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1082 lines
42 KiB
XML
1082 lines
42 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<article>
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<!--$Id$-->
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<articleinfo>
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<title>Xen and the Art of Consolidation</title>
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<authorgroup>
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<author>
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<firstname>Tom</firstname>
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<surname>Eastep</surname>
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</author>
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</authorgroup>
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<pubdate>2006-03-26</pubdate>
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<copyright>
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<year>2006</year>
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<holder>Thomas M. Eastep</holder>
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</copyright>
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<legalnotice>
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<para>Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License, Version
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1.2 or any later version published by the Free Software Foundation; with
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no Invariant Sections, with no Front-Cover, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled
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<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
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License</ulink></quote>.</para>
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</legalnotice>
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</articleinfo>
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<section>
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<title>Before Xen</title>
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<para>Prior to adopting <ulink url="Xen.html">Xen</ulink>, I had a home
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office crowded with 5 systems, three monitors a scanner and a printer. The
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systems were:</para>
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<orderedlist>
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<listitem>
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<para>Firewall</para>
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</listitem>
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<listitem>
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<para>Public Server in a DMZ (mail)</para>
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</listitem>
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<listitem>
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<para>Private Server (wookie)</para>
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</listitem>
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<listitem>
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<para>My personal Linux Desktop (ursa)</para>
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</listitem>
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<listitem>
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<para>My work system (docked laptop running Windows XP).</para>
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</listitem>
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</orderedlist>
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<para>The result was a very crowded and noisy room.</para>
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</section>
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<section>
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<title>After Xen</title>
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<para>Xen has allowed me to reduce the noise and clutter considerably. I
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now have three systems with two monitors. I've also replaced the
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individual printer and scanner with a Multifunction
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FAX/Scanner/Printer.</para>
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<para>The systems now include:</para>
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<orderedlist>
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<listitem>
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<para>Combination Firewall/Public Server/Private Server using Xen
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(created by building out my Linux desktop system).</para>
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</listitem>
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<listitem>
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<para>My work system.</para>
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</listitem>
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<listitem>
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<para>My Linux desktop (wookie, which is actually the old public
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server box)</para>
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</listitem>
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</orderedlist>
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<para>All of the Linux systems run SuSE 10.0 or SuSE 10.1 Beta.</para>
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<para>If you are unfamiliar with Xen networking, I recommend that you read
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the first section of the companion <ulink url="Xen.html">Xen and
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Shorewall</ulink> article.</para>
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<para>Here is a high-level diagram of our network.</para>
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<graphic align="center" fileref="images/Xen5.png" />
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<para>As shown in this diagram, the Xen system has three physical network
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interfaces. These are:</para>
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<itemizedlist>
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<listitem>
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<para><filename class="devicefile">eth0</filename> -- conntected to
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the switch in my office. That switch is cabled to a second switch in
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my wife's office where my wife has her desktop and networked printer
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(I sure wish that there had been wireless back when I strung that
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CAT-5 cable halfway across the house).</para>
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</listitem>
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<listitem>
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<para><filename class="devicefile">eth1</filename> -- connected to our
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DSL "Modem".</para>
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</listitem>
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<listitem>
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<para><filename class="devicefile">eth2</filename> -- connected to a
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Wireless Access Point (WAP) that interfaces to our wireless
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network.</para>
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</listitem>
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</itemizedlist>
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<para>There are four Xen domains. Dom0 (ursa.shorewall.net) is used as a
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file server (NFS and Samba). The first DomU (Dom name <emphasis
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role="bold">firewall</emphasis>, gateway.shorewall.net) is used as our
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main firewall; the second DomU (Dom name <emphasis
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role="bold">lists</emphasis>, lists.shorewall.net) is used as a public
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Web/FTP/Mail/DNS server while the third DomU (Dom name <emphasis
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role="bold">wireless</emphasis>, wireless.shorewall.net) is used as a
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gateway to our wireless network. A seperate wireless gateway is necessary
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because Xen 3 only supports three virtual interfaces per DomU and the
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firewall DomU already has three interfaces. Shorewall runs in Dom0, in the
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firewall domain and in the wireless gateway.</para>
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<section id="Domains">
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<title>Domain Configuration</title>
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<para>Below are the relevant configuration files for the four domains.
