About My NetworkTomEastep2005-02-062001-2005Thomas M. EastepPermission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version
1.2 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.My Current NetworkI use a combination of One-to-one 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 environment.The configuration shown here corresponds to Shorewall version
2.2.0. My configuration uses features not available in earlier Shorewall
releases.I have DSL service and have 5 static IP addresses
(206.124.146.176-180). My DSL modem (Westell 2200 running
in Bridge mode) is connected to eth2 and has IP address 192.168.1.1
(factory default). The modem is configured in bridge mode
so PPPoE is not involved. I have a local network connected to eth3 (subnet
192.168.1.0/24), a wireless network (192.168.3.0/24) connected to eth0,
and a DMZ connected to eth1 (206.124.146.176/32). Note that I configure
the same IP address on both eth1
and eth2.In this configuration:I use one-to-one NAT for Ursa (my personal system that run SuSE
9.2) - Internal address 192.168.1.5 and external address
206.124.146.178.I use one-to-one NAT for Eastepnc6000 (My work system -- Windows
XP SP1). Internal address 192.168.1.7 and external address
206.124.146.180.I use SNAT through 206.124.146.176 for my Wife's Windows XP
system Tarry, and our dual-booting (SuSE
9.2/Windows XP) laptop Tipper which connects through
the Wireless Access Point (wap) via a Wireless Bridge (wet), and my
work laptop when it is not docked in my office.While the distance between the WAP and where I usually use
the laptop isn't very far (50 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 :-).Squid runs on the firewall and is configured as a transparent
proxy.The firewall runs on a P-II/233 with Debian Sarge (testing).Ursa runs Samba for file sharing with the Windows systems and is
configured as a Wins server.The wireless network connects to the firewall's eth0 via a LinkSys
WAP11. In additional to using the rather weak WEP 40-bit encryption
(64-bit with the 24-bit preamble), I use MAC verification and Kernel 2.6 IPSEC or OpenVPN.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) under Fedora Core 3. 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.I have one system (Roadwarrior, 206.124.146.179) outside the
firewall. This system, which runs Debian Sarge (testing) is used for
roadwarrior VPN testing and for checking my firewall "from the
outside".All administration and publishing is done using ssh/scp. I have a
desktop environment installed on the firewall but I am not usually logged
in to it. X applications tunnel through SSH to Ursa. The server also has 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 Fedora).I run an SNMP server on my firewall to serve 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, an entry in my
/etc/network/interfaces file (see below) adds a host route to
206.124.146.177 through eth1 when that interface is brought up.The firewall is configured with OpenVPN for VPN access from our
second home in Omak,
Washington or when we are otherwise out of town. Secure remote
access via IPSEC is also available.Firewall ConfigurationShorewall.conf
MIRRORS=<list of shorewall mirror ip addresses>
NTPSERVERS=<list of the NTP servers I sync with>
TEXAS=<ip address of gateway in Plano>
LOG=ULOG
WIFI_IF=eth0
EXT_IF=eth2
INT_IF=eth3
DMZ_IF=eth1
Zones File
#ZONE DISPLAY COMMENTS
net Internet Internet
dmz DMZ Demilitarized zone
loc Local Local networks
tx Texas Peer Network in Dallas
Wifi Wireless Wirewall Network
sec Secure Secure Wireless Zone
#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.#ZONE INTERFACE BROADCAST OPTIONS
net $EXT_IF 206.124.146.255 dhcp,norfc1918,routefilter,logmartians,blacklist,tcpflags,nosmurfs
loc $INT_IF detect dhcp
dmz $DMZ_IF -
- texas -
vpn tun+ -
Wifi $WIFI_IF - maclist
