2003-12-16 22:08:51 +01:00
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<?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 id="IPSEC">
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<articleinfo>
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<title>IPSEC Tunnels</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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2003-12-16 23:22:21 +01:00
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<pubdate>2003-10-29</pubdate>
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2003-12-16 22:08:51 +01:00
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<copyright>
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<year>2001</year>
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<year>2002</year>
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<year>2003</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 "<ulink
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url="GnuCopyright.htm">GNU Free Documentation License</ulink>".</para>
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</legalnotice>
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</articleinfo>
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<section>
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<title>Configuring FreeS/Wan</title>
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<para>There is an excellent guide to configuring IPSEC tunnels at <ulink
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url="http://www.geocities.com/jixen66/">http://www.geocities.com/jixen66/</ulink>.
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I highly recommend that you consult that site for information about
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configuring FreeS/Wan.</para>
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<warning>
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<para>Do not use Proxy ARP and FreeS/Wan on the same system unless you
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are prepared to suffer the consequences. If you start or restart
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Shorewall with an IPSEC tunnel active, the proxied IP addresses are
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mistakenly assigned to the IPSEC tunnel device (ipsecX) rather than to
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the interface that you specify in the INTERFACE column of
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/etc/shorewall/proxyarp. I haven't had the time to debug this
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problem so I can't say if it is a bug in the Kernel or in FreeS/Wan.</para>
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<para>You <emphasis role="bold">might</emphasis> be able to work around
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this problem using the following (I haven't tried it):</para>
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<para>In /etc/shorewall/init, include:</para>
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<programlisting>qt service ipsec stop</programlisting>
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<para>In /etc/shorewall/start, include:</para>
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<programlisting>qt service ipsec start</programlisting>
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</warning>
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<important>
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<para>The documentation below assumes that you have disabled
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opportunistic encryption feature in FreeS/Wan 2.0 using the following
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additional entries in ipsec.conf:</para>
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<programlisting>conn block
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auto=ignore
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conn private
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auto=ignore
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conn private-or-clear
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auto=ignore
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conn clear-or-private
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auto=ignore
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conn clear
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auto=ignore
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conn packetdefault
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auto=ignore</programlisting>
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<para>For further information see <ulink
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url="http://www.freeswan.org/freeswan_trees/freeswan-2.03/doc/policygroups.html">http://www.freeswan.org/freeswan_trees/freeswan-2.03/doc/policygroups.html</ulink>.</para>
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</important>
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</section>
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<section>
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<title>IPSec Gateway on the Firewall System</title>
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<para>Suppose that we have the following sutuation:</para>
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<graphic fileref="images/TwoNets1.png" />
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<para>We want systems in the 192.168.1.0/24 sub-network to be able to
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communicate with systems in the 10.0.0.0/8 network.</para>
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<para>To make this work, we need to do two things:</para>
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<orderedlist numeration="loweralpha">
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<listitem>
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<para>Open the firewall so that the IPSEC tunnel can be established
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2003-12-16 23:22:21 +01:00
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(allow the ESP and AH protocols and UDP Port 500).</para>
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2003-12-16 22:08:51 +01:00
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</listitem>
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<listitem>
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<para>Allow traffic through the tunnel.</para>
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</listitem>
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</orderedlist>
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<para>Opening the firewall for the IPSEC tunnel is accomplished by adding
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an entry to the /etc/shorewall/tunnels file.</para>
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<para>In /etc/shorewall/tunnels on system A, we need the following</para>
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<table>
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<title>/etc/shorewall/tunnels system A</title>
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<tgroup cols="4">
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<thead>
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<row>
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<entry align="center">TYPE</entry>
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<entry align="center">ZONE</entry>
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<entry align="center">GATEWAY</entry>
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2003-12-16 23:22:21 +01:00
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<entry align="center">GATEWAY ZONE</entry>