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The "loopback.nloopbacks=..." entries are used to restrict the number of
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"veth<emphasis>n</emphasis>" devices that the Xen kernel creates. I use
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partitions on my hard drives for DomU storage devices.</para>
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<blockquote>
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<para><filename>/boot/grub/menu.lst</filename> — here is the entry
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that boots Xen in Dom0.</para>
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<programlisting>title XEN
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root (hd0,1)
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kernel /boot/xen.gz dom0_mem=458752 sched=bvt
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module /boot/vmlinuz-xen root=/dev/hda2 vga=0x31a selinux=0 resume=/dev/hda1 splash=silent showopts loopback.nloopbacks=1
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module /boot/initrd-xen</programlisting>
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<para><filename>/etc/xen/auto/01-firewall</filename> — configuration
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file for the firewall domain</para>
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<programlisting># -*- mode: python; -*-
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# configuration name:
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name = "firewall"
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# usable ram:
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memory = 256
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# kernel and initrd:
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kernel = "/boot/vmlinuz-xen"
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ramdisk = "/boot/initrd-xen"
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# boot device:
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root = "/dev/hdb2"
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# boot to run level:
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extra = "loopback.nloopbacks=0 3"
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# network interface:
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vif = [ 'mac=aa:cc:00:00:00:02, bridge=xenbr0', 'mac=aa:cc:00:00:00:03, bridge=xenbr1' , 'mac=00:a0:cc:63:66:89, bridge=xenbr2' ]
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hostname = name
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# storage devices:
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disk = [ 'phy:hdb2,hdb2,w' ]</programlisting>
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<para><filename>/etc/xen/auto/02-lists</filename> — configuration file
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for the lists domain</para>
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<programlisting># -*- mode: python; -*-
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# configuration name:
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name = "lists"
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# usable ram:
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memory = 512
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# kernel and initrd:
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kernel = "/boot/vmlinuz-xen"
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ramdisk = "/boot/initrd-xen"
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# boot device:
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root = "/dev/hda3"
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# boot to run level:
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extra = "loopback.nloopbacks=0 3"
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# network interface:
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vif = [ 'mac=aa:cc:00:00:00:01, bridge=xenbr1' ]
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hostname = name
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# storage devices:
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disk = [ 'phy:hda3,hda3,w' ]</programlisting>
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<para>/etc/xen/auto/03-wireless — configuration file for the wireless
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domain.</para>
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<programlisting># -*- mode: python; -*-
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# configuration name:
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name = "wireless"
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# usable ram:
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memory = 256
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# kernel and initrd:
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kernel = "/boot/vmlinuz-xen"
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ramdisk = "/boot/initrd-xen"
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# boot device:
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root = "/dev/hdb4"
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# boot to run level:
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extra = "loopback.nloopbacks=0 3"
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# network interface:
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vif = [ 'mac=aa:cc:00:00:00:04, bridge=xenbr0', 'mac=00:a0:cc:d1:db:12, bridge=xenbr3' ]
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dhcp = 'dhcp'
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hostname = name
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# storage devices:
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disk = [ 'phy:hdb4,hdb4,w' ]</programlisting>
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</blockquote>
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<para>With all four Xen domains up and running, the system looks as
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shown in the following diagram.</para>
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<graphic align="center" fileref="images/Xen4.png" />
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<para>The zones correspond to the Shorewall zones in the Dom0
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configuration.</para>
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<para>SuSE 10.0 includes Xen 3.0 which does not support PCI delegation;
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I therefore use a bridged configuration with four bridges (one for each
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network interface). When Shorewall starts during bootup of Dom0, it
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creates the four bridges using this
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<filename>/etc/shorewall/init</filename> extension script:</para>
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<blockquote>
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<programlisting>for bridge in xenbr0 xenbr1 xenbr2 xenbr3; do
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if [ -z "$(/sbin/brctl show 2> /dev/null | fgrep $bridge)" ]; then
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/sbin/brctl addbr $bridge
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case $bridge in
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xenbr2)
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mac=`ip link show eth1 | grep 'link\/ether' | sed -e 's/.*ether \(..:..:..:..:..:..\).*/\1/'`
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[ "$mac" = "fe:ff:ff:ff:ff:ff" ] || /sbin/ip link set dev eth1 addr fe:ff:ff:ff:ff:ff
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/sbin/ip link set dev eth1 up
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/sbin/brctl addif xenbr2 eth1
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;;
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xenbr3)
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mac=`ip link show eth2 | grep 'link\/ether' | sed -e 's/.*ether \(..:..:..:..:..:..\).*/\1/'`
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[ "$mac" = "fe:ff:ff:ff:ff:ff" ] || /sbin/ip link set dev eth2 addr fe:ff:ff:ff:ff:ff
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/sbin/ip link set dev eth2 up
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/sbin/brctl addif xenbr3 eth2
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;;
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esac
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/sbin/ip link set dev $bridge up
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fi
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done</programlisting>
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</blockquote>
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</section>
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<section id="Dom0">
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<title>Dom0 Configuration</title>
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<para>The goals for the Shorewall configuration in Dom0 are as
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follows:</para>
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<itemizedlist>
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<listitem>
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<para>Allow traffic to flow unrestricted through the four bridges.