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
Hosts File
#ZONE HOST(S) OPTIONS
tx texas:192.168.8.0/22
sec eth0:192.168.3.0/24
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
Ipsec File
#ZONE IPSEC OPTIONS IN OUT
# ONLY OPTIONS OPTIONS
sec yes mode=tunnel mss=1400
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
Routestopped File
#INTERFACE HOST(S)
$DMZ_IF 206.124.146.177
$INT_IF -
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
Blacklist File (Partial)
#ADDRESS/SUBNET PROTOCOL PORT
0.0.0.0/0 udp 1434
0.0.0.0/0 tcp 1433
0.0.0.0/0 tcp 3127
0.0.0.0/0 tcp 8081
0.0.0.0/0 tcp 57
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
RFC1918 File
Because my DSL modem has an RFC 1918 address (192.168.1.1) and
is connected to eth0, I need to make an exception for that address in
my rfc1918 file. I copied /usr/share/shorewall/rfc1918 to
/etc/shorewall/rfc1918 and changed it as follows:#SUBNET TARGET
192.168.1.1 RETURN
172.16.0.0/12 logdrop # RFC 1918
192.168.0.0/16 logdrop # RFC 1918
10.0.0.0/8 logdrop # RFC 1918
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
Policy File
#SOURCE DESTINATION POLICY LOG LEVEL BURST:LIMIT
fw fw ACCEPT
loc net ACCEPT
$FW vpn ACCEPT
vpn net ACCEPT
vpn loc ACCEPT
sec vpn ACCEPT
vpn sec ACCEPT
sec loc ACCEPT
loc sec ACCEPT
fw sec ACCEPT
sec net ACCEPT
Wifi sec NONE
sec Wifi NONE
fw Wifi ACCEPT
loc vpn ACCEPT
$FW loc ACCEPT
$FW tx ACCEPT
loc tx ACCEPT
loc fw REJECT $LOG
dmz tx ACCEPT
net all DROP $LOG 10/sec:40
all all REJECT $LOG
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
Masq File
Although most of our internal systems use one-to-one NAT, my
wife's system (192.168.1.4) uses IP Masquerading (actually SNAT) as
does our laptop (192.168.1.8) and visitors with laptops.The first entry allows access to the DSL modem and uses features
introduced in Shorewall 2.1.1. The leading plus sign ("+_") causes the
rule to be placed before rules generated by the /etc/shorewall/nat
file below. The double colons ("::") causes the entry to be exempt
from ADD_SNAT_ALIASES=Yes in my shorewall.conf file above.#INTERFACE SUBNET ADDRESS
+$EXT_IF::192.168.1.1 0.0.0.0/0 192.168.1.254
$EXT_IF:: eth2 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
206.124.146.180 eth0:1 192.168.1.7 No No
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
Proxy ARP File
I configure the host route to 206.124.146.177 on eth1 in /etc/network/interfaces.#ADDRESS INTERFACE EXTERNAL HAVEROUTE PERSISTENT
206.124.146.177 eth1 eth0 Yes
192.168.1.1 eth0 eth2 yes # Allow access to DSL modem from the local zone
#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
openvpn:1194 net 0.0.0.0/0
openvpn:1194 Wifi 192.168.3.0/24
ipsec Wifi 192.168.3.0/24 sec
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
Actions File
#ACTION
Mirrors #Accept traffic from the Shorewall Mirror sites
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
action.Mirrors File
The $MIRRORS variable expands to a list of approximately 10 IP
addresses. So moving these checks into a separate chain reduces the
number of rules that most net->dmz traffic needs to
traverse.#TARGET SOURCE DEST PROTO DEST SOURCE ORIGINAL RATE
# PORT PORT(S) DEST LIMIT
ACCEPT $MIRRORS
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
/etc/shorewall/action.Reject
This is my common action for the REJECT policy. It is like the
standard Reject action except that it
allows Ping and contains one rule that guards against
log flooding by broken software running in my local zone.#TARGET SOURCE DEST PROTO DEST SOURCE RATE USER/
# PORT(S) PORT(S) LIMIT GROUP
RejectAuth
AllowPing
dropBcast
RejectSMB
DropUPnP
dropNotSyn
DropDNSrep
DROP loc:eth2:!192.168.1.0/24 #So that my braindead Windows[tm] XP system doesn't flood my log
#with NTP requests with a source address in 16.0.0.0/8 (address of
#its PPTP tunnel to HP).
