mandrake installation of Shorewall, please say so.
-
-
-
+
+
+
If you installed Shorewall using one of the QuickStart
+ Guides, please indicate which one.
+
+
+
If you are running Shorewall under Mandrake using
+ the Mandrake installation of Shorewall, please say so.
+
+
+
-
As a general matter, please do not edit the diagnostic
- information in an attempt to conceal your IP address,
- netmask, nameserver addresses, domain name, etc. These aren't
- secrets, and concealing them often misleads us (and 80% of the time,
- a hacker could derive them anyway from information contained
-in the SMTP headers of your post).
-
-
-
Do you see any "Shorewall" messages
- ("/sbin/shorewall show log")
- when you exercise the function that is giving you problems?
- If so, include the message(s) in your post along with a copy of
+
As a general matter, please do not edit the
+diagnostic information in an attempt to conceal
+your IP address, netmask, nameserver addresses, domain name,
+etc. These aren't secrets, and concealing them often misleads us
+(and 80% of the time, a hacker could derive them anyway from
+information contained in the SMTP headers of your post).
+
+
+
Do you see any "Shorewall" messages
+ ("/sbin/shorewall show log")
+ when you exercise the function that is giving you problems?
+ If so, include the message(s) in your post along with a copy of
your /etc/shorewall/interfaces file.
-
-
-
Please include any of the Shorewall configuration
- files (especially the /etc/shorewall/hosts file
- if you have modified that file) that you think are
- relevant. If you include /etc/shorewall/rules, please include
- /etc/shorewall/policy as well (rules are meaningless unless
- one also knows the policies).
-
-
-
If an error occurs when you try to
- "shorewall start", include
- a trace (See the Troubleshooting
- section for instructions).
-
-
-
The list server limits posts to 120kb so
- don't post GIFs of your network layout,
- etc. to the Mailing List -- your post will be rejected.
-
+
+
+
Please include any of the Shorewall configuration
+ files (especially the /etc/shorewall/hosts file
+ if you have modified that file) that you think are
+ relevant. If you include /etc/shorewall/rules, please include
+ /etc/shorewall/policy as well (rules are meaningless unless
+ one also knows the policies).
+
+
+
If an error occurs when you try
+to "shorewall start", include
+ a trace (See the Troubleshooting
+ section for instructions).
+
+
+
The list server limits posts to 120kb
+so don't post GIFs of your network
+layout, etc. to the Mailing List -- your post will be
+rejected.
When using the mailing list, please post in plain text
-
-
A growing number of MTAs serving list subscribers are rejecting
- all HTML traffic. At least one MTA has gone so far as to blacklist
- shorewall.net "for continuous abuse" because it has been my policy
- to allow HTML in list posts!!
-
- I think that blocking all
-HTML is a Draconian way to control spam and that the
-ultimate losers here are not the spammers but the list subscribers
- whose MTAs are bouncing all shorewall.net mail. As one list
- subscriber wrote to me privately "These e-mail admin's need
- to get a (expletive deleted) life instead of trying to rid
- the planet of HTML based e-mail". Nevertheless, to allow subscribers
- to receive list posts as must as possible, I have now configured
-the list server at shorewall.net to strip all HTML from outgoing
- posts.
-
- If you run your own outgoing mail server
- and it doesn't have a valid DNS PTR record, your email won't reach the lists
- unless/until the postmaster notices that your posts are being rejected.
-To avoid this problem, you should configure your MTA to forward posts to
-shorewall.net through an MTA that does have a valid PTR record (such
+
+
A growing number of MTAs serving list subscribers are
+rejecting all HTML traffic. At least one MTA has gone so far as to
+blacklist shorewall.net "for continuous abuse" because it has been
+my policy to allow HTML in list posts!!
+
+ I think that blocking all
+HTML is a Draconian way to control spam and that the ultimate
+ losers here are not the spammers but the list subscribers
+ whose MTAs are bouncing all shorewall.net mail. As one list
+ subscriber wrote to me privately "These e-mail admin's need
+ to get a (expletive deleted) life instead of trying to
+rid the planet of HTML based e-mail". Nevertheless, to allow
+subscribers to receive list posts as must as possible, I have now
+ configured the list server at shorewall.net to strip all HTML from
+ outgoing posts.
+
+ If you run your own outgoing mail server
+ and it doesn't have a valid DNS PTR record, your email won't reach the
+lists unless/until the postmaster notices that your posts are being rejected.
+To avoid this problem, you should configure your MTA to forward posts to
+shorewall.net through an MTA that does have a valid PTR record (such
as the one at your ISP).
-
-
+
+
Where to Send your Problem Report or to Ask for Help
- If you run Shorewall under
- MandrakeSoft Multi Network Firewall (MNF) and you have
- not purchased an MNF license from MandrakeSoft then you can
+ If you run Shorewall under
+ MandrakeSoft Multi Network Firewall (MNF) and you have
+ not purchased an MNF license from MandrakeSoft then you can
post non MNF-specific Shorewall questions to the Shorewall users mailing
- list. Do not expect to get free MNF support on the list
-
+ href="mailto:shorewall-users@lists.shorewall.net">Shorewall users mailing
+ list. Do not expect to get free MNF support on the list
+
Setting up a Linux system as a firewall for a small network
- with DMZ is a fairly straight-forward task if you understand the
+
+
Setting up a Linux system as a firewall for a small network
+ with DMZ is a fairly straight-forward task if you understand the
basics and follow the documentation.
-
-
This guide doesn't attempt to acquaint you with all of the features of
- Shorewall. It rather focuses on what is required to configure Shorewall
+
+
This guide doesn't attempt to acquaint you with all of the features of
+ Shorewall. It rather focuses on what is required to configure Shorewall
in one of its more popular configurations:
-
+
-
Linux system used as a firewall/router for a small
- local network.
-
Single public IP address.
-
DMZ connected to a separate ethernet interface.
-
Connection through DSL, Cable Modem, ISDN, Frame
-Relay, dial-up, ...
-
+
Linux system used as a firewall/router for a small
+ local network.
Shorewall requires that you have the iproute/iproute2 package installed
- (on RedHat, the package is called iproute). You can
- tell if this package is installed by the presence of an ip
-program on your firewall system. As root, you can use the 'which'
-command to check for this program:
-
-
[root@gateway root]# which ip /sbin/ip [root@gateway root]#
-
-
I recommend that you first read through the guide to familiarize yourself
- with what's involved then go back through it again making your
-configuration changes. Points at which configuration changes are
- recommended are flagged with
- . Configuration notes that are unique to LEAF/Bering are marked with
-
+
+
Shorewall requires that you have the iproute/iproute2 package installed
+ (on RedHat, the package is called iproute). You can
+ tell if this package is installed by the presence of an ip
+program on your firewall system. As root, you can use the 'which' command
+to check for this program:
+
+
[root@gateway root]# which ip /sbin/ip [root@gateway root]#
+
+
I recommend that you first read through the guide to familiarize yourself
+ with what's involved then go back through it again making your configuration
+ changes. Points at which configuration changes are recommended
+are flagged with
+ . Configuration notes that are unique to LEAF/Bering are marked with
+
+
- If you edit your configuration files on a Windows
-system, you must save them as Unix files if your editor supports
-that option or you must run them through dos2unix before trying to
-use them. Similarly, if you copy a configuration file from your Windows
-hard drive to a floppy disk, you must run dos2unix against the copy
-before using it with Shorewall.
-
+ If you edit your configuration files on a Windows
+system, you must save them as Unix files if your editor supports
+that option or you must run them through dos2unix before trying to
+use them. Similarly, if you copy a configuration file from your Windows
+hard drive to a floppy disk, you must run dos2unix against the copy before
+using it with Shorewall.
+
- The configuration files for Shorewall are contained in the
-directory /etc/shorewall -- for simple setups, you will only need to
-deal with a few of these as described in this guide. After you have
-installed Shorewall, download the three-interface
- sample, un-tar it (tar -zxvf three-interfaces.tgz) and and copy
- the files to /etc/shorewall (the files will replace files with the
+ The configuration files for Shorewall are contained in the
+directory /etc/shorewall -- for simple setups, you will only need to
+deal with a few of these as described in this guide. After you have installed Shorewall, download the three-interface
+ sample, un-tar it (tar -zxvf three-interfaces.tgz) and and copy
+ the files to /etc/shorewall (the files will replace files with the
same names that were placed in /etc/shorewall when Shorewall was installed).
-
-
As each file is introduced, I suggest that you look through the actual
- file on your system -- each file contains detailed configuration
+
+
As each file is introduced, I suggest that you look through the actual
+ file on your system -- each file contains detailed configuration
instructions and default entries.
-
-
Shorewall views the network where it is running as being composed of a
- set of zones. In the three-interface sample configuration,
+
+
Shorewall views the network where it is running as being composed of a
+ set of zones. In the three-interface sample configuration,
the following zone names are used:
For each connection request entering the firewall, the request is first
- checked against the /etc/shorewall/rules file. If no rule in that
- file matches the connection request then the first policy in /etc/shorewall/policy
- that matches the request is applied. If that policy is REJECT
-or DROP the request is first checked against the rules in /etc/shorewall/common
+
+
For each connection request entering the firewall, the request is first
+ checked against the /etc/shorewall/rules file. If no rule in that
+ file matches the connection request then the first policy in /etc/shorewall/policy
+ that matches the request is applied. If that policy is REJECT or
+ DROP the request is first checked against the rules in /etc/shorewall/common
(the samples provide that file for you).
-
-
The /etc/shorewall/policy file included with the three-interface sample
+
+
The /etc/shorewall/policy file included with the three-interface sample
has the following policies:
-
-
+
+
-
+
+
+
Source Zone
+
Destination Zone
+
Policy
+
Log Level
+
Limit:Burst
+
-
Source Zone
-
Destination Zone
-
Policy
-
Log Level
-
Limit:Burst
-
-
-
loc
-
net
-
ACCEPT
-
-
-
-
-
net
-
all
-
DROP
-
info
-
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
+
loc
+
net
+
ACCEPT
+
+
+
+
+
net
+
all
+
DROP
+
info
+
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
-
-
-
-
In the three-interface sample, the line below is included but commented
- out. If you want your firewall system to have full access to servers
+
+
+
+
In the three-interface sample, the line below is included but commented
+ out. If you want your firewall system to have full access to servers
on the internet, uncomment that line.
-
+
-
+
+
+
Source Zone
+
Destination Zone
+
Policy
+
Log Level
+
Limit:Burst
+
-
Source Zone
-
Destination Zone
-
Policy
-
Log Level
-
Limit:Burst
-
-
-
fw
-
net
-
ACCEPT
-
-
-
-
-
+
fw
+
net
+
ACCEPT
+
+
+
+
+
-
-
+
+
The above policy will:
-
+
-
allow all connection requests from your local network
+
allow all connection requests from your local network
to the internet
-
drop (ignore) all connection requests from the internet
- to your firewall or local network
-
optionally accept all connection requests from the
- firewall to the internet (if you uncomment the additional policy)
-
reject all other connection requests.
-
+
drop (ignore) all connection requests from the
+internet to your firewall or local network
+
optionally accept all connection requests from
+the firewall to the internet (if you uncomment the additional
+policy)
+
reject all other connection requests.
+
-
+
- At this point, edit your /etc/shorewall/policy file
+ At this point, edit your /etc/shorewall/policy file
and make any changes that you wish.
-
+
Network Interfaces
-
+
-
-
-
The firewall has three network interfaces. Where Internet
- connectivity is through a cable or DSL "Modem", the External
-Interface will be the ethernet adapter that is connected to
-that "Modem" (e.g., eth0) unless you connect via Point-to-Point
- Protocol over Ethernet (PPPoE) or Point-to-Point
- Tunneling Protocol (PPTP) in which case the External
- Interface will be a ppp interface (e.g., ppp0). If you connect
- via a regular modem, your External Interface will also be ppp0.
+
+
+
The firewall has three network interfaces. Where Internet
+ connectivity is through a cable or DSL "Modem", the External
+Interface will be the ethernet adapter that is connected to that
+"Modem" (e.g., eth0) unless you connect via Point-to-Point
+ Protocol over Ethernet (PPPoE) or Point-to-Point
+ Tunneling Protocol (PPTP) in which case the External
+ Interface will be a ppp interface (e.g., ppp0). If you connect
+ via a regular modem, your External Interface will also be ppp0.
If you connect using ISDN, you external interface will be ippp0.
-
+
- If your external interface is ppp0 or ippp0
+ If your external interface is ppp0 or ippp0
then you will want to set CLAMPMSS=yes in /etc/shorewall/shorewall.conf.
-
-
Your Local Interface will be an ethernet adapter (eth0,
- eth1 or eth2) and will be connected to a hub or switch. Your local
- computers will be connected to the same switch (note: If you have
- only a single local system, you can connect the firewall directly
-to the computer using a cross-over cable).
-
-
Your DMZ Interface will also be an ethernet adapter
- (eth0, eth1 or eth2) and will be connected to a hub or switch.
-Your DMZ computers will be connected to the same switch (note: If
-you have only a single DMZ system, you can connect the firewall directly
+
+
Your Local Interface will be an ethernet adapter (eth0,
+ eth1 or eth2) and will be connected to a hub or switch. Your local
+ computers will be connected to the same switch (note: If you have
+ only a single local system, you can connect the firewall directly to
+ the computer using a cross-over cable).
+
+
Your DMZ Interface will also be an ethernet adapter
+ (eth0, eth1 or eth2) and will be connected to a hub or switch. Your
+ DMZ computers will be connected to the same switch (note: If you
+have only a single DMZ system, you can connect the firewall directly
to the computer using a cross-over cable).
-
+
- Do not connect more than one interface to the
-same hub or switch (even for testing). It won't work the way that
-you expect it to and you will end up confused and believing that Shorewall
+ Do not connect more than one interface to the
+same hub or switch (even for testing). It won't work the way that
+you expect it to and you will end up confused and believing that Shorewall
doesn't work at all.
-
+
- The Shorewall three-interface sample configuration
-assumes that the external interface is eth0, the local interface
-is eth1 and the DMZ interface is eth2. If your configuration
- is different, you will have to modify the sample /etc/shorewall/interfaces
- file accordingly. While you are there, you may wish to review the
+ The Shorewall three-interface sample configuration
+assumes that the external interface is eth0, the local interface
+is eth1 and the DMZ interface is eth2. If your configuration
+ is different, you will have to modify the sample /etc/shorewall/interfaces
+ file accordingly. While you are there, you may wish to review the
list of options that are specified for the interfaces. Some hints:
-
+
-
-
If your external interface is ppp0 or ippp0,
- you can replace the "detect" in the second column with "-".
-
-
-
-
If your external interface is ppp0 or ippp0
- or if you have a static IP address, you can remove "dhcp" from
+
+
If your external interface is ppp0 or ippp0,
+ you can replace the "detect" in the second column with "-".
+
+
+
+
If your external interface is ppp0 or ippp0
+ or if you have a static IP address, you can remove "dhcp" from
the option list.
-
-
+
+
-
+
IP Addresses
-
-
Before going further, we should say a few words about Internet
- Protocol (IP) addresses. Normally, your ISP will assign
-you a single Public IP address. This address may be assigned
-via the Dynamic Host Configuration Protocol (DHCP) or as part
-of establishing your connection when you dial in (standard modem) or
-establish your PPP connection. In rare cases, your ISP may assign you
-a static IP address; that means that you configure your firewall's
-external interface to use that address permanently.Regardless
-of how the address is assigned, it will be shared by all of your systems
-when you access the Internet. You will have to assign your own addresses
- for your internal network (the local and DMZ Interfaces on your firewall
-plus your other computers). RFC 1918 reserves several Private IP
-address ranges for this purpose:
-
-
+
+
Before going further, we should say a few words about Internet
+ Protocol (IP) addresses. Normally, your ISP will assign you
+ a single Public IP address. This address may be assigned via
+ the Dynamic Host Configuration Protocol (DHCP) or as part of
+ establishing your connection when you dial in (standard modem) or establish
+ your PPP connection. In rare cases, your ISP may assign you a static
+ IP address; that means that you configure your firewall's external interface
+ to use that address permanently.Regardless of how the address
+ is assigned, it will be shared by all of your systems when you access
+ the Internet. You will have to assign your own addresses for your internal
+ network (the local and DMZ Interfaces on your firewall plus your other
+computers). RFC 1918 reserves several Private IP address ranges
+for this purpose:
- Before starting Shorewall, you should look at the
- IP address of your external interface and if it is one of the
-above ranges, you should remove the 'norfc1918' option from the
-external interface's entry in /etc/shorewall/interfaces.
-
-
-
-
You will want to assign your local addresses from one
- sub-network or subnet and your DMZ addresses from another
- subnet. For our purposes, we can consider a subnet to consists
-of a range of addresses x.y.z.0 - x.y.z.255. Such a subnet will have
-a Subnet Mask of 255.255.255.0. The address x.y.z.0 is reserved
- as the Subnet Address and x.y.z.255 is reserved as the Subnet
+ Before starting Shorewall, you should look at the
+ IP address of your external interface and if it is one of the above
+ ranges, you should remove the 'norfc1918' option from the external
+ interface's entry in /etc/shorewall/interfaces.
+
+
+
+
You will want to assign your local addresses from one
+ sub-network or subnet and your DMZ addresses from another
+ subnet. For our purposes, we can consider a subnet to consists of
+ a range of addresses x.y.z.0 - x.y.z.255. Such a subnet will have
+a Subnet Mask of 255.255.255.0. The address x.y.z.0 is reserved
+ as the Subnet Address and x.y.z.255 is reserved as the Subnet
BroadcastAddress. In Shorewall, a subnet is described using Classless InterDomain Routing
- (CIDR) notation with consists of the subnet address followed
- by "/24". The "24" refers to the number of consecutive "1" bits
+ href="shorewall_setup_guide.htm#Subnets">Classless InterDomain Routing
+ (CIDR) notation with consists of the subnet address followed
+ by "/24". The "24" refers to the number of consecutive "1" bits
from the left of the subnet mask.
-
-
-
+
+
+
Example sub-network:
-
-
-
-
+
+
+
+
-
-
-
Range:
-
10.10.10.0 - 10.10.10.255
-
+
-
Subnet Address:
-
10.10.10.0
-
-
-
Broadcast Address:
-
10.10.10.255
-
-
-
CIDR Notation:
-
10.10.10.0/24
-
-
-
+
Range:
+
10.10.10.0 - 10.10.10.255
+
+
+
Subnet Address:
+
10.10.10.0
+
+
+
Broadcast Address:
+
10.10.10.255
+
+
+
CIDR Notation:
+
10.10.10.0/24
+
+
+
-
-
-
-
-
It is conventional to assign the internal interface either
- the first usable address in the subnet (10.10.10.1 in the above
+
+
+
+
+
It is conventional to assign the internal interface either
+ the first usable address in the subnet (10.10.10.1 in the above
example) or the last usable address (10.10.10.254).
-
-
-
-
One of the purposes of subnetting is to allow all computers
- in the subnet to understand which other computers can be communicated
- with directly. To communicate with systems outside of the subnetwork,
+
+
+
+
One of the purposes of subnetting is to allow all computers
+ in the subnet to understand which other computers can be communicated
+ with directly. To communicate with systems outside of the subnetwork,
systems send packets through a gateway (router).
-
-
-
+
+
+
- Your local computers (Local Computers 1 & 2)
- should be configured with their default gateway set to
-the IP address of the firewall's internal interface and your DMZ
-computers ( DMZ Computers 1 & 2) should be configured with their
- default gateway set to the IP address of the firewall's DMZ interface.
-
-
-
-
The foregoing short discussion barely scratches the surface
- regarding subnetting and routing. If you are interested in learning
- more about IP addressing and routing, I highly recommend "IP
-Fundamentals: What Everyone Needs to Know about Addressing &
-Routing", Thomas A. Maufer, Prentice-Hall, 1999, ISBN 0-13-975483-0.
-
-
The remainder of this quide will assume that you have configured
+ Your local computers (Local Computers 1 &
+2) should be configured with their default gateway set
+to the IP address of the firewall's internal interface and your
+DMZ computers ( DMZ Computers 1 & 2) should be configured with
+their default gateway set to the IP address of the firewall's DMZ
+interface.
+
+
+
The foregoing short discussion barely scratches the surface
+ regarding subnetting and routing. If you are interested in learning
+ more about IP addressing and routing, I highly recommend "IP Fundamentals:
+ What Everyone Needs to Know about Addressing & Routing",
+ Thomas A. Maufer, Prentice-Hall, 1999, ISBN 0-13-975483-0.
+
+
The remainder of this quide will assume that you have configured
your network as shown here:
-
+
-
-
-
The default gateway for the DMZ computers would be 10.10.11.254
+
+
+
The default gateway for the DMZ computers would be 10.10.11.254
and the default gateway for the Local computers would be 10.10.10.254.
-
-
-
- WARNING: Your ISP might
-assign your external interface an RFC 1918 address. If that address is
-in the 10.10.10.0/24 subnet then you will need to select a DIFFERENT RFC
-1918 subnet for your local network and if it is in the 10.10.11.0/24 subnet
-then you will need to select a different RFC 1918 subnet for your DMZ.
-
-
IP Masquerading (SNAT)
-
-
The addresses reserved by RFC 1918 are sometimes referred
- to as non-routable because the Internet backbone routers
-don't forward packets which have an RFC-1918 destination address.
-When one of your local systems (let's assume local computer 1) sends
-a connection request to an internet host, the firewall must perform
-Network Address Translation (NAT). The firewall rewrites the
-source address in the packet to be the address of the firewall's external
-interface; in other words, the firewall makes it look as if the firewall
- itself is initiating the connection. This is necessary so that the
- destination host will be able to route return packets back to the firewall
- (remember that packets whose destination address is reserved by RFC
-1918 can't be routed accross the internet). When the firewall receives
-a return packet, it rewrites the destination address back to 10.10.10.1
- and forwards the packet on to local computer 1.
-
-
On Linux systems, the above process is often referred to
-as IP Masquerading and you will also see the term Source Network
-Address Translation (SNAT) used. Shorewall follows the convention used
-with Netfilter:
-
-
-
-
Masquerade describes the case where you let your
- firewall system automatically detect the external interface address.
-
-
-
-
SNAT refers to the case when you explicitly specify
- the source address that you want outbound packets from your local
- network to use.
-
-
-
-
-
In Shorewall, both Masquerading and SNAT are configured with
- entries in the /etc/shorewall/masq file.
-
-
- If your external firewall interface is eth0,
-your local interface eth1 and your DMZ interface is eth2
- then you do not need to modify the file provided with the sample. Otherwise,
- edit /etc/shorewall/masq and change it to match your configuration.
-
-
- If your external IP is static, you can enter it in
-the third column in the /etc/shorewall/masq entry if you like although
- your firewall will work fine if you leave that column empty. Entering
- your static IP in column 3 makes
- processing outgoing packets a little more efficient.
-
-
+
- If you are using the Debian package, please check your shorewall.conf
- file to ensure that the following are set correctly; if they are not,
+ WARNING: Your ISP might
+ assign your external interface an RFC 1918 address. If that address is
+ in the 10.10.10.0/24 subnet then you will need to select a DIFFERENT RFC
+ 1918 subnet for your local network and if it is in the 10.10.11.0/24 subnet
+ then you will need to select a different RFC 1918 subnet for your DMZ.
+
+
+
IP Masquerading (SNAT)
+
+
The addresses reserved by RFC 1918 are sometimes referred
+ to as non-routable because the Internet backbone routers don't
+ forward packets which have an RFC-1918 destination address. When
+one of your local systems (let's assume local computer 1) sends a
+connection request to an internet host, the firewall must perform Network
+Address Translation (NAT). The firewall rewrites the source address
+in the packet to be the address of the firewall's external interface;
+in other words, the firewall makes it look as if the firewall itself
+is initiating the connection. This is necessary so that the destination
+host will be able to route return packets back to the firewall (remember
+that packets whose destination address is reserved by RFC 1918 can't
+ be routed accross the internet). When the firewall receives a return
+packet, it rewrites the destination address back to 10.10.10.1 and forwards
+the packet on to local computer 1.
+
+
On Linux systems, the above process is often referred to as
+ IP Masquerading and you will also see the term Source Network Address
+ Translation (SNAT) used. Shorewall follows the convention used with
+ Netfilter:
+
+
+
+
Masquerade describes the case where you let your
+ firewall system automatically detect the external interface address.
+
+
+
+
SNAT refers to the case when you explicitly specify
+ the source address that you want outbound packets from your local
+ network to use.
+
+
+
+
+
In Shorewall, both Masquerading and SNAT are configured with
+ entries in the /etc/shorewall/masq file.
+
+
+ If your external firewall interface is eth0,
+ your local interface eth1 and your DMZ interface is eth2
+ then you do not need to modify the file provided with the sample. Otherwise,
+ edit /etc/shorewall/masq and change it to match your configuration.
+
+
+ If your external IP is static, you can enter it in
+ the third column in the /etc/shorewall/masq entry if you like although
+ your firewall will work fine if you leave that column empty. Entering
+ your static IP in column 3 makes
+ processing outgoing packets a little more efficient.
+
+
+
+ If you are using the Debian package, please check your shorewall.conf
+ file to ensure that the following are set correctly; if they are not,
change them appropriately:
-
-
+
+
-
NAT_ENABLED=Yes (Shorewall versions earlier than 1.4.6)
-
IP_FORWARDING=On
-
-
+
NAT_ENABLED=Yes (Shorewall versions earlier than 1.4.6)
+
IP_FORWARDING=On
+
+
-
+
Port Forwarding (DNAT)
-
-
One of your goals will be to run one or more servers on your
- DMZ computers. Because these computers have RFC-1918 addresses,
-it is not possible for clients on the internet to connect directly
-to them. It is rather necessary for those clients to address their
-connection requests to your firewall who rewrites the destination
-address to the address of your server and forwards the packet to that
-server. When your server responds, the firewall automatically performs
-SNAT to rewrite the source address in the response.
-
-
The above process is called Port Forwarding or
- Destination Network Address Translation (DNAT). You configure
- port forwarding using DNAT rules in the /etc/shorewall/rules file.
-
-
The general form of a simple port forwarding rule in /etc/shorewall/rules
+
+
One of your goals will be to run one or more servers on your
+ DMZ computers. Because these computers have RFC-1918 addresses, it
+ is not possible for clients on the internet to connect directly to
+ them. It is rather necessary for those clients to address their connection
+ requests to your firewall who rewrites the destination address to
+the address of your server and forwards the packet to that server.
+When your server responds, the firewall automatically performs SNAT
+to rewrite the source address in the response.
+
+
The above process is called Port Forwarding or
+ Destination Network Address Translation (DNAT). You configure
+ port forwarding using DNAT rules in the /etc/shorewall/rules file.
+
+
The general form of a simple port forwarding rule in /etc/shorewall/rules
is:
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
dmz:<server local ip address> [:<server
+
DNAT
+
net
+
dmz:<server local ip address> [:<server
port>]
-
<protocol>
-
<port>
-
-
-
-
-
+
<protocol>
+
<port>
+
+
+
+
+
-
-
-
If you don't specify the <server port>, it is assumed to
-be the same as <port>.
-
-
Example - you run a Web Server on DMZ 2 and you want to forward incoming
+
+
+
If you don't specify the <server port>, it is assumed to be
+the same as <port>.
+
+
Example - you run a Web Server on DMZ 2 and you want to forward incoming
TCP port 80 to that system:
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
dmz:10.10.11.2
-
tcp
-
80
-
# Forward port 80
-
from the internet
-
-
-
ACCEPT
-
loc
-
dmz:10.10.11.2
-
tcp
-
80
-
#Allow connections
-
from the local network
-
-
-
+
DNAT
+
net
+
dmz:10.10.11.2
+
tcp
+
80
+
# Forward port 80
+
from the internet
+
+
+
ACCEPT
+
loc
+
dmz:10.10.11.2
+
tcp
+
80
+
#Allow connections
+
from the local network
+
+
+
-
-
+
+
A couple of important points to keep in mind:
-
+
-
When you are connecting to your server from your
-local systems, you must use the server's internal IP address (10.10.11.2).
-
Many ISPs block incoming connection requests to
-port 80. If you have problems connecting to your web server, try
-the following rule and try connecting to port 5000 (e.g., connect
-to http://w.x.y.z:5000 where w.x.y.z
-is your external IP).
