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<?xml version="1.0" encoding="UTF-8"?>
<article>
<!--$Id$-->
<articleinfo>
<title>Xen and the Art of Consolidation</title>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Eastep</surname>
</author>
</authorgroup>
<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
<copyright>
<year>2006</year>
<year>2007</year>
<holder>Thomas M. Eastep</holder>
</copyright>
<legalnotice>
<para>Permission 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
<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
License</ulink></quote>.</para>
</legalnotice>
</articleinfo>
<caution>
<para>This article applies to Shorewall 3.0 and later. If you are running
a version of Shorewall earlier than Shorewall 3.0.0 then please see the
documentation for that release.</para>
</caution>
<section>
<title>Xen Network Environment</title>
<para><ulink
url="http://www.cl.cam.ac.uk/Research/SRG/netos/xen/">Xen</ulink> is a
<firstterm>paravirtualization</firstterm> tool that allows you to run
multiple virtual machines on one physical machine. It is available on a
wide number of platforms and is included in recent
<trademark>SUSE</trademark> distributions.</para>
<para>Xen refers to the virtual machines as
<firstterm>Domains</firstterm>. Domains are numbered with the first domain
being domain 0, the second domain 1, and so on. Domain 0
(<firstterm>Dom0</firstterm>) is special because that is the domain
created when to machine is booted. Additional domains (called
<firstterm>DomU</firstterm>'s) are created using the <command>xm
create</command> command from within Domain 0. Additional domains can also
be created automatically at boot time by using the
<command>xendomains</command> service.</para>
<para>Xen virtualizes a network interface named <filename
class="devicefile">eth0</filename><footnote>
<para>This assumes the default Xen configuration created by
<command>xend </command>and assumes that the host system has a single
ethernet interface named <filename
class="devicefile">eth0</filename>.</para>
</footnote>in each domain. In Dom0, Xen also creates a bridge (<filename
class="devicefile">xenbr0</filename>) and a number of virtual interfaces
as shown in the following diagram.</para>
<graphic align="center" fileref="images/Xen1.png" />
<para>I use the term <firstterm>Extended Dom0</firstterm> to distinguish
the bridge and virtual interfaces from Dom0 itself. That distinction is
important when we try to apply Shorewall in this environment.</para>
<para>The bridge has a number of ports:</para>
<itemizedlist>
<listitem>
<para>peth0 — This is the port that connects to the physical network
interface in your system.</para>
</listitem>
<listitem>
<para>vif0.0 — This is the bridge port that is used by traffic to/from
Domain 0.</para>
</listitem>
<listitem>
<para>vifX.0 — This is the bridge port that is used by traffic to/from
Domain X.</para>
</listitem>
</itemizedlist>
</section>
<section id="Before">
<title>Before Xen</title>
<para>Prior to adopting Xen, I had a home office crowded with 5 systems,
three monitors a scanner and a printer. The systems were:</para>
<orderedlist>
<listitem>
<para>Firewall</para>
</listitem>
<listitem>
<para>Public Server in a DMZ (mail)</para>
</listitem>
<listitem>
<para>Private Server (wookie)</para>
</listitem>
<listitem>
<para>My personal Linux Desktop (ursa)</para>
</listitem>
<listitem>
<para>My work system (docked laptop running Windows XP).</para>
</listitem>
</orderedlist>
<para>The result was a very crowded and noisy room.</para>
</section>
<section id="After">
<title>After Xen</title>
<para>Xen has allowed me to reduce the noise and clutter considerably. I