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This is done by configuring the hosts connected to each bridge as a
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separate zone and relying on Shorewall's implicit intra-zone ACCEPT
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policy to permit traffic through the bridge.</para>
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</listitem>
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<listitem>
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<para>Ensure that there is no stray traffic between the zones. This
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is a "belt+suspenders" measure since there should be no routing
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between the bridges (because they don't have IP addresses).</para>
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</listitem>
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</itemizedlist>
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<para>The configuration is a simple one:</para>
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<blockquote>
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<para><filename>/etc/shorewall/zones</filename>:</para>
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<programlisting>#ZONE TYPE OPTIONS IN OUT
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# OPTIONS OPTIONS
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fw firewall
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Wifi ipv4
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loc ipv4
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dmz ipv4
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net ipv4
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#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
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</programlisting>
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<para><filename>/etc/shorewall/policy</filename> (Note the unusual use
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of an ACCEPT all->all policy):</para>
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<programlisting>#SOURCE DEST POLICY LOG LIMIT:BURST
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# LEVEL
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Wifi all REJECT info
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all Wifi REJECT info
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dmz all REJECT info
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all dmz REJECT info
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net all REJECT info
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all net REJECT info
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all all ACCEPT
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#LAST LINE -- DO NOT REMOVE</programlisting>
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<para><filename>/etc/shorewall/interfaces</filename>:</para>
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<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
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Wifi xenbr3 - routeback
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loc xenbr0 192.168.1.255 dhcp,routeback
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dmz xenbr1 - routeback
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net xenbr2 - routeback
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#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
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<para><filename>/etc/shorewall/rules</filename>:</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL RATE USER/
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# PORT PORT(S) DEST LIMIT GROUP
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#SECTION ESTABLISHED
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#SECTION RELATED
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SECTION NEW
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#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
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</blockquote>
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</section>
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<section id="Firewall">
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<title>Firewall DomU Configuration</title>
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<para>In the firewall DomU, I run a conventional three-interface
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firewall with Proxy ARP DMZ -- it is very similar to the firewall
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described in the <ulink url="shorewall_setup_guide.htm">Shorewall Setup
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Guide</ulink>. The firewall runs a routed <ulink
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url="OPENVPN.html">OpenVPN server</ulink> to provide roadwarrior access
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for our two laptops. Here is the firewall's view of the network:</para>
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<graphic align="center" fileref="images/network4.png" />
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<para>The two laptops can be directly attached to the LAN as shown above
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or they can be attached wirelessly through the <link
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linkend="Wireless">wireless gateway</link> -- their IP addresses are the
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same in either case.</para>
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<para>The Shorewall configuration files are shown below. All routing and
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secondary IP addresses are handled in the SuSE network
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configuration.</para>