-
+
When you are connecting to your server from your
+ local systems, you must use the server's internal IP address (10.10.11.2).
+
Many ISPs block incoming connection requests to
+port 80. If you have problems connecting to your web server, try
+the following rule and try connecting to port 5000 (e.g., connect
+to http://w.x.y.z:5000 where w.x.y.z
+ is your external IP).
+
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
dmz:10.10.11.2:80
-
tcp
-
5000
-
-
-
-
-
+
DNAT
+
net
+
dmz:10.10.11.2:80
+
tcp
+
5000
+
+
+
+
+
-
-
-
If you want to be able to access your server from the local network using
- your external address, then if you have a static external IP you
+
+
+
If you want to be able to access your server from the local network using
+ your external address, then if you have a static external IP you
can replace the loc->dmz rule above with:
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
dmz:10.10.11.2:80
-
tcp
-
80
-
-
-
<external IP>
-
-
-
+
DNAT
+
net
+
dmz:10.10.11.2:80
+
tcp
+
80
+
-
+
<external IP>
+
+
+
-
-
-
If you have a dynamic ip then you must ensure that your external interface
- is up before starting Shorewall and you must take steps as follows
+
+
+
If you have a dynamic ip then you must ensure that your external interface
+ is up before starting Shorewall and you must take steps as follows
(assume that your external interface is eth0):
-
+
-
Include the following in /etc/shorewall/params:
-
- ETH0_IP=`find_interface_address eth0`
-
-
Make your loc->dmz rule:
-
+
Include the following in /etc/shorewall/params:
+
+ ETH0_IP=`find_interface_address eth0`
+
+
Make your loc->dmz rule:
+
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
loc
-
-
dmz:10.10.11.2:80
-
tcp
-
80
-
-
-
$ETH0_IP
-
-
-
+
DNAT
+
loc
+
+
dmz:10.10.11.2:80
+
tcp
+
80
+
-
+
$ETH0_IP
+
+
+
-
-
-
If you want to access your server from the DMZ using your external IP
- address, see FAQ 2a.
-
+
+
+
If you want to access your server from the DMZ using your external IP
+address, see FAQ 2a.
+
- At this point, add the DNAT and ACCEPT rules for your
- servers.
-
+ At this point, add the DNAT and ACCEPT rules for
+your servers.
+
Domain Name Server (DNS)
-
-
Normally, when you connect to your ISP, as part of getting
- an IP address your firewall's Domain Name Service (DNS)
-resolver will be automatically configured (e.g., the /etc/resolv.conf
-file will be written). Alternatively, your ISP may have given you
-the IP address of a pair of DNS name servers for you to manually
-configure as your primary and secondary name servers. It is your
-responsibility to configure the resolver in your internal systems.
-You can take one of two approaches:
-
+
+
Normally, when you connect to your ISP, as part of getting
+ an IP address your firewall's Domain Name Service (DNS) resolver
+ will be automatically configured (e.g., the /etc/resolv.conf file
+ will be written). Alternatively, your ISP may have given you the IP
+ address of a pair of DNS name servers for you to manually configure
+ as your primary and secondary name servers. It is your responsibility
+ to configure the resolver in your internal systems. You can take
+one of two approaches:
+
-
-
You can configure your internal systems to use your ISP's
- name servers. If you ISP gave you the addresses of their servers
- or if those addresses are available on their web site, you can
-configure your internal systems to use those addresses. If that
-information isn't available, look in /etc/resolv.conf on your firewall
-system -- the name servers are given in "nameserver" records in that
-file.
-
-
+
+
You can configure your internal systems to use your ISP's
+ name servers. If you ISP gave you the addresses of their servers
+ or if those addresses are available on their web site, you can configure
+ your internal systems to use those addresses. If that information
+ isn't available, look in /etc/resolv.conf on your firewall system
+ -- the name servers are given in "nameserver" records in that file.
+
+
+
- You can configure a Caching Name Server on your
- firewall or in your DMZ.Red Hat has an RPM for a caching
- name server (which also requires the 'bind' RPM) and for Bering
-users, there is dnscache.lrp. If you take this approach, you configure
-your internal systems to use the caching name server as their primary
-(and only) name server. You use the internal IP address of the firewall
-(10.10.10.254 in the example above) for the name server address if
-you choose to run the name server on your firewall. To allow your local
-systems to talk to your caching name server, you must open port 53
-(both UDP and TCP) from the local network to the server; you do that
+ You can configure a Caching Name Server on
+your firewall or in your DMZ.Red Hat has an RPM for a caching
+ name server (which also requires the 'bind' RPM) and for Bering
+users, there is dnscache.lrp. If you take this approach, you configure
+your internal systems to use the caching name server as their primary
+(and only) name server. You use the internal IP address of the firewall
+(10.10.10.254 in the example above) for the name server address if
+you choose to run the name server on your firewall. To allow your local
+systems to talk to your caching name server, you must open port 53
+(both UDP and TCP) from the local network to the server; you do that
by adding the rules in /etc/shorewall/rules.
-
-
+
+
-
-
-
If you run the name server on the firewall:
-
+
+
+
If you run the name server on the firewall:
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
53
-
-
-
-
-
ACCEPT
-
loc
-
fw
-
udp
-
53
-
-
-
-
-
ACCEPT
-
dmz
-
fw
-
tcp
-
53
-
-
-
-
-
ACCEPT
-
dmz
-
fw
-
udp
-
53
-
-
-
-
-
+
ACCEPT
+
loc
+
fw
+
tcp
+
53
+
+
+
+
+
ACCEPT
+
loc
+
fw
+
udp
+
53
+
+
+
+
+
ACCEPT
+
dmz
+
fw
+
tcp
+
53
+
+
+
+
+
ACCEPT
+
dmz
+
fw
+
udp
+
53
+
+
+
+
+
-
-
-
-
-
+
+
+
+
+
Run name server on DMZ computer 1
-
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
loc
-
dmz:10.10.11.1
-
tcp
-
53
-
-
-
-
-
ACCEPT
-
loc
-
dmz:10.10.11.1
-
udp
-
53
-
-
-
-
-
ACCEPT
-
fw
-
dmz:10.10.10.1
-
tcp
-
53
-
-
-
-
-
ACCEPT
-
fw
-
dmz:10.10.10.1
-
udp
-
53
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
loc
+
dmz:10.10.11.1
+
tcp
+
53
+
+
+
+
+
ACCEPT
+
loc
+
dmz:10.10.11.1
+
udp
+
53
+
+
+
+
+
ACCEPT
+
fw
+
dmz:10.10.10.1
+
tcp
+
53
+
+
+
+
+
ACCEPT
+
fw
+
dmz:10.10.10.1
+
udp
+
53
+
+
+
+
+
-
-
-
-
+
+
+
+
Other Connections
-
-
-
+
+
+
The three-interface sample includes the following rules:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
fw
-
net
-
udp
-
53
-
-
-
-
-
ACCEPT
-
fw
-
net
-
tcp
-
53
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
fw
+
net
+
udp
+
53
+
+
+
+
+
ACCEPT
+
fw
+
net
+
tcp
+
53
+
+
+
+
+
-
-
-
-
-
Those rules allow DNS access from your firewall and may be
- removed if you commented out the line in /etc/shorewall/policy
+
+
+
+
+
Those rules allow DNS access from your firewall and may be
+ removed if you commented out the line in /etc/shorewall/policy
allowing all connections from the firewall to the internet.
-
-
-
+
+
+
The sample also includes:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
loc
-
fw
-
tcp
-
22
-
-
-
-
-
ACCEPT
-
loc
-
dmz
-
tcp
-
22
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
22
+
+
+
+
+
ACCEPT
+
loc
+
dmz
+
tcp
+
22
+
+
+
+
+
-
-
-
-
-
That rule allows you to run an SSH server on your firewall
- and in each of your DMZ systems and to connect to those servers
+
+
+
+
+
That rule allows you to run an SSH server on your firewall
+ and in each of your DMZ systems and to connect to those servers
from your local systems.
-
-
-
-
If you wish to enable other connections between your systems,
+
+
+
+
If you wish to enable other connections between your systems,
the general format is:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
<source zone>
-
<destination zone>
-
<protocol>
-
<port>
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
<source zone>
+
<destination zone>
+
<protocol>
+
<port>
+
+
+
+
+
-
-
-
-
-
Example - You want to run a publicly-available DNS server
+
+
+
+
+
Example - You want to run a publicly-available DNS server
on your firewall system:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
net
-
fw
-
tcp
-
53
-
#Allow DNS access
-
from the internet
-
-
-
ACCEPT
-
net
-
fw
-
udp
-
-
53
-
#Allow DNS access
-
from the internet
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
53
+
#Allow DNS access
+
from the internet
+
+
+
ACCEPT
+
net
+
fw
+
udp
+
+
53
+
#Allow DNS access
+
from the internet
+
+
+
-
-
-
-
-
Those two rules would of course be in addition to the rules
+
+
+
+
+
Those two rules would of course be in addition to the rules
listed above under "If you run the name server on your firewall".
-
-
-
-
If you don't know what port and protocol a particular application
- uses, look here.
-
-
-
-
Important: I don't recommend enabling telnet to/from
- the internet because it uses clear text (even for login!). If
+
+
+
+
If you don't know what port and protocol a particular application
+ uses, look here.
+
+
+
+
Important: I don't recommend enabling telnet to/from
+ the internet because it uses clear text (even for login!). If
you want shell access to your firewall from the internet, use SSH:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
net
-
fw
-
tcp
-
22
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
22
+
+
+
+
+
-
-
-
-
+
+
+
+
-
+
- Bering users will want to add the following two rules to be compatible
+ Bering users will want to add the following two rules to be compatible
with Jacques's Shorewall configuration.
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
loc
-
-
fw
-
udp
-
-
53
-
-
#Allow DNS Cache to
-
work
-
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
80
-
#Allow weblet to work
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
loc
+
+
fw
+
udp
+
+
53
+
+
#Allow DNS Cache to
+
work
+
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
80
+
#Allow weblet to work
+
+
+
+
+
-
-
-
+
+
+
- Now modify /etc/shorewall/rules to add or remove
-other connections as required.
-
-
-
-
Starting and Stopping Your Firewall
+ Now modify /etc/shorewall/rules to add or remove
+ other connections as required.
-
-
+
+
+
Starting and Stopping Your Firewall
+
+
+
- The installation procedure
- configures your system to start Shorewall at system boot but beginning
- with Shorewall version 1.3.9 startup is disabled so that your system
- won't try to start Shorewall before configuration is complete. Once you
- have completed configuration of your firewall, you can enable Shorewall
- startup by removing the file /etc/shorewall/startup_disabled.
-
-
+ The installation procedure
+ configures your system to start Shorewall at system boot but beginning
+ with Shorewall version 1.3.9 startup is disabled so that your system
+ won't try to start Shorewall before configuration is complete. Once
+you have completed configuration of your firewall, you can enable Shorewall
+ startup by removing the file /etc/shorewall/startup_disabled.
+
+
IMPORTANT: Users of the .deb package must edit /etc/default/shorewall
+ color="#ff0000">Users of the .deb package must edit /etc/default/shorewall
and set 'startup=1'.
-
-
-
-
-
The firewall is started using the "shorewall start" command
- and stopped using "shorewall stop". When the firewall is stopped,
+
+
+
+
+
The firewall is started using the "shorewall start" command
+ and stopped using "shorewall stop". When the firewall is stopped,
routing is enabled on those hosts that have an entry in /etc/shorewall/routestopped. A
- running firewall may be restarted using the "shorewall restart"
- command. If you want to totally remove any trace of Shorewall
-from your Netfilter configuration, use "shorewall clear".
-
-
-
+ href="Documentation.htm#Routestopped">/etc/shorewall/routestopped. A
+ running firewall may be restarted using the "shorewall restart"
+ command. If you want to totally remove any trace of Shorewall from
+ your Netfilter configuration, use "shorewall clear".
+
+
+
- The three-interface sample assumes that you want to
-enable routing to/from eth1 (your local network) and eth2
-(DMZ) when Shorewall is stopped. If these two interfaces don't
-connect to your local network and DMZ or if you want to enable a
-different set of hosts, modify /etc/shorewall/routestopped accordingly.
WARNING: If you are connected to your firewall from
+ the internet, do not issue a "shorewall stop" command unless you
+ have added an entry for the IP address that you are connected from
+ to /etc/shorewall/routestopped.
+ Also, I don't recommend using "shorewall restart"; it is better to
+create an alternate
configuration and test it using the "shorewall try" command.
Notes du traducteur :
- Je ne prétends pas être un vrai traducteur dans le sens ou mon travail
- n?est pas des plus précis (loin de là...). Je ne me suis pas attaché à une
- traduction exacte du texte, mais plutôt à en faire une version française
-intelligible par tous (et par moi). Les termes techniques sont la plupart
-du temps conservés sous leur forme originale et mis entre parenthèses car
-vous pouvez les retrouver dans le reste des documentations ainsi que dans
-les fichiers de configuration. N?hésitez pas à me contacter afin d?améliorer
-ce document VETSEL Patrice
-(merci à JMM pour sa relecture et ses commentaires pertinents, ainsi qu'à
+ Je ne prétends pas être un vrai traducteur dans le sens ou mon travail
+ n?est pas des plus précis (loin de là...). Je ne me suis pas attaché à une
+ traduction exacte du texte, mais plutôt à en faire une version française
+intelligible par tous (et par moi). Les termes techniques sont la plupart
+du temps conservés sous leur forme originale et mis entre parenthèses car
+vous pouvez les retrouver dans le reste des documentations ainsi que dans
+les fichiers de configuration. N?hésitez pas à me contacter afin d?améliorer
+ce document VETSEL Patrice
+(merci à JMM pour sa relecture et ses commentaires pertinents, ainsi qu'à
Tom EASTEP pour son formidable outil et sa disponibilité).
-
+
- Mettre en place un système linux en tant que firewall pour un petit réseau
- contenant une DMZ est une chose assez simple à réaliser si vous comprenez
- les bases et suivez cette documentation.
-
-
Ce guide ne prétend pas vous mettre au courant de toutes les possibilités
- de Shorewall. Il se focalise sur les besoins pour configurer Shorewall dans
- une de ses utilisations les plus populaire :
-
+ Mettre en place un système linux en tant que firewall pour un petit
+réseau contenant une DMZ est une chose assez simple à réaliser si vous
+comprenez les bases et suivez cette documentation.
+
+
Ce guide ne prétend pas vous mettre au courant de toutes les possibilités
+ de Shorewall. Il se focalise sur les besoins pour configurer Shorewall
+dans une de ses utilisations les plus populaire :
+
-
Un système Linux utilisé en tant que firewall/routeur pour un petit
- réseau local.
-
Une seule adresse IP publique.
-
Une DMZ connectée sur une interface Ethernet séparée.
-
Une connexion passant par l'ADSL, un Modem Câble, ISDN, Frame Relay,
- RTC, ...
-
+
Un système Linux utilisé en tant que firewall/routeur pour un
+petit réseau local.
+
Une seule adresse IP publique.
+
Une DMZ connectée sur une interface Ethernet séparée.
+
Une connexion passant par l'ADSL, un Modem Câble, ISDN, Frame
+Relay, RTC, ...
+
-
+
Voici le schéma d'une installation typique.
-
+
-
-
-
Ce guide suppose que vous avez le paquet iproute/iproute2 d'installé. Vous
-pouvez voir si le paquet est installé en vérifiant la présence du programme
- ip sur votre système de firewall. Sous root, utilisez la commande 'which'
- pour rechercher le programme :
-
+
+
+
Ce guide suppose que vous avez le paquet iproute/iproute2 d'installé.
+Vous pouvez voir si le paquet est installé en vérifiant la présence du programme
+ ip sur votre système de firewall. Sous root, utilisez la commande 'which'
+ pour rechercher le programme :
+
[root@gateway root]# which ip /sbin/ip [root@gateway root]#
-
-
Je vous recommande dans un premier temps de parcourir tout le guide pour
- vous familiariser avec ce qu'il va se passer, et de revenir au début en effectuant
- le changements dans votre configuration. Les points où, les changements dans
- la configuration sont recommandées, sont signalés par une Je vous recommande dans un premier temps de parcourir tout le guide pour
+ vous familiariser avec ce qu'il va se passer, et de revenir au début en
+effectuant le changements dans votre configuration. Les points où, les changements
+dans la configuration sont recommandées, sont signalés par une
-
-
+
+
- Si vous éditez vos fichiers de configuration sur un système Windows,
-vous devez les sauver comme des fichiers Unix si votre éditeur offre cette
-option sinon vous devez les faire passer par dos2unix avant d'essayer de
-les utiliser. De la même manière, si vous copiez un fichier de configuration
-depuis votre disque dur Windows vers une disquette, vous devez lancer dos2unix
+ Si vous éditez vos fichiers de configuration sur un système Windows,
+vous devez les sauver comme des fichiers Unix si votre éditeur offre cette
+option sinon vous devez les faire passer par dos2unix avant d'essayer de
+les utiliser. De la même manière, si vous copiez un fichier de configuration
+depuis votre disque dur Windows vers une disquette, vous devez lancer dos2unix
sur la copie avant de l'utiliser avec Shorewall.
- Les fichiers de configuration pour Shorewall sont situés dans le répertoire
- /etc/shorewall -- pour de simples paramétrages, vous n'avez à faire qu'avec
- quelques un d'entre eux comme décris dans ce guide. Après avoir installé Shorewall, téléchargez la configuration
- d'exemple three-interface
- sample, un-tarez la (tar -zxvf three-interfaces.tgz) et copiez
- les fichiers vers /etc/shorewall (Ils remplaceront les fichiers de même
-nom déjà existant dans /etc/shorewall installés lors de l'installation de
-Shorewall).
-
-
En même temps que chacun des fichiers est présenté, je vous suggère de
- jeter un oeil à ceux qui se trouvent réellement sur votre système -- chacun
- des fichiers contient des instructions de configuration détaillées et des
- entrées par défaut.
-
-
Shorewall voit le réseau où il tourne comme composé par un ensemble de
- zones. Dans les fichiers de configuration fournis pour trois interfaces,
- trois zones sont définies :
-
+ Les fichiers de configuration pour Shorewall sont situés dans le répertoire
+ /etc/shorewall -- pour de simples paramétrages, vous n'avez à faire qu'avec
+ quelques un d'entre eux comme décris dans ce guide. Après avoir installé Shorewall, téléchargez la configuration
+ d'exemple three-interface
+ sample, un-tarez la (tar -zxvf three-interfaces.tgz) et copiez
+ les fichiers vers /etc/shorewall (Ils remplaceront les fichiers de même
+ nom déjà existant dans /etc/shorewall installés lors de l'installation de
+ Shorewall).
+
+
En même temps que chacun des fichiers est présenté, je vous suggère de
+ jeter un oeil à ceux qui se trouvent réellement sur votre système -- chacun
+ des fichiers contient des instructions de configuration détaillées et des
+ entrées par défaut.
+
+
Shorewall voit le réseau où il tourne comme composé par un ensemble de
+ zones. Dans les fichiers de configuration fournis pour trois interfaces,
+ trois zones sont définies :
Shorewall reconnaît aussi le système de firewall comme sa propre zone -
-par défaut, le firewall lui même est connu en tant que fw.
-
-
Les règles concernant le trafic à autoriser ou à interdire sont exprimées
- en utilisant les termes de zones.
-
+
+
Shorewall reconnaît aussi le système de firewall comme sa propre zone
+- par défaut, le firewall lui même est connu en tant que fw.
+
+
Les règles concernant le trafic à autoriser ou à interdire sont exprimées
+ en utilisant les termes de zones.
+
-
Vous exprimez les politiques par défaut pour les connexions d'une
- zone à une autre dans le fichier /etc/shorewall/policy
- .
-
Vous définissez les exceptions à ces règles de politiques par défaut
- dans le fichier /etc/shorewall/rules.
-
+
Vous exprimez les politiques par défaut pour les connexions d'une
+ zone à une autre dans le fichier /etc/shorewall/policy
+ .
+
Vous définissez les exceptions à ces règles de politiques par
+défaut dans le fichier /etc/shorewall/rules.
+
-
-
Pour chacune des demandes de connexion entrantes dans le firewall, les
- demandes sont en premier lieu comparées par rapport au fichier /etc/shorewall/rules.
- Si aucune des règles dans ce fichier ne correspondent, alors la première
-politique dans /etc/shorewall/policy qui y correspond est appliquée. Si cette
-politique est REJECT ou DROP la requête est alors comparée par rapport aux
-règles contenues dans /etc/shorewall/common (l'archive d'exemple vous fournit
-ce fichier).
-
-
Le fichier /etc/shorewall/policy d'exemple contenu dans l'archive three-interface
- sample a les politiques suivantes :
-
-
+
+
Pour chacune des demandes de connexion entrantes dans le firewall, les
+ demandes sont en premier lieu comparées par rapport au fichier /etc/shorewall/rules.
+ Si aucune des règles dans ce fichier ne correspondent, alors la première
+ politique dans /etc/shorewall/policy qui y correspond est appliquée. Si
+cette politique est REJECT ou DROP la requête est alors comparée par rapport
+aux règles contenues dans /etc/shorewall/common (l'archive d'exemple vous
+fournit ce fichier).
+
+
Le fichier /etc/shorewall/policy d'exemple contenu dans l'archive three-interface
+ sample a les politiques suivantes :
+
+
-
-
-
Source Zone
-
Destination Zone
-
Policy
-
Log Level
-
Limit:Burst
-
-
-
loc
-
net
-
ACCEPT
-
-
-
-
-
-
-
net
-
all
-
DROP
-
info
-
-
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
-
+
+
+
Source Zone
+
Destination Zone
+
Policy
+
Log Level
+
Limit:Burst
+
+
+
loc
+
net
+
ACCEPT
+
+
+
+
+
+
+
net
+
all
+
DROP
+
info
+
+
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
+
-
-
-
-
Dans l'archive three-interface, la ligne suivante est existante mais
- elle est commentée. Si vous souhaitez que votre système de firewall puisse
- avoir un accès complet aux serveurs sur Internet, décommentez la.
-
+
+
+
+
Dans l'archive three-interface, la ligne suivante est existante mais
+ elle est commentée. Si vous souhaitez que votre système de firewall puisse
+ avoir un accès complet aux serveurs sur Internet, décommentez la.
+
-
-
-
Source Zone
-
Destination Zone
-
Policy
-
Log Level
-
Limit:Burst
-
-
-
fw
-
net
-
ACCEPT
-
-
-
-
-
-
-
+
+
+
Source Zone
+
Destination Zone
+
Policy
+
Log Level
+
Limit:Burst
+
+
+
fw
+
net
+
ACCEPT
+
+
+
+
+
+
+
-
-
+
+
Les politiques précédentes vont :
-
+
-
permettre toutes demandes de connexion depuis le firewall vers
+
permettre toutes demandes de connexion depuis le firewall vers
l'Internet
-
drop (ignorer) toutes les demandes de connexion depuis l'Internet
+
drop (ignorer) toutes les demandes de connexion depuis l'Internet
vers votre firewall ou vers votre réseau local
-
Facultativement accepter toutes les demandes de connexion depuis
+
Facultativement accepter toutes les demandes de connexion depuis
votre firewall et vers Internet (si vous decommentez la politique précédente)
-
reject (rejeter) toutes les autres demandes de connexion.
-
+
reject (rejeter) toutes les autres demandes de connexion.
+
-
+
- A ce point, éditez votre /etc/shorewall/policy et faites y les changements
- que vous désire
-
+ A ce point, éditez votre /etc/shorewall/policy et faites y les changements
+ que vous désire
+
Les Interfaces Réseau
-
+
-
-
-
Le firewall a trois interfaces de réseau. Lorsque la connexion
- Internet passe par le câble ou par un ROUTEUR (pas un simple modem) ADSL
-(non USB), l'interface vers l'extérieur (External Interface) sera l'adaptateur
- sur lequel est connecté le routeur (e.g., eth0) à moins que vous ne vous
- connectiez par Point-to-PointProtocol overEthernet (PPPoE) ou par Point-to-PointTunneling
- Protocol (PPTP), dans ce cas l'interface extérieure sera une interface de
- type ppp (e.g., ppp0). Si vous vous connectez par un simple modem (RTC),
-votre interface extérieure sera aussi ppp0. Si votre connexion passe par Numéris
-(ISDN), votre interface extérieure sera ippp0.
-
+
+
+
Le firewall a trois interfaces de réseau. Lorsque la connexion
+ Internet passe par le câble ou par un ROUTEUR (pas un simple modem) ADSL
+ (non USB), l'interface vers l'extérieur (External Interface) sera l'adaptateur
+ sur lequel est connecté le routeur (e.g., eth0) à moins que vous ne vous
+ connectiez par Point-to-PointProtocol overEthernet (PPPoE) ou par Point-to-PointTunneling
+ Protocol (PPTP), dans ce cas l'interface extérieure sera une interface
+de type ppp (e.g., ppp0). Si vous vous connectez par un simple modem (RTC),
+ votre interface extérieure sera aussi ppp0. Si votre connexion passe par
+Numéris (ISDN), votre interface extérieure sera ippp0.
+
- Si votre interface vers l'extérieur est ppp0 ou ippp0 alors vous mettrez
- CLAMPMSS=yes dans /etc/shorewall/shorewall.conf.
-
-
Votre Interface locale sera un adaptateur Ethernet
- (eth0, eth1 ou eth2) et sera connecté à un hub ou un switch. Vos ordinateurs
- locaux seront connectés à ce même switch (note : si vous n'avez qu'un seul
- ordinateur en local, vous pouvez le connecter directement au firewall par
- un câble croisé).
-
-
Votre interface DMZ sera aussi un adaptateur Ethernet
- (eth0, eth1 ou eth2) et sera connecté à un hub ou un switch. Vos ordinateurs
- appartenant à la DMZ seront connectés à ce même switch (note : si vous n'avez
- qu'un seul ordinateur dans la DMZ, vous pouvez le connecter directement au
- firewall par un câble croisé).
-
+ Si votre interface vers l'extérieur est ppp0 ou ippp0 alors vous mettrez
+ CLAMPMSS=yes dans /etc/shorewall/shorewall.conf.
+
+
Votre Interface locale sera un adaptateur Ethernet
+ (eth0, eth1 ou eth2) et sera connecté à un hub ou un switch. Vos
+ordinateurs locaux seront connectés à ce même switch (note : si vous n'avez
+qu'un seul ordinateur en local, vous pouvez le connecter directement au
+firewall par un câble croisé).
+
+
Votre interface DMZ sera aussi un adaptateur Ethernet
+ (eth0, eth1 ou eth2) et sera connecté à un hub ou un switch. Vos ordinateurs
+ appartenant à la DMZ seront connectés à ce même switch (note : si vous
+n'avez qu'un seul ordinateur dans la DMZ, vous pouvez le connecter directement
+au firewall par un câble croisé).
+
- Ne connectez pas l'interface interne et externe sur le même hub
- ou switch (même pour tester). Cela ne fonctionnera pas et ne croyez pas que
- ce soit shorewall qui ne marche pas.
-
+ Ne connectez pas l'interface interne et externe sur le même
+hub ou switch (même pour tester). Cela ne fonctionnera pas et ne croyez
+pas que ce soit shorewall qui ne marche pas.
+
- L'exemple de configuration de Shorewall pour trois interfaces suppose
-que l'interface externe est eth0, l'interface locale est eth1
-et que la DMZ est sur l'interface eth2. Si votre configuration diffère,
- vous devrez modifier le fichier d'exemple /etc/shorewall/interfaces en conséquence.
- Tant que vous y êtes, vous pourriez parcourir la liste des options qui sont
- spécifiées pour les interfaces. Quelques trucs :
-
+ L'exemple de configuration de Shorewall pour trois interfaces suppose
+ que l'interface externe est eth0, l'interface locale est eth1
+ et que la DMZ est sur l'interface eth2. Si votre configuration
+diffère, vous devrez modifier le fichier d'exemple /etc/shorewall/interfaces
+en conséquence. Tant que vous y êtes, vous pourriez parcourir la liste des
+options qui sont spécifiées pour les interfaces. Quelques trucs :
+
-
-
Si votre interface externe est ppp0 ou ippp0, vous pouvez
- remplacer le "detect" dans la seconde colonne par un "-".