now have three systems with two monitors. I've also replaced the
individual printer and scanner with a Multifunction
FAX/Scanner/Printer.</para>
<para>The systems now include:</para>
<orderedlist>
<listitem>
<para>Combination Firewall/Public Server/Private Server/Wireless
Gateway using Xen (created by building out my Linux desktop
system).</para>
</listitem>
<listitem>
<para>My work system.</para>
</listitem>
<listitem>
<para>My Linux desktop (wookie, which is actually the old public
server box)</para>
</listitem>
</orderedlist>
<para>Most of the Linux systems run <trademark>SuSE </trademark>10.1; my
personal Linux desktop system and our Linux Laptop run
<trademark>Ubuntu</trademark> "Dapper Drake".</para>
<para><emphasis role="bold">The configuration described below uses a
bridged Xen Networking configuration; if you want to see how to accomplish
a similar configuration using a Routed Xen configuration then please see
<ulink url="XenMyWay-Routed.html">this article</ulink>. I am now using the
routed configuration because it results in one fewer domains to
administer.</emphasis></para>
<para>Here is a high-level diagram of our network.</para>
<graphic align="center" fileref="images/Xen5.png" />
<para>As shown in this diagram, the Xen system has three physical network
interfaces. These are:</para>
<itemizedlist>
<listitem>
<para><filename class="devicefile">eth0</filename> -- connected to the
switch in my office. That switch is cabled to a second switch in my
wife's office where my wife has her desktop and networked printer (I
sure wish that there had been wireless back when I strung that CAT-5
cable halfway across the house).</para>
</listitem>
<listitem>
<para><filename class="devicefile">eth1</filename> -- connected to our
DSL "Modem".</para>
</listitem>
<listitem>
<para><filename class="devicefile">eth2</filename> -- connected to a
Wireless Access Point (WAP) that interfaces to our wireless
network.</para>
</listitem>
</itemizedlist>
<para>There are three Xen domains.</para>
<orderedlist>
<listitem>
<para>Dom0 (DNS name ursa.shorewall.net) is used as a local file
server (NFS and Samba).</para>
</listitem>
<listitem>
<para>The first DomU (Dom name <emphasis
role="bold">firewall</emphasis>, DNS name gateway.shorewall.net) is
used as our main firewall and wireless gateway.</para>
</listitem>
<listitem>
<para>The second DomU (Dom name <emphasis
role="bold">lists</emphasis>, DNS name lists.shorewall.net) is used as
a public Web/FTP/Mail/DNS server.</para>
</listitem>
</orderedlist>
<para>Shorewall runs in Dom0 and in the firewall domain.</para>
<caution>
<para>As the developer of Shorewall, I have enough experience to be very
comfortable with Linux networking and Shorewall/iptables. I arrived at
this configuration after a fair amount of trial and error
experimentation. If you are a Linux networking novice, I recommend that
you do not attempt a configuration like this one for your first
Shorewall installation. You are very likely to frustrate both yourself
and the Shorewall support team. Rather I suggest that you start with
something simple like a <ulink url="standalone.htm">standalone
installation</ulink> in a domU; once you are comfortable with that then
you will be ready to try something more substantial.</para>
<para>As Paul Gear says: <emphasis>Shorewall might make iptables easy,
but it doesn't make understanding fundamental networking principles,
traffic shaping, or multi-ISP routing any easier</emphasis>.</para>
<para>The same goes for Xen networking.</para>
</caution>
<section id="Domains">
<title>Domain Configuration</title>
<para>Below are the relevant configuration files for the three domains.