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<blockquote>
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<para>/etc/shorewall/shorewall.conf:</para>
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<programlisting>STARTUP_ENABLED=Yes
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VERBOSITY=0
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LOGFILE=/var/log/firewall
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LOGFORMAT="Shorewall:%s:%s:"
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LOGTAGONLY=No
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LOGRATE=
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LOGBURST=
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LOGALLNEW=
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BLACKLIST_LOGLEVEL=
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MACLIST_LOG_LEVEL=$LOG
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TCP_FLAGS_LOG_LEVEL=$LOG
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RFC1918_LOG_LEVEL=$LOG
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SMURF_LOG_LEVEL=$LOG
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LOG_MARTIANS=No
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IPTABLES=/usr/sbin/iptables
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PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:/usr/local/sbin
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SHOREWALL_SHELL=/bin/bash
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SUBSYSLOCK=
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MODULESDIR=
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CONFIG_PATH=/etc/shorewall:/usr/share/shorewall
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RESTOREFILE=standard
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IPSECFILE=zones
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IP_FORWARDING=On
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ADD_IP_ALIASES=No
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ADD_SNAT_ALIASES=No
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RETAIN_ALIASES=No
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TC_ENABLED=Internal
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CLEAR_TC=Yes
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MARK_IN_FORWARD_CHAIN=Yes
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CLAMPMSS=Yes
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ROUTE_FILTER=No
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DETECT_DNAT_IPADDRS=Yes
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MUTEX_TIMEOUT=60
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ADMINISABSENTMINDED=Yes
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BLACKLISTNEWONLY=Yes
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DELAYBLACKLISTLOAD=No
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MODULE_SUFFIX=
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DISABLE_IPV6=Yes
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BRIDGING=No
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DYNAMIC_ZONES=No
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PKTTYPE=No
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RFC1918_STRICT=Yes
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MACLIST_TTL=60
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SAVE_IPSETS=No
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MAPOLDACTIONS=No
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FASTACCEPT=Yes
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BLACKLIST_DISPOSITION=DROP
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MACLIST_TABLE=mangle
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MACLIST_DISPOSITION=DROP
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TCP_FLAGS_DISPOSITION=DROP</programlisting>
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<para><filename>/etc/shorewall/zones</filename>:</para>
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<programlisting>#ZONE TYPE OPTIONS IN OUT
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# OPTIONS OPTIONS
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fw firewall
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net ipv4 #Internet
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loc ipv4 #Local wired Zone
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dmz:loc ipv4 #DMZ -- server running in virtual machine at 206.124.146.177
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vpn ipv4 #Open VPN clients
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#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
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</programlisting>
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|
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<para><filename>/etc/shorewall/policy</filename>:</para>
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|
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<programlisting>#SOURCE DEST POLICY LOG LIMIT:BURST
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# LEVEL
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$FW $FW ACCEPT
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$FW net ACCEPT
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loc net ACCEPT
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$FW vpn ACCEPT
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vpn net ACCEPT
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vpn loc ACCEPT
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loc vpn ACCEPT
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$FW loc ACCEPT
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loc $FW REJECT $LOG
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net all DROP $LOG 10/sec:40
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all all REJECT $LOG
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#LAST LINE -- DO NOT REMOVE</programlisting>