-
-
-
Si votre interface externe est ppp0 ou ippp0 ou bien si
-vous avez une adresse IP statique, vous pouvez enlever le "dhcp" de la liste
-d'option.
-
-
+
+
Si votre interface externe est ppp0 ou ippp0, vous pouvez
+ remplacer le "detect" dans la seconde colonne par un "-".
+
+
+
Si votre interface externe est ppp0 ou ippp0 ou bien
+si vous avez une adresse IP statique, vous pouvez enlever le "dhcp" de la
+liste d'option.
+
+
-
+
Adresses IP
-
-
Avant d'aller plus loin, nous devons dire quelques mots au
- sujet du Protocole d'adresse Internet (IP). Normalement, votre fournisseur
- Internet (ISP) vous assignera une seule adresse IP (single Public IP address).
- Cette adresse peut être assignée par le Dynamic Host Configuration Protocol
- (DHCP) ou lors de l'établissement de votre connexion lorsque vous vous connectez
- (modem standard) ou établissez votre connexion PPP. Dans de rares cas , votre
- provider peu vous assigner une adresse statique (staticIP address); cela
-signifie que vous configurez votre interface externe sur votre firewall afin
-d'utiliser cette adresse de manière permanente. Une fois votre adresse externe
-assignée, elle va être partagée par tout vos systèmes lors de l'accès à Internet.
-Vous devrez assigner vos propres adresses à votre réseau local (votre interface
- interne sur le firewall ainsi que les autres ordinateurs). La RFC 1918
-réserve plusieurs plages d'IP (Private IP address ranges) à cette fin :
-
-
+
+
Avant d'aller plus loin, nous devons dire quelques mots au
+ sujet du Protocole d'adresse Internet (IP). Normalement, votre fournisseur
+ Internet (ISP) vous assignera une seule adresse IP (single Public IP address).
+ Cette adresse peut être assignée par le Dynamic Host Configuration Protocol
+ (DHCP) ou lors de l'établissement de votre connexion lorsque vous vous
+connectez (modem standard) ou établissez votre connexion PPP. Dans de rares
+cas , votre provider peu vous assigner une adresse statique (staticIP address);
+cela signifie que vous configurez votre interface externe sur votre firewall
+afin d'utiliser cette adresse de manière permanente. Une fois votre adresse
+externe assignée, elle va être partagée par tout vos systèmes lors de l'accès
+à Internet. Vous devrez assigner vos propres adresses à votre réseau local
+(votre interface interne sur le firewall ainsi que les autres ordinateurs).
+La RFC 1918 réserve plusieurs plages d'IP (Private IP address ranges) à
+cette fin :
- Avant de lancer Shorewall, vous devriez regarder l'adresse de votre interface
- externe et si elle est comprise dans une des plages précédentes, vous devriez
- enlever l'option 'norfc1918' dans le fichier /etc/shorewall/interfaces.
-
-
-
-
Vous devrez assigner les adresses locales à un sous-réseau
- (sub-network ou subnet) et les adresse pour la DMZ à un autre
- sous-réseau. Pour ce faire, nous pouvons considérer qu'un sous-réseau consiste
- en une plage d'adresse x.y.z.0 à x.y.z.255. Chacun des sous-réseaux possèdera
- une masque (Subnet Mask) de 255.255.255.0. L'adresse x.y.z.0 est
- réservée comme l'adresse du sous-réseau (Subnet Address) et x.y.z.255
- est réservée en tant qu'adresse de broadcast du sous-réseau (Subnet Broadcast
- Address). Sous Shorewall, un sous-réseau est décrit/désigné en utilisant
- la notation Classless InterDomain
- Routing(CIDR) qui consiste en l'adresse du sous-réseau suivie par
- "/24". Le "24" se réfère au nombre de bits "1" consécutifs dans la partie
- gauche du masque de sous-réseau.
-
-
-
+ Avant de lancer Shorewall, vous devriez regarder l'adresse de votre
+interface externe et si elle est comprise dans une des plages précédentes,
+vous devriez enlever l'option 'norfc1918' dans le fichier /etc/shorewall/interfaces.
+
+
+
+
Vous devrez assigner les adresses locales à un sous-réseau
+ (sub-network ou subnet) et les adresse pour la DMZ à un autre
+ sous-réseau. Pour ce faire, nous pouvons considérer qu'un sous-réseau consiste
+ en une plage d'adresse x.y.z.0 à x.y.z.255. Chacun des sous-réseaux possèdera
+ une masque (Subnet Mask) de 255.255.255.0. L'adresse x.y.z.0
+est réservée comme l'adresse du sous-réseau (Subnet Address)
+et x.y.z.255 est réservée en tant qu'adresse de broadcast du sous-réseau
+(Subnet BroadcastAddress). Sous Shorewall, un sous-réseau
+est décrit/désigné en utilisant la notation Classless InterDomain Routing(CIDR)
+qui consiste en l'adresse du sous-réseau suivie par "/24". Le "24" se réfère
+au nombre de bits "1" consécutifs dans la partie gauche du masque de sous-réseau.
+
+
+
+
Exemple de sous-réseau (subnet) :
-
-
-
-
+
+
+
+
-
-
-
Plage:
-
10.10.10.0 - 10.10.10.255
-
-
-
Subnet Address:
-
10.10.10.0
-
-
-
Broadcast Address:
-
10.10.10.255
-
-
-
CIDR Notation:
-
10.10.10.0/24
-
-
-
+
+
+
Plage:
+
10.10.10.0 - 10.10.10.255
+
+
+
Subnet Address:
+
10.10.10.0
+
+
+
Broadcast Address:
+
10.10.10.255
+
+
+
CIDR Notation:
+
10.10.10.0/24
+
+
+
-
-
-
-
-
Il est de convention d'assigner à l'interface interne la première
-adresse utilisable dans le sous-réseau (10.10.10.1 dans l'exemple précédent)
- ou la dernière utilisable (10.10.10.254).
-
-
-
-
L'un des buts d'un sous-réseau est de permettre à tous les
- ordinateurs dans le sous-réseau de savoir avec quels autres ordinateurs ils
- peuvent communiquer directement. Pour communiquer avec des systèmes en dehors
- du sous-réseau, les ordinateurs envoient des paquets à travers le gateway
- (routeur).
-
-
-
+
+
+
+
+
Il est de convention d'assigner à l'interface interne la
+première adresse utilisable dans le sous-réseau (10.10.10.1 dans l'exemple
+précédent) ou la dernière utilisable (10.10.10.254).
+
+
+
+
L'un des buts d'un sous-réseau est de permettre à tous les
+ ordinateurs dans le sous-réseau de savoir avec quels autres ordinateurs
+ils peuvent communiquer directement. Pour communiquer avec des systèmes
+en dehors du sous-réseau, les ordinateurs envoient des paquets à travers
+le gateway (routeur).
+
+
+
- Vos ordinateurs locaux (ordinateur local 1 et 2) devraient être configurés
- avec leur passerelle par défaut (default gateway)pointant sur l'adresse
- IP de l'interface interne du firewall, et les ordinateurs de la DMZ devraient
- être configurés avec leur passerelle par défaut (default gateway)
-pointant sur l'adresse IP de l'interface DMZ du firewall.
-
-
-
Cette courte description ne fait que survoler les concepts
- de routage et de sous-réseau. Si vous vous voulez en apprendre plus sur l'adressage
- IP et le routage, je vous recommande chaudement "IP Fundamentals:
-What Everyone Needs to Know about Addressing & Routing", Thomas
- A. Maufer, Prentice-Hall, 1999, ISBN 0-13-975483-0.
-
-
Pour rappel, ce guide supposera que vous avez configuré votre
- réseau comme montrer ci-dessous :
-
+ Vos ordinateurs locaux (ordinateur local 1 et 2) devraient être configurés
+ avec leur passerelle par défaut (default gateway)pointant sur l'adresse
+ IP de l'interface interne du firewall, et les ordinateurs de la DMZ devraient
+ être configurés avec leur passerelle par défaut (default gateway)
+ pointant sur l'adresse IP de l'interface DMZ du firewall.
+
+
+
Cette courte description ne fait que survoler les concepts
+ de routage et de sous-réseau. Si vous vous voulez en apprendre plus sur
+l'adressage IP et le routage, je vous recommande chaudement "IP Fundamentals:
+ What Everyone Needs to Know about Addressing & Routing", Thomas
+ A. Maufer, Prentice-Hall, 1999, ISBN 0-13-975483-0.
+
+
Pour rappel, ce guide supposera que vous avez configuré votre
+ réseau comme montrer ci-dessous :
+
-
-
-
La passerelle par défaut (default gateway) pour les ordinateurs
- de la DMZ sera 10.10.11.254 et le passerelle par défaut pour les ordinateurs
- en local sera 10.10.10.254.
-
+
+
+
La passerelle par défaut (default gateway) pour les ordinateurs
+ de la DMZ sera 10.10.11.254 et le passerelle par défaut pour les
+ordinateurs en local sera 10.10.10.254.
+
IP Masquerading (SNAT)
-
-
Les adresses réservées par la RFC 1918 sont parfois désignées
- comme non-routables car les routeurs Internet (backbone) ne font pas circuler
- les paquets qui ont une adresse de destination appartenant à la RFC-1918.
- Lorsqu'un de vos systèmes en local (supposons l'ordinateur1) demande une
-connexion à un serveur par Internet, le firewall doit appliquer un NAT (Network
-Address Translation). Le firewall ré écrit l'adresse source dans le paquet,
-et l'a remplace par l'adresse de l'interface externe du firewall; en d'autres
-mots, le firewall fait croire que c'est lui même qui initie la connexion.
-Ceci est nécessaire afin que l'hôte de destination soit capable de renvoyer
-les paquets au firewall (souvenez vous que les paquets qui ont pour adresse
-de destination, une adresse réservée par la RFC 1918 ne pourront pas être
-routés à travers Internet, donc l'hôte Internet ne pourra adresser sa réponse
-à l'ordinateur 1). Lorsque le firewall reçoit le paquet de réponse, il remet
- l'adresse de destination à 10.10.10.1 et fait passer le paquet vers l'ordinateur
- 1.
-
-
Sur les systèmes Linux, ce procédé est souvent appelé de l'IP
-Masquerading mais vous verrez aussi le terme de Source Network Address Translation
-(SNAT) utilisé. Shorewall suit la convention utilisée avec Netfilter :
-
+
+
Les adresses réservées par la RFC 1918 sont parfois désignées
+ comme non-routables car les routeurs Internet (backbone) ne font pas circuler
+ les paquets qui ont une adresse de destination appartenant à la RFC-1918.
+ Lorsqu'un de vos systèmes en local (supposons l'ordinateur1) demande une
+ connexion à un serveur par Internet, le firewall doit appliquer un NAT (Network
+ Address Translation). Le firewall ré écrit l'adresse source dans le paquet,
+ et l'a remplace par l'adresse de l'interface externe du firewall; en d'autres
+ mots, le firewall fait croire que c'est lui même qui initie la connexion.
+ Ceci est nécessaire afin que l'hôte de destination soit capable de renvoyer
+ les paquets au firewall (souvenez vous que les paquets qui ont pour adresse
+ de destination, une adresse réservée par la RFC 1918 ne pourront pas être
+ routés à travers Internet, donc l'hôte Internet ne pourra adresser sa réponse
+ à l'ordinateur 1). Lorsque le firewall reçoit le paquet de réponse, il remet
+ l'adresse de destination à 10.10.10.1 et fait passer le paquet vers l'ordinateur
+ 1.
+
+
Sur les systèmes Linux, ce procédé est souvent appelé de
+l'IP Masquerading mais vous verrez aussi le terme de Source Network Address
+Translation (SNAT) utilisé. Shorewall suit la convention utilisée avec Netfilter
+:
+
-
-
Masquerade désigne le cas ou vous laissez votre firewall
- détecter automatiquement l'adresse de l'interface externe.
-
-
-
SNAT désigne le cas où vous spécifiez explicitement l'adresse
- source des paquets sortant de votre réseau local.
-
-
+
+
Masquerade désigne le cas ou vous laissez votre firewall
+ détecter automatiquement l'adresse de l'interface externe.
+
+
+
SNAT désigne le cas où vous spécifiez explicitement l'adresse
+ source des paquets sortant de votre réseau local.
+
+
-
-
Sous Shorewall, autant le Masquerading que le SNAT sont configuré
- avec des entrés dans le fichier /etc/shorewall/masq.
-
+
+
Sous Shorewall, autant le Masquerading que le SNAT sont configuré
+ avec des entrés dans le fichier /etc/shorewall/masq.
+
- Si votre interface externe est eth0, votre interface locale eth1
- et votre interface pour la DMZ eth2 vous n'avez pas besoin de modifier
- le fichier fourni avec l'exemple. Dans le cas contraire, éditez /etc/shorewall/masq
- et changez le en conséquence.
-
+ Si votre interface externe est eth0, votre interface locale eth1
+ et votre interface pour la DMZ eth2 vous n'avez pas besoin de modifier
+ le fichier fourni avec l'exemple. Dans le cas contraire, éditez /etc/shorewall/masq
+ et changez le en conséquence.
+
- Si votre IP externe est statique, vous pouvez la mettre dans la troisième
- colonne dans /etc/shorewall/masq si vous le désirez, de toutes façons votre
- firewall fonctionnera bien si vous laissez cette colonne vide. Le fait de
- mettre votre IP statique dans la troisième colonne permet un traitement des
- paquets sortant un peu plus efficace.
-
-
+ Si votre IP externe est statique, vous pouvez la mettre dans la troisième
+ colonne dans /etc/shorewall/masq si vous le désirez, de toutes façons votre
+ firewall fonctionnera bien si vous laissez cette colonne vide. Le fait
+de mettre votre IP statique dans la troisième colonne permet un traitement
+des paquets sortant un peu plus efficace.
+
+
- Si vous utilisez les paquets Debian, vérifiez que votre fichier de configuration
- shorewall.conf contient bien les valeurs suivantes, si elles n'y sont pas
- faite les changements nécessaires :
-
-
+ Si vous utilisez les paquets Debian, vérifiez que votre fichier de configuration
+ shorewall.conf contient bien les valeurs suivantes, si elles n'y sont pas
+ faite les changements nécessaires :
+
+
-
NAT_ENABLED=Yes
-
IP_FORWARDING=On
-
-
+
NAT_ENABLED=Yes
+
IP_FORWARDING=On
+
+
-
+
Port Forwarding (DNAT)
-
-
Un de nos buts est de, peut être, faire tourner un ou plusieurs
- serveurs sur nos ordinateurs dans la DMZ. que ces ordinateurs on une adresse
- RFC-1918, il n'est pas possible pour les clients sur Internet de se connecter
- directement à eux. Il est nécessaire à ces clients d'adresser leurs demandes
- de connexion au firewall qui ré écrit l'adresse de destination de votre serveur,
- et fait passer le paquet à celui-ci. Lorsque votre serveur répond, le firewall
- applique automatiquement un SNAT pour ré écrire l'adresse source dans la
-réponse.
-
-
Ce procédé est appelé Port Forwarding ou Destination Network
- Address Translation(DNAT). Vous configurez le port forwarding en utilisant
- les règles DNAT dans le fichier /etc/shorewall/rules.
-
-
La forme générale d'une simple règle de port forwarding dans /etc/shorewall/rules
- est :
-
-
+
+
Un de nos buts est de, peut être, faire tourner un ou plusieurs
+ serveurs sur nos ordinateurs dans la DMZ. que ces ordinateurs on une adresse
+ RFC-1918, il n'est pas possible pour les clients sur Internet de se connecter
+ directement à eux. Il est nécessaire à ces clients d'adresser leurs demandes
+ de connexion au firewall qui ré écrit l'adresse de destination de votre
+serveur, et fait passer le paquet à celui-ci. Lorsque votre serveur répond,
+le firewall applique automatiquement un SNAT pour ré écrire l'adresse source
+dans la réponse.
+
+
Ce procédé est appelé Port Forwarding ou Destination Network
+ Address Translation(DNAT). Vous configurez le port forwarding en utilisant
+ les règles DNAT dans le fichier /etc/shorewall/rules.
+
+
La forme générale d'une simple règle de port forwarding dans /etc/shorewall/rules
+ est :
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
dmz:<server local ip address> [:<server
-port>]
-
<protocol>
-
<port>
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
DNAT
+
net
+
dmz:<server local ip address> [:<server
+ port>]
+
<protocol>
+
<port>
+
+
+
+
+
+
+
-
-
-
Si vous ne spécifiez pas le <server port>, il est supposé
- être le même que <port>.
-
-
Exemple - vous faites tourner un serveur Web dans votre DMZ (2) et vous
- voulez faire passer les paquets entrant en TCP sur le port 80 à ce système
- :
-
-
+
+
+
Si vous ne spécifiez pas le <server port>, il est supposé
+ être le même que <port>.
+
+
Exemple - vous faites tourner un serveur Web dans votre DMZ (2) et vous
+ voulez faire passer les paquets entrant en TCP sur le port 80 à ce système
+ :
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
dmz:10.10.11.2
-
tcp
-
80
-
# Fait suivre le port 80
-
depuis Internet
-
-
-
ACCEPT
-
loc
-
dmz:10.10.11.2
-
tcp
-
80
-
#Permet les connexions
-
depuis le réseau local
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
DNAT
+
net
+
dmz:10.10.11.2
+
tcp
+
80
+
# Fait suivre le port 80
+
depuis Internet
+
+
+
ACCEPT
+
loc
+
dmz:10.10.11.2
+
tcp
+
80
+
#Permet les connexions
+
depuis le réseau local
+
+
+
-
-
+
+
Deux points importants à garder en mémoire :
-
+
-
Lorsque vous vous connectez à votre serveur à partir de votre réseau
- local, vous devez utiliser l'adresse IP interne du serveur (10.10.11.2).
-
Quelques fournisseurs Internet (Provider/ISP) bloquent les requêtes
- de connexion entrantes sur le port 80. Si vous avez des problèmes pour vous
- connecter à votre serveur web, essayez la règle suivante et connectez vous
- sur le port 5000 (c.a.d., connectez vous à http://w.x.y.z:5000 où w.x.y.z est votre
-IP externe).
-
+
Lorsque vous vous connectez à votre serveur à partir de votre
+réseau local, vous devez utiliser l'adresse IP interne du serveur (10.10.11.2).
+
Quelques fournisseurs Internet (Provider/ISP) bloquent les requêtes
+ de connexion entrantes sur le port 80. Si vous avez des problèmes pour
+vous connecter à votre serveur web, essayez la règle suivante et connectez
+vous sur le port 5000 (c.a.d., connectez vous à http://w.x.y.z:5000 où w.x.y.z est votre
+ IP externe).
+
-
-
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
dmz:10.10.11.2:80
-
tcp
-
5000
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
DNAT
+
net
+
dmz:10.10.11.2:80
+
tcp
+
5000
+
+
+
+
+
+
+
-
-
-
Si vous voulez avoir la possibilité de vous connecter à votre serveur depuis
-le réseau local en utilisant votre adresse externe, et si vous avez une adresse
-IP externe statique (fixe), vous pouvez remplacer la règle loc->dmz précédente
-par :
-
-
+
+
+
Si vous voulez avoir la possibilité de vous connecter à votre serveur
+depuis le réseau local en utilisant votre adresse externe, et si vous avez
+une adresse IP externe statique (fixe), vous pouvez remplacer la règle loc->dmz
+précédente par :
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
dmz:10.10.11.2:80
-
tcp
-
80
-
-
-
<external IP>
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
DNAT
+
net
+
dmz:10.10.11.2:80
+
tcp
+
80
+
-
+
<external IP>
+
+
+
-
-
-
Si vous avez une IP dynamique, alors vous devez vous assurer que votre
- interface externe est en route avant de lancer Shorewall et vous devez suivre
- les étapes suivantes (en supposant que votre interface externe est eth0)
- :
-
+
+
+
Si vous avez une IP dynamique, alors vous devez vous assurer que votre
+ interface externe est en route avant de lancer Shorewall et vous devez
+suivre les étapes suivantes (en supposant que votre interface externe est
+eth0) :
+
-
Insérez ce qui suit dans /etc/shorewall/params :
-
- ETH0_IP=`find_interface_address eth0`
-
-
Faites votre règle loc->dmz :
-
+
Insérez ce qui suit dans /etc/shorewall/params :
+
+ ETH0_IP=`find_interface_address eth0`
+
+
Faites votre règle loc->dmz :
+
-
-
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
loc
-
-
dmz:10.10.11.2:80
-
tcp
-
80
-
-
-
$ETH0_IP
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
DNAT
+
loc
+
+
dmz:10.10.11.2:80
+
tcp
+
80
+
-
+
$ETH0_IP
+
+
+
-
-
-
Si vous voulez accéder à votre serveur dans la DMZ en utilisant votre adresse
-IP externe, regardez FAQ 2a.
-
+
+
+
Si vous voulez accéder à votre serveur dans la DMZ en utilisant votre
+adresse IP externe, regardez FAQ 2a.
+
- A ce point, ajoutez les règles DNAT et ACCEPT pour vos serveurs..
-
+ A ce point, ajoutez les règles DNAT et ACCEPT pour vos serveurs..
+
Domain Name Server (DNS)
-
-
Normalement, quand vous vous connectez à votre fournisseur
- (ISP), une partie consiste à obtenir votre adresse IP, votre DNS pour le
-firewall (Domain Name Service) est configuré automatiquement (c.a.d., le fichier
-/etc/resolv.conf a été écrit). Il arrive que votre provider vous donne une
-paire d'adresse IP pour les DNS (name servers) afin que vous configuriez manuellement
-votre serveur de nom primaire et secondaire. La manière dont le DNS est configuré
-sur votre firewall est de votre responsabilité. Vous pouvez procéder d'une
-de ses deux façons :
-
+
+
Normalement, quand vous vous connectez à votre fournisseur
+ (ISP), une partie consiste à obtenir votre adresse IP, votre DNS pour le
+ firewall (Domain Name Service) est configuré automatiquement (c.a.d., le
+fichier /etc/resolv.conf a été écrit). Il arrive que votre provider vous
+donne une paire d'adresse IP pour les DNS (name servers) afin que vous configuriez
+manuellement votre serveur de nom primaire et secondaire. La manière dont
+le DNS est configuré sur votre firewall est de votre responsabilité. Vous
+pouvez procéder d'une de ses deux façons :
+
-
-
Vous pouvez configurer votre système interne pour utiliser
- les noms de serveurs de votre provider. Si votre fournisseur vous donne les
- adresses de leurs serveurs ou si ces adresses sont disponibles sur leur site
- web, vous pouvez configurer votre système interne afin de les utiliser. Si
- cette information n'est pas disponible, regardez dans /etc/resolv.conf sur
- votre firewall -- les noms des serveurs sont donnés dans l'enregistrement
- "nameserver" dans ce fichier.
-
-
+
+
Vous pouvez configurer votre système interne pour utiliser
+ les noms de serveurs de votre provider. Si votre fournisseur vous donne
+les adresses de leurs serveurs ou si ces adresses sont disponibles sur leur
+site web, vous pouvez configurer votre système interne afin de les utiliser.
+Si cette information n'est pas disponible, regardez dans /etc/resolv.conf
+sur votre firewall -- les noms des serveurs sont donnés dans l'enregistrement
+ "nameserver" dans ce fichier.
+
+
- Vous pouvez installer/configurer un cache dns (Caching Name Server) sur
- votre firewall ou dans la DMZ.Red Hat a un RPM pour mettre en cache
- un serveur de nom (le RPM requis aussi le RPM 'bind') et pour les utilisateurs
- de Bering, il y a dnscache.lrp. Si vous adoptez cette approche, vous configurez
- votre système interne pour utiliser le firewall lui même comme étant le seul
- serveur de nom primaire. Vous pouvez utiliser l'adresse IP interne du firewall
- (10.10.10.254 dans l'exemple) pour l'adresse de serveur de nom si vous décidez
- de faire tourner le serveur de nom sur votre firewall. Pour permettre à
-vos systèmes locaux de discuter avec votre serveur cache de nom, vous devez
-ouvrir le port 53 (UDP ET TCP) sur le firewall vers le réseau local; vous
-ferez ceci en ajoutant les règles suivantes dans /etc/shorewall/rules.
-
-
-
+ Vous pouvez installer/configurer un cache dns (Caching Name Server)
+sur votre firewall ou dans la DMZ.Red Hat a un RPM pour mettre
+en cache un serveur de nom (le RPM requis aussi le RPM 'bind') et pour
+les utilisateurs de Bering, il y a dnscache.lrp. Si vous adoptez cette
+approche, vous configurez votre système interne pour utiliser le firewall
+lui même comme étant le seul serveur de nom primaire. Vous pouvez utiliser
+l'adresse IP interne du firewall (10.10.10.254 dans l'exemple) pour l'adresse
+de serveur de nom si vous décidez de faire tourner le serveur de nom sur
+votre firewall. Pour permettre à vos systèmes locaux de discuter avec votre
+serveur cache de nom, vous devez ouvrir le port 53 (UDP ET TCP) sur le
+firewall vers le réseau local; vous ferez ceci en ajoutant les règles suivantes
+dans /etc/shorewall/rules.
+
+
-
-
-
Si vous faites tourner le serveur de nom sur le firewall
- :
+
+
+
Si vous faites tourner le serveur de nom sur le firewall
+ :
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
53
-
-
-
-
-
-
-
ACCEPT
-
loc
-
fw
-
udp
-
53
-
-
-
-
-
-
-
ACCEPT
-
dmz
-
fw
-
tcp
-
53
-
-
-
-
-
-
-
ACCEPT
-
dmz
-
fw
-
udp
-
53
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
53
+
+
+
+
+
+
+
ACCEPT
+
loc
+
fw
+
udp
+
53
+
+
+
+
+
+
+
ACCEPT
+
dmz
+
fw
+
tcp
+
53
+
+
+
+
+
+
+
ACCEPT
+
dmz
+
fw
+
udp
+
53
+
+
+
+
+
+
+
-
-
-
-
-
+
+
+
+
+
Le serveur de nom tourne sur l'ordinateur 1 de la DMZ
-
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
loc
-
dmz:10.10.11.1
-
tcp
-
53
-
-
-
-
-
-
-
ACCEPT
-
loc
-
dmz:10.10.11.1
-
udp
-
53
-
-
-
-
-
-
-
ACCEPT
-
fw
-
dmz:10.10.10.1
-
tcp
-
53
-
-
-
-
-
-
-
ACCEPT
-
fw
-
dmz:10.10.10.1
-
udp
-
53
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
loc
+
dmz:10.10.11.1
+
tcp
+
53
+
+
+
+
+
+
+
ACCEPT
+
loc
+
dmz:10.10.11.1
+
udp
+
53
+
+
+
+
+
+
+
ACCEPT
+
fw
+
dmz:10.10.10.1
+
tcp
+
53
+
+
+
+
+
+
+
ACCEPT
+
fw
+
dmz:10.10.10.1
+
udp
+
53
+
+
+
+
+
+
+
-
-
-
-
+
+
+
+
Autres Connexions
-
-
-
-
L'exemple pour trois interfaces contient les règles suivantes
- :
-
-
-
-
+
+
+
+
L'exemple pour trois interfaces contient les règles suivantes
+ :
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
fw
-
net
-
udp
-
53
-
-
-
-
-
-
-
ACCEPT
-
fw
-
net
-
tcp
-
53
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
fw
+
net
+
udp
+
53
+
+
+
+
+
+
+
ACCEPT
+
fw
+
net
+
tcp
+
53
+
+
+
+
+
+
+
-
-
-
-
-
Ces règles permettent l'accès DNS depuis votre firewall et
- peuvent être enlevées si vous avez décommenté la ligne dans /etc/shorewall/policy
- autorisant toutes les connexions depuis votre firewall et vers Internet.
-
-
-
+
+
+
+
+
Ces règles permettent l'accès DNS depuis votre firewall et
+ peuvent être enlevées si vous avez décommenté la ligne dans /etc/shorewall/policy
+ autorisant toutes les connexions depuis votre firewall et vers Internet.