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2003-12-16 22:08:51 +01:00
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</row>
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</thead>
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<tbody>
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<row>
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<entry>ipsec</entry>
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<entry>net</entry>
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<entry>134.28.54.2</entry>
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<entry></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>In /etc/shorewall/tunnels on system B, we would have:</para>
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<table>
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<title>/etc/shorewall/tunnels system B</title>
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<tgroup cols="4">
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<thead>
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<row>
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<entry align="center">TYPE</entry>
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<entry align="center">ZONE</entry>
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<entry align="center">GATEWAY</entry>
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<entry align="center">GATEWAY ZONE</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>ipsec</entry>
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<entry>net</entry>
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<entry>206.161.148.9</entry>
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<entry></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<note>
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<para>If either of the endpoints is behind a NAT gateway then the
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tunnels file entry on the <emphasis role="bold">other</emphasis>
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endpoint should specify a tunnel type of ipsecnat rather than ipsec and
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the GATEWAY address should specify the external address of the NAT
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gateway.</para>
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</note>
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<example>
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<title>VPN</title>
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<para>You need to define a zone for the remote subnet or include it in
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your local zone. In this example, we'll assume that you have created
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a zone called "vpn" to represent the remote subnet.</para>
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<para><table><title>/etc/shorewall/zones local</title><tgroup cols="3"><thead><row><entry
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align="center">ZONE</entry><entry align="center">DISPLAY</entry><entry
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align="center">COMMENTS</entry></row></thead><tbody><row><entry>vpn</entry><entry>VPN</entry><entry>Remote
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Subnet</entry></row></tbody></tgroup></table></para>
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<para>At both systems, ipsec0 would be included in
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/etc/shorewall/interfaces as a "vpn" interface:</para>
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<para><table><title>/etc/shorewall/interfaces system local & remote</title><tgroup
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cols="4"><thead><row><entry align="center">ZONE</entry><entry
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align="center">INTERFACE</entry><entry align="center">BROADCAST</entry><entry
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align="center">OPTIONS</entry></row></thead><tbody><row><entry>vpn</entry><entry>ipsec0</entry><entry></entry><entry></entry></row></tbody></tgroup></table></para>
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<para>You will need to allow traffic between the "vpn" zone and
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the "loc" zone -- if you simply want to admit all traffic in
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both directions, you can use the policy file:</para>
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<para><table><title>/etc/shorewall/policy local & remote</title><tgroup
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cols="4"><thead><row><entry align="center">SOURCE</entry><entry
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align="center">DEST</entry><entry align="center">POLICY</entry><entry
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align="center">LOG LEVEL</entry></row></thead><tbody><row><entry>loc</entry><entry>vpn</entry><entry>ACCEPT</entry><entry></entry></row><row><entry>vpn</entry><entry>loc</entry><entry>ACCEPT</entry><entry></entry></row></tbody></tgroup></table></para>
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<para>Once you have these entries in place, restart Shorewall (type
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shorewall restart); you are now ready to configure the tunnel in <ulink
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url="http://www.xs4all.nl/%7Efreeswan/">FreeS/WAN</ulink>.</para>
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</example>
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</section>
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<section>
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<title>VPN Hub</title>
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<para>Shorewall can be used in a VPN Hub environment where multiple remote
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networks are connected to a gateway running Shorewall. This environment is
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shown in this diatram.</para>
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<graphic fileref="images/ThreeNets.png" />
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<para>We want systems in the 192.168.1.0/24 sub-network to be able to
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communicate with systems in the 10.0.0.0/16 and 10.1.0.0/16 networks and
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we want the 10.0.0.0/16 and 10.1.0.0/16 networks to be able to
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communicate.</para>
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<para>To make this work, we need to do several things:</para>
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<orderedlist numeration="loweralpha">
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<listitem>
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<para>Open the firewall so that two IPSEC tunnels can be established
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(allow the ESP and AH protocols and UDP Port 500).</para>
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</listitem>
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<listitem>
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<para>Allow traffic through the tunnels two/from the local zone
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(192.168.1.0/24).</para>
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</listitem>
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<listitem>
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<para>Deny traffic through the tunnels between the two remote
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networks.</para>