I use partitions on my hard drives for DomU storage devices.</para>
<blockquote>
<para><filename>/boot/grub/menu.lst</filename> — here is the entry
that boots Xen in Dom0.</para>
<programlisting>title XEN
root (hd0,1)
kernel /boot/xen.gz dom0_mem=458752 sched=bvt
module /boot/vmlinuz-xen root=/dev/hda2 vga=0x31a selinux=0 resume=/dev/hda1 splash=silent showopts
module /boot/initrd-xen</programlisting>
<para><filename>/etc/modprobe.conf.local</filename></para>
<para><filename class="devicefile">eth1</filename> (PCI 00:09.0) and
<filename class="devicefile">eth2</filename> (PCI 00:0a.0) are
delegated to the firewall DomU where they become <filename
class="devicefile">eth3</filename> and <filename
class="devicefile">eth4</filename> respectively. The SuSE 10.1 Xen
kernel compiles pciback as a module so the instructions for PCI
delegation in the Xen Users Manual can't be followed directly (see
<ulink
url="http://wiki.xensource.com/xenwiki/Assign_hardware_to_DomU_with_PCIBack_as_module">http://wiki.xensource.com/xenwiki/Assign_hardware_to_DomU_with_PCIBack_as_module</ulink>).</para>
<programlisting>options pciback hide=(00:09.0)(00:0a.0)
install tulip /sbin/modprobe pciback ; /sbin/modprobe --first-time --ignore-install tulip
options netloop nloopbacks=1</programlisting>
<para><filename>/etc/xen/auto/01-firewall</filename> — configuration
file for the firewall domain</para>
<programlisting># -*- mode: python; -*-
# configuration name:
name = "firewall"
# usable ram:
memory = 384
# kernel and initrd:
kernel = "/xen2/vmlinuz-xen"
ramdisk = "/xen2/initrd-xen"
# boot device:
root = "/dev/hdb2"
# boot to run level:
extra = "3"
# network interface:
vif = [ 'mac=aa:cc:00:00:00:02, bridge=xenbr0', 'mac=aa:cc:00:00:00:03, bridge=xenbr1' ]
# Interfaces deletgated from Dom0
pci=[ '00:09.0' , '00:0a.0' ]
# storage devices:
disk = [ 'phy:hdb2,hdb2,w' ]</programlisting>
<para><filename>/etc/xen/auto/02-lists</filename> — configuration file
for the lists domain</para>
<programlisting># -*- mode: python; -*-
# configuration name:
name = "lists"
# usable ram:
memory = 512
# kernel and initrd:
kernel = "/xen2/vmlinuz-xen"
ramdisk = "/xen2/initrd-xen"
# boot device:
root = "/dev/hda3"
# boot to run level:
extra = "3"
# network interface:
vif = [ 'mac=aa:cc:00:00:00:01, bridge=xenbr1' ]
hostname = name
# storage devices:
disk = [ 'phy:hda3,hda3,w' ]</programlisting>
</blockquote>
<para>With all three Xen domains up and running, the system looks as
shown in the following diagram.</para>
<graphic align="center" fileref="images/Xen4.png" />
<para>The zones correspond to the Shorewall zones in the firewall DomU
configuration.</para>
<note>
<para>If you want to run a simple NAT gateway in a Xen DomU, just omit
the second bridge (xenbr1), the second delegated interface, and the
second DomU from the above configuration. You can then install the
<ulink url="two-interface.htm">normal Shorewall two-interface sample
configuration</ulink> in the DomU.</para>
</note>
<caution>
<para>Under some circumstances, UDP and/or TCP communication from a
domU won't work for no obvious reason. That happened with the
<emphasis role="bold">lists</emphasis> domain in my setup. Looking at
the IP traffic with <command>tcpdump -nvvi eth1</command> in the
<emphasis role="bold">firewall</emphasis> domU showed that UDP packets
from the <emphasis role="bold">lists</emphasis> domU had incorrect
checksums. That problem was corrected by arranging for the following
command to be executed in the <emphasis role="bold">lists</emphasis>
domain when its <filename class="devicefile">eth0</filename> device
was brought up:</para>
<para><command>ethtool -K eth0 tx off</command></para>
<para>Under SuSE 10.1, I placed the following in
<filename>/etc/sysconfig/network/if-up.d/resettx</filename> (that file
is executable):</para>
<programlisting>#!/bin/sh