+
+
+
L'exemple contient aussi :
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
22
-
-
-
-
-
-
-
ACCEPT
-
loc
-
dmz
-
tcp
-
22
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
22
+
+
+
+
+
+
+
ACCEPT
+
loc
+
dmz
+
tcp
+
22
+
+
+
+
+
+
+
-
-
-
-
-
Cette règle permet de faire fonctionner une serveur SSH sur
- le firewall et sur tous les systèmes de la DMZ et d'y autoriser la connexion
- à partir de votre réseau local.
-
-
-
-
Si vous désirez permettre d'autres connexions entre vos systèmes,
- la forme générale est :
-
-
-
-
+
+
+
+
+
Cette règle permet de faire fonctionner une serveur SSH sur
+ le firewall et sur tous les systèmes de la DMZ et d'y autoriser la connexion
+ à partir de votre réseau local.
+
+
+
+
Si vous désirez permettre d'autres connexions entre vos systèmes,
+ la forme générale est :
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
<source zone>
-
<destination zone>
-
<protocol>
-
<port>
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
<source zone>
+
<destination zone>
+
<protocol>
+
<port>
+
+
+
+
+
+
+
-
-
-
-
-
Exemple - Vous voulez faire tourner un serveur DNS disponible
- pour le publique sur votre firewall :
-
-
-
-
+
+
+
+
+
Exemple - Vous voulez faire tourner un serveur DNS disponible
+ pour le publique sur votre firewall :
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
net
-
fw
-
tcp
-
53
-
#permet les accès DNS
-
depuis Internet
-
-
-
ACCEPT
-
net
-
fw
-
udp
-
-
53
-
#permet les accès DNS
-
depuis Internet
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
53
+
#permet les accès DNS
+
depuis Internet
+
+
+
ACCEPT
+
net
+
fw
+
udp
+
+
53
+
#permet les accès DNS
+
depuis Internet
+
+
+
-
-
-
-
-
Ces deux règles seront, bien sur, ajoutées aux règles décrites
- dans "Vous pouvez installer/configurer un cache dns (Caching Name Server)
- sur votre firewall ou dans la DMZ".
-
-
-
-
Si vous ne savez pas quel port ou protocole une application
- particulière utilise, regardez ici.
-
-
-
-
Important: Je ne vous recommande pas d'autoriser le telnet
- depuis ou vers l'Internet car il utilise du texte en clair (même pour le
-login et le mot de passe !). Si vous voulez avoir un accès au shell de votre
-firewall depuis Internet, utilisez SSH :
-
-
-
-
+
+
+
+
+
Ces deux règles seront, bien sur, ajoutées aux règles décrites
+ dans "Vous pouvez installer/configurer un cache dns (Caching Name Server)
+ sur votre firewall ou dans la DMZ".
+
+
+
+
Si vous ne savez pas quel port ou protocole une application
+ particulière utilise, regardez ici.
+
+
+
+
Important: Je ne vous recommande pas d'autoriser le telnet
+ depuis ou vers l'Internet car il utilise du texte en clair (même pour le
+ login et le mot de passe !). Si vous voulez avoir un accès au shell de votre
+ firewall depuis Internet, utilisez SSH :
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
net
-
fw
-
tcp
-
22
-
-
-
-
-
-
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
22
+
+
+
+
+
+
+
-
-
-
-
+
+
+
+
- Et maintenant, éditez /etc/shorewall/rules pour rajouter les autres connexions
- désirées.
-
-
-
+ Et maintenant, éditez /etc/shorewall/rules pour rajouter les autres
+connexions désirées.
+
+
+
Lancer et Arrêter son Firewall
-
-
-
+
+
+
- La procédure d'installation configure votre
-système pour lancer Shorewall au boot du système, mais au début avec la version
-1.3.9 de Shorewall le lancement est désactivé, n'essayer pas de lancer Shorewall
- avec que la configuration soit finie. Une fois que vous en avez fini avec
- la configuration du firewall, vous pouvez permettre le lancement de Shorewall
- en supprimant le fichier /etc/shorewall/startup_disabled.
-
-
-
IMPORTANT: Les utilisateurs des paquets .deb doivent éditer
- /etc/default/shorewall et mettre 'startup=1'.
-
-
-
-
-
Le firewall est activé en utilisant la commande "shorewall
- start" et arrêté avec "shorewall stop". Lorsque le firewall est stoppé, le
- routage est autorisé sur les hôtes qui possèdent une entrée dans /etc/shorewall/routestopped. Un
- firewall qui tourne peut être relancé en utilisant la commande "shorewall
- restart". Si vous voulez enlever toutes traces de Shorewall sur votre configuration
- de Netfilter, utilisez "shorewall clear".
-
-
-
+ La procédure d'installation configure votre
+ système pour lancer Shorewall au boot du système, mais au début avec la
+version 1.3.9 de Shorewall le lancement est désactivé, n'essayer pas de
+lancer Shorewall avec que la configuration soit finie. Une fois que vous
+en avez fini avec la configuration du firewall, vous pouvez permettre le
+lancement de Shorewall en supprimant le fichier /etc/shorewall/startup_disabled.
+
+
+
IMPORTANT: Les utilisateurs des paquets .deb doivent éditer
+ /etc/default/shorewall et mettre 'startup=1'.
+
+
+
+
+
Le firewall est activé en utilisant la commande "shorewall
+ start" et arrêté avec "shorewall stop". Lorsque le firewall est stoppé,
+le routage est autorisé sur les hôtes qui possèdent une entrée dans /etc/shorewall/routestopped. Un
+ firewall qui tourne peut être relancé en utilisant la commande "shorewall
+ restart". Si vous voulez enlever toutes traces de Shorewall sur votre configuration
+ de Netfilter, utilisez "shorewall clear".
+
+
+
- L'exemple pour trois interfaces suppose que vous voulez permettre le
-routage depuis/vers eth1 (votre réseau local) et eth2(DMZ)
- lorsque Shorewall est arrêté. Si ces deux interfaces ne sont pas
-connectées à votre réseau local et votre DMZ, ou si vous voulez permettre
-un ensemble d'hôtes différents, modifiez /etc/shorewall/routestopped en
-conséquence.
ATTENTION: Si vous êtes connecté à votre firewall depuis
+Internet, n'essayez pas une commande "shorewall stop" tant que vous n'avez
+pas ajouté une entrée pour votre adresse IP (celle à partir de laquelle vous
+êtes connectée) dans /etc/shorewall/routestopped.
+ De la même manière, je ne vous recommande pas d'utiliser "shorewall restart";
+ il est plus intéressant de créer une configuration alternativeet de la
- tester en utilisant la commande alternativeet de la
+ tester en utilisant la commande "shorewall try".
Shorewall has limited support for traffic shaping/control.
- In order to use traffic shaping under Shorewall, it is essential that
- you get a copy of the Linux Advanced Routing
- and Shaping HOWTO, version 0.3.0 or later. It is also necessary
+
+
Shorewall has limited support for traffic shaping/control.
+ In order to use traffic shaping under Shorewall, it is essential that
+ you get a copy of the Linux Advanced Routing
+ and Shaping HOWTO, version 0.3.0 or later. It is also necessary
to be running Linux Kernel 2.4.18 or later.
-
+
Shorewall traffic shaping support consists of the following:
-
+
-
A new TC_ENABLED parameter in /etc/shorewall.conf.
+
A new TC_ENABLED parameter in /etc/shorewall.conf.
Traffic Shaping also requires that you enable packet mangling.
-
A new CLEAR_TC parameter in /etc/shorewall.conf (Added
- in Shorewall 1.3.13). When Traffic Shaping is enabled (TC_ENABLED=Yes),
- the setting of this variable determines whether Shorewall clears the traffic
+
A new CLEAR_TC parameter in /etc/shorewall.conf (Added
+ in Shorewall 1.3.13). When Traffic Shaping is enabled (TC_ENABLED=Yes),
+ the setting of this variable determines whether Shorewall clears the traffic
shaping configuration during Shorewall [re]start and Shorewall stop.
-
-
/etc/shorewall/tcrules - A file where you can
- specify firewall marking of packets. The firewall mark value may
- be used to classify packets for traffic shaping/control.
-
-
/etc/shorewall/tcstart - A user-supplied file
- that is sourced by Shorewall during "shorewall start" and which
- you can use to define your traffic shaping disciplines and classes.
+
+
/etc/shorewall/tcrules - A file where you
+can specify firewall marking of packets. The firewall mark value
+may be used to classify packets for traffic shaping/control.
+
+
/etc/shorewall/tcstart - A user-supplied file
+ that is sourced by Shorewall during "shorewall start" and which
+ you can use to define your traffic shaping disciplines and classes.
I have provided a sample that does
- table-driven CBQ shaping but if you read the traffic shaping sections
- of the HOWTO mentioned above, you can probably code your own
-faster than you can learn how to use my sample. I personally use
- HTB (see below).
- HTB support may eventually become an integral part of Shorewall
- since HTB is a lot simpler and better-documented than CBQ. As of
-2.4.20, HTB is a standard part of the kernel but iproute2 must be patched
- in order to use it.
-
- In tcstart, when you want to run the 'tc' utility, use
- the run_tc function supplied by shorewall if you want tc errors
+ href="ftp://ftp.shorewall.net/pub/shorewall/cbq">sample that does
+ table-driven CBQ shaping but if you read the traffic shaping sections
+ of the HOWTO mentioned above, you can probably code your own faster
+ than you can learn how to use my sample. I personally use
+ HTB (see below).
+ HTB support may eventually become an integral part of Shorewall
+since HTB is a lot simpler and better-documented than CBQ. As of 2.4.20,
+ HTB is a standard part of the kernel but iproute2 must be patched in
+ order to use it.
+
+ In tcstart, when you want to run the 'tc' utility,
+use the run_tc function supplied by shorewall if you want tc errors
to stop the firewall.
-
- You can generally use off-the-shelf traffic shaping scripts by
+
+ You can generally use off-the-shelf traffic shaping scripts by
simply copying them to /etc/shorewall/tcstart. I use The Wonder Shaper (HTB version)
- that way (i.e., I just copied wshaper.htb to /etc/shorewall/tcstart and
- modified it according to the Wonder Shaper README). WARNING: If
- you use use Masquerading or SNAT (i.e., you only have one external IP address)
- then listing internal hosts in the NOPRIOHOSTSRC variable in the wshaper[.htb]
- script won't work. Traffic shaping occurs after SNAT has already been applied
- so when traffic shaping happens, all outbound traffic will have as a source
- address the IP addresss of your firewall's external interface.
-
-
/etc/shorewall/tcclear - A user-supplied file
- that is sourced by Shorewall when it is clearing traffic shaping.
- This file is normally not required as Shorewall's method of clearing
+ href="http://lartc.org/wondershaper/">The Wonder Shaper (HTB version)
+ that way (i.e., I just copied wshaper.htb to /etc/shorewall/tcstart
+and modified it according to the Wonder Shaper README). WARNING: If
+ you use use Masquerading or SNAT (i.e., you only have one external IP address)
+ then listing internal hosts in the NOPRIOHOSTSRC variable in the wshaper[.htb]
+ script won't work. Traffic shaping occurs after SNAT has already been
+applied so when traffic shaping happens, all outbound traffic will have
+as a source address the IP addresss of your firewall's external interface.
+
+
/etc/shorewall/tcclear - A user-supplied file
+ that is sourced by Shorewall when it is clearing traffic shaping.
+ This file is normally not required as Shorewall's method of clearing
qdisc and filter definitions is pretty general.
-
+
- Shorewall allows you to start traffic shaping when Shorewall itself
- starts or it allows you to bring up traffic shaping when you bring up
-your interfaces.
-
- To start traffic shaping when Shorewall starts:
-
+ Shorewall allows you to start traffic shaping when Shorewall itself
+ starts or it allows you to bring up traffic shaping when you bring up your
+ interfaces.
+
+ To start traffic shaping when Shorewall starts:
+
-
Set TC_ENABLED=Yes and CLEAR_TC=Yes
-
Supply an /etc/shorewall/tcstart script to configure your traffic
+
Set TC_ENABLED=Yes and CLEAR_TC=Yes
+
Supply an /etc/shorewall/tcstart script to configure your traffic
shaping rules.
-
Optionally supply an /etc/shorewall/tcclear script to stop traffic
- shaping. That is usually unnecessary.
-
If your tcstart script uses the 'fwmark' classifier, you can
+
Optionally supply an /etc/shorewall/tcclear script to stop
+traffic shaping. That is usually unnecessary.
+
If your tcstart script uses the 'fwmark' classifier, you can
mark packets using entries in /etc/shorewall/tcrules.
-
+
- To start traffic shaping when you bring up your network interfaces,
- you will have to arrange for your traffic shaping configuration script
-to be run at that time. How you do that is distribution dependent and will
+ To start traffic shaping when you bring up your network interfaces,
+ you will have to arrange for your traffic shaping configuration script
+to be run at that time. How you do that is distribution dependent and will
not be covered here. You then should:
-
+
-
Set TC_ENABLED=Yes and CLEAR_TC=No
-
Do not supply /etc/shorewall/tcstart or /etc/shorewall/tcclear
+
Set TC_ENABLED=Yes and CLEAR_TC=No
+
Do not supply /etc/shorewall/tcstart or /etc/shorewall/tcclear
scripts.
-
If your tcstart script uses the 'fwmark' classifier,
+
If your tcstart script uses the 'fwmark' classifier,
you can mark packets using entries in /etc/shorewall/tcrules.
-
+
-
+
Kernel Configuration
-
+
This screen shot show how I've configured QoS in my Kernel:
-
+
-
-
+
+
/etc/shorewall/tcrules
-
-
The fwmark classifier provides a convenient way to classify
- packets for traffic shaping. The /etc/shorewall/tcrules file provides
+
+
The fwmark classifier provides a convenient way to classify
+ packets for traffic shaping. The /etc/shorewall/tcrules file provides
a means for specifying these marks in a tabular fashion.
-
-
-
Normally, packet marking occurs in the PREROUTING chain before
- any address rewriting takes place. This makes it impossible to mark inbound
- packets based on their destination address when SNAT or Masquerading are
- being used. Beginning with Shorewall 1.3.12, you can cause packet marking
- to occur in the FORWARD chain by using the MARK_IN_FORWARD_CHAIN option
- in shorewall.conf.
-
-
+
+
+
Normally, packet marking occurs in the PREROUTING chain before
+ any address rewriting takes place. This makes it impossible to mark inbound
+ packets based on their destination address when SNAT or Masquerading
+are being used. Beginning with Shorewall 1.3.12, you can cause packet
+marking to occur in the FORWARD chain by using the MARK_IN_FORWARD_CHAIN
+option in shorewall.conf.
+
+
Columns in the file are as follows:
-
+
-
MARK - Specifies the mark value is to be assigned
-in case of a match. This is an integer in the range 1-255. Beginning
-with Shorewall version 1.3.14, this value may be optionally followed by ":"
-and either 'F' or 'P' to designate that the marking will occur in the FORWARD
-or PREROUTING chains respectively. If this additional specification is omitted,
-the chain used to mark packets will be determined by the setting of the
-MARK_IN_FORWARD_CHAIN option in shorewall.conf.
-
- Example - 5
-
-
SOURCE - The source of the packet. If the packet originates
- on the firewall, place "fw" in this column. Otherwise, this is
-a comma-separated list of interface names, IP addresses, MAC addresses
- in Shorewall Format and/or Subnets.
-
- Examples
- eth0
- 192.168.2.4,192.168.1.0/24
-
-
DEST -- Destination of the packet. Comma-separated
+
MARK - Specifies the mark value is to be assigned
+in case of a match. This is an integer in the range 1-255. Beginning
+with Shorewall version 1.3.14, this value may be optionally followed by
+":" and either 'F' or 'P' to designate that the marking will occur in the
+FORWARD or PREROUTING chains respectively. If this additional specification
+is omitted, the chain used to mark packets will be determined by the setting
+of the MARK_IN_FORWARD_CHAIN option in shorewall.conf.
+
+ Example - 5
+
+
SOURCE - The source of the packet. If the packet
+originates on the firewall, place "fw" in this column. Otherwise,
+this is a comma-separated list of interface names, IP addresses, MAC
+addresses in Shorewall Format and/or
+Subnets.
+
+ Examples
+ eth0
+ 192.168.2.4,192.168.1.0/24
+
+
DEST -- Destination of the packet. Comma-separated
list of IP addresses and/or subnets.
-
-
PROTO - Protocol - Must be the name of a protocol
+
+
PROTO - Protocol - Must be the name of a protocol
from /etc/protocol, a number or "all"
-
-
PORT(S) - Destination Ports. A comma-separated list
- of Port names (from /etc/services), port numbers or port ranges
-(e.g., 21:22); if the protocol is "icmp", this column is interpreted
-as the destination icmp type(s).
-
-
CLIENT PORT(S) - (Optional) Port(s) used by the client.
- If omitted, any source port is acceptable. Specified as a comma-separate
+
+
PORT(S) - Destination Ports. A comma-separated list
+ of Port names (from /etc/services), port numbers or port ranges (e.g.,
+ 21:22); if the protocol is "icmp", this column is interpreted as
+ the destination icmp type(s).
+
+
CLIENT PORT(S) - (Optional) Port(s) used by the client.
+ If omitted, any source port is acceptable. Specified as a comma-separate
list of port names, port numbers or port ranges.
-
+
-
-
Example 1 - All packets arriving on eth1 should be marked
- with 1. All packets arriving on eth2 and eth3 should be marked with
- 2. All packets originating on the firewall itself should be marked
-with 3.
-
+
+
Example 1 - All packets arriving on eth1 should be marked
+ with 1. All packets arriving on eth2 and eth3 should be marked with
+ 2. All packets originating on the firewall itself should be marked with
+ 3.
+
-
+
+
+
MARK
+
SOURCE
+
DEST
+
PROTO
+
PORT(S)
+
CLIENT PORT(S)
+
-
MARK
-
SOURCE
-
DEST
-
PROTO
-
PORT(S)
-
CLIENT PORT(S)
-
-
-
1
-
eth1
-
0.0.0.0/0
-
all
-
-
-
-
-
2
-
eth2
-
0.0.0.0/0
-
all
-
-
-
-
-
2
-
-
eth3
-
-
0.0.0.0/0
-
-
all
-
-
-
-
-
-
-
-
3
-
fw
-
0.0.0.0/0
-
all
-
-
-
-
-
+
1
+
eth1
+
0.0.0.0/0
+
all
+
+
+
+
+
2
+
eth2
+
0.0.0.0/0
+
all
+
+
+
+
+
2
+
+
eth3
+
+
0.0.0.0/0
+
+
all
+
+
+
+
+
+
+
+
3
+
fw
+
0.0.0.0/0
+
all
+
+
+
+
+
-
-
Example 2 - All GRE (protocol 47) packets not originating
- on the firewall and destined for 155.186.235.151 should be marked
+
+
Example 2 - All GRE (protocol 47) packets not originating
+ on the firewall and destined for 155.186.235.151 should be marked
with 12.
-
+
-
+
+
+
MARK
+
SOURCE
+
DEST
+
PROTO
+
PORT(S)
+
CLIENT PORT(S)
+
-
MARK
-
SOURCE
-
DEST
-
PROTO
-
PORT(S)
-
CLIENT PORT(S)
-
-
-
12
-
0.0.0.0/0
-
155.186.235.151
-
47
-
-
-
-
-
+
12
+
0.0.0.0/0
+
155.186.235.151
+
47
+
+
+
+
+
-
-
Example 3 - All SSH packets originating in 192.168.1.0/24
+
+
Example 3 - All SSH packets originating in 192.168.1.0/24
and destined for 155.186.235.151 should be marked with 22.
-
+
-
+
+
+
MARK
+
SOURCE
+
DEST
+
PROTO
+
PORT(S)
+
CLIENT PORT(S)
+
-
MARK
-
SOURCE
-
DEST
-
PROTO
-
PORT(S)
-
CLIENT PORT(S)
-
-
-
22
-
192.168.1.0/24
-
155.186.235.151
-
tcp
-
22
-
-
-
-
+
22
+
192.168.1.0/24
+
155.186.235.151
+
tcp
+
22
+
+
+
+
-
+
My Setup
-
-
+
+
While I am currently using the HTB version of The Wonder Shaper (I just copied
- wshaper.htb to /etc/shorewall/tcstart and modified it as shown
- in the Wondershaper README), I have also run with the following set of
+ href="http://lartc.org/wondershaper/">The Wonder Shaper (I just copied
+ wshaper.htb to /etc/shorewall/tcstart and modified it as shown
+ in the Wondershaper README), I have also run with the following set of
hand-crafted rules in my /etc/shorewall/tcstart file:
-
run_tc qdisc add dev eth0 parent 1:10 pfifo limit 5 run_tc qdisc add dev eth0 parent 1:20 pfifo limit 10 run_tc qdisc add dev eth0 parent 1:30 pfifo limit 5
-
-
echo " Enabled PFIFO on Second Level Classes"
-
-
run_tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 1 fw classid 1:10 run_tc filter add dev eth0 protocol ip parent 1:0 prio 0 handle 2 fw classid 1:20 run_tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 3 fw classid 1:30
-
-
echo " Defined fwmark filters"
-
-
-
My tcrules file that went with this tcstart file is shown in Example 1
- above. You can look at my configuration to
-see why I wanted shaping of this type.
run_tc qdisc add dev eth0 parent 1:10 pfifo limit 5 run_tc qdisc add dev eth0 parent 1:20 pfifo limit 10 run_tc qdisc add dev eth0 parent 1:30 pfifo limit 5
+
+
echo " Enabled PFIFO on Second Level Classes"
+
+
run_tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 1 fw classid 1:10 run_tc filter add dev eth0 protocol ip parent 1:0 prio 0 handle 2 fw classid 1:20 run_tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 3 fw classid 1:30
+
+
echo " Defined fwmark filters"
+
+
+
My tcrules file that went with this tcstart file is shown in Example 1
+ above. You can look at my configuration to
+see why I wanted shaping of this type.
+
+
-
I wanted to allow up to 140kbits/second for traffic outbound
- from my DMZ (note that the ceiling is set to 384kbit so outbound DMZ
-traffic can use all available bandwidth if there is no traffic from the
+
I wanted to allow up to 140kbits/second for traffic outbound
+ from my DMZ (note that the ceiling is set to 384kbit so outbound DMZ
+traffic can use all available bandwidth if there is no traffic from the
local systems or from my laptop or firewall).
-
My laptop and local systems could use up to 224kbits/second.
-
My firewall could use up to 20kbits/second.
-
+
My laptop and local systems could use up to 224kbits/second.
Check the Shorewall Errata to be
- sure that there isn't an update that you are missing for your version
- of the firewall.
-
+
+
Check the Shorewall Errata to be
+ sure that there isn't an update that you are missing for your version
+ of the firewall.
+
Check the FAQs
-
-
Check the FAQs for solutions to common
- problems.
-
+
+
Check the FAQs for solutions to common
+ problems.
+
If the firewall fails to start
- If you receive an error message when starting or restarting
- the firewall and you can't determine the cause, then do the following:
-
+ If you receive an error message when starting or restarting
+ the firewall and you can't determine the cause, then do the following:
+
-
Make a note of the error message that you see.
-
-
shorewall debug start 2> /tmp/trace
-
Look at the /tmp/trace file and see if that helps you
- determine what the problem is. Be sure you find the place in the log
- where the error message you saw is generated -- If you are using Shorewall
+
Make a note of the error message that you see.
+
+
shorewall debug start 2> /tmp/trace
+
Look at the /tmp/trace file and see if that helps you
+ determine what the problem is. Be sure you find the place in the log
+ where the error message you saw is generated -- If you are using Shorewall
1.4.0 or later, you should find the message near the end of the log.
-
If you still can't determine what's wrong then see the
- support page.
-
+
If you still can't determine what's wrong then see the
+ support page.
+
- Here's an example. During startup, a user sees the following:
-
-
+ Here's an example. During startup, a user sees the following:
+
+
Adding Common Rules iptables: No chain/target/match by that name Terminated
-
- A search through the trace for "No chain/target/match by that name" turned
- up the following:
-
+
+ A search through the trace for "No chain/target/match by that name"
+turned up the following:
+
+ echo 'Adding Common Rules' + add_common_rules + run_iptables -A reject -p tcp -j REJECT --reject-with tcp-reset ++ echo -A reject -p tcp -j REJECT --reject-with tcp-reset ++ sed 's/!/! /g' + iptables -A reject -p tcp -j REJECT --reject-with tcp-reset iptables: No chain/target/match by that name
-
- The command that failed was: "iptables -A reject -p tcp -j REJECT --reject-with
- tcp-reset". In this case, the user had compiled his own kernel and had forgotten
- to include REJECT target support (see kernel.htm)
-
+
+ The command that failed was: "iptables -A reject -p tcp -j REJECT --reject-with
+ tcp-reset". In this case, the user had compiled his own kernel and had
+forgotten to include REJECT target support (see kernel.htm)
+
Your network environment
-
-
Many times when people have problems with Shorewall, the problem is actually
+
+
Many times when people have problems with Shorewall, the problem is actually
an ill-conceived network setup. Here are several popular snafus:
-
+
-
Port Forwarding where client and server are
+
Port Forwarding where client and server are
in the same subnet. See FAQ 2.
-
Changing the IP address of a local system to be in the
-external subnet, thinking that Shorewall will suddenly believe that
-the system is in the 'net' zone.
-
Multiple interfaces connected to the same HUB or Switch.
- Given the way that the Linux kernel respond to ARP "who-has" requests,
- this type of setup does NOT work the way that you expect it to.
-
+
Changing the IP address of a local system to be in the
+ external subnet, thinking that Shorewall will suddenly believe
+that the system is in the 'net' zone.
+
Multiple interfaces connected to the same HUB or Switch.
+ Given the way that the Linux kernel respond to ARP "who-has" requests,
+ this type of setup does NOT work the way that you expect it to.
+
-
+
If you are having connection problems:
-
-
If the appropriate policy for the connection that you are
- trying to make is ACCEPT, please DO NOT ADD ADDITIONAL ACCEPT RULES TRYING
- TO MAKE IT WORK. Such additional rules will NEVER make it work, they
-add clutter to your rule set and they represent a big security hole in
-the event that you forget to remove them later.
-
-
I also recommend against setting all of your policies to
- ACCEPT in an effort to make something work. That robs you of one of
- your best diagnostic tools - the "Shorewall" messages that Netfilter
- will generate when you try to connect in a way that isn't permitted
- by your rule set.
-
-
Check your log ("/sbin/shorewall show log"). If you don't
- see Shorewall messages, then your problem is probably NOT a Shorewall
- problem. If you DO see packet messages, it may be an indication that you
- are missing one or more rules -- see FAQ 17.
-
-
While you are troubleshooting, it is a good idea to clear
- two variables in /etc/shorewall/shorewall.conf:
-
+
+
If the appropriate policy for the connection that you are
+ trying to make is ACCEPT, please DO NOT ADD ADDITIONAL ACCEPT RULES
+TRYING TO MAKE IT WORK. Such additional rules will NEVER make it work,
+they add clutter to your rule set and they represent a big security hole
+in the event that you forget to remove them later.
+
+
I also recommend against setting all of your policies to
+ ACCEPT in an effort to make something work. That robs you of one of
+ your best diagnostic tools - the "Shorewall" messages that Netfilter
+ will generate when you try to connect in a way that isn't permitted
+ by your rule set.
+
+
Check your log ("/sbin/shorewall show log"). If you don't
+ see Shorewall messages, then your problem is probably NOT a Shorewall
+ problem. If you DO see packet messages, it may be an indication that
+you are missing one or more rules -- see FAQ 17.
+
+
While you are troubleshooting, it is a good idea to clear
+ two variables in /etc/shorewall/shorewall.conf:
+
LOGRATE=""
- LOGBURST=""
-
-
This way, you will see all of the log messages being generated
+ LOGBURST=""
+
+
This way, you will see all of the log messages being generated
(be sure to restart shorewall after clearing these variables).
Let's look at the important parts of this message:
-
+
-
all2all:REJECT - This packet was REJECTed out of the all2all
- chain -- the packet was rejected under the "all"->"all" REJECT
-policy (see FAQ 17).