Rules File (The shell variables are set in
/etc/shorewall/params)
##########################################################################################################################################################################
#####
#RESULT CLIENT(S) SERVER(S) PROTO PORT(S) CLIENT ORIGINAL RATE USER
# PORT(S) DEST:SNAT SET
##########################################################################################################################################################################
#####
# Local Network to Internet - Reject attempts by Trojans to call home, direct SMTP and MS Message Service
#
REJECT:$LOG loc net tcp 25
REJECT:$LOG loc net udp 1025:1031
#
# Stop NETBIOS crap
#
REJECT loc net tcp 137,445
REJECT loc net udp 137:139
REJECT sec net tcp 137,445
REJECT sec net udp 137:139
#
# Stop my idiotic XP box from sending to the net with an HP source IP address
#
DROP loc:!192.168.0.0/22 net
#
# SQUID
#
REDIRECT loc 3128 tcp 80
REDIRECT sec 3128 tcp 80
##########################################################################################################################################################################
#####
# Local Network to Firewall
#
DROP loc:!192.168.0.0/22 fw # Silently drop traffic with an HP source IP from my XP box
ACCEPT loc fw tcp ssh,time,631,8080
ACCEPT loc fw udp 161,ntp,631
DROP loc fw tcp 3185 #SuSE Meta pppd
##########################################################################################################################################################################
#####
# Secure wireless to Firewall
#
ACCEPT sec fw tcp ssh,time,631,8080
ACCEPT sec fw udp 161,ntp,631
DROP sec fw tcp 3185 #SuSE Meta pppd
##########################################################################################################################################################################
#####
# Roadwarriors to Firewall
#
ACCEPT vpn fw tcp ssh,time,631,8080
ACCEPT vpn fw udp 161,ntp,631
##########################################################################################################################################################################
#####
# Local Network to DMZ
#
DROP loc:!192.168.0.0/22 dmz
ACCEPT loc dmz udp domain,xdmcp
ACCEPT loc dmz tcp www,smtp,smtps,domain,ssh,imap,https,imaps,cvspserver,ftp,10023,pop3 -
##########################################################################################################################################################################
#####
# Insecure Wireless to DMZ
#
ACCEPT Wifi dmz udp domain
ACCEPT Wifi dmz tcp domain
##########################################################################################################################################################################
#####
# Secure Wireless to DMZ
#
DROP sec:!192.168.0.0/22 dmz
ACCEPT sec dmz udp domain,xdmcp
ACCEPT sec dmz tcp www,smtp,smtps,domain,ssh,imap,https,imaps,cvspserver,ftp,10023,pop3 -
##########################################################################################################################################################################
#####
# Road Warriors to DMZ
#
ACCEPT vpn dmz udp domain
ACCEPT vpn dmz tcp www,smtp,smtps,domain,ssh,imap,https,imaps,cvspserver,ftp,10023,pop3 -
##########################################################################################################################################################################
#####
# Internet to ALL -- drop NewNotSyn packets
#
dropNotSyn net fw tcp
dropNotSyn net loc tcp
dropNotSyn net dmz tcp
#
# Drop ping to firewall and local
#
DropPing net fw
DropPing net loc
##########################################################################################################################################################################
#####
# Internet to DMZ
#
DNAT- net dmz:206.124.146.177 tcp smtp - 206.124.146.178
ACCEPT net dmz tcp smtp,smtps,www,ftp,imaps,domain,https,cvspserver -
ACCEPT net dmz udp domain
ACCEPT net dmz udp 33434:33454
Mirrors net dmz tcp rsync
ACCEPT net:$OMAK dmz tcp 22 #SSH from Omak
AllowPing net dmz
##########################################################################################################################################################################