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<para><filename>/etc/shorewall/params (edited)</filename>:</para>
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<programlisting>MIRRORS=<comma-separated list of Shorewall mirrors>
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NTPSERVERS=<comma-separated list of NTP servers I sync with>
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POPSERVERS=<comma-separated list of server IP addresses>
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LOG=info
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INT_IF=eth0
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DMZ_IF=eth1
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EXT_IF=eth3
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OMAK=<IP address at our second home>
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|
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#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE</programlisting>
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|
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<para><filename>/etc/shorewall/init</filename>:</para>
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|
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<programlisting>echo 1 > /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_be_liberal</programlisting>
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|
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<para><filename>/etc/shorewall/interfaces</filename>:</para>
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<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
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net $EXT_IF 206.124.146.255 dhcp,norfc1918,logmartians,blacklist,tcpflags,nosmurfs
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dmz $DMZ_IF 192.168.0.255 logmartians
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loc $INT_IF 192.168.1.255 dhcp,routeback,logmartians
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vpn tun+ -
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#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
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|
|
<para><filename>/etc/shorewall/nat</filename>:</para>
|
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|
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<programlisting>#EXTERNAL INTERFACE INTERNAL ALL LOCAL
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# INTERFACES
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206.124.146.178 $EXT_IF 192.168.1.3 No No
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206.124.146.180 $EXT_IF 192.168.1.6 No No
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#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE</programlisting>
|
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|
|
<para><filename>/etc/shorewall/masq (Note the cute trick here and in
|
|
the <filename>proxyarp</filename> file that follows that allows me to
|
|
access the DSL "Modem" using it's default IP address
|
|
(192.168.1.1))</filename>:</para>
|
|
|
|
<programlisting>#INTERFACE SUBNET ADDRESS PROTO PORT(S) IPSEC
|
|
+$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
|
|
#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
|
|
LOG:$LOG net:64.126.128.0/18 dmz tcp smtp
|
|
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:$LOG:SSHA,3,60\
|
|
net loc tcp 22
|
|
|
|
#
|
|
# ICQ
|
|
#
|
|
ACCEPT net loc:192.168.1.3 tcp 113,4000:4100
|
|
#
|
|
# Bittorrent
|
|
#
|
|
ACCEPT net loc:192.168.1.3 tcp 6881:6889,6969
|
|
ACCEPT net loc:192.168.1.3 udp 6881:6889,6969
|
|
#
|
|
# Real Audio
|
|
#
|
|
ACCEPT net loc:192.168.1.3 udp 6970:7170
|
|
#
|
|
# Skype
|
|
#
|
|
ACCEPT net loc:192.168.1.6 tcp 1194
|
|
#
|
|
# Traceroute
|
|
#
|
|
Trcrt/ACCEPT net loc:192.168.1.3
|
|
#
|
|
# Silently Handle common probes
|
|
#
|
|
REJECT net loc tcp www,ftp,https
|
|
DROP net loc icmp 8
|
|
###############################################################################################################################################################################
|
|
# DMZ to Internet
|
|
#
|
|
ACCEPT dmz net udp domain,ntp
|
|
ACCEPT dmz net tcp echo,ftp,ssh,smtp,whois,domain,www,81,https,cvspserver,2702,2703,8080
|
|
ACCEPT dmz net:$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:$LOG dmz net tcp 1024: 20
|
|
###############################################################################################################################################################################
|
|
# Local to DMZ
|
|
#
|
|
ACCEPT loc dmz udp domain,xdmcp
|
|
ACCEPT loc dmz tcp www,smtp,smtps,domain,ssh,imap,rsync,https,imaps,ftp,10023,pop3,3128
|
|
Trcrt/ACCEPT loc dmz
|
|
###############################################################################################################################################################################
|
|
# DMZ to Local
|
|
#
|
|
ACCEPT dmz net:192.168.1.254 udp 123
|
|
ACCEPT dmz loc:192.168.1.5 tcp 21
|
|
Ping/ACCEPT dmz loc
|
|
|
|
###############################################################################################################################################################################
|
|
# DMZ to Firewall -- ntp & snmp, Silently reject Auth
|
|
#
|
|
ACCEPT dmz fw tcp 161,ssh
|
|
ACCEPT dmz fw udp 161
|
|
REJECT dmz fw tcp auth
|
|
Ping/ACCEPT dmz fw
|
|
###############################################################################################################################################################################
|
|
# Internet to Firewall
|
|
#
|
|
REJECT net fw tcp www,ftp,https
|
|
DROP net fw icmp 8
|
|
ACCEPT net fw udp 33434:33454
|
|
ACCEPT net:$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>
|
|
</blockquote>
|
|
</section>
|
|
|
|
<section id="Wireless">
|
|
<title>Wireless Gateway DomU Configuration</title>
|
|
|
|
<para>The Shorewall configuration in the 'wireless' DomU is very simple.