-
IN=eth2 - the packet entered the firewall via eth2
-
OUT=eth1 - if accepted, the packet would be sent on eth1
-
SRC=192.168.2.2 - the packet was sent by 192.168.2.2
-
DST=192.168.1.3 - the packet is destined for 192.168.1.3
-
PROTO=UDP - UDP Protocol
-
DPT=53 - DNS
-
+
all2all:REJECT - This packet was REJECTed out of the
+all2all chain -- the packet was rejected under the "all"->"all"
+REJECT policy (see FAQ 17).
+
IN=eth2 - the packet entered the firewall via eth2
+
OUT=eth1 - if accepted, the packet would be sent on eth1
+
SRC=192.168.2.2 - the packet was sent by 192.168.2.2
+
DST=192.168.1.3 - the packet is destined for 192.168.1.3
+
PROTO=UDP - UDP Protocol
+
DPT=53 - DNS
+
-
-
In this case, 192.168.2.2 was in the "dmz" zone and 192.168.1.3
- is in the "loc" zone. I was missing the rule:
-
+
+
In this case, 192.168.2.2 was in the "dmz" zone and 192.168.1.3
+ is in the "loc" zone. I was missing the rule:
+
ACCEPT dmz loc udp 53
-
-
-
See FAQ 17 for additional information
- about how to interpret the chain name appearing in a Shorewall log message.
-
-
+
+
+
See FAQ 17 for additional information
+ about how to interpret the chain name appearing in a Shorewall log message.
+
+
'Ping' Problems?
- Either can't ping when you think you should be able to or are able to
+ Either can't ping when you think you should be able to or are able to
ping when you think that you shouldn't be allowed? Shorewall's 'Ping' Management is described here.
-
+
Other Gotchas
-
+
-
Seeing rejected/dropped packets logged out of the INPUT
-or FORWARD chains? This means that:
+
Seeing rejected/dropped packets logged out of the INPUT
+ or FORWARD chains? This means that:
-
your zone definitions are screwed up and the host that
- is sending the packets or the destination host isn't in any zone
- (using an /etc/shorewall/hosts
- file are you?); or
-
the source and destination hosts are both connected
-to the same interface and you don't have a policy or rule for
-the source zone to or from the destination zone.
-
+
your zone definitions are screwed up and the host that
+ is sending the packets or the destination host isn't in any zone
+ (using an /etc/shorewall/hosts
+ file are you?); or
+
the source and destination hosts are both connected
+to the same interface and you don't have a policy or rule for the
+source zone to or from the destination zone.
+
-
-
Remember that Shorewall doesn't automatically allow ICMP
- type 8 ("ping") requests to be sent between zones. If you want pings
+
+
Remember that Shorewall doesn't automatically allow ICMP
+ type 8 ("ping") requests to be sent between zones. If you want pings
to be allowed between zones, you need a rule of the form:
-
- ACCEPT <source zone> <destination
+
+ ACCEPT <source zone> <destination
zone> icmp echo-request
-
- The ramifications of this can be subtle. For example, if
+
+ The ramifications of this can be subtle. For example, if
you have the following in /etc/shorewall/nat:
-
- 10.1.1.2 eth0 130.252.100.18
-
- and you ping 130.252.100.18, unless you have allowed icmp
-type 8 between the zone containing the system you are pinging from
-and the zone containing 10.1.1.2, the ping requests will be dropped.
-
If you specify "routefilter" for an interface, that
-interface must be up prior to starting the firewall.
-
Is your routing correct? For example, internal systems
-usually need to be configured with their default gateway set to the
-IP address of their nearest firewall interface. One often overlooked
-aspect of routing is that in order for two hosts to communicate, the
-routing between them must be set up in both directions. So when
-setting up routing between A and B, be sure to verify
-that the route from B back to A is defined.
If you specify "routefilter" for an interface, that
+ interface must be up prior to starting the firewall.
+
Is your routing correct? For example, internal systems
+ usually need to be configured with their default gateway set to
+the IP address of their nearest firewall interface. One often overlooked
+ aspect of routing is that in order for two hosts to communicate,
+the routing between them must be set up in both directions.
+So when setting up routing between A and B, be sure
+to verify that the route from B back to A is defined.
Shorewall requires the "ip" program. That program
- is generally included in the "iproute" package which should be included
- with your distribution (though many distributions don't install iproute
- by default). You may also download the latest source tarball from ftp://ftp.inr.ac.ru/ip-routing
- .
-
Problems with NAT? Be sure that you let Shorewall
-add all external addresses to be use with NAT unless you have set ADD_IP_ALIASES =No in /etc/shorewall/shorewall.conf.
-
+
Shorewall requires the "ip" program. That program
+ is generally included in the "iproute" package which should be included
+ with your distribution (though many distributions don't install iproute
+ by default). You may also download the latest source tarball from
+ ftp://ftp.inr.ac.ru/ip-routing
+ .
+
Problems with NAT? Be sure that you let
+Shorewall add all external addresses to be use with NAT unless you
+have set ADD_IP_ALIASES =No
+in /etc/shorewall/shorewall.conf.
Setting up a Linux system as a firewall for a small network
- is a fairly straight-forward task if you understand the basics
+
+
Setting up a Linux system as a firewall for a small network
+ is a fairly straight-forward task if you understand the basics
and follow the documentation.
-
-
This guide doesn't attempt to acquaint you with all of the features of
- Shorewall. It rather focuses on what is required to configure
-Shorewall in its most common configuration:
-
+
+
This guide doesn't attempt to acquaint you with all of the features of
+ Shorewall. It rather focuses on what is required to configure Shorewall
+ in its most common configuration:
+
-
Linux system used as a firewall/router for a small
- local network.
-
Single public IP address.
-
Internet connection through cable modem, DSL,
+
Linux system used as a firewall/router for a
+small local network.
+
Single public IP address.
+
Internet connection through cable modem, DSL,
ISDN, Frame Relay, dial-up ...
-
+
-
+
Here is a schematic of a typical installation.
-
+
-
-
-
If you are running Shorewall under Mandrake 9.0 or later, you can easily
- configure the above setup using the Mandrake "Internet Connection
-Sharing" applet. From the Mandrake Control Center, select "Network
-& Internet" then "Connection Sharing".
-
-
-
Note however, that the Shorewall configuration produced by Mandrake
- Internet Connection Sharing is strange and is apt to confuse you if you
-use the rest of this documentation (it has two local zones; "loc" and "masq"
- where "loc" is empty; this conflicts with this documentation which assumes
- a single local zone "loc"). We therefore recommend that once you have set
- up this sharing that you uninstall the Mandrake Shorewall RPM and install
- the one from the download page then follow the
- instructions in this Guide.
-
-
-
Shorewall requires that you have the iproute/iproute2 package installed
- (on RedHat, the package is called iproute). You
-can tell if this package is installed by the presence of an ip
- program on your firewall system. As root, you can use the 'which'
+
+
+
If you are running Shorewall under Mandrake 9.0 or later, you can easily
+ configure the above setup using the Mandrake "Internet Connection Sharing"
+ applet. From the Mandrake Control Center, select "Network & Internet"
+ then "Connection Sharing".
+
+
+
Note however, that the Shorewall configuration produced by Mandrake
+ Internet Connection Sharing is strange and is apt to confuse you if you
+use the rest of this documentation (it has two local zones; "loc" and "masq"
+ where "loc" is empty; this conflicts with this documentation which assumes
+ a single local zone "loc"). We therefore recommend that once you have set
+ up this sharing that you uninstall the Mandrake Shorewall RPM and install
+ the one from the download page then follow the
+ instructions in this Guide.
+
+
+
Shorewall requires that you have the iproute/iproute2 package installed
+ (on RedHat, the package is called iproute). You can
+ tell if this package is installed by the presence of an ip
+ program on your firewall system. As root, you can use the 'which'
command to check for this program:
-
+
[root@gateway root]# which ip /sbin/ip [root@gateway root]#
-
-
I recommend that you first read through the guide to familiarize yourself
- with what's involved then go back through it again making your
-configuration changes. Points at which configuration changes are
+
+
I recommend that you first read through the guide to familiarize yourself
+ with what's involved then go back through it again making your
+configuration changes. Points at which configuration changes are
recommended are flagged with
- . Configuration notes that are unique to LEAF/Bering
+ . Configuration notes that are unique to LEAF/Bering
are marked with
-
-
+
+
- If you edit your configuration files on a Windows
- system, you must save them as Unix files if your editor supports
- that option or you must run them through dos2unix before trying
-to use them. Similarly, if you copy a configuration file from your
-Windows hard drive to a floppy disk, you must run dos2unix against the
- copy before using it with Shorewall.
-
+ If you edit your configuration files on a Windows
+ system, you must save them as Unix files if your editor supports
+ that option or you must run them through dos2unix before trying to
+ use them. Similarly, if you copy a configuration file from your Windows
+ hard drive to a floppy disk, you must run dos2unix against the copy
+before using it with Shorewall.
+
- The configuration files for Shorewall are contained in the
- directory /etc/shorewall -- for simple setups, you will only need to
- deal with a few of these as described in this guide. After you have installed Shorewall, download the two-interface sample,
- un-tar it (tar -zxvf two-interfaces.tgz) and and copy the files
-to /etc/shorewall (these files will replace files with the same
-name).
-
-
As each file is introduced, I suggest that you look through the actual
- file on your system -- each file contains detailed configuration
+ The configuration files for Shorewall are contained in
+the directory /etc/shorewall -- for simple setups, you will only need
+to deal with a few of these as described in this guide. After you have
+installed Shorewall, download the two-interface sample,
+ un-tar it (tar -zxvf two-interfaces.tgz) and and copy the files to
+ /etc/shorewall (these files will replace files with the same name).
+
+
As each file is introduced, I suggest that you look through the actual
+ file on your system -- each file contains detailed configuration
instructions and default entries.
-
-
Shorewall views the network where it is running as being composed of a
- set of zones. In the two-interface sample configuration,
+
+
Shorewall views the network where it is running as being composed of a
+ set of zones. In the two-interface sample configuration,
the following zone names are used:
For each connection request entering the firewall, the request is first
- checked against the /etc/shorewall/rules file. If no rule in that
- file matches the connection request then the first policy in /etc/shorewall/policy
- that matches the request is applied. If that policy is REJECT
-or DROP the request is first checked against the rules in /etc/shorewall/common
+
+
For each connection request entering the firewall, the request is first
+ checked against the /etc/shorewall/rules file. If no rule in that
+ file matches the connection request then the first policy in /etc/shorewall/policy
+ that matches the request is applied. If that policy is REJECT
+or DROP the request is first checked against the rules in /etc/shorewall/common
(the samples provide that file for you).
-
-
The /etc/shorewall/policy file included with the two-interface sample
-has the following policies:
-
-
+
+
The /etc/shorewall/policy file included with the two-interface sample has
+the following policies:
+
+
-
+
+
+
Source Zone
+
Destination Zone
+
Policy
+
Log Level
+
Limit:Burst
+
-
Source Zone
-
Destination Zone
-
Policy
-
Log Level
-
Limit:Burst
-
-
-
loc
-
net
-
ACCEPT
-
-
-
-
-
net
-
all
-
DROP
-
info
-
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
+
loc
+
net
+
ACCEPT
+
+
+
+
+
net
+
all
+
DROP
+
info
+
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
-
-
-
-
In the two-interface sample, the line below is included but commented
- out. If you want your firewall system to have full access to servers
+
+
+
+
In the two-interface sample, the line below is included but commented
+ out. If you want your firewall system to have full access to servers
on the internet, uncomment that line.
-
+
-
+
+
+
Source Zone
+
Destination Zone
+
Policy
+
Log Level
+
Limit:Burst
+
-
Source Zone
-
Destination Zone
-
Policy
-
Log Level
-
Limit:Burst
-
-
-
fw
-
net
-
ACCEPT
-
-
-
-
-
+
fw
+
net
+
ACCEPT
+
+
+
+
+
-
-
+
+
The above policy will:
-
+
-
allow all connection requests from your local
+
allow all connection requests from your local
network to the internet
-
drop (ignore) all connection requests from the
-internet to your firewall or local network
-
optionally accept all connection requests from
-the firewall to the internet (if you uncomment the additional policy)
-
reject all other connection requests.
-
+
drop (ignore) all connection requests from the
+ internet to your firewall or local network
+
optionally accept all connection requests from
+ the firewall to the internet (if you uncomment the additional
+policy)
+
reject all other connection requests.
+
-
+
- At this point, edit your /etc/shorewall/policy and
+ At this point, edit your /etc/shorewall/policy and
make any changes that you wish.
-
+
Network Interfaces
-
+
-
-
-
The firewall has two network interfaces. Where Internet connectivity
-is through a cable or DSL "Modem", the External Interface will be
-the ethernet adapter that is connected to that "Modem" (e.g., eth0)
- unless you connect via Point-to-Point Protocol
- over Ethernet (PPPoE) or Point-to-Point
- Tunneling Protocol (PPTP) in which case the External
- Interface will be a ppp interface (e.g., ppp0). If you connect
- via a regular modem, your External Interface will also be ppp0.
+
+
+
The firewall has two network interfaces. Where Internet
+connectivity is through a cable or DSL "Modem", the External Interface
+ will be the ethernet adapter that is connected to that "Modem" (e.g., eth0)
+ unless you connect via Point-to-Point Protocol
+ over Ethernet (PPPoE) or Point-to-Point
+ Tunneling Protocol (PPTP) in which case the External
+ Interface will be a ppp interface (e.g., ppp0). If you connect
+ via a regular modem, your External Interface will also be ppp0.
If you connect via ISDN, your external interface will be ippp0.
-
+
- If your external interface is ppp0 or
+ If your external interface is ppp0 or
ippp0 then you will want to set CLAMPMSS=yes in /etc/shorewall/shorewall.conf.
-
-
Your Internal Interface will be an ethernet adapter
- (eth1 or eth0) and will be connected to a hub or switch. Your
-other computers will be connected to the same hub/switch (note:
-If you have only a single internal system, you can connect the firewall
+
+
Your Internal Interface will be an ethernet adapter
+ (eth1 or eth0) and will be connected to a hub or switch. Your other
+ computers will be connected to the same hub/switch (note: If you
+ have only a single internal system, you can connect the firewall
directly to the computer using a cross-over cable).
-
+
- Do not connect the internal and external interface
- to the same hub or switch (even for testing). It won't work the
-way that you think that it will and you will end up confused and
-believing that Shorewall doesn't work at all.
-
+ Do not connect the internal and external interface
+ to the same hub or switch (even for testing). It won't work the way
+ that you think that it will and you will end up confused and believing
+ that Shorewall doesn't work at all.
+
- The Shorewall two-interface sample configuration
-assumes that the external interface is eth0 and the internal
-interface is eth1. If your configuration is different, you
+ The Shorewall two-interface sample configuration
+assumes that the external interface is eth0 and the internal
+interface is eth1. If your configuration is different, you
will have to modify the sample /etc/shorewall/interfaces file
- accordingly. While you are there, you may wish to review the list
- of options that are specified for the interfaces. Some hints:
-
+ href="Documentation.htm#Interfaces">/etc/shorewall/interfaces file
+ accordingly. While you are there, you may wish to review the list
+of options that are specified for the interfaces. Some hints:
+
-
-
If your external interface is ppp0 or ippp0,
- you can replace the "detect" in the second column with "-".
-
-
-
-
If your external interface is ppp0 or ippp0
- or if you have a static IP address, you can remove "dhcp" from
+
+
If your external interface is ppp0 or ippp0,
+ you can replace the "detect" in the second column with "-".
+
+
+
+
If your external interface is ppp0 or ippp0
+ or if you have a static IP address, you can remove "dhcp" from
the option list.
-
-
+
+
-
+
IP Addresses
-
-
Before going further, we should say a few words about Internet
- Protocol (IP) addresses. Normally, your ISP will assign
-you a single Public IP address. This address may be assigned
-via the Dynamic Host Configuration Protocol (DHCP) or as part
-of establishing your connection when you dial in (standard modem) or
-establish your PPP connection. In rare cases, your ISP may assign you
-a static IP address; that means that you configure your firewall's
-external interface to use that address permanently.However
-your external address is assigned, it will be shared by all of your systems
-when you access the Internet. You will have to assign your own addresses
-in your internal network (the Internal Interface on your firewall plus
-your other computers). RFC 1918 reserves several Private IP address
+
+
Before going further, we should say a few words about Internet
+ Protocol (IP) addresses. Normally, your ISP will assign
+you a single Public IP address. This address may be assigned
+via the Dynamic Host Configuration Protocol (DHCP) or as part
+of establishing your connection when you dial in (standard modem) or
+establish your PPP connection. In rare cases, your ISP may assign you
+a static IP address; that means that you configure your firewall's
+external interface to use that address permanently.However your
+external address is assigned, it will be shared by all of your systems
+when you access the Internet. You will have to assign your own addresses
+in your internal network (the Internal Interface on your firewall plus
+your other computers). RFC 1918 reserves several Private IP address
ranges for this purpose:
- Before starting Shorewall, you should look at
-the IP address of your external interface and if it is one of
-the above ranges, you should remove the 'norfc1918' option from
+ Before starting Shorewall, you should look at
+the IP address of your external interface and if it is one of
+the above ranges, you should remove the 'norfc1918' option from
the external interface's entry in /etc/shorewall/interfaces.
-
-
-
-
You will want to assign your addresses from the same
- sub-network (subnet). For our purposes, we can consider a subnet
- to consists of a range of addresses x.y.z.0 - x.y.z.255. Such
- a subnet will have a Subnet Mask of 255.255.255.0. The
-address x.y.z.0 is reserved as the Subnet Address and x.y.z.255
-is reserved as the Subnet BroadcastAddress. In Shorewall,
+
+
+
+
You will want to assign your addresses from the same
+sub-network (subnet). For our purposes, we can consider a subnet
+ to consists of a range of addresses x.y.z.0 - x.y.z.255. Such
+ a subnet will have a Subnet Mask of 255.255.255.0. The address
+ x.y.z.0 is reserved as the Subnet Address and x.y.z.255
+is reserved as the Subnet BroadcastAddress. In Shorewall,
a subnet is described using Classless InterDomain Routing
- (CIDR) notation with consists of the subnet address followed
- by "/24". The "24" refers to the number of consecutive leading "1"
+ href="shorewall_setup_guide.htm#Subnets">Classless InterDomain Routing
+ (CIDR) notation with consists of the subnet address followed
+ by "/24". The "24" refers to the number of consecutive leading "1"
bits from the left of the subnet mask.
-
-
-
+
+
+
Example sub-network:
-
-
-
-
+
+
+
+
-
-
-
Range:
-
10.10.10.0 - 10.10.10.255
-
+
-
Subnet Address:
-
10.10.10.0
-
-
-
Broadcast Address:
-
10.10.10.255
-
-
-
CIDR Notation:
-
10.10.10.0/24
-
-
-
+
Range:
+
10.10.10.0 - 10.10.10.255
+
+
+
Subnet Address:
+
10.10.10.0
+
+
+
Broadcast Address:
+
10.10.10.255
+
+
+
CIDR Notation:
+
10.10.10.0/24
+
+
+
-
-
-
-
-
It is conventional to assign the internal interface either
- the first usable address in the subnet (10.10.10.1 in the above
+
+
+
+
+
It is conventional to assign the internal interface either
+ the first usable address in the subnet (10.10.10.1 in the above
example) or the last usable address (10.10.10.254).
-
-
-
-
One of the purposes of subnetting is to allow all computers
- in the subnet to understand which other computers can be communicated
- with directly. To communicate with systems outside of the subnetwork,
+
+
+
+
One of the purposes of subnetting is to allow all computers
+ in the subnet to understand which other computers can be communicated
+ with directly. To communicate with systems outside of the subnetwork,
systems send packets through a gateway (router).
-
-
-
+
+
+
- Your local computers (computer 1 and computer
-2 in the above diagram) should be configured with their default
- gateway to be the IP address of the firewall's internal interface.
+ Your local computers (computer 1 and computer
+2 in the above diagram) should be configured with their default
+ gateway to be the IP address of the firewall's internal interface.
-
-
-
The foregoing short discussion barely scratches the surface
- regarding subnetting and routing. If you are interested in learning
- more about IP addressing and routing, I highly recommend "IP
-Fundamentals: What Everyone Needs to Know about Addressing &
+
+
+
The foregoing short discussion barely scratches the surface
+ regarding subnetting and routing. If you are interested in learning
+ more about IP addressing and routing, I highly recommend "IP
+Fundamentals: What Everyone Needs to Know about Addressing &
Routing", Thomas A. Maufer, Prentice-Hall, 1999, ISBN 0-13-975483-0.
-
-
The remainder of this quide will assume that you have configured
+
+
The remainder of this quide will assume that you have configured
your network as shown here:
-
+
-
-
+
+
The default gateway for computer's 1 & 2 would be 10.10.10.254.
-
-
+
+
- WARNING: Your ISP might
- assign your external interface an RFC 1918 address. If that address is
- in the 10.10.10.0/24 subnet then you will need to select a DIFFERENT RFC
+ WARNING: Your ISP might
+ assign your external interface an RFC 1918 address. If that address is
+ in the 10.10.10.0/24 subnet then you will need to select a DIFFERENT RFC
1918 subnet for your local network.
-
-
+
+
IP Masquerading (SNAT)
-
-
The addresses reserved by RFC 1918 are sometimes referred
- to as non-routable because the Internet backbone routers
-don't forward packets which have an RFC-1918 destination address.
-When one of your local systems (let's assume computer 1) sends a connection
- request to an internet host, the firewall must perform Network
- Address Translation (NAT). The firewall rewrites the source
-address in the packet to be the address of the firewall's external
-interface; in other words, the firewall makes it look as if the firewall
- itself is initiating the connection. This is necessary so that the
- destination host will be able to route return packets back to the
-firewall (remember that packets whose destination address is reserved
-by RFC 1918 can't be routed across the internet so the remote host
-can't address its response to computer 1). When the firewall receives
-a return packet, it rewrites the destination address back to 10.10.10.1
- and forwards the packet on to computer 1.
-
-
On Linux systems, the above process is often referred to
-as IP Masquerading but you will also see the term Source Network
-Address Translation (SNAT) used. Shorewall follows the convention used
-with Netfilter:
-
+
+
The addresses reserved by RFC 1918 are sometimes referred
+ to as non-routable because the Internet backbone routers
+don't forward packets which have an RFC-1918 destination address.
+When one of your local systems (let's assume computer 1) sends a connection
+ request to an internet host, the firewall must perform Network
+ Address Translation (NAT). The firewall rewrites the source address
+ in the packet to be the address of the firewall's external interface;
+ in other words, the firewall makes it look as if the firewall itself
+ is initiating the connection. This is necessary so that the destination
+ host will be able to route return packets back to the firewall (remember
+ that packets whose destination address is reserved by RFC 1918 can't
+ be routed across the internet so the remote host can't address its
+response to computer 1). When the firewall receives a return packet,
+it rewrites the destination address back to 10.10.10.1 and forwards
+the packet on to computer 1.
+
+
On Linux systems, the above process is often referred to as
+ IP Masquerading but you will also see the term Source Network Address
+ Translation (SNAT) used. Shorewall follows the convention used with
+ Netfilter:
+
-
-
Masquerade describes the case where you let your
- firewall system automatically detect the external interface
-address.
-
-
-
SNAT refers to the case when you explicitly specify
- the source address that you want outbound packets from your
-local network to use.
-
-
+
+
Masquerade describes the case where you let your
+ firewall system automatically detect the external interface address.
+
+
+
+
SNAT refers to the case when you explicitly specify
+ the source address that you want outbound packets from your local
+ network to use.
+
+
-
-
In Shorewall, both Masquerading and SNAT are configured with
- entries in the /etc/shorewall/masq file. You will normally use
-Masquerading if your external IP is dynamic and SNAT if the IP
-is static.
-
+
+
In Shorewall, both Masquerading and SNAT are configured with
+ entries in the /etc/shorewall/masq file. You will normally use
+Masquerading if your external IP is dynamic and SNAT if the IP is
+static.
+
- If your external firewall interface is eth0,
- you do not need to modify the file provided with the sample. Otherwise,
- edit /etc/shorewall/masq and change the first column to the name
- of your external interface and the second column to the name of your
- internal interface.
-
+ If your external firewall interface is eth0,
+ you do not need to modify the file provided with the sample. Otherwise,
+ edit /etc/shorewall/masq and change the first column to the name
+ of your external interface and the second column to the name of
+your internal interface.
+
- If your external IP is static, you can enter it
-in the third column in the /etc/shorewall/masq entry if you like
-although your firewall will work fine if you leave that column empty.
- Entering your static IP in column 3 makes processing outgoing packets
+ If your external IP is static, you can enter it
+in the third column in the /etc/shorewall/masq entry if you like
+although your firewall will work fine if you leave that column empty.
+ Entering your static IP in column 3 makes processing outgoing packets
a little more efficient.
-
-
+
- If you are using the Debian package, please check your shorewall.conf
- file to ensure that the following are set correctly; if they are not,
+ If you are using the Debian package, please check your shorewall.conf
+ file to ensure that the following are set correctly; if they are not,
change them appropriately:
-
-
+
+
-
NAT_ENABLED=Yes (Shorewall versions earlier than 1.4.6)
-
IP_FORWARDING=On
-
-
+
NAT_ENABLED=Yes (Shorewall versions earlier than 1.4.6)
+
IP_FORWARDING=On
+
+
-
+
Port Forwarding (DNAT)
-
-
One of your goals may be to run one or more servers on your
- local computers. Because these computers have RFC-1918 addresses,
- it is not possible for clients on the internet to connect directly
- to them. It is rather necessary for those clients to address their
-connection requests to the firewall who rewrites the destination address
-to the address of your server and forwards the packet to that server.
-When your server responds, the firewall automatically performs SNAT
+
+
One of your goals may be to run one or more servers on your
+ local computers. Because these computers have RFC-1918 addresses,
+ it is not possible for clients on the internet to connect directly
+ to them. It is rather necessary for those clients to address their
+connection requests to the firewall who rewrites the destination address
+to the address of your server and forwards the packet to that server.
+When your server responds, the firewall automatically performs SNAT
to rewrite the source address in the response.
-
-
The above process is called Port Forwarding or
- Destination Network Address Translation (DNAT). You configure
+
+
The above process is called Port Forwarding or
+ Destination Network Address Translation (DNAT). You configure
port forwarding using DNAT rules in the /etc/shorewall/rules file.
-
-
The general form of a simple port forwarding rule in /etc/shorewall/rules
+
+
The general form of a simple port forwarding rule in /etc/shorewall/rules
is:
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
loc:<server local ip address> [:<server
+
DNAT
+
net
+
loc:<server local ip address> [:<server
port>]
-
<protocol>
-
<port>
-
-
-
-
-
+
<protocol>
+
<port>
+
+
+
+
+
-
-
-
Example - you run a Web Server on computer 2 and you want to forward incoming
+
+
+
Example - you run a Web Server on computer 2 and you want to forward incoming
TCP port 80 to that system:
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
loc:10.10.10.2
-
tcp
-
80
-
-
-
-
-
+
DNAT
+
net
+
loc:10.10.10.2
+
tcp
+
80
+
+
+
+
+
-
-
+
+
A couple of important points to keep in mind:
-
+
-
You must test the above rule from a client outside
- of your local network (i.e., don't test from a browser running
-on computers 1 or 2 or on the firewall). If you want to be able
-to access your web server using the IP address of your external interface,
- see Shorewall FAQ #2.
-
Many ISPs block incoming connection requests to
- port 80. If you have problems connecting to your web server,
+
You must test the above rule from a client outside
+ of your local network (i.e., don't test from a browser running
+on computers 1 or 2 or on the firewall). If you want to be able
+to access your web server using the IP address of your external interface,
+ see Shorewall FAQ #2.
+
Many ISPs block incoming connection requests
+to port 80. If you have problems connecting to your web server,
try the following rule and try connecting to port 5000.
-
+
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
DNAT
-
net
-
loc:10.10.10.2:80
-
tcp
-
5000
-
-
-
-
-
+
DNAT
+
net
+
loc:10.10.10.2:80
+
tcp
+
5000
+
+
+
+
+
-
-
+
+
- At this point, modify /etc/shorewall/rules to add
+ At this point, modify /etc/shorewall/rules to add
any DNAT rules that you require.