if [ $2 = eth0 ]; then
ethtool -K eth0 tx off
echo "TX Checksum reset on eth0"
fi</programlisting>
<para>Under other distributions, the technique will vary. For example,
under <trademark>Debian</trademark> or <trademark>Ubuntu</trademark>,
you can just add a 'post-up' entry to
<filename>/etc/network/interfaces</filename> as shown here:</para>
<programlisting> iface eth0 inet static
address 206.124.146.177
netmask 255.255.255.0
post-up ethtool -K eth0 tx off</programlisting>
</caution>
<caution>
<para>Update. Under SuSE 10.2, communication from a domU works okay
without running ethtool <emphasis role="bold">but traffic shaping in
dom0 doesn't work!</emphasis> So it's a good idea to run it just to be
safe.</para>
</caution>
<para>SuSE 10.1 includes Xen 3.0.2 which supports PCI delegation. The
network interfaces that connect to the net and wifi zones are delegated
to the firewall DomU.</para>
<para>When Shorewall starts during bootup of Dom0, it creates the two
bridges using this <filename>/etc/shorewall/init</filename> extension
script:</para>
<blockquote>
<programlisting>for bridge in xenbr0 xenbr1; do
if [ -z "$(/sbin/brctl show 2&gt; /dev/null | fgrep $bridge)" ]; then
/sbin/brctl addbr $bridge
/sbin/ip link set dev $bridge up
fi
done</programlisting>
</blockquote>
</section>
<section id="Dom0">
<title>Dom0 Configuration</title>
<para>The goals for the Shorewall configuration in Dom0 are as
follows:</para>
<itemizedlist>
<listitem>
<para>Allow traffic to flow unrestricted through the two bridges.
This is done by configuring the hosts connected to each bridge as a
separate zone and relying on Shorewall's implicit intra-zone ACCEPT
policy to permit traffic through the bridge.</para>
</listitem>
<listitem>
<para>Ensure that there is no stray traffic between the zones. This
is a "belt+suspenders" measure since there should be no routing
between the bridges (because they don't have IP addresses).</para>
</listitem>
</itemizedlist>
<para>The configuration is a simple one:</para>
<blockquote>
<para><filename>/etc/shorewall/zones</filename>:</para>
<programlisting>#ZONE TYPE OPTIONS IN OUT
# OPTIONS OPTIONS
fw firewall
loc ipv4
dmz ipv4
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
</programlisting>
<para><filename>/etc/shorewall/policy</filename> (Note the unusual use
of an ACCEPT all-&gt;all policy):</para>
<programlisting>#SOURCE DEST POLICY LOG LIMIT:BURST
# LEVEL
dmz all REJECT info
all dmz REJECT info
all all ACCEPT
#LAST LINE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/interfaces</filename>:</para>
<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
loc xenbr0 192.168.1.255 dhcp,routeback
dmz xenbr1 - routeback
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/rules</filename>:</para>
<programlisting>#ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL RATE USER/
# PORT PORT(S) DEST LIMIT GROUP
#SECTION ESTABLISHED
#SECTION RELATED
SECTION NEW
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
</blockquote>
</section>
<section id="Firewall">
<title>Firewall DomU Configuration</title>
<para>In the firewall DomU, I run a conventional three-interface
firewall with Proxy ARP DMZ -- it is very similar to the firewall
described in the <ulink url="shorewall_setup_guide.htm">Shorewall Setup
Guide</ulink> with the exception that I've added a fourth interface for
our wireless network. The firewall runs a routed <ulink
url="OPENVPN.html">OpenVPN server</ulink> to provide roadwarrior access
for our two laptops and a bridged OpenVPN server for the wireless
network in our home. Here is the firewall's view of the network:</para>
<graphic align="center" fileref="images/network4.png" />
<para>The two laptops can be directly attached to the LAN as shown above
or they can be attached wirelessly -- their IP addresses are the same in
either case; when they are directly attached, the IP address is assigned