#####
#
# Net to Local
#
# When I'm "on the road", the following two rules allow me VPN access back home.
#
DNAT net loc:192.168.1.4 tcp 1723 -
DNAT net:!$TEXAS loc:192.168.1.4 gre -
ACCEPT net loc:192.168.1.5 tcp 22
#
# ICQ
#
ACCEPT net loc:192.168.1.5 tcp 4000:4100
#
# Real Audio
#
ACCEPT net loc:192.168.1.5 udp 6970:7170
#
# Overnet
#
#ACCEPT net loc:192.168.1.5 tcp 4662
#ACCEPT net loc:192.168.1.5 udp 12112
#
# OpenVPN
#
ACCEPT net loc:192.168.1.5 udp 1194
#
# Silently Handle common probes
#
REJECT net loc tcp www,ftp,https
##########################################################################################################################################################################
#####
# DMZ to Internet
#
ACCEPT dmz net tcp smtp,domain,www,81,https,whois,echo,2702,21,2703,ssh,8080
ACCEPT dmz net udp domain,ntp
REJECT:$LOG dmz net udp 1025:1031
ACCEPT dmz net:$POPSERVERS tcp pop3
#
# Something is wrong with the FTP connection tracking code or there is some client out there
# that is sending a PORT command which that code doesn't understand. Either way,
# the following works around the problem.
#
ACCEPT:$LOG dmz net tcp 1024: 20
##########################################################################################################################################################################
#####
# DMZ to Firewall -- ntp & snmp, Silently reject Auth
#
ACCEPT dmz fw udp ntp ntp
ACCEPT dmz fw tcp 161,ssh
ACCEPT dmz fw udp 161
REJECT dmz fw tcp auth
##########################################################################################################################################################################
#####
# DMZ to Local Network
#
ACCEPT dmz loc tcp smtp,6001:6010
ACCEPT dmz:206.124.146.177 loc:192.168.1.5 tcp 111
ACCEPT dmz:206.124.146.177 loc:192.168.1.5 udp
##########################################################################################################################################################################
#####
# Internet to Firewall
#
REJECT net fw tcp www,ftp,https
ACCEPT net dmz udp 33434:33454
ACCEPT net:$OMAK fw udp ntp
ACCEPT net:$OMAK fw tcp 22 #SSH from Omak
##########################################################################################################################################################################
#####
# 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,ftp,2702,2703,7
ACCEPT fw net udp 33435:33535
ACCEPT fw net icmp
REJECT:$LOG fw net udp 1025:1031
DROP fw net udp ntp
##########################################################################################################################################################################
#####
# Firewall to DMZ
#
ACCEPT fw dmz tcp www,ftp,ssh,smtp,993,465
ACCEPT fw dmz udp domain
REJECT fw dmz udp 137:139
##########################################################################################################################################################################
#####
ACCEPT tx loc:192.168.1.5 all
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
/etc/network/interfacesThis file is Debian-specific and defines the configuration of the
network interfaces.
# The loopback network interface
auto lo
iface lo inet loopback
# DMZ interface -- After the interface is up, add a route to the server. This allows the 'Yes' setting
# in the HAVEROUTE column of /etc/shorewall/proxyarp above.
auto eth1
iface eth1 inet static
address 206.124.146.176
netmask 255.255.255.255
broadcast 0.0.0.0
up ip route add 206.124.146.177 dev eth1
# Internet interface -- After the interface is up, add a route to the Westell 2200 DSL "Modem"
auto eth2
iface eth2 inet static
address 206.124.146.176
netmask 255.255.255.0
gateway 206.124.146.254
up ip route add 192.168.1.1 dev eth2
# Wireless interface
auto eth0
iface eth0 inet static
address 192.168.3.254
netmask 255.255.255.0
# LAN interface
auto eth3
iface eth3 inet static
address 192.168.1.254
netmask 255.255.255.0
/etc/ulogd.confThis is the default /etc/ulogd.conf from the Debian package. Only
the relevant entries are shown.