-
+
Domain Name Server (DNS)
-
-
Normally, when you connect to your ISP, as part of getting
- an IP address your firewall's Domain Name Service (DNS)
-resolver will be automatically configured (e.g., the /etc/resolv.conf
-file will be written). Alternatively, your ISP may have given you
-the IP address of a pair of DNS name servers for you to manually
-configure as your primary and secondary name servers. Regardless of
-how DNS gets configured on your firewall, it is your responsibility
-to configure the resolver in your internal systems. You can take one
+
+
Normally, when you connect to your ISP, as part of getting
+ an IP address your firewall's Domain Name Service (DNS)
+resolver will be automatically configured (e.g., the /etc/resolv.conf
+file will be written). Alternatively, your ISP may have given you the
+IP address of a pair of DNS name servers for you to manually
+configure as your primary and secondary name servers. Regardless of
+how DNS gets configured on your firewall, it is your responsibility
+to configure the resolver in your internal systems. You can take one
of two approaches:
-
+
-
-
You can configure your internal systems to use your ISP's
- name servers. If you ISP gave you the addresses of their servers
- or if those addresses are available on their web site, you can
-configure your internal systems to use those addresses. If that
-information isn't available, look in /etc/resolv.conf on your firewall
-system -- the name servers are given in "nameserver" records in that
+
+
You can configure your internal systems to use your ISP's
+ name servers. If you ISP gave you the addresses of their servers
+ or if those addresses are available on their web site, you can
+configure your internal systems to use those addresses. If that
+information isn't available, look in /etc/resolv.conf on your firewall
+system -- the name servers are given in "nameserver" records in that
file.
-
-
+
+
- You can configure a Caching Name Server on
-your firewall.Red Hat has an RPM for a caching name
-server (the RPM also requires the 'bind' RPM) and for Bering users,
-there is dnscache.lrp. If you take this approach, you configure your
-internal systems to use the firewall itself as their primary (and only)
-name server. You use the internal IP address of the firewall (10.10.10.254
- in the example above) for the name server address. To allow your
-local systems to talk to your caching name server, you must open port
-53 (both UDP and TCP) from the local network to the firewall; you do
-that by adding the following rules in /etc/shorewall/rules.
-
-
+ You can configure a Caching Name Server on
+ your firewall.Red Hat has an RPM for a caching name
+ server (the RPM also requires the 'bind' RPM) and for Bering users,
+ there is dnscache.lrp. If you take this approach, you configure
+your internal systems to use the firewall itself as their primary
+(and only) name server. You use the internal IP address of the firewall
+(10.10.10.254 in the example above) for the name server address.
+To allow your local systems to talk to your caching name server,
+you must open port 53 (both UDP and TCP) from the local network to the
+ firewall; you do that by adding the following rules in /etc/shorewall/rules.
+
+
+
-
-
+
+
-
+
+
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
53
-
-
-
-
-
ACCEPT
-
loc
-
fw
-
udp
-
53
-
-
-
-
-
+
ACCEPT
+
loc
+
fw
+
tcp
+
53
+
+
+
+
+
ACCEPT
+
loc
+
fw
+
udp
+
53
+
+
+
+
+
-
-
-
+
+
+
Other Connections
-
-
-
+
+
+
The two-interface sample includes the following rules:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
fw
-
net
-
tcp
-
53
-
-
-
-
-
ACCEPT
-
fw
-
net
-
udp
-
53
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
fw
+
net
+
tcp
+
53
+
+
+
+
+
ACCEPT
+
fw
+
net
+
udp
+
53
+
+
+
+
+
-
-
-
-
-
Those rules allow DNS access from your firewall and may be
- removed if you uncommented the line in /etc/shorewall/policy
+
+
+
+
+
Those rules allow DNS access from your firewall and may be
+ removed if you uncommented the line in /etc/shorewall/policy
allowing all connections from the firewall to the internet.
-
-
-
+
+
+
The sample also includes:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
loc
-
fw
-
tcp
-
22
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
22
+
+
+
+
+
-
-
-
-
-
That rule allows you to run an SSH server on your firewall
+
+
+
+
+
That rule allows you to run an SSH server on your firewall
and connect to that server from your local systems.
-
-
-
-
If you wish to enable other connections between your firewall
+
+
+
+
If you wish to enable other connections between your firewall
and other systems, the general format is:
-
-
-
-
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
<source zone>
-
<destination zone>
-
<protocol>
-
<port>
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
<source zone>
+
<destination zone>
+
<protocol>
+
<port>
+
+
+
+
+
-
+
+
+
+
+
Example - You want to run a Web Server on your firewall
+system:
-
-
-
Example - You want to run a Web Server on your firewall system:
-
-
-
-
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
net
-
fw
-
tcp
-
80
-
#Allow web access
-
from the internet
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
80
-
#Allow web access
-
from the local network
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
80
+
#Allow web access
+
from the internet
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
80
+
#Allow web access
+
from the local network
+
+
+
-
+
+
+
+
+
Those two rules would of course be in addition to the rules
+ listed above under "You can configure a Caching Name Server on
+ your firewall"
-
-
-
Those two rules would of course be in addition to the rules
- listed above under "You can configure a Caching Name Server
-on your firewall"
-
-
-
-
If you don't know what port and protocol a particular application
- uses, look here.
-
-
-
-
Important: I don't recommend enabling telnet to/from
- the internet because it uses clear text (even for login!). If
- you want shell access to your firewall from the internet, use
-SSH:
-
-
-
-
+
+
+
If you don't know what port and protocol a particular application
+ uses, look here.
+
+
+
+
Important: I don't recommend enabling telnet to/from
+ the internet because it uses clear text (even for login!). If
+ you want shell access to your firewall from the internet, use SSH:
+
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
net
-
fw
-
tcp
-
22
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
net
+
fw
+
tcp
+
22
+
+
+
+
+
-
-
-
-
+
+
+
+
- Bering users will want to add the following two rules to be compatible
+ Bering users will want to add the following two rules to be compatible
with Jacques's Shorewall configuration.
-
-
-
+
+
+
-
-
-
ACTION
-
SOURCE
-
DESTINATION
-
PROTOCOL
-
PORT
-
SOURCE PORT
-
ORIGINAL ADDRESS
-
+
-
ACCEPT
-
loc
-
-
fw
-
udp
-
-
53
-
-
#Allow DNS Cache to
-
work
-
-
-
-
ACCEPT
-
loc
-
fw
-
tcp
-
80
-
#Allow weblet to work
-
-
-
-
-
+
ACTION
+
SOURCE
+
DESTINATION
+
PROTOCOL
+
PORT
+
SOURCE PORT
+
ORIGINAL ADDRESS
+
+
+
ACCEPT
+
loc
+
+
fw
+
udp
+
+
53
+
+
#Allow DNS Cache to
+
work
+
+
+
+
ACCEPT
+
loc
+
fw
+
tcp
+
80
+
#Allow weblet to work
+
+
+
+
+
-
-
-
+
+
+
-
- Now edit your /etc/shorewall/rules file to add
-or delete other connections as required.
-
-
-
-
Starting and Stopping Your Firewall
+
+ Now edit your /etc/shorewall/rules file to add
+ or delete other connections as required.
-
-
+
+
+
Starting and Stopping Your Firewall
+
+
+
- The installation procedure
- configures your system to start Shorewall at system boot but beginning
- with Shorewall version 1.3.9 startup is disabled so that your system
- won't try to start Shorewall before configuration is complete. Once
- you have completed configuration of your firewall, you can enable Shorewall
- startup by removing the file /etc/shorewall/startup_disabled.
-
-
+ The installation procedure
+ configures your system to start Shorewall at system boot
+but beginning with Shorewall version 1.3.9 startup is disabled so
+that your system won't try to start Shorewall before configuration
+is complete. Once you have completed configuration of your firewall,
+you can enable Shorewall startup by removing the file /etc/shorewall/startup_disabled.
+
+
IMPORTANT: Users of the .deb package must edit /etc/default/shorewall
+ color="#ff0000">Users of the .deb package must edit /etc/default/shorewall
and set 'startup=1'.
-
-
-
-
-
The firewall is started using the "shorewall start" command
- and stopped using "shorewall stop". When the firewall is stopped,
+
+
+
+
+
The firewall is started using the "shorewall start" command
+ and stopped using "shorewall stop". When the firewall is stopped,
routing is enabled on those hosts that have an entry in /etc/shorewall/routestopped. A
- running firewall may be restarted using the "shorewall restart"
- command. If you want to totally remove any trace of Shorewall
+ href="Documentation.htm#Routestopped">/etc/shorewall/routestopped. A
+ running firewall may be restarted using the "shorewall restart"
+ command. If you want to totally remove any trace of Shorewall
from your Netfilter configuration, use "shorewall clear".
-
-
-
+
+
+
- The two-interface sample assumes that you want to
-enable routing to/from eth1 (the local network) when Shorewall
- is stopped. If your local network isn't connected to eth1 or
- if you wish to enable access to/from other hosts, change /etc/shorewall/routestopped
+ The two-interface sample assumes that you want to
+ enable routing to/from eth1 (the local network) when Shorewall
+ is stopped. If your local network isn't connected to eth1 or
+ if you wish to enable access to/from other hosts, change /etc/shorewall/routestopped
accordingly.
-
-
-
-
WARNING: If you are connected to your firewall from
- the internet, do not issue a "shorewall stop" command unless
-you have added an entry for the IP address that you are connected
-from to /etc/shorewall/routestopped.
- Also, I don't recommend using "shorewall restart"; it is better to
- create an alternate
+
+
+
+
WARNING: If you are connected to your firewall from
+ the internet, do not issue a "shorewall stop" command unless
+you have added an entry for the IP address that you are connected
+from to /etc/shorewall/routestopped.
+ Also, I don't recommend using "shorewall restart"; it is better to
+ create an alternate
configuration and test it using the "shorewall try" command.
- Notes du traducteur :
- Je ne prétends pas être un vrai traducteur dans le sens ou
-mon travail n’est pas des plus précis (loin de là...). Je ne
-me suis pas attaché à une traduction exacte du texte, mais
-plutôt à en faire une version française intelligible
-par tous (et par moi). Les termes techniques sont la plupart du temps conservés
-sous leur forme originale et mis entre parenthèses car vous pouvez
-les retrouver dans le reste des documentations ainsi que dans les fichiers
-de configuration. N’hésitez pas à me contacter afin d’améliorer
-ce document VETSEL Patrice
- (merci à JMM pour sa relecture et ses commentaires pertinents, ainsi
-qu'à Tom EASTEP pour son formidable outil et sa disponibilité).
-
-
-
-
Mettre en place un système Linux en tant que firewall
-pour un petit réseau est une chose assez simple, si vous comprenez
-les bases et suivez la documentation.
-
-
Ce guide ne veut pas vous apprendre tous les rouages de Shorewall. Il se
-focalise sur ce qui est nécessaire pour configurer Shorewall, dans
-son utilisation la plus courante :
-
+ Notes du traducteur :
+ Je ne prétends pas être un vrai traducteur dans le sens ou
+mon travail n’est pas des plus précis (loin de là...). Je ne
+me suis pas attaché à une traduction exacte du texte, mais plutôt
+à en faire une version française intelligible par tous (et
+par moi). Les termes techniques sont la plupart du temps conservés
+ sous leur forme originale et mis entre parenthèses car vous pouvez
+ les retrouver dans le reste des documentations ainsi que dans les fichiers
+ de configuration. N’hésitez pas à me contacter afin d’améliorer
+ ce document VETSEL Patrice
+ (merci à JMM pour sa relecture et ses commentaires pertinents, ainsi
+ qu'à Tom EASTEP pour son formidable outil et sa disponibilité).
+
+
+
+
Mettre en place un système Linux en tant que firewall
+ pour un petit réseau est une chose assez simple, si vous comprenez
+ les bases et suivez la documentation.
+
+
Ce guide ne veut pas vous apprendre tous les rouages de Shorewall. Il
+se focalise sur ce qui est nécessaire pour configurer Shorewall, dans
+ son utilisation la plus courante :
+
-
-
Un système Linux utilisé
- en tant que firewall/routeur pour un petit réseau local.
-
-
+
+
Un système Linux utilisé
+ en tant que firewall/routeur pour un petit réseau local.
+
+
Une seule adresse IP publique.
-
-
-
Une connexion Internet par le biais d'un modem câble, ADSL,
-ISDN, "Frame Relay", RTC ...
-
-
+
+
+
Une connexion Internet par le biais d'un modem câble, ADSL,
+ ISDN, "Frame Relay", RTC ...
+
+
-
+
Voici un schéma d'une installation typique.
-
+
-
-
-
Si vous faites tourner Shorewall sous Mandrake 9.0 ou plus récent,
-vous pouvez facilement réaliser la configuration ci-dessus en utilisant
-l'applet Mandrake "Internet Connection Sharing". Depuis le "Mandrake Control
-Center", sélectionnez "Network & Internet" et "Connection Sharing".
-Vous ne devriez pas avoir besoin de vous référer à ce
-guide.
-
-
Ce guide suppose que vous avez le paquet iproute/iproute2 d'installé.
-Vous pouvez voir si le paquet est installé en vérifiant
-la présence du programme ip sur votre système de firewall. Sous
-root, utilisez la commande 'which' pour rechercher le programme :
-
+
+
+
Si vous faites tourner Shorewall sous Mandrake 9.0 ou plus récent,
+ vous pouvez facilement réaliser la configuration ci-dessus en utilisant
+ l'applet Mandrake "Internet Connection Sharing". Depuis le "Mandrake Control
+ Center", sélectionnez "Network & Internet" et "Connection Sharing".
+ Vous ne devriez pas avoir besoin de vous référer à
+ce guide.
+
+
Ce guide suppose que vous avez le paquet iproute/iproute2 d'installé.
+ Vous pouvez voir si le paquet est installé en vérifiant
+ la présence du programme ip sur votre système de firewall.
+Sous root, utilisez la commande 'which' pour rechercher le programme :
+
[root@gateway root]# which ip /sbin/ip [root@gateway root]#
-
-
Je vous recommande dans un premier temps de parcourir tout le guide pour
-vous familiariser avec ce qui va se passer, et de revenir au début
-en effectuant le changements dans votre configuration. Les points où,
-les changements dans la configuration sont recommandées, sont signalés
-par une Je vous recommande dans un premier temps de parcourir tout le guide pour
+ vous familiariser avec ce qui va se passer, et de revenir au début
+ en effectuant le changements dans votre configuration. Les points où,
+ les changements dans la configuration sont recommandées, sont signalés
+ par une
- .
-
+ .
+
- Si vous éditez vos fichiers de configuration sur
-un système Windows, vous devez les sauver comme des fichiers Unix si
-votre éditeur offre cette option sinon vous devez les faire passer
-par dos2unix avant d'essayer de les utiliser. De la même manière,
-si vous copiez un fichier de configuration depuis votre disque dur Windows
-vers une disquette, vous devez lancer dos2unix sur la copie avant de l'utiliser
-avec Shorewall.
-
+ Si vous éditez vos fichiers de configuration
+sur un système Windows, vous devez les sauver comme des fichiers
+Unix si votre éditeur offre cette option sinon vous devez les faire
+passer par dos2unix avant d'essayer de les utiliser. De la même manière,
+ si vous copiez un fichier de configuration depuis votre disque dur Windows
+ vers une disquette, vous devez lancer dos2unix sur la copie avant de l'utiliser
+ avec Shorewall.
+
- Les fichiers de configuration pour Shorewall sont dans
-le répertoire /etc/shorewall -- pour de simples configurations, vous
-n'aurez seulement à faire qu'avec quelques fichiers comme décrit
- dans ce guide. Après avoir installé
-Shorewall, télé chargez le two-interface sample,
-un-tarez le (tar -zxvf two-interfaces.tgz) et copiez les fichiers vers /etc/shorewall
+ Les fichiers de configuration pour Shorewall sont dans
+ le répertoire /etc/shorewall -- pour de simples configurations, vous
+ n'aurez seulement à faire qu'avec quelques fichiers comme décrit
+ dans ce guide. Après avoir installé Shorewall,
+télé chargez le two-interface sample,
+un-tarez le (tar -zxvf two-interfaces.tgz) et copiez les fichiers vers /etc/shorewall
(ces fichiers remplaceront les fichiers de même nom).
-
-
Parallèlement à la présentation de chacun des fichiers,
-je vous suggère de regarder le fichier qui se trouve réellement
-sur votre système -- tous les fichiers contiennent des instructions
-de configuration détaillées et des valeurs par défaut.
-
-
Shorewall voit le réseau où il tourne, comme un ensemble
-de zones. Dans une configuration avec deux interfaces, les noms des
-zones suivantes sont utilisés:
-
+
+
Parallèlement à la présentation de chacun des fichiers,
+ je vous suggère de regarder le fichier qui se trouve réellement
+ sur votre système -- tous les fichiers contiennent des instructions
+ de configuration détaillées et des valeurs par défaut.
+
+
Shorewall voit le réseau où il tourne, comme un ensemble
+ de zones. Dans une configuration avec deux interfaces, les noms des
+ zones suivantes sont utilisés:
Vous définissez les exceptions à ces politiques pas
-défaut dans le fichier /etc/shorewall/rules
+
+
+
Vous définissez les exceptions à ces politiques pas
+ défaut dans le fichier /etc/shorewall/rules
.
-
-
+
+
-
-
Pour chaque connexion demandant à entrer dans le firewall, la requête
-est en premier lieu comparée par rapport au fichier /etc/shorewall/rules.
-Si aucune règle dans ce fichier ne correspond à la demande de
-connexion alors la première politique dans le fichier /etc/shorewall/policy
-qui y correspond sera appliquée. Si cette politique est REJECT ou DROP
-la requête est dans un premier temps comparée par rapport aux
-règles contenues dans /etc/shorewall/common.
-
-
Le fichier /etc/shorewall/policy inclue dans l'archive d'exemple (two-interface)
-a les politiques suivantes:
-
+
+
Pour chaque connexion demandant à entrer dans le firewall, la requête
+ est en premier lieu comparée par rapport au fichier /etc/shorewall/rules.
+ Si aucune règle dans ce fichier ne correspond à la demande
+de connexion alors la première politique dans le fichier /etc/shorewall/policy
+ qui y correspond sera appliquée. Si cette politique est REJECT ou
+DROP la requête est dans un premier temps comparée par
+rapport aux règles contenues dans /etc/shorewall/common.
+
+
Le fichier /etc/shorewall/policy inclue dans l'archive d'exemple (two-interface)
+ a les politiques suivantes:
+
-
+
-
-
-
+
+
+
Source Zone
-
-
+
+
Destination Zone
-
-
+
+
Policy
-
-
+
+
Log Level
-
-
+
+
Limit:Burst
-
-
-
-
+
+
+
+
loc
-
-
+
+
net
-
-
+
+
ACCEPT
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
net
-
-
+
+
all
-
-
+
+
DROP
-
-
+
+
info
-
-
+
+
-
-
-
-
+
+
+
+
all
-
-
+
+
all
-
-
+
+
REJECT
-
-
+
+
info
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
-
Dans le fichier d'exemple (two-interface), la ligne suivante est
-inclue mais elle est commentée. Si vous voulez que votre firewall puisse
-avoir un accès complet aux serveurs sur Internet, décommentez
-la ligne.
-
+
+
Dans le fichier d'exemple (two-interface), la ligne suivante
+est inclue mais elle est commentée. Si vous voulez que votre firewall
+puisse avoir un accès complet aux serveurs sur Internet, décommentez
+ la ligne.
+
-
+
-
-
-
+
+
+
Source Zone
-
-
+
+
Destination Zone
-
-
+
+
Policy
-
-
+
+
Log Level
-
-
+
+
Limit:Burst
-
-
-
-
+
+
+
+
fw
-
-
+
+
net
-
-
+
+
ACCEPT
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
+
Ces politiques vont:
-
+
-
-
permettre toutes les demandes de connexion
-depuis votre réseau local vers l'Internet
-
-
-
drop (ou ignorer) toutes les demandes
-de connexion depuis l'Internet vers votre firewall ou votre réseau
-local.
-
-
-
Facultativement accepter toutes les
- demandes de connexion de votre firewall vers l'Internet (si vous avez dé
-commenté la politique additionnelle)
-
-
+
+
permettre toutes les demandes de connexion
+ depuis votre réseau local vers l'Internet
+
+
+
drop (ou ignorer) toutes les demandes
+ de connexion depuis l'Internet vers votre firewall ou votre réseau
+ local.
+
+
+
Facultativement accepter toutes les
+ demandes de connexion de votre firewall vers l'Internet (si vous avez
+dé commenté la politique additionnelle)
+
+
reject (rejeter) toutes les autres demandes de connexion.
-
-
+
+
-
+
- A ce point, éditez votre fichier /etc/shorewall/policy
-et faite les changements que vous désirez.
-
+ A ce point, éditez votre fichier /etc/shorewall/policy
+ et faite les changements que vous désirez.
+
Network Interfaces
-
+
-
-
-
Le firewall a deux interfaces de réseau. Lorsque la
-connexion Internet passe par le câble ou par un ROUTEUR (pas un simple
-modem) ADSL (non USB), l'interface vers l'extérieur (External Interface)
-sera l'adaptateur sur lequel est connecté le routeur (e.g., eth0)
-à moins que vous ne vous connectiez par Point-to-PointProtocol
-overEthernet (PPPoE) ou par Point-to-PointTunnelingProtocol(PPTP),
- dans ce cas l'interface extérieure sera une interface de type ppp
-(e.g., ppp0). Si vous vous connectez par un simple modem (RTC), votre
-interface extérieure sera aussi ppp0. Si votre connexion passe
-par Numéris (ISDN), votre interface extérieure seraippp0.
-
+
+
+
Le firewall a deux interfaces de réseau. Lorsque la
+ connexion Internet passe par le câble ou par un ROUTEUR (pas un simple
+ modem) ADSL (non USB), l'interface vers l'extérieur (External
+Interface) sera l'adaptateur sur lequel est connecté le routeur
+(e.g., eth0) à moins que vous ne vous connectiez
+par Point-to-PointProtocol overEthernet
+(PPPoE) ou par Point-to-PointTunnelingProtocol(PPTP),
+ dans ce cas l'interface extérieure sera une interface de type ppp
+ (e.g., ppp0). Si vous vous connectez par un simple modem (RTC), votre
+ interface extérieure sera aussi ppp0. Si votre connexion passe
+ par Numéris (ISDN), votre interface extérieure seraippp0.
Votre Internal Interface (interface vers votre réseau
-local -> LAN) sera un adaptateur Ethernet (eth1 ou eth0) et sera connectée
-à un hub ou switch (ou un PC avec un câble croisé). Vos
-autres ordinateurs seront connectés à ce même hub/switch
-
+
+
Votre Internal Interface (interface vers votre réseau
+ local -> LAN) sera un adaptateur Ethernet (eth1 ou eth0) et sera connectée
+ à un hub ou switch (ou un PC avec un câble croisé).
+Vos autres ordinateurs seront connectés à ce même hub/switch
+
- Ne connectez pas l'interface interne et externe sur le même
-hub ou switch (même pour tester). Cela ne fonctionnera pas et ne croyez
-pas que ce soit shorewall qui ne marche pas.
-
+ Ne connectez pas l'interface interne et externe sur le même
+ hub ou switch (même pour tester). Cela ne fonctionnera pas et ne croyez
+ pas que ce soit shorewall qui ne marche pas.
+
- Le fichier de configuration d'exemple pour deux interfaces
-suppose que votre interface externe est eth0et que l'interne est eth1.
- Si votre configuration est différente, vous devrez modifier le fichier
-/etc/shorewall/interfaces en conséquence.
-Tant que vous y êtes, vous pourriez parcourir la liste des options qui
-sont spécifiées pour les interfaces. Quelques trucs:
-
+ Le fichier de configuration d'exemple pour deux interfaces
+ suppose que votre interface externe est eth0et que l'interne est
+eth1. Si votre configuration est différente, vous devrez modifier
+le fichier /etc/shorewall/interfaces
+en conséquence. Tant que vous y êtes, vous pourriez parcourir
+la liste des options qui sont spécifiées pour les interfaces.
+Quelques trucs:
+
-
-
Si votre interface vers l'extérieur est ppp0
- ou ippp0, vous pouvez remplacer le "detect" dans la seconde colonne
-par un "-".
-
-
-
Si votre interface vers l'extérieur est ppp0
-ou ippp0 ou si vous avez une adresse IP statique, vous pouvez enlever
-"dhcp" dans la liste des options.
-
-
+
+
Si votre interface vers l'extérieur est ppp0
+ ou ippp0, vous pouvez remplacer le "detect" dans la seconde colonne
+ par un "-".
+
+
+
Si votre interface vers l'extérieur est ppp0
+ ou ippp0 ou si vous avez une adresse IP statique, vous pouvez enlever
+ "dhcp" dans la liste des options.
+
+
-
+
Adresses IP
-
-
Avant d'aller plus loin, nous devons dire quelques mots au
-sujet de Internet Protocol (IP) addresses. Normalement, votre fournisseur
-Internet (ISP) vous assignera une seule adresse IP (single PublicIP
- address). Cette adresse peut être assignée par le Dynamic
- Host Configuration Protocol(DHCP) ou lors de l'établissement
-de votre connexion lorsque vous vous connectez (modem standard) ou établissez
-votre connexion PPP. Dans de rares cas , votre provider peut vous assigner
-une adresse statique (staticIP address); cela signifie que vous devez
-configurer l'interface externe de votre firewall afin d'utiliser cette adresse
-de manière permanente. Votre adresse externe assignée, elle
-va être partagée par tous vos systèmes lors de l'accès
- à Internet. Vous devrez assigner vos propres adresses dans votre
-réseau local (votre interface interne sur le firewall ainsi
-que les autres ordinateurs). La RFC 1918 réserve plusieurs plages
-d'IP (PrivateIP address ranges) à cette fin :
-
+
+
Avant d'aller plus loin, nous devons dire quelques mots au
+ sujet de Internet Protocol (IP) addresses. Normalement, votre fournisseur
+ Internet (ISP) vous assignera une seule adresse IP (single PublicIP
+ address). Cette adresse peut être assignée par le Dynamic
+ Host Configuration Protocol(DHCP) ou lors de l'établissement de
+votre connexion lorsque vous vous connectez (modem standard) ou établissez
+ votre connexion PPP. Dans de rares cas , votre provider peut vous assigner
+ une adresse statique (staticIP address); cela signifie que vous devez
+ configurer l'interface externe de votre firewall afin d'utiliser cette adresse
+ de manière permanente. Votre adresse externe assignée, elle
+ va être partagée par tous vos systèmes lors de l'accès
+ à Internet. Vous devrez assigner vos propres adresses dans votre réseau
+local (votre interface interne sur le firewall ainsi que les autres
+ordinateurs). La RFC 1918 réserve plusieurs plages d'IP (PrivateIP
+address ranges) à cette fin :
- Avant de lancer Shorewall, vous devriez regarder l'adresse
-IP de votre interface externe, et si elle est dans les plages précédentes,
-vous devriez enlever l'option 'norfc1918' dans la ligne concernant l'interface
-externe dans le fichier /etc/shorewall/interfaces.
-
-
Vous devrez assigner vos adresses depuis le même sous-réseau
-(sub-network/subnet). Pour ce faire, nous pouvons considérer
-un sous-réseau dans une plage d'adresses x.y.z.0 - x.y.z.255. Chaque
-sous-réseau aura un masque (Subnet Mask) de 255.255.255.0. L'adresse
-x.y.z.0 est réservée comme l'adresse de sous-réseau (Subnet
-Address) et x.y.z.255 est réservée en tant qu'adresse de
-broadcast (Subnet BroadcastAddress). Dans Shorewall, un sous-réseau
-est décrit en utilisant la notation Classless InterDomain
-Routing (CIDR) qui consiste en l'adresse du sous-réseau suivie
-par "/24". Le "24" se réfère au nombre consécutif de
-bits marquant "1" dans la partie gauche du masque de sous-réseau.
-
+ Avant de lancer Shorewall, vous devriez regarder l'adresse
+ IP de votre interface externe, et si elle est dans les plages précédentes,
+ vous devriez enlever l'option 'norfc1918' dans la ligne concernant l'interface
+ externe dans le fichier /etc/shorewall/interfaces.