by the DHCP server running in Dom0 and when they are attached
wirelessly, the IP address is assigned by OpenVPN.</para>
<para>The Shorewall configuration files are shown below. All routing and
secondary IP addresses are handled in the SUSE network
configuration.</para>
<blockquote>
<para>/etc/shorewall/shorewall.conf:</para>
<programlisting>STARTUP_ENABLED=Yes
VERBOSITY=0
LOGFILE=/var/log/firewall
LOGFORMAT="Shorewall:%s:%s:"
LOGTAGONLY=No
LOGRATE=
LOGBURST=
LOGALLNEW=
BLACKLIST_LOGLEVEL=
MACLIST_LOG_LEVEL=$LOG
TCP_FLAGS_LOG_LEVEL=$LOG
RFC1918_LOG_LEVEL=$LOG
SMURF_LOG_LEVEL=$LOG
LOG_MARTIANS=No
IPTABLES=/usr/sbin/iptables
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:/usr/local/sbin
SHOREWALL_SHELL=/bin/bash
SUBSYSLOCK=
MODULESDIR=
CONFIG_PATH=/etc/shorewall:/usr/share/shorewall
RESTOREFILE=standard
IPSECFILE=zones
IP_FORWARDING=On
ADD_IP_ALIASES=No
ADD_SNAT_ALIASES=No
RETAIN_ALIASES=No
TC_ENABLED=Internal
CLEAR_TC=Yes
MARK_IN_FORWARD_CHAIN=Yes
CLAMPMSS=Yes
ROUTE_FILTER=No
DETECT_DNAT_IPADDRS=Yes
MUTEX_TIMEOUT=60
ADMINISABSENTMINDED=Yes
BLACKLISTNEWONLY=Yes
DELAYBLACKLISTLOAD=No
MODULE_SUFFIX=
DISABLE_IPV6=Yes
BRIDGING=No
DYNAMIC_ZONES=No
PKTTYPE=No
RFC1918_STRICT=Yes
MACLIST_TTL=60
SAVE_IPSETS=No
MAPOLDACTIONS=No
FASTACCEPT=Yes
BLACKLIST_DISPOSITION=DROP
MACLIST_TABLE=mangle
MACLIST_DISPOSITION=DROP
TCP_FLAGS_DISPOSITION=DROP</programlisting>
<para><filename>/etc/shorewall/zones</filename>:</para>
<programlisting>#ZONE TYPE OPTIONS IN OUT
# OPTIONS OPTIONS
fw firewall
net ipv4 #Internet
loc ipv4 #Local wired Zone
dmz ipv4 #DMZ
vpn ipv4 #Open VPN clients
wifi ipv4 #Local Wireless Zone
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
</programlisting>
<para><filename>/etc/shorewall/policy</filename>:</para>
<programlisting>#SOURCE DEST POLICY LOG LIMIT:BURST
# LEVEL
$FW $FW ACCEPT
$FW net ACCEPT
loc net ACCEPT
$FW vpn ACCEPT
vpn net ACCEPT
vpn loc ACCEPT
loc vpn ACCEPT
$FW loc ACCEPT
wifi all REJECT $LOG
loc $FW REJECT $LOG
net $FW DROP $LOG 1/sec:2
net loc DROP $LOG 2/sec:4
net dmz DROP $LOG 8/sec:30
net vpn DROP $LOG
all all REJECT $LOG
#LAST LINE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/params (edited)</filename>:</para>
<programlisting>MIRRORS=&lt;comma-separated list of Shorewall mirrors&gt;
NTPSERVERS=&lt;comma-separated list of NTP servers I sync with&gt;
POPSERVERS=&lt;comma-separated list of server IP addresses&gt;
LOG=info
INT_IF=eth0
DMZ_IF=eth1
EXT_IF=eth3
WIFI_IF=eth4
OMAK=&lt;IP address at our second home&gt;
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/init</filename>:</para>
<programlisting>echo 1 &gt; /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_be_liberal</programlisting>
<para><filename>/etc/shorewall/interfaces</filename>:</para>
<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
net $EXT_IF 206.124.146.255 dhcp,norfc1918,logmartians,blacklist,tcpflags,nosmurfs
dmz $DMZ_IF 192.168.0.255 logmartians
loc $INT_IF 192.168.1.255 dhcp,routeback,logmartians
wifi $WIFI_IF 192.168.3.255 dhcp,maclist
vpn tun+ -
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/nat</filename>:</para>
<programlisting>#EXTERNAL INTERFACE INTERNAL ALL LOCAL
# INTERFACES
206.124.146.178 $EXT_IF 192.168.1.3 No No #Wookie
206.124.146.180 $EXT_IF 192.168.1.6 No No #Work LapTop
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/masq (Note the cute trick here and in
the <filename>following proxyarp</filename> file that allows me to
access the DSL "Modem" using its default IP address
(192.168.1.1))</filename>. The leading "+" is required to place the
rule before the SNAT rules generated by entries in
<filename>/etc/shorewall/nat</filename> above.</para>
<programlisting>#INTERFACE SUBNET ADDRESS PROTO PORT(S) IPSEC
+$EXT_IF:192.168.1.1 0.0.0.0/0 192.168.1.254
$EXT_IF 192.168.0.0/22 206.124.146.179