# where to write to
syslogfile /var/log/ulog/syslogemu.log
# do we want to fflush() the file after each write?
syslogsync 1
# First of all flush the SAD and SPD databases
flush;
spdflush;
# Add some SPD rules
spdadd 0.0.0.0/0 192.168.3.8/32 any -P out ipsec esp/tunnel/192.168.3.254-192.168.3.8/require;
spdadd 192.168.3.8/32 0.0.0.0/0 any -P in ipsec esp/tunnel/192.168.3.8-192.168.3.254/require;
Tipper Configuration while at HomeThis laptop is either configured on our wireless network
(192.168.3.8) or as a standalone system on the road. While this system is
connected via our wireless network, it uses IPSEC tunnel mode for all
access.Given that I use OpenVPN for remote access, it would be more
convenient to also use it for wireless access at home. I use IPSEC just
so that I always have a working IPSEC testbed.Tipper's view of the world is shown in the following diagram:The key configuration files are shown in the following
sections.zones
#ZONE DISPLAY COMMENTS
home Home Shorewall Network
net Net Internet
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
policy
#SOURCE DEST POLICY LOG LEVEL LIMIT:BURST
fw net ACCEPT
fw home ACCEPT
home fw ACCEPT
net home NONE
home net NONE
net all DROP info
# The FOLLOWING POLICY MUST BE LAST
all all REJECT info
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
interfaces
#ZONE INTERFACE BROADCAST OPTIONS
net eth0 detect dhcp,tcpflags
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
ipsec
#ZONE IPSEC OPTIONS IN OUT
# ONLY OPTIONS OPTIONS
home yes mode=tunnel
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
hosts
#ZONE HOST(S) OPTIONS
home eth0:0.0.0.0/0
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS LINE -- DO NOT REMOVE
rules
#ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL RATE USER/
# PORT PORT(S) DEST LIMIT GROUP
ACCEPT net fw icmp 8
ACCEPT net fw tcp 22
ACCEPT net fw tcp 4000:4100
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
/etc/racoon/setkey.conf
flush;
spdflush;
# Policies for while we're connected via Wireless at home
spdadd 192.168.3.8/32 192.168.3.8/32 any -P in none;
spdadd 192.168.3.8/32 192.168.3.8/32 any -P out none;
spdadd 127.0.0.0/8 127.0.0.0/8 any -P in none;
spdadd 127.0.0.0/8 127.0.0.0/8 any -P out none;
spdadd 0.0.0.0/0 192.168.3.8/32 any -P in ipsec esp/tunnel/192.168.3.254-192.168.3.8/require;
spdadd 192.168.3.8/32 0.0.0.0/0 any -P out ipsec esp/tunnel/192.168.3.8-192.168.3.254/require;
Tipper Configuration on the RoadWhen Tipper is on the road, it's world view is the same as in the
diagram above.zones
#ZONE DISPLAY COMMENTS
home Home Shorewall Network
net Net Internet
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
policy
#SOURCE DEST POLICY LOG LEVEL LIMIT:BURST
fw net ACCEPT
fw home ACCEPT
home fw ACCEPT
net home NONE
home net NONE
net all DROP info
# The FOLLOWING POLICY MUST BE LAST
all all REJECT info
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
interfaces
#ZONE INTERFACE BROADCAST OPTIONS
net eth0 detect dhcp,tcpflags
home tun0 -
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
rules
#ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL RATE USER/
# PORT PORT(S) DEST LIMIT GROUP
ACCEPT net fw icmp 8
ACCEPT net fw tcp 22
ACCEPT net fw tcp 4000:4100
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
/etc/openvpn/home.conf
dev tun
remote ursa.shorewall.net
up /etc/openvpn/home.up
tls-client
pull
ca /etc/certs/cacert.pem
cert /etc/certs/tipper.pem
key /etc/certs/tipper_key.pem
port 1194
user nobody
group nogroup
comp-lzo
ping 15
ping-restart 45
ping-timer-rem
persist-tun
persist-key
verb 3
/etc/openvpn/home.up
#!/bin/bash
ip route add 192.168.1.0/24 via $5 #Access to Home Network
ip route add 206.124.146.177/32 via $5 #So that DNS names will resolve in my
#Internal Bind 9 view because the source IP will
#be in 192.168.2.0/24