+
+
Vous devrez assigner vos adresses depuis le même sous-réseau
+ (sub-network/subnet). Pour ce faire, nous pouvons considérer
+ un sous-réseau dans une plage d'adresses x.y.z.0 - x.y.z.255. Chaque
+ sous-réseau aura un masque (Subnet Mask) de 255.255.255.0.
+L'adresse x.y.z.0 est réservée comme l'adresse de sous-réseau
+(Subnet Address) et x.y.z.255 est réservée en tant qu'adresse
+de broadcast (Subnet BroadcastAddress). Dans Shorewall, un
+sous-réseau est décrit en utilisant la notation Classless InterDomain
+ Routing (CIDR) qui consiste en l'adresse du sous-réseau suivie
+ par "/24". Le "24" se réfère au nombre consécutif de
+ bits marquant "1" dans la partie gauche du masque de sous-réseau.
+
Un exemple de sous-réseau (sub-network) :
-
+
-
+
-
-
-
+
+
+
Plage:
-
-
+
+
10.10.10.0 - 10.10.10.255
-
-
-
-
+
+
+
+
Subnet Address:
-
-
+
+
10.10.10.0
-
-
-
-
+
+
+
+
Broadcast Address:
-
-
+
+
10.10.10.255
-
-
-
-
+
+
+
+
CIDR Notation:
-
-
+
+
10.10.10.0/24
-
-
-
-
+
+
+
+
-
+
-
-
Il est de mise d'assigner l'interface interne (LAN) à
-la première adresse utilisable du sous-réseau (10.10.10.1 dans
-l'exemple précédent) ou la dernière adresse utilisable
-(10.10.10.254).
-
-
L'un des buts d'un sous-réseau est de permettre à
-tous les ordinateurs dans le sous-réseau de savoir avec quels autres
-ordinateurs ils peuvent communiquer directement. Pour communiquer avec des
-systèmes en dehors du sous-réseau, les ordinateurs envoient
-des paquets à travers le gateway (routeur).
-
+
+
Il est de mise d'assigner l'interface interne (LAN) à
+ la première adresse utilisable du sous-réseau (10.10.10.1
+dans l'exemple précédent) ou la dernière adresse utilisable
+ (10.10.10.254).
+
+
L'un des buts d'un sous-réseau est de permettre à
+ tous les ordinateurs dans le sous-réseau de savoir avec quels autres
+ ordinateurs ils peuvent communiquer directement. Pour communiquer avec des
+ systèmes en dehors du sous-réseau, les ordinateurs envoient
+ des paquets à travers le gateway (routeur).
+
- Vos ordinateurs en local (ordinateur 1 et ordinateur
-2 dans le diagramme) devraient être configurés avec leur passerelle
- par défaut (default gateway) pointant sur l'adresse IP de
-l'interface interne du firewall.
-
-
The foregoing short discussion barely scratches the surface
-regarding subnetting and routing. If you are interested in learning more about
-IP addressing and routing, I highly recommend "IP Fundamentals: What Everyone
-Needs to Know about Addressing & Routing", Thomas A. Maufer, Prentice-Hall,
-1999, ISBN 0-13-975483-0.
-
-
Le reste de ce guide assumera que vous avez configuré
-votre réseau comme montré ci-dessous :
-
+ Vos ordinateurs en local (ordinateur 1 et ordinateur
+2 dans le diagramme) devraient être configurés avec leur passerelle
+ par défaut (default gateway) pointant sur l'adresse IP de l'interface
+interne du firewall.
+
+
The foregoing short discussion barely scratches the surface
+ regarding subnetting and routing. If you are interested in learning more
+about IP addressing and routing, I highly recommend "IP Fundamentals:
+What Everyone Needs to Know about Addressing & Routing", Thomas A.
+Maufer, Prentice-Hall, 1999, ISBN 0-13-975483-0.
+
+
Le reste de ce guide assumera que vous avez configuré
+ votre réseau comme montré ci-dessous :
+
-
-
-
La passerelle par défaut pour les ordinateurs 1 et
-2 devrait être 10.10.10.254.
-
+
+
+
La passerelle par défaut pour les ordinateurs 1 et
+ 2 devrait être 10.10.10.254.
+
IP Masquerading (SNAT)
-
-
Les adresses réservées par la RFC 1918 sont
-parfois désignées comme non-routables car les routeurs
-Internet (backbone) ne font pas circuler les paquets qui ont une adresse de
-destination appartenant à la RFC-1918. Lorsqu'un de vos systèmes
-en local (supposons l'ordinateur1) demande une connexion à un serveur
-par Internet, le firewall doit appliquer un NAT (Network Address Translation).
-Le firewall ré écrit l'adresse source dans le paquet, et l'a
-remplace par l'adresse de l'interface externe du firewall; en d'autres mots,
-le firewall fait croire que c'est lui même qui initie la connexion.
- Ceci est nécessaire afin que l'hôte de destination soit capable
-de renvoyer les paquets au firewall (souvenez vous que les paquets qui ont
-pour adresse de destination, une adresse réservée par la RFC
-1918 ne pourront pas être routés à travers Internet, donc
-l'hôte Internet ne pourra adresser sa réponse à l'ordinateur
-1). Lorsque le firewall reçoit le paquet de réponse, il remet
-l'adresse de destination à 10.10.10.1 et fait passer le paquet vers
-l'ordinateur 1.
-
-
Sur les systèmes Linux, ce procédé est
-souvent appelé de l'IP Masquerading mais vous verrez aussi le
-terme de Source Network Address Translation (SNAT) utilisé.
-Shorewall suit la convention utilisée avec Netfilter:
-
+
+
Les adresses réservées par la RFC 1918 sont
+ parfois désignées comme non-routables car les routeurs
+ Internet (backbone) ne font pas circuler les paquets qui ont une adresse
+de destination appartenant à la RFC-1918. Lorsqu'un de vos systèmes
+ en local (supposons l'ordinateur1) demande une connexion à un serveur
+ par Internet, le firewall doit appliquer un NAT (Network Address Translation).
+ Le firewall ré écrit l'adresse source dans le paquet, et l'a
+ remplace par l'adresse de l'interface externe du firewall; en d'autres mots,
+ le firewall fait croire que c'est lui même qui initie la connexion.
+ Ceci est nécessaire afin que l'hôte de destination soit capable
+ de renvoyer les paquets au firewall (souvenez vous que les paquets qui ont
+ pour adresse de destination, une adresse réservée par la RFC
+ 1918 ne pourront pas être routés à travers Internet,
+donc l'hôte Internet ne pourra adresser sa réponse à
+l'ordinateur 1). Lorsque le firewall reçoit le paquet de réponse,
+il remet l'adresse de destination à 10.10.10.1 et fait passer le paquet
+vers l'ordinateur 1.
+
+
Sur les systèmes Linux, ce procédé est
+ souvent appelé de l'IP Masquerading mais vous verrez aussi
+le terme de Source Network Address Translation (SNAT) utilisé.
+ Shorewall suit la convention utilisée avec Netfilter:
+
-
-
Masquerade désigne le cas ou vous laissez
-votre firewall détecter automatiquement l'adresse de l'interface externe.
-
-
-
-
SNAT désigne le cas où vous spécifiez
-explicitement l'adresse source des paquets sortant de votre réseau
-local.
-
-
+
+
Masquerade désigne le cas ou vous laissez
+ votre firewall détecter automatiquement l'adresse de l'interface
+externe.
+
+
+
SNAT désigne le cas où vous spécifiez
+ explicitement l'adresse source des paquets sortant de votre réseau
+ local.
+
+
-
-
Sous Shorewall, autant le Masquerading que le SNAT sont configuré
-avec des entrés dans le fichier /etc/shorewall/masq. Vous utiliserez
-normalement le Masquerading si votre adresse IP externe est dynamique, et
-SNAT si elle est statique.
-
+
+
Sous Shorewall, autant le Masquerading que le SNAT sont configuré
+ avec des entrés dans le fichier /etc/shorewall/masq. Vous utiliserez
+ normalement le Masquerading si votre adresse IP externe est dynamique, et
+ SNAT si elle est statique.
+
- Si votre interface externe du firewall est eth0,
-vous n'avez pas besoin de modifier le fichier fourni avec l'exemple. Dans
-le cas contraire, éditez /etc/shorewall/masq et changez la première
-colonne par le nom de votre interface externe, et la seconde colonne par le
-nom de votre interface interne.
-
+ Si votre interface externe du firewall est eth0,
+ vous n'avez pas besoin de modifier le fichier fourni avec l'exemple. Dans
+ le cas contraire, éditez /etc/shorewall/masq et changez la première
+ colonne par le nom de votre interface externe, et la seconde colonne par
+le nom de votre interface interne.
+
- Si votre IP externe est statique, vous pouvez la mettre
-dans la troisième colonne dans /etc/shorewall/masq si vous le désirez,
-de toutes façons votre firewall fonctionnera bien si vous laissez cette
-colonne vide. Le fait de mettre votre IP statique dans la troisième
-colonne permet un traitement des paquets sortant un peu plus efficace.
-
-
+
+
- Si vous utilisez les paquets Debian, vérifiez
-que votre fichier de configuration shorewall.conf contient bien les valeurs
+ Si vous utilisez les paquets Debian, vérifiez
+que votre fichier de configuration shorewall.conf contient bien les valeurs
suivantes, si elles n'y sont pas faite les changements nécessaires:
-
+
-
+
NAT_ENABLED=Yes
-
-
+
+
IP_FORWARDING=On
-
-
+
+
-
+
Port Forwarding (DNAT)
-
-
Un de nos buts est de , peut être, faire tourner un
-ou plusieurs serveurs sur nos ordinateurs locaux. Parce que ces ordinateurs
-on une adresse RFC-1918, il n' est pas possible pour les clients sur Internet
-de se connecter directement à eux. Il est nécessaire à
-ces clients d'adresser leurs demandes de connexion au firewall qui ré
-écrit l'adresse de destination de votre serveur, et fait passer le
-paquet à celui-ci. Lorsque votre serveur répond, le firewall
-applique automatiquement un SNAT pour ré écrire l'adresse source
- dans la réponse.
-
-
Ce procédé est appelé Port Forwarding
-ou Destination Network Address Translation(DNAT). Vous configurez le
-port forwarding en utilisant les règles DNAT dans le fichier /etc/shorewall/rules.
-
-
La forme générale d'une simple règle de port forwarding
-dans /etc/shorewall/rules est:
-
+
+
Un de nos buts est de , peut être, faire tourner un
+ ou plusieurs serveurs sur nos ordinateurs locaux. Parce que ces ordinateurs
+ on une adresse RFC-1918, il n' est pas possible pour les clients sur Internet
+ de se connecter directement à eux. Il est nécessaire à
+ ces clients d'adresser leurs demandes de connexion au firewall qui ré
+ écrit l'adresse de destination de votre serveur, et fait passer le
+ paquet à celui-ci. Lorsque votre serveur répond, le firewall
+ applique automatiquement un SNAT pour ré écrire l'adresse
+source dans la réponse.
+
+
Ce procédé est appelé Port Forwarding
+ ou Destination Network Address Translation(DNAT). Vous configurez
+le port forwarding en utilisant les règles DNAT dans le fichier /etc/shorewall/rules.
+
+
La forme générale d'une simple règle de port forwarding
+ dans /etc/shorewall/rules est:
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
DNAT
-
-
+
+
net
-
-
+
+
loc:<server local ip address> [:<server port>]
-
-
+
+
<protocol>
-
-
+
+
<port>
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
-
Exemple - vous faites tourner un serveur Web sur l'ordinateur 2 et vous
-voulez faire passer les requêtes TCP sur le port 80 à ce système
-:
-
+
+
Exemple - vous faites tourner un serveur Web sur l'ordinateur 2 et vous
+ voulez faire passer les requêtes TCP sur le port 80 à ce système
+ :
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
DNAT
-
-
+
+
net
-
-
+
+
loc:10.10.10.2
-
-
+
+
tcp
-
-
+
+
80
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
+
Deux points importants à garder en mémoire :
-
+
-
-
Vous devez tester la règle précédente
-depuis un client à l'extérieur de votre réseau local
-(c.a.d., ne pas tester depuis un navigateur tournant sur l'ordinateur 1 ou
-2 ou sur le firewall). Si vous voulez avoir la possibilité d'accéder
-à votre serveur web en utilisant l'adresse IP externe de votre firewall,
-regardez Shorewall FAQ #2.
-
-
-
Quelques fournisseurs Internet (Provider/ISP) bloquent les requêtes
-entrantes de connexion sur le port 80. Si vous avez des problèmes
-à vous connecter à votre serveur web, essayez la règle
-suivante et connectez vous sur le port 5000.
-
-
+
+
Vous devez tester la règle précédente
+ depuis un client à l'extérieur de votre réseau local
+ (c.a.d., ne pas tester depuis un navigateur tournant sur l'ordinateur 1
+ou 2 ou sur le firewall). Si vous voulez avoir la possibilité d'accéder
+ à votre serveur web en utilisant l'adresse IP externe de votre firewall,
+ regardez Shorewall FAQ #2.
+
+
+
Quelques fournisseurs Internet (Provider/ISP) bloquent les requêtes
+ entrantes de connexion sur le port 80. Si vous avez des problèmes
+ à vous connecter à votre serveur web, essayez la règle
+ suivante et connectez vous sur le port 5000.
+
+
-
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
DNAT
-
-
+
+
net
-
-
+
+
loc:10.10.10.2:80
-
-
+
+
tcp
-
-
+
+
5000
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
+
- A ce point, modifiez /etc/shorewall/rules pour ajouter
-les règles DNAT dont vous avez besoin.
-
+ A ce point, modifiez /etc/shorewall/rules pour ajouter
+ les règles DNAT dont vous avez besoin.
+
Domain Name Server (DNS)
-
-
Normalement, quand vous vous connectez à votre fournisseur
-(ISP), une partie consiste à obtenir votre adresse IP, votre DNS pour
-le firewall (Domain Name Service) est configuré automatiquement
-(c.a.d.,le fichier /etc/resolv.conf a été écrit). Il
-arrive que votre provider vous donne une paire d'adresse IP pour les DNS
-(name servers) afin que vous configuriez manuellement votre serveur de
-nom primaire et secondaire. La manière dont le DNS est configuré
-sur votre firewall est de votre responsabilité. Vous pouvez
+
+
Normalement, quand vous vous connectez à votre fournisseur
+ (ISP), une partie consiste à obtenir votre adresse IP, votre DNS
+pour le firewall (Domain Name Service) est configuré automatiquement
+ (c.a.d.,le fichier /etc/resolv.conf a été écrit). Il
+ arrive que votre provider vous donne une paire d'adresse IP pour les DNS
+ (name servers) afin que vous configuriez manuellement votre serveur
+de nom primaire et secondaire. La manière dont le DNS est configuré
+ sur votre firewall est de votre responsabilité. Vous pouvez
procéder d'une de ses deux façons :
-
+
-
-
Vous pouvez configurer votre système interne pour
-utiliser les noms de serveurs de votre provider. Si votre fournisseur vous
-donne les adresses de leurs serveurs ou si ces adresses sont disponibles
-sur leur site web, vous pouvez configurer votre système interne afin
-de les utiliser. Si cette information n' est pas disponible, regardez dans
- /etc/resolv.conf sur votre firewall -- les noms des serveurs sont donnés
-dans l'enregistrement "nameserver" dans ce fichier.
-
-
+
+
Vous pouvez configurer votre système interne
+pour utiliser les noms de serveurs de votre provider. Si votre fournisseur
+vous donne les adresses de leurs serveurs ou si ces adresses sont disponibles
+ sur leur site web, vous pouvez configurer votre système interne
+afin de les utiliser. Si cette information n' est pas disponible, regardez
+dans /etc/resolv.conf sur votre firewall -- les noms des serveurs sont
+ donnés dans l'enregistrement "nameserver" dans ce fichier.
+
+
- Vous pouvez configurer un cache dns (Caching Name
-Server) sur votre firewall.Red Hat a un RPM pour mettre en cache
-un serveur de nom (le RPM requis aussi le RPM 'bind') et pour les utilisateurs
- de Bering, il y a dnscache.lrp. Si vous adoptez cette approche, vous configurez
-votre système interne pour utiliser le firewall lui même comme
-étant le seul serveur de nom primaire. Vous pouvez utiliser l'adresse
-IP interne du firewall (10.10.10.254 dans l'exemple) pour l'adresse de serveur
-de nom. Pour permettre à vos systèmes locaux de discuter avec
-votre serveur cache de nom, vous devez ouvrir le port 53 (UDP ET TCP)
- sur le firewall vers le réseau local; vous ferez ceci en ajoutant
-les règles suivantes dans /etc/shorewall/rules.
-
-
+ Vous pouvez configurer un cache dns (Caching Name
+ Server) sur votre firewall.Red Hat a un RPM pour mettre en
+cache un serveur de nom (le RPM requis aussi le RPM 'bind') et pour les
+utilisateurs de Bering, il y a dnscache.lrp. Si vous adoptez cette approche,
+vous configurez votre système interne pour utiliser le firewall
+lui même comme étant le seul serveur de nom primaire. Vous
+pouvez utiliser l'adresse IP interne du firewall (10.10.10.254 dans l'exemple)
+pour l'adresse de serveur de nom. Pour permettre à vos systèmes
+locaux de discuter avec votre serveur cache de nom, vous devez ouvrir le
+port 53 (UDP ET TCP) sur le firewall vers le réseau local;
+vous ferez ceci en ajoutant les règles suivantes dans /etc/shorewall/rules.
+
+
+
-
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
loc
-
-
+
+
fw
-
-
+
+
tcp
-
-
+
+
53
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
loc
-
-
+
+
fw
-
-
+
+
udp
-
-
+
+
53
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
+
Autres Connexions
-
-
Les fichiers exemples inclus dans l'archive (two-interface)
-contiennent les règles suivantes :
-
+
+
Les fichiers exemples inclus dans l'archive (two-interface)
+ contiennent les règles suivantes :
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
fw
-
-
+
+
net
-
-
+
+
tcp
-
-
+
+
53
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
fw
-
-
+
+
net
-
-
+
+
udp
-
-
+
+
53
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
-
Ces règles autorisent l'accès DNS à partir
-de votre firewall et peuvent être enlevées si vous avez dé
-commenté la ligne dans /etc/shorewall/policy autorisant toutes les
-connexions depuis le firewall vers Internet.
-
+
+
Ces règles autorisent l'accès DNS à
+partir de votre firewall et peuvent être enlevées si vous avez
+dé commenté la ligne dans /etc/shorewall/policy autorisant
+toutes les connexions depuis le firewall vers Internet.
+
Les exemples contiennent aussi :
-
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
loc
-
-
+
+
fw
-
-
+
+
tcp
-
-
+
+
22
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
-
Cette règle vous autorise à faire tourner un
-serveur SSH sur votre firewall et à vous y connecter depuis votre réseau
-local.
-
-
Si vous voulez permettre d'autres connexions entre votre firewall
-et d'autres systèmes, la forme générale est :
-
+
+
Cette règle vous autorise à faire tourner un
+ serveur SSH sur votre firewall et à vous y connecter depuis votre
+réseau local.
+
+
Si vous voulez permettre d'autres connexions entre votre
+firewall et d'autres systèmes, la forme générale est
+:
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
<source zone>
-
-
+
+
<destination zone>
-
-
+
+
<protocol>
-
-
+
+
<port>
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
-
Exemple - Vous voulez faire tourner un serveur Web sur votre
-firewall :
-
+
+
Exemple - Vous voulez faire tourner un serveur Web sur votre
+ firewall :
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
net
-
-
+
+
fw
-
-
+
+
tcp
-
-
+
+
80
-
-
+
+
#Permet l'accès Web
-
-
+
+
depuis Internet
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
loc
-
-
+
+
fw
-
-
+
+
tcp
-
-
+
+
80
-
-
+
+
#Permet l'accès Web
-
-
-
+
+
+
depuis Internet
-
-
-
-
+
+
+
+
-
+
-
-
Ces deux règles bien sûr viennent s'ajouter aux
-règles décrites précédemment dans "Vous pouvez
-configurer un cache dns (Caching Name Server) sur votre firewall"
-
-
Si vous ne savez pas quel port et quel protocole une application
-particulière utilise, regardez ici.
-
-
Important: Je ne vous recommande pas de permettre le
-telnet depuis ou vers Internet car il utilise du texte en clair (même
-pour le login et le mot de passe!). Si vous voulez un accès au shell
-sur votre firewall depuis Internet, utilisez SSH :
-
+
+
Ces deux règles bien sûr viennent s'ajouter
+aux règles décrites précédemment dans "Vous pouvez
+ configurer un cache dns (Caching Name Server) sur votre firewall"
+
+
Si vous ne savez pas quel port et quel protocole une application
+ particulière utilise, regardez ici.
+
+
Important: Je ne vous recommande pas de permettre
+le telnet depuis ou vers Internet car il utilise du texte en clair (même
+ pour le login et le mot de passe!). Si vous voulez un accès au shell
+ sur votre firewall depuis Internet, utilisez SSH :
+
-
+
-
-
-
+
+
+
ACTION
-
-
+
+
SOURCE
-
-
+
+
DESTINATION
-
-
+
+
PROTOCOL
-
-
+
+
PORT
-
-
+
+
SOURCE PORT
-
-
+
+
ORIGINAL ADDRESS
-
-
-
-
+
+
+
+
ACCEPT
-
-
+
+
net
-
-
+
+
fw
-
-
+
+
tcp
-
-
+
+
22
-
-
+
+
-
-
+
+
-
-
-
-
+
+
+
+
-
+
-
+
- Maintenant éditez votre fichier /etc/shorewall/rules
-pour ajouter ou supprimer les connexions voulues.
-
+ Maintenant éditez votre fichier /etc/shorewall/rules
+ pour ajouter ou supprimer les connexions voulues.
+
Lancer et Arrêter votre Firewall
-
+
- La procédure d'installation
- configure votre système pour lancer Shorewall au boot du système,
-mais pour les débutants sous Shorewall version 1.3.9, le lancement
-est désactivé tant que la configuration n' est pas finie. Une
-fois la configuration de votre firewall achevée, vous pouvez permettre
-le lancement de Shorewall en enlevant le fichier /etc/shorewall/startup_disabled.
-
-
IMPORTANT: Les utilisateurs des
-paquets .deb doivent éditer /etc/default/shorewall et mettre 'startup=1'.
-
-
Le firewall est lancé en utilisant la commande "shorewall
-start" et stoppé avec "shorewall stop". Lorsque le firewall est stoppé,
-le routage est permis sur les hôtes qui sont dans le fichier/etc/shorewall/routestopped. Un
-firewall fonctionnant peut être relancé en utilisant la commande
-"shorewall restart". Si vous voulez enlever toutes les traces de Shorewall
-dans votre configuration de Netfilter, utilisez "shorewall clear".
-
+ La procédure d'installation
+ configure votre système pour lancer Shorewall au boot du système,
+ mais pour les débutants sous Shorewall version 1.3.9, le lancement
+ est désactivé tant que la configuration n' est pas finie.
+Une fois la configuration de votre firewall achevée, vous pouvez
+permettre le lancement de Shorewall en enlevant le fichier /etc/shorewall/startup_disabled.
+
+
IMPORTANT: Les utilisateurs
+des paquets .deb doivent éditer /etc/default/shorewall et mettre 'startup=1'.
+
+
Le firewall est lancé en utilisant la commande "shorewall
+ start" et stoppé avec "shorewall stop". Lorsque le firewall est stoppé,
+ le routage est permis sur les hôtes qui sont dans le fichier/etc/shorewall/routestopped. Un
+ firewall fonctionnant peut être relancé en utilisant la commande
+ "shorewall restart". Si vous voulez enlever toutes les traces de Shorewall
+ dans votre configuration de Netfilter, utilisez "shorewall clear".
+
- Les exemples (two-interface) supposent que vous voulez
-permettre le routage depuis ou vers eth1 (le réseau local) lorsque
-Shorewall est stoppé. Si votre réseau local n' est pas connecté
-à eth1 ou si vous voulez permettre l'accès depuis ou
-vers d'autres hôtes, changez /etc/shorewall/routestopped en conséquence.
ATTENTION: Si vous êtes connecté à
+ votre firewall depuis Internet, n'essayez pas la commande "shorewall stop"
+ tant que vous n'avez pas ajouté une entrée pour votre adresse
+ IP depuis laquelle vous êtes connecté dans/etc/shorewall/routestopped. De
+ plus, je ne vous recommande pas d'utiliser "shorewall restart"; il est mieux
+ de créer une configuration
alternative et de l'essayer en utilisant la commande"shorewall try".
It is important that you read all of the sections on this page where the
- version number mentioned in the section title is later than what you
+
+
+
It is important that you read all of the sections on this page where the
+ version number mentioned in the section title is later than what you
are currently running.
-
-
-
In the descriptions that follows, the term group refers
- to a particular network or subnetwork (which may be 0.0.0.0/0 or it may
+
+
+
In the descriptions that follows, the term group refers
+ to a particular network or subnetwork (which may be 0.0.0.0/0 or it may
be a host address) accessed through a particular interface.
+
You can use the "shorewall check" command to see the groups associated
- with each of your zones.
-
-
+
You can use the "shorewall check" command to see the groups associated
+ with each of your zones.
+
+
-
+
Version >= 1.4.6
-
-
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have been removed
-from shorewall.conf. These capabilities are now automatically detected by
-Shorewall.
-
An undocumented feature previously allowed entries in the host
-file as follows:
-
- zone eth1:192.168.1.0/24,eth2:192.168.2.0/24
-
-This capability was never documented and has been removed in 1.4.6 to allow
-entries of the following format:
-
- zone eth1:192.168.1.0/24,192.168.2.0/24
-
-
-
Version >= 1.4.4
- If you are upgrading from 1.4.3 and have set the LOGMARKER variable in
- /etc/shorewall/shorewall.conf, then
-you must set the new LOGFORMAT variable appropriately and remove your setting
- of LOGMARKER
-
+
+
The NAT_ENABLED, MANGLE_ENABLED and MULTIPORT options have been removed
+from shorewall.conf. These capabilities are now automatically detected by
+Shorewall.
+
An undocumented feature previously allowed entries in the host
+file as follows:
+
+ zone eth1:192.168.1.0/24,eth2:192.168.2.0/24
+
+ This capability was never documented and has been removed in 1.4.6 to allow
+entries of the following format:
+
+ zone eth1:192.168.1.0/24,192.168.2.0/24
+
+
+
+
Version >= 1.4.4
+ If you are upgrading from 1.4.3 and have set the LOGMARKER variable
+in /etc/shorewall/shorewall.conf, then
+you must set the new LOGFORMAT variable appropriately and remove your setting
+ of LOGMARKER
+
+
Version 1.4.4
-
- If you have zone names that are 5 characters long, you may experience problems
- starting Shorewall because the --log-prefix in a logging rule is too long.
- Upgrade to Version 1.4.4a to fix this problem..
-
+
+ If you have zone names that are 5 characters long, you may experience
+problems starting Shorewall because the --log-prefix in a logging rule
+is too long. Upgrade to Version 1.4.4a to fix this problem..
+
Version >= 1.4.2
- There are some cases where you may want to handle traffic from a particular
- group to itself. While I personally think that such a setups are ridiculous,
+ There are some cases where you may want to handle traffic from a particular
+ group to itself. While I personally think that such a setups are ridiculous,
there are two cases covered in this documentation where it can occur:
-
+
-
- If you have either of these cases, you will want to review the current
+ If you have either of these cases, you will want to review the current
documentation and change your configuration accordingly.
-
+
Version >= 1.4.1
-
+
-
Beginning with Version 1.4.1, traffic between groups in the
- same zone is accepted by default. Previously, traffic from a zone to itself
- was treated just like any other traffic; any matching rules were applied
- followed by enforcement of the appropriate policy. With 1.4.1 and later
- versions, unless you have explicit rules for traffic from Z to Z or you
- have an explicit Z to Z policy (where "Z" is some zone) then traffic between
- the groups in zone Z will be accepted. If you do have one or more explicit
- rules for Z to Z or if you have an explicit Z to Z policy then the behavior
- is as it was in prior versions.