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/proxyarp</filename>:</para>
<programlisting>#ADDRESS INTERFACE EXTERNAL HAVEROUTE PERSISTENT
192.168.1.1 $EXT_IF $INT_IF yes
206.124.146.177 $DMZ_IF $EXT_IF yes
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/tunnels</filename>:</para>
<programlisting>#TYPE ZONE GATEWAY GATEWAY
# ZONE
openvpnserver:udp net 0.0.0.0/0 #Routed server for RoadWarrior access
openvpnserver:udp wifi 192.168.3.0/24 #Home wireless network server
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/actions</filename>:</para>
<programlisting>#ACTION
Mirrors # Accept traffic from Shorewall Mirrors
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/action.Mirrors</filename>:</para>
<programlisting>#TARGET SOURCE DEST PROTO DEST SOURCE ORIGINAL RATE
# PORT PORT(S) DEST LIMIT
ACCEPT $MIRRORS
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/rules</filename>:</para>
<programlisting>SECTION NEW
###############################################################################################################################################################################
#ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL RATE USER/
# PORT PORT(S) DEST LIMIT GROUP
###############################################################################################################################################################################
REJECT:$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
#
# Stop my idiotic work laptop from sending to the net with an HP source/dest IP address
#
DROP loc:!192.168.0.0/22 net
###############################################################################################################################################################################
# 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 22
ACCEPT loc fw tcp time,631,8080
ACCEPT loc fw udp 161,ntp,631
ACCEPT loc:192.168.1.5 fw udp 111
DROP loc fw tcp 3185 #SUSE Meta pppd
Ping/ACCEPT loc fw
REDIRECT loc 3128 tcp 80 - !206.124.146.177
###############################################################################################################################################################################
# Road Warriors to Firewall
#
ACCEPT vpn fw tcp ssh,time,631,8080
ACCEPT vpn fw udp 161,ntp,631
Ping/ACCEPT vpn fw
###############################################################################################################################################################################
# Road Warriors to DMZ
#
ACCEPT vpn dmz udp domain
ACCEPT vpn dmz tcp www,smtp,smtps,domain,ssh,imap,https,imaps,ftp,10023,pop3 -
Ping/ACCEPT vpn dmz
###############################################################################################################################################################################
# Local network to DMZ
#
ACCEPT loc dmz udp domain
ACCEPT loc dmz tcp ssh,smtps,www,ftp,imaps,domain,https -
ACCEPT loc dmz tcp smtp
Trcrt/ACCEPT loc dmz
###############################################################################################################################################################################
# Internet to ALL -- drop NewNotSyn packets
#
dropNotSyn net fw tcp
dropNotSyn net loc tcp
dropNotSyn net dmz tcp
###############################################################################################################################################################################
# Internet to DMZ
#
ACCEPT net dmz udp domain
ACCEPT net dmz tcp smtps,www,ftp,imaps,domain,https -
ACCEPT net dmz tcp smtp - 206.124.146.177,206.124.146.178
ACCEPT net dmz udp 33434:33454
Mirrors net dmz tcp rsync
Limit:$LOG:SSHA,3,60\
net dmz tcp 22
Trcrt/ACCEPT net dmz
##############################################################################################################################################################################