|
|
It's sole purpose is to protect the local network from the Wireless net
|
|
by restricting wireless access to clients that have established an
|
|
<ulink url="OPENVPN.html">OpenVPN</ulink> Bridged connection. This
|
|
configuration illustrates that you can use any system on your internal
|
|
LAN as a wireless gateway -- it doesn't have to be your main firewall
|
|
(and it doesn't have to run in a Xen domain either and it doesn't even
|
|
have to run Linux). Our wireless gateway runs a DHCP server that assigns
|
|
wireless hosts an IP address in 192.168.3.0/24 -- The OpenVPN server
|
|
running on the gateway assigns its clients an IP address in
|
|
192.168.1.0/24 so, thanks to bridging, these clients appear to be
|
|
physically attached to the LAN). That allows our two laptops to have the
|
|
same IP address in 192.168.1.0/24 regardless of whether they are
|
|
connected to the LAN directly or are connected via the wireless
|
|
network.</para>
|
|
|
|
<graphic align="center" fileref="images/Xen6.png" />
|
|
|
|
<para>The 'tap0' device used by OpenVPN is bridged to eth2 using this
|
|
SuSE-specific startup script (see the <ulink url="bridge.html">Shorewall
|
|
Bridge Documentation</ulink> for scripts that work on other
|
|
distributions):</para>
|
|
|
|
<blockquote>
|
|
<para><filename>/etc/init.d/bridge</filename>:</para>
|
|
|
|
<programlisting>#!/bin/sh
|
|
#
|
|
# The Shoreline Firewall (Shorewall) Packet Filtering Firewall - V3.0
|
|
#
|
|
# This program is under GPL [http://www.gnu.org/copyleft/gpl.htm]
|
|
#
|
|
# (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., 675 Mass Ave, Cambridge, MA 02139, 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 address
|
|
#
|
|
INTERFACES="eth2"
|
|
|
|
#
|
|
# 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=$1 first second rest 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= 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"
|
|
}
|
|
################################################################################
|
|
# Configure the Bridge -- IP configuration is left to the SuSE network scripts
|
|
################################################################################
|
|
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>
|
|
|
|
<para>As mentioned in the comments in the above script, IP
|
|
configuration of the bridge is done through the normal SuSE network
|
|
scripts. Here's the config file:</para>
|
|
|
|
<programlisting>BOOTPROTO='static'
|
|
BROADCAST=''
|
|
IPADDR='192.168.1.7'
|
|
MTU=''
|
|
NAME='Ethernet Network Card'
|
|
NETMASK='255.255.255.0'
|
|
NETWORK=''
|
|
REMOTE_IPADDR=''
|
|
STARTMODE='auto'
|
|
USERCONTROL='no'
|
|
_nm_name='br0'</programlisting>
|
|
|
|
<para>Since there is no requirement to restrict connections through
|
|
the bridge, I set BRIDGING=No in
|
|
<filename>/etc/shorewall/shorewall.conf</filename>.</para>
|
|
|
|
<para><filename>/etc/shorewall/zones</filename>:</para>
|
|
|
|
<programlisting>#ZONE TYPE OPTIONS IN OUT
|
|
# OPTIONS OPTIONS
|
|
fw firewall
|
|
Wifi ipv4
|
|
loc ipv4
|
|
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE</programlisting>
|
|
|
|
<para><filename>/etc/shorewall/interfaces</filename>:</para>
|
|
|
|
<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
|
|
Wifi eth4 192.168.3.255 dhcp,maclist
|
|
loc br0 192.168.1.255 dhcp,routeback
|
|
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
|
|
</programlisting>
|
|
|
|
<para><filename>/etc/shorewall/policy</filename> (again, note the use
|
|
of an ACCEPT all->all policy):</para>
|
|
|
|
<programlisting>#SOURCE DEST POLICY LOG LIMIT:BURST
|
|
# LEVEL
|
|
Wifi all REJECT info
|
|
all all ACCEPT
|
|
#LAST LINE -- DO NOT REMOVE</programlisting>
|
|
|
|
<para><filename>/etc/shorewall/tunnels</filename>:</para>
|
|
|
|
<programlisting>#TYPE ZONE GATEWAY GATEWAY
|
|
# ZONE
|
|
openvpnserver Wifi 192.168.3.0/24
|
|
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
|
|
|
|
<para><filename>/etc/shorewall/maclist (Note that this system runs
|
|
Shorewall 3.2 so there is an additional 'TARGET'
|
|
column)</filename>:</para>
|
|
|
|
<programlisting>#TARGET INTERFACE MAC IP ADDRESSES (Optional)
|
|
ACCEPT eth4 00:04:5a:0e:85:b9 #WAP11
|
|
ACCEPT eth4 00:06:25:45:33:3c #WET11
|
|
ACCEPT eth4 00:0b:cd:53:cc:97 192.168.3.8 #TIPPER
|
|
ACCEPT eth4 00:0f:66:ef:b6:f6 192.168.3.8 #TIPPER1
|
|
ACCEPT eth4 00:12:79:3d:fe:2e 192.168.3.6 #Work Laptop
|
|
ACCEPT eth4 - 192.168.3.254 #Broadcast/Multicast from us
|
|
DROP:info eth4 - 192.168.3.0/24
|
|
DROP:info eth4 - 169.254.0.0/16 #Stop autoconfigured hosts.