-
+
Beginning with Version 1.4.1, traffic between groups in
+the same zone is accepted by default. Previously, traffic from a zone
+to itself was treated just like any other traffic; any matching rules
+were applied followed by enforcement of the appropriate policy. With 1.4.1
+and later versions, unless you have explicit rules for traffic from Z
+to Z or you have an explicit Z to Z policy (where "Z" is some zone) then
+traffic between the groups in zone Z will be accepted. If you do have one
+or more explicit rules for Z to Z or if you have an explicit Z to Z policy
+then the behavior is as it was in prior versions.
+
-
-
+
+
-
If you have a Z Z ACCEPT policy for a zone to allow traffic
- between two interfaces to the same zone, that policy can be removed and
- traffic between the interfaces will traverse fewer rules than previously.
-
If you have a Z Z DROP or Z Z REJECT policy or you have
-Z->Z rules then your configuration should not require any change.
-
If you are currently relying on a implicit policy (one that
- has "all" in either the SOURCE or DESTINATION column) to prevent traffic
- between two interfaces to a zone Z and you have no rules for Z->Z
-then you should add an explicit DROP or REJECT policy for Z to Z.
-
-
+
If you have a Z Z ACCEPT policy for a zone to allow traffic
+ between two interfaces to the same zone, that policy can be removed
+and traffic between the interfaces will traverse fewer rules than previously.
+
If you have a Z Z DROP or Z Z REJECT policy or you have
+ Z->Z rules then your configuration should not require any change.
+
If you are currently relying on a implicit policy (one
+that has "all" in either the SOURCE or DESTINATION column) to prevent
+traffic between two interfaces to a zone Z and you have no rules for
+Z->Z then you should add an explicit DROP or REJECT policy for Z to
+Z.
+
+
-
-
+
+
-
Sometimes, you want two separate zones on one interface but
- you don't want Shorewall to set up any infrastructure to handle traffic
+
Sometimes, you want two separate zones on one interface but
+ you don't want Shorewall to set up any infrastructure to handle traffic
between them.
-
+
-
+
Example:
-
-
+
+
/etc/shorewall/zones
z1 Zone1 The first Zone z2 Zone2 The secont Zone
/etc/shorewall/interfaces
z2 eth1 192.168.1.255
/etc/shorewall/hosts
z1 eth1:192.168.1.3
-
- Here, zone z1 is nested in zone z2 and the firewall is not going
-to be involved in any traffic between these two zones. Beginning with Shorewall
- 1.4.1, you can prevent Shorewall from setting up any infrastructure to
-handle traffic between z1 and z2 by using the new NONE policy:
-
-
+
+ Here, zone z1 is nested in zone z2 and the firewall is not going
+ to be involved in any traffic between these two zones. Beginning with
+Shorewall 1.4.1, you can prevent Shorewall from setting up any infrastructure
+to handle traffic between z1 and z2 by using the new NONE policy:
+
+
/etc/shorewall/policy
z1 z2 NONE z2 z1 NONE
-
- Note that NONE policies are generally used in pairs unless there
-is asymetric routing where only the traffic on one direction flows through
- the firewall and you are using a NONE polciy in the other direction.
-
-
Version 1.4.1
-
-
-
-
In Version 1.4.1, Shorewall will never create rules to
-deal with traffic from a given group back to itself. The multi
- interface option is no longer available so if you want to route traffic
-between two subnetworks on the same interface then I recommend that you
-upgrade to Version 1.4.2 and use the 'routeback' interface or host option.
-
-
-
-
Version >= 1.4.0
- IMPORTANT: Shorewall >=1.4.0 requiresthe
- iproute package ('ip' utility).
-
- Note: Unfortunately, some distributions call this package
- iproute2 which will cause the upgrade of Shorewall to fail with the diagnostic:
-
- error: failed dependencies:iproute is needed by shorewall-1.4.0-1
-
-
- This may be worked around by using the --nodeps option of rpm
-(rpm -Uvh --nodeps <shorewall rpm>).
-
- If you are upgrading from a version < 1.4.0, then:
-
-
-
The noping and forwardping interface
-options are no longer supported nor is the FORWARDPING option
-in shorewall.conf. ICMP echo-request (ping) packets are treated just
-like any other connection request and are subject to rules and policies.
-
Interface names of the form <device>:<integer>
- in /etc/shorewall/interfaces now generate a Shorewall error at startup
- (they always have produced warnings in iptables).
-
The MERGE_HOSTS variable has been removed from shorewall.conf.
- Shorewall 1.4 behaves like 1.3 did when MERGE_HOSTS=Yes; that is zone
- contents are determined by BOTH the interfaces and hosts files when
-there are entries for the zone in both files.
-
The routestopped option in the interfaces and
- hosts file has been eliminated; use entries in the routestopped file
- instead.
-
The Shorewall 1.2 syntax for DNAT and REDIRECT rules
- is no longer accepted; you must convert to using the new syntax.
-
The ALLOWRELATED variable in shorewall.conf
- is no longer supported. Shorewall 1.4 behavior is the same as 1.3
-with ALLOWRELATED=Yes.
-
Late-arriving DNS replies are now dropped
- by default; there is no need for your own /etc/shorewall/common file
- simply to avoid logging these packets.
-
The 'firewall', 'functions' and 'version'
- file have been moved to /usr/share/shorewall.
-
The icmp.def file has been removed. If you
- include it from /etc/shorewall/icmpdef, you will need to modify that
- file.
-
-
-
-
-
If you followed the advice in FAQ #2 and call find_interface_address
- in /etc/shorewall/params, that code should be moved to /etc/shorewall/init.
-
-
-
-
-
-
-
-
-
Version 1.4.0
-
-
-
The 'multi' interface option is no longer supported.
- Shorewall will generate rules for sending packets back out the same
- interface that they arrived on in two cases:
-
-
-
-
-
-
There is an explicit policy for the source zone
-to or from the destination zone. An explicit policy names both zones
-and does not use the 'all' reserved word.
-
-
-
-
-
There are one or more rules for traffic for the source
-zone to or from the destination zone including rules that use the 'all'
-reserved word. Exception: if the source zone and destination zone are
-the same then the rule must be explicit - it must name the zone in both
-the SOURCE and DESTINATION columns.
-
-
-
-
Version >= 1.3.14
-
- Beginning in version 1.3.14, Shorewall treats entries
- in /etc/shorewall/masq differently.
- The change involves entries with an interface name in the
-SUBNET (second) column:
-
+ Note that NONE policies are generally used in pairs unless there
+ is asymetric routing where only the traffic on one direction flows through
+ the firewall and you are using a NONE polciy in the other direction.
+
+
Version 1.4.1
+
+
-
Prior to 1.3.14, Shorewall would detect the FIRST
- subnet on the interface (as shown by "ip addr show interface")
- and would masquerade traffic from that subnet. Any other subnets that
- routed through eth1 needed their own entry in /etc/shorewall/masq
-to be masqueraded or to have SNAT applied.
-
Beginning with Shorewall 1.3.14, Shorewall uses
-the firewall's routing table to determine ALL subnets routed through
-the named interface. Traffic originating in ANY of those subnets
-is masqueraded or has SNAT applied.
-
+
In Version 1.4.1, Shorewall will never create rules to
+ deal with traffic from a given group back to itself. The multi
+ interface option is no longer available so if you want to route traffic
+between two subnetworks on the same interface then I recommend that you
+upgrade to Version 1.4.2 and use the 'routeback' interface or host option.
+
- You will need to make a change to your configuration if:
-
-
-
You have one or more entries in /etc/shorewall/masq
- with an interface name in the SUBNET (second) column; and
-
That interface connects to more than one subnetwork.
-
-
- Two examples:
-
- Example 1 -- Suppose that your current config
-is as follows:
-
-
-
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 eth0 192.168.10.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE [root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
-
-
In this case, the second entry in /etc/shorewall/masq is no longer
- required.
-
- Example 2-- What if your current configuration
-is like this?
-
-
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE [root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
-
-
In this case, you would want to change the entry in /etc/shorewall/masq
- to:
-
-
-
#INTERFACE SUBNET ADDRESS eth0 192.168.1.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+
Version >= 1.4.0
+ IMPORTANT: Shorewall >=1.4.0 requiresthe
+ iproute package ('ip' utility).
+
+ Note: Unfortunately, some distributions call this package
+ iproute2 which will cause the upgrade of Shorewall to fail with the
+diagnostic:
+
+ error: failed dependencies:iproute is needed by shorewall-1.4.0-1
+
+
+ This may be worked around by using the --nodeps option of rpm
+ (rpm -Uvh --nodeps <shorewall rpm>).
+
+ If you are upgrading from a version < 1.4.0, then:
+
+
+
The noping and forwardping interface
+ options are no longer supported nor is the FORWARDPING option
+ in shorewall.conf. ICMP echo-request (ping) packets are treated just
+ like any other connection request and are subject to rules and policies.
+
Interface names of the form <device>:<integer>
+ in /etc/shorewall/interfaces now generate a Shorewall error at startup
+ (they always have produced warnings in iptables).
+
The MERGE_HOSTS variable has been removed from shorewall.conf.
+ Shorewall 1.4 behaves like 1.3 did when MERGE_HOSTS=Yes; that is zone
+ contents are determined by BOTH the interfaces and hosts files when
+ there are entries for the zone in both files.
+
The routestopped option in the interfaces
+and hosts file has been eliminated; use entries in the routestopped
+file instead.
+
The Shorewall 1.2 syntax for DNAT and REDIRECT rules
+ is no longer accepted; you must convert to using the new syntax.
+
The ALLOWRELATED variable in shorewall.conf
+ is no longer supported. Shorewall 1.4 behavior is the same as 1.3
+with ALLOWRELATED=Yes.
+
Late-arriving DNS replies are now dropped
+ by default; there is no need for your own /etc/shorewall/common file
+ simply to avoid logging these packets.
+
The 'firewall', 'functions' and 'version'
+ file have been moved to /usr/share/shorewall.
+
The icmp.def file has been removed. If you
+ include it from /etc/shorewall/icmpdef, you will need to modify that
+ file.
+
+
+
+
+
If you followed the advice in FAQ #2 and call find_interface_address
+ in /etc/shorewall/params, that code should be moved to /etc/shorewall/init.
+
+
+
+
+
+
+
+
+
Version 1.4.0
+
+
+
The 'multi' interface option is no longer supported.
+ Shorewall will generate rules for sending packets back out the same
+ interface that they arrived on in two cases:
+
+
+
+
+
+
There is an explicit policy for the source zone
+to or from the destination zone. An explicit policy names both zones
+and does not use the 'all' reserved word.
+
+
+
+
+
There are one or more rules for traffic for the source
+zone to or from the destination zone including rules that use the 'all'
+reserved word. Exception: if the source zone and destination zone are
+the same then the rule must be explicit - it must name the zone in both
+the SOURCE and DESTINATION columns.
+
+
+
+
+
Version >= 1.3.14
- Version 1.3.14 also introduced simplified ICMP echo-request
- (ping) handling. The option OLD_PING_HANDLING=Yes in /etc/shorewall/shorewall.conf
- is used to specify that the old (pre-1.3.14) ping handling is to
-be used (If the option is not set in your /etc/shorewall/shorewall.conf
- then OLD_PING_HANDLING=Yes is assumed). I don't plan on supporting
-the old handling indefinitely so I urge current users to migrate to using
- the new handling as soon as possible. See the 'Ping'
- handling documentation for details.
-
-
Version 1.3.10
- If you have installed the 1.3.10 Beta 1 RPM and are now
- upgrading to version 1.3.10, you will need to use the '--force' option:
+ Beginning in version 1.3.14, Shorewall treats entries
+ in /etc/shorewall/masq differently.
+ The change involves entries with an interface name in the SUBNET
+ (second) column:
+
+
+
Prior to 1.3.14, Shorewall would detect the FIRST
+ subnet on the interface (as shown by "ip addr show interface")
+ and would masquerade traffic from that subnet. Any other subnets that
+ routed through eth1 needed their own entry in /etc/shorewall/masq to
+ be masqueraded or to have SNAT applied.
+
Beginning with Shorewall 1.3.14, Shorewall uses
+the firewall's routing table to determine ALL subnets routed through
+the named interface. Traffic originating in ANY of those subnets is
+masqueraded or has SNAT applied.
+
+
+ You will need to make a change to your configuration
+if:
+
+
+
You have one or more entries in /etc/shorewall/masq
+ with an interface name in the SUBNET (second) column; and
+
That interface connects to more than one subnetwork.
+
+
+ Two examples:
-
-
-
rpm -Uvh --force shorewall-1.3.10-1.noarch.rpm
+ Example 1 -- Suppose that your current config
+is as follows:
+
+
+
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 eth0 192.168.10.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE [root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
+
+
In this case, the second entry in /etc/shorewall/masq is no longer
+ required.
-
+ Example 2-- What if your current configuration
+is like this?
+
+
[root@gateway test]# cat /etc/shorewall/masq #INTERFACE SUBNET ADDRESS eth0 eth2 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE [root@gateway test]# ip route show dev eth2 192.168.1.0/24 scope link 192.168.10.0/24 proto kernel scope link src 192.168.10.254 [root@gateway test]#
+
+
In this case, you would want to change the entry in /etc/shorewall/masq
+ to:
+
+
+
#INTERFACE SUBNET ADDRESS eth0 192.168.1.0/24 206.124.146.176 #LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
+
+ Version 1.3.14 also introduced simplified ICMP echo-request
+ (ping) handling. The option OLD_PING_HANDLING=Yes in /etc/shorewall/shorewall.conf
+ is used to specify that the old (pre-1.3.14) ping handling is to
+be used (If the option is not set in your /etc/shorewall/shorewall.conf
+ then OLD_PING_HANDLING=Yes is assumed). I don't plan on supporting
+the old handling indefinitely so I urge current users to migrate to using
+ the new handling as soon as possible. See the 'Ping'
+ handling documentation for details.
+
+
Version 1.3.10
+ If you have installed the 1.3.10 Beta 1 RPM and are
+now upgrading to version 1.3.10, you will need to use the '--force'
+option:
+
+
+
+
rpm -Uvh --force shorewall-1.3.10-1.noarch.rpm
+
+
Version >= 1.3.9
- The 'functions' file has moved to /usr/lib/shorewall/functions.
- If you have an application that uses functions from that file,
-your application will need to be changed to reflect this change of
-location.
-
+ The 'functions' file has moved to /usr/lib/shorewall/functions.
+ If you have an application that uses functions from that file, your
+ application will need to be changed to reflect this change of location.
+
Version >= 1.3.8
-
-
If you have a pair of firewall systems configured for failover
- or if you have asymmetric routing, you will need to modify
- your firewall setup slightly under Shorewall
- versions >= 1.3.8. Beginning with version 1.3.8,
- you must set NEWNOTSYN=Yes in your
- /etc/shorewall/shorewall.conf file.
-
+
+
If you have a pair of firewall systems configured for failover
+ or if you have asymmetric routing, you will need to modify
+ your firewall setup slightly under Shorewall
+ versions >= 1.3.8. Beginning with version 1.3.8,
+ you must set NEWNOTSYN=Yes in your
+ /etc/shorewall/shorewall.conf file.
+
Version >= 1.3.7
-
-
Users specifying ALLOWRELATED=No in /etc/shorewall.conf
- will need to include the following
- rules in their /etc/shorewall/icmpdef file (creating this
+
+
Users specifying ALLOWRELATED=No in /etc/shorewall.conf
+ will need to include the following
+ rules in their /etc/shorewall/icmpdef file (creating this
file if necessary):
-
+
run_iptables -A icmpdef -p ICMP --icmp-type echo-reply -j ACCEPT run_iptables -A icmpdef -p ICMP --icmp-type source-quench -j ACCEPT run_iptables -A icmpdef -p ICMP --icmp-type destination-unreachable -j ACCEPT run_iptables -A icmpdef -p ICMP --icmp-type time-exceeded -j ACCEPT run_iptables -A icmpdef -p ICMP --icmp-type parameter-problem -j ACCEPT
-
-
Users having an /etc/shorewall/icmpdef file may remove the ". /etc/shorewall/icmp.def"
+
+
Users having an /etc/shorewall/icmpdef file may remove the ". /etc/shorewall/icmp.def"
command from that file since the icmp.def file is now empty.
To properly upgrade with Shorewall version 1.3.3 and later:
-
+
-
Be sure you
-have a backup -- you will need
- to transcribe any Shorewall configuration
- changes that you have made to the new
- configuration.
-
Replace the
-shorwall.lrp package provided on
- the Bering floppy with the later one. If you did
- not obtain the later version from Jacques's
-site, see additional instructions below.
-
Edit the /var/lib/lrpkg/root.exclude.list
- file and remove the /var/lib/shorewall
- entry if present. Then do not
+
Be sure you
+have a backup -- you will need
+to transcribe any Shorewall configuration
+ changes that you have made to the new
+ configuration.
+
Replace the
+shorwall.lrp package provided on
+ the Bering floppy with the later one. If you did
+ not obtain the later version from Jacques's site,
+ see additional instructions below.
+
Edit the /var/lib/lrpkg/root.exclude.list
+ file and remove the /var/lib/shorewall
+ entry if present. Then do not
forget to backup root.lrp !
-
+
-
-
The .lrp that I release isn't set up for a two-interface firewall like
+
+
The .lrp that I release isn't set up for a two-interface firewall like
Jacques's. You need to follow the instructions for setting up a two-interface
- firewall plus you also need to add the following two Bering-specific
+ href="two-interface.htm">instructions for setting up a two-interface
+ firewall plus you also need to add the following two Bering-specific
rules to /etc/shorewall/rules:
-
-
+
+
# Bering specific rules: # allow loc to fw udp/53 for dnscache to work # allow loc to fw tcp/80 for weblet to work # ACCEPT loc fw udp 53 ACCEPT loc fw tcp 80
-
-
+
+
Version 1.3.6 and 1.3.7
-
-
If you have a pair of firewall systems configured for
- failover or if you have asymmetric routing, you will need to modify
- your firewall setup slightly under Shorewall versions 1.3.6
- and 1.3.7
-
+
+
If you have a pair of firewall systems configured for
+ failover or if you have asymmetric routing, you will need to modify
+ your firewall setup slightly under Shorewall versions
+1.3.6 and 1.3.7
+
-
-
-
Create the file /etc/shorewall/newnotsyn and in it add
+
+
+
Create the file /etc/shorewall/newnotsyn and in it add
the following rule
-
- run_iptables -A newnotsyn
- -j RETURN # So that the connection tracking table can
- be rebuilt
- #
-from non-SYN packets after takeover.
-
-
-
-
Create /etc/shorewall/common (if you don't already
- have that file) and include the following:
-
- run_iptables -A common
- -p tcp --tcp-flags ACK,FIN,RST ACK -j ACCEPT #Accept
- Acks to rebuild connection
-
+
+ run_iptables -A
+newnotsyn -j RETURN # So that the connection tracking
+table can be rebuilt
+
+# from non-SYN packets after takeover.
+
+
+
+
+
Create /etc/shorewall/common (if you don't already
+ have that file) and include the following:
+
+ run_iptables -A
+common -p tcp --tcp-flags ACK,FIN,RST ACK -j ACCEPT
+#Accept Acks to rebuild connection
+
#tracking table.
- . /etc/shorewall/common.def
-
-
+ . /etc/shorewall/common.def
+
+
-
+
Versions >= 1.3.5
-
-
Some forms of pre-1.3.0 rules file syntax are no longer
- supported.
-
+
+
Some forms of pre-1.3.0 rules file syntax are no longer
+ supported.
+
Example 1:
-
-
+
+
ACCEPT net loc:192.168.1.12:22 tcp 11111 - all
-
-
+
+
Must be replaced with:
-
-
+
+
DNAT net loc:192.168.1.12:22 tcp 11111
-
-
-
+
+
+
Example 2:
-
-
-
+
+
+
ACCEPT loc fw::3128 tcp 80 - all
-
-
-
+
+
+
Must be replaced with:
-
-
-
+
+
+
REDIRECT loc 3128 tcp 80
-
-
+
+
Version >= 1.3.2
-
-
The functions and versions files together with the 'firewall'
- symbolic link have moved from /etc/shorewall to /var/lib/shorewall.
- If you have applications that access these files, those
-applications should be modified accordingly.
For a brief time, the 1.2 version of Shorewall supported an
- /etc/shorewall/whitelist file. This file was intended to contain a list of
-IP addresses of hosts whose POLICY to all zones was ACCEPT. The whitelist
-file was implemented as a stop-gap measure until the facilities necessary
-for implementing white lists using zones was in place. As of Version 1.3
+
+
For a brief time, the 1.2 version of Shorewall supported
+an /etc/shorewall/whitelist file. This file was intended to contain a list
+of IP addresses of hosts whose POLICY to all zones was ACCEPT. The whitelist
+file was implemented as a stop-gap measure until the facilities necessary
+for implementing white lists using zones was in place. As of Version 1.3
RC1, those facilities were available.
-
-
White lists are most often used to give special privileges
-to a set of hosts within an organization. Let us suppose that we have the
+
+
White lists are most often used to give special privileges
+to a set of hosts within an organization. Let us suppose that we have the
following environment:
-
+
-
A firewall with three interfaces -- one to the internet, one to
-a local network and one to a DMZ.
-
The local network uses SNAT to the internet and is comprised of
-the class B network 10.10.0.0/16 (Note: While this example uses an RFC 1918
- local network, the technique described here in no way depends on that or
-on SNAT. It may be used with Proxy ARP, Subnet Routing, Static NAT, etc.).
-
The network operations staff have workstations with IP addresses
+
A firewall with three interfaces -- one to the internet, one
+to a local network and one to a DMZ.
+
The local network uses SNAT to the internet and is comprised
+of the class B network 10.10.0.0/16 (Note: While this example uses an RFC
+1918 local network, the technique described here in no way depends on
+that or on SNAT. It may be used with Proxy ARP, Subnet Routing, Static
+NAT, etc.).
+
The network operations staff have workstations with IP addresses
in the class C network 10.10.10.0/24
-
We want the network operations staff to have full access to all
+
We want the network operations staff to have full access to all
other hosts.
-
We want the network operations staff to bypass the transparent
- HTTP proxy running on our firewall.
-
+
We want the network operations staff to bypass the transparent
+HTTP proxy running on our firewall.
+
-
-
The basic approach will be that we will place the operations
- staff's class C in its own zone called ops. Here are the appropriate
+
+
The basic approach will be that we will place the operations
+ staff's class C in its own zone called ops. Here are the appropriate
configuration files:
-
+
Zone File
-
-
+
+
-
-
-
ZONE
-
DISPLAY
-
COMMENTS
-
-
-
net
-
Net
-
Internet
-
-
-
ops
-
Operations
-
Operations Staff's Class C
-
-
-
loc
-
Local
-
Local Class B
-
-
-
dmz
-
DMZ
-
Demilitarized zone
-
-
-
-
-
-
-
The ops zone has been added to the standard 3-zone zones file --
-since ops is a sub-zone of loc, we list it BEFOREloc.
-
-
Interfaces File
-
-
-
-
-
-
ZONE
-
INTERFACE
-
BROADCAST
-
OPTIONS
-
-
-
net
-
eth0
-
<whatever>
-
<options>
-
-
-
dmz
-
eth1
-
<whatever>
-
-
-
-
-
-
-
eth2
-
10.10.255.255
-
-
-
-
-
-
-
-
-
Because eth2 interfaces to two zones (ops and loc),
-we don't specify a zone for it here.
-
-
Hosts File
-
-
-
-
-
-
-
-
ZONE
-
HOST(S)
-
OPTIONS
-
-
-
ops
-
eth2:10.10.10.0/24
-
-
-
-
-
loc
-
eth2:0.0.0.0/0
-
-
-
-
-
-
-
-
-
Here we define the ops and loc zones. When Shorewall is
-stopped, only the hosts in the ops zone will be allowed to access the
- firewall and the DMZ. I use 0.0.0.0/0 to define the loc zone rather
-than 10.10.0.0/16 so that the limited broadcast address (255.255.255.255)
-falls into that zone. If I used 10.10.0.0/16 then I would have to have a
-separate entry for that special address.
-
-
Policy File
-
-
-
-
-
-
-
-
SOURCE
-
DEST
-
POLICY
-
LOG LEVEL
-
LIMIT:BURST
-
-
-
ops
-
all
-
ACCEPT
-
-
-
-
-
-
-
all
-
ops
-
CONTINUE
-
-
-
-
-
-
-
loc
-
net
-
ACCEPT
-
-
-
-
-
-
net
-
all
-
DROP
-
info
-
-
-
-
all
-
all
-
REJECT
-
info
-
-
-
-
-
-
-
-
-
Two entries for ops have been added to the standard 3-zone policy
-file.
-
-
Rules File
-
-
-
-
-
-
-
ACTION
-
SOURCE
-
DEST
-
PROTO
-
DEST
- PORT(S)
-
SOURCE
- PORT(S)
-
ORIGINAL
- DEST
-
-
-
REDIRECT
-
loc!ops
-
3128
-
tcp
-
http
-
-
-
-
-
...
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
This is the rule that transparently redirects web traffic to the transparent
- proxy running on the firewall. The SOURCE column explicitly excludes the
-ops zone from the rule.
The ops zone has been added to the standard 3-zone zones file --
+since ops is a sub-zone of loc, we list it BEFOREloc.
+
+
Interfaces File
+
+
+
+
+
+
ZONE
+
INTERFACE
+
BROADCAST
+
OPTIONS
+
+
+
net
+
eth0
+
<whatever>
+
<options>
+
+
+
dmz
+
eth1
+
<whatever>
+
+
+
+
+
-
+
eth2
+
10.10.255.255
+
+
+
+
+
+
+
+
Because eth2 interfaces to two zones (ops and loc),
+we don't specify a zone for it here.
+
+
Hosts File
+
+
+
+
+
+
+
ZONE
+
HOST(S)
+
OPTIONS
+
+
+
ops
+
eth2:10.10.10.0/24
+
+
+
+
+
loc
+
eth2:0.0.0.0/0
+
+
+
+
+
+
+
+
Here we define the ops and loc zones. When Shorewall is stopped,
+only the hosts in the ops zone will be allowed to access the firewall
+and the DMZ. I use 0.0.0.0/0 to define the loc zone rather than 10.10.0.0/16
+so that the limited broadcast address (255.255.255.255) falls into that
+zone. If I used 10.10.0.0/16 then I would have to have a separate entry for
+ that special address.
+
+
Policy File
+
+
+
+
+
+
+
SOURCE
+
DEST
+
POLICY
+
LOG LEVEL
+
LIMIT:BURST
+
+
+
ops
+
all
+
ACCEPT
+
+
+
+
+
all
+
ops
+
CONTINUE
+
+
+
+
+
loc
+
net
+
ACCEPT
+
+
+
+
+
net
+
all
+
DROP
+
info
+
+
+
+
all
+
all
+
REJECT
+
info
+
+
+
+
+
+
+
+
Two entries for ops have been added to the standard 3-zone policy
+file.
+
+
Rules File
+
+
+
+
+
+
+
ACTION
+
SOURCE
+
DEST
+
PROTO
+
DEST
+ PORT(S)
+
SOURCE
+ PORT(S)
+
ORIGINAL
+ DEST
+
+
+
REDIRECT
+
loc!ops
+
3128
+
tcp
+
http
+
+
+
+
+
...
+
+
+
+
+
+
+
+
+
+
+
+
+
This is the rule that transparently redirects web traffic to the transparent
+ proxy running on the firewall. The SOURCE column explicitly excludes the
+ops zone from the rule.
- 
+ 
- .
-
- 
- 
- 
- 
-
-A couple of recent configuration changes at www.shorewall.net
- broke the Search facility:
- 
- 
- 
+ 
-
-
- 
- 
- Please observe the following general requirements:
- In all cases, Squid should be configured
-to run as a transparent proxy as described at 
-
- 
- 
- 
- 
- 
- 
- 
- 
+ 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
I recommend that you first read through the guide to familiarize yourself
+ with what's involved then go back through it again making your configuration
+ changes. Points at which configuration changes are recommended are
+ flagged with 
- 
- If your external interface is ppp0 or ippp0
+ If your external interface is ppp0 or ippp0
then you will want to set CLAMPMSS=yes in 
- Edit the /etc/shorewall/interfaces file and define the
-network interfaces on your firewall and associate each interface with
-a zone. If you have a zone that is interfaced through more than one interface,
- simply include one entry for each interface and repeat the zone name
-as many times as necessary.
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
-