#
# Net to Local
#
# When I'm "on the road", the following two rules allow me VPN access back home using PPTP.
#
DNAT net loc:192.168.1.4 tcp 1729
DNAT net loc:192.168.1.4 gre
#
# Roadwarrior access to Wookie
#
ACCEPT net:$OMAK loc tcp 22
Limit:$LOG:SSHA,3,60\
net loc tcp 22
#
# ICQ
#
ACCEPT net loc:192.168.1.3 tcp 113,4000:4100
#
# Bittorrent
#
ACCEPT net loc:192.168.1.3 tcp 6881:6889,6969
ACCEPT net loc:192.168.1.3 udp 6881:6889,6969
#
# Skype
#
ACCEPT net loc:192.168.1.6 tcp 1194
#
# Traceroute
#
Trcrt/ACCEPT net loc:192.168.1.3
#
# Silently Handle common probes
#
REJECT net loc tcp www,ftp,https
DROP net loc icmp 8
###############################################################################################################################################################################
# DMZ to Internet
#
ACCEPT dmz net udp domain,ntp
ACCEPT dmz net tcp echo,ftp,ssh,smtp,whois,domain,www,81,https,cvspserver,2702,2703,8080
ACCEPT dmz net:$POPSERVERS tcp pop3
Ping/ACCEPT dmz net
#
# Some FTP clients seem prone to sending the PORT command split over two packets. This prevents the FTP connection tracking
# code from processing the command and setting up the proper expectation. The following rule allows active FTP to work in these cases
# but logs the connection so I can keep an eye on this potential security hole.
#
ACCEPT:$LOG dmz net tcp 1024: 20
###############################################################################################################################################################################
# Local to DMZ
#
ACCEPT loc dmz udp domain,xdmcp
ACCEPT loc dmz tcp www,smtp,smtps,domain,ssh,imap,rsync,https,imaps,ftp,10023,pop3,3128
Trcrt/ACCEPT loc dmz
###############################################################################################################################################################################
# DMZ to Local
#
ACCEPT dmz loc:192.168.1.5 udp 123
ACCEPT dmz loc:192.168.1.5 tcp 21
Ping/ACCEPT dmz loc
###############################################################################################################################################################################
# DMZ to Firewall -- ntp &amp; snmp, Silently reject Auth
#
ACCEPT dmz fw tcp 161,ssh
ACCEPT dmz fw udp 161
REJECT dmz fw tcp auth
Ping/ACCEPT dmz fw
###############################################################################################################################################################################
# Internet to Firewall
#
REJECT net fw tcp www,ftp,https
DROP net fw icmp 8
ACCEPT net fw udp 33434:33454
ACCEPT net:$OMAK fw udp ntp
ACCEPT net fw tcp auth
ACCEPT net:$OMAK fw tcp 22
Limit:$LOG:SSHA,3,60\
net fw tcp 22
Trcrt/ACCEPT net fw
###############################################################################################################################################################################
# Firewall to DMZ
#
ACCEPT fw dmz tcp domain,www,ftp,ssh,smtp,https,993,465
ACCEPT fw dmz udp domain
REJECT fw dmz udp 137:139
Ping/ACCEPT fw dmz
##############################################################################################################################################################################
# Avoid logging Freenode.net probes
#
DROP net:82.96.96.3 all
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
<para><filename>/etc/shorewall/tcdevices</filename></para>
<programlisting>#INTERFACE IN-BANDWITH OUT-BANDWIDTH
$EXT_IF 1300kbit 384kbit
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
</programlisting>
<para><filename>/etc/shorewall/tcclasses</filename><programlisting>#INTERFACE MARK RATE CEIL PRIORITY OPTIONS
$EXT_IF 10 5*full/10 full 1 tcp-ack,tos-minimize-delay
$EXT_IF 20 3*full/10 9*full/10 2 default
$EXT_IF 30 2*full/10 6*full/10 3
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting></para>
<para><filename>/etc/shorewall/tcrules</filename><programlisting>#MARK SOURCE DEST PROTO PORT(S) CLIENT USER TEST
# PORT(S)
1:110 192.168.0.0/22 $EXT_IF #Our internel nets get priority
#over the server
1:130 206.124.146.177 $EXT_IF tcp - 873 #Throttle rsync traffic to the
#Shorewall Mirrors.