|
|
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE</programlisting>
|
|
|
|
<para>The routing table on the wireless gateway is as follows:</para>
|
|
|
|
<blockquote>
|
|
<programlisting>192.168.3.0/24 dev eth4 proto kernel scope link src 192.168.3.254
|
|
192.168.1.0/24 dev br0 proto kernel scope link src 192.168.1.7
|
|
169.254.0.0/16 dev eth4 scope link
|
|
127.0.0.0/8 dev lo scope link
|
|
default via 192.168.1.254 dev br0</programlisting>
|
|
</blockquote>
|
|
|
|
<para>The route to 169.254.0.0/16 is automatically generated by the
|
|
SuSE network scripts so I include that network in the
|
|
<filename>/etc/shorewall/maclist</filename> file for
|
|
completeness.</para>
|
|
|
|
<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
|
|
ACCEPT Wifi loc:192.168.1.5 udp 123 #Allow NTP before OpenVPN is up.
|
|
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
|
|
</blockquote>
|
|
|
|
<para>Here is the configuration of OpenVPN on this system:</para>
|
|
|
|
<blockquote>
|
|
<para><filename>/etc/openvpn/server-bridge</filename> (Note that I
|
|
prefer to push two /1 routes rather than to use the <emphasis
|
|
role="bold">redirect-gateway</emphasis> directive on the client
|
|
systems; I find that <emphasis role="bold">redirect-gateway</emphasis>
|
|
occasionally leaves a client system with <emphasis
|
|
role="bold">no</emphasis> default gateway):</para>
|
|
|
|
<programlisting>dev tap0
|
|
|
|
local 192.168.3.254
|
|
|
|
server-bridge 192.168.1.5 255.255.255.0 192.168.1.64 192.168.1.71
|
|
|
|
client-to-client
|
|
|
|
dh dh1024.pem
|
|
|
|
ca /etc/certs/cacert.pem
|
|
|
|
crl-verify /etc/certs/crl.pem
|
|
|
|
cert /etc/certs/wireless.pem
|
|
key /etc/certs/wireless_key.pem
|
|
|
|
port 1194
|
|
|
|
comp-lzo
|
|
|
|
user nobody
|
|
group nogroup
|
|
|
|
keepalive 15 45
|
|
ping-timer-rem
|
|
persist-tun
|
|
persist-key
|
|
|
|
client-config-dir /etc/openvpn/bridge-clients
|
|
ccd-exclusive
|
|
|
|
verb 3
|
|
|
|
push "route 0.0.0.0 128.0.0.0 192.168.1.254"
|
|
push "route 128.0.0.0 128.0.0.0 192.168.1.254"</programlisting>
|
|
|
|
<para><filename>/etc/bridge-clients/tipper.shorewall.net</filename>
|
|
(used to assign a fixed IP address to clients -- there are other
|
|
similar files in this directory):</para>
|
|
|
|
<programlisting>ifconfig-push 192.168.1.8 255.255.255.0</programlisting>
|
|
</blockquote>
|
|
|
|
<para>Finally, here's a copy of the OpenVPN configuration file on
|
|
tipper, one of the laptops:</para>
|
|
|
|
<blockquote>
|
|
<programlisting>dev tap
|
|
|
|
remote 192.168.3.254
|
|
tls-remote wireless.shorewall.net
|
|
|
|
client
|
|
tls-client
|
|
explicit-exit-notify
|
|
|
|
ca /etc/certs/cacert.pem
|
|
|
|
cert /etc/certs/tipper.pem
|
|
key /etc/certs/tipper_key.pem
|
|
|
|
port 1194
|
|
|
|
comp-lzo
|
|
|
|
ping 15
|
|
ping-restart 45
|
|
ping-timer-rem
|
|
persist-tun
|
|
persist-key
|
|
|
|
mute-replay-warnings
|
|
|
|
verb 3</programlisting>
|
|
</blockquote>
|
|
</section>
|
|
</section>
|
|
</article> |