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting></para>
</blockquote>
<para>The tap0 device used by the bridged OpenVPN server is bridged to
eth0 using a SuSE-specific SysV init script:</para>
<blockquote>
<programlisting>#!/bin/sh
#
# The Shoreline Firewall (Shorewall) Packet Filtering Firewall - V3.0
#
# This program is under GPL [http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt]
#
# (c) 1999,2000,2001,2002,2003,2004,2005 - Tom Eastep (teastep@shorewall.net)
#
# On most distributions, this file should be called /etc/init.d/shorewall.
#
# Complete documentation is available at http://shorewall.net
#
# 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.
#
# 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# If an error occurs while starting or restarting the firewall, the
# firewall is automatically stopped.
#
# Commands are:
#
# bridge start Starts the bridge
# bridge restart Restarts the bridge
# bridge reload Restarts the bridge
# bridge stop Stops the bridge
# bridge status Displays bridge status
#
# chkconfig: 2345 4 99
# description: Packet filtering firewall
### BEGIN INIT INFO
# Provides: bridge
# Required-Start: boot.udev
# Required-Stop:
# Default-Start: 2 3 5
# Default-Stop: 0 1 6
# Description: starts and stops the bridge
### END INIT INFO
################################################################################
# Interfaces to be bridged -- may be listed by device name or by MAC
#
INTERFACES="eth0"
#
# Tap Devices
#
TAPS="tap0"
################################################################################
# Give Usage Information #
################################################################################
usage() {
echo "Usage: $0 start|stop|reload|restart|status"
exit 1
}
#################################################################################
# Find the interface with the passed MAC address
#################################################################################
find_interface_by_mac() {
local mac
mac=$1
local first
local second
local rest
local dev
/sbin/ip link ls | while read first second rest; do
case $first in
*:)
dev=$second
;;
*)
if [ "$second" = $mac ]; then
echo ${dev%:}
return
fi
esac
done
}
################################################################################
# Convert MAC addresses to interface names
################################################################################
get_interfaces() {
local interfaces
interfaces=
local interface
for interface in $INTERFACES; do
case $interface in
*:*:*)
interface=$(find_interface_by_mac $interface)
[ -n "$interface" ] || echo "WARNING: Can't find an interface with MAC address $mac"
;;
esac
interfaces="$interfaces $interface"
done
INTERFACES="$interfaces"
}
################################################################################
# Start the Bridge
################################################################################
do_start()
{
local interface
get_interfaces
for interface in $TAPS; do
/usr/sbin/openvpn --mktun --dev $interface
done
/sbin/brctl addbr br0
for interface in $INTERFACES $TAPS; do
/sbin/ip link set $interface up
/sbin/brctl addif br0 $interface
done
}
################################################################################
# Stop the Bridge
################################################################################
do_stop()
{
local interface
get_interfaces
for interface in $INTERFACES $TAPS; do
/sbin/brctl delif br0 $interface
/sbin/ip link set $interface down
done
/sbin/ip link set br0 down
/sbin/brctl delbr br0
for interface in $TAPS; do
/usr/sbin/openvpn --rmtun --dev $interface
done
}
################################################################################
# E X E C U T I O N B E G I N S H E R E #
################################################################################
command="$1"
case "$command" in
start)
do_start
;;
stop)
do_stop
;;
restart|reload)
do_stop
do_start
;;
status)
/sbin/brctl show
;;
*)
usage
;;
esac
</programlisting>
</blockquote>
</section>
</section>
</article>
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