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</listitem>
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</orderedlist>
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<para>Opening the firewall for the IPSEC tunnels is accomplished by adding
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two entries to the /etc/shorewall/tunnels file.</para>
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2003-12-16 23:22:21 +01:00
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<para>In /etc/shorewall/tunnels on system A, we need the following</para>
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<table>
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<title>/etc/shorewall/tunnels system A</title>
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<tgroup cols="4">
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<thead>
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<row>
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<entry align="center">TYPE</entry>
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<entry align="center">ZONE</entry>
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<entry align="center">GATEWAY</entry>
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2003-12-16 23:22:21 +01:00
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<entry align="center">GATEWAY ZONE</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>ipsec</entry>
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<entry>net</entry>
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<entry>134.28.54.2</entry>
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<entry></entry>
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</row>
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<row>
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<entry>ipsec</entry>
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<entry>net</entry>
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<entry>130.152.100.14</entry>
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<entry></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>In /etc/shorewall/tunnels on systems B and C, we would have:</para>
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<table>
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<title>/etc/shorewall/tunnels system B & C</title>
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<tgroup cols="4">
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<thead>
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<row>
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<entry align="center">TYPE</entry>
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<entry align="center">ZONE</entry>
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<entry align="center">GATEWAY</entry>
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<entry align="center">GATEWAY ZONE</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>ipsec</entry>
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<entry>net</entry>
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<entry>206.161.148.9</entry>
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|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<note>
|
|
|
|
|
<para>If either of the endpoints is behind a NAT gateway then the
|
|
|
|
|
tunnels file entry on the <emphasis role="bold">other</emphasis>
|
|
|
|
|
endpoint should specify a tunnel type of <emphasis>ipsecnat</emphasis>
|
|
|
|
|
rather than ipsec and the GATEWAY address should specify the external
|
|
|
|
|
address of the NAT gateway.</para>
|
|
|
|
|
</note>
|
|
|
|
|
|
|
|
|
|
<para>On each system, we will create a zone to represent the remote
|
|
|
|
|
networks. On System A:</para>
|
|
|
|
|
|
|
|
|
|
<table>
|
|
|
|
|
<title>/etc/shorewall/zones system A</title>
|
|
|
|
|
|
|
|
|
|
<tgroup cols="3">
|
|
|
|
|
<thead>
|
|
|
|
|
<row>
|
|
|
|
|
<entry align="center">ZONE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">DISPLAY</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">COMMENTS</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</thead>
|
|
|
|
|
|
|
|
|
|
<tbody>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn1</entry>
|
|
|
|
|
|
|
|
|
|
<entry>VPN1</entry>
|
|
|
|
|
|
|
|
|
|
<entry>Remote Subnet on system B</entry>
|
|
|
|
|
</row>
|
|
|
|
|
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn2</entry>
|
|
|
|
|
|
|
|
|
|
<entry>VPN2</entry>
|
|
|
|
|
|
|
|
|
|
<entry>Remote Subnet on system C</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<para>On systems B and C:</para>
|
|
|
|
|
|
|
|
|
|
<table>
|
|
|
|
|
<title>/etc/shorewall/zones system B & C</title>
|
|
|
|
|
|
|
|
|
|
<tgroup cols="3">
|
|
|
|
|
<thead>
|
|
|
|
|
<row>
|
|
|
|
|
<entry align="center">ZONE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">DISPLAY</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">COMMENTS</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</thead>
|
|
|
|
|
|
|
|
|
|
<tbody>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn</entry>
|
|
|
|
|
|
|
|
|
|
<entry>VPN</entry>
|
|
|
|
|
|
|
|
|
|
<entry>Remote Subnet on system A</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<para>At system A, ipsec0 represents two zones so we have the following in
|
|
|
|
|
/etc/shorewall/interfaces:</para>
|
|
|
|
|
|
|
|
|
|
<table>
|
|
|
|
|
<title>/etc/shorewall/interfaces system A</title>
|
|
|
|
|
|
|
|
|
|
<tgroup cols="4">
|
|
|
|
|
<thead>
|
|
|
|
|
<row>
|
|
|
|
|
<entry align="center">ZONE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">INTERFACE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">BROADCAST</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">OPTIONS</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</thead>
|
|
|
|
|
|
|
|
|
|
<tbody>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>-</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ipsec0</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<para>The /etc/shorewall/hosts file on system A defines the two VPN zones:</para>
|
|
|
|
|
|
|
|
|
|
<table>
|
|
|
|
|
<title>/etc/shorewall/hosts system A</title>
|
|
|
|
|
|
|
|
|
|
<tgroup cols="3">
|
|
|
|
|
<thead>
|
|
|
|
|
<row>
|
|
|
|
|
<entry align="center">ZONE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">HOSTS</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">OPTIONS</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</thead>
|
|
|
|
|
|
|
|
|
|
<tbody>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn1</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ipsec0:10.0.0.0/16</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn2</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ipsec0:10.1.0.0/16</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<para>At systems B and C, ipsec0 represents a single zone so we have the
|
|
|
|
|
following in /etc/shorewall/interfaces:</para>
|
|
|
|
|
|
|
|
|
|
<table>
|
|
|
|
|
<title>/etc/shorewall/interfaces system B & C</title>
|
|
|
|
|
|
|
|
|
|
<tgroup cols="4">
|
|
|
|
|
<thead>
|
|
|
|
|
<row>
|
|
|
|
|
<entry align="center">ZONE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">INTERFACE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">BROADCAST</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">OPTIONS</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</thead>
|
|
|
|
|
|
|
|
|
|
<tbody>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ipsec0</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<para>On systems A, you will need to allow traffic between the
|
|
|
|
|
"vpn1" zone and the "loc" zone as well as between
|
|
|
|
|
"vpn2" and the "loc" zone -- if you simply want to admit
|
|
|
|
|
all traffic in both directions, you can use the following policy file
|
|
|
|
|
entries on all three gateways:</para>
|
|
|
|
|
|
|
|
|
|
<table>
|
|
|
|
|
<title>/etc/shorewall/policy system A</title>
|
|
|
|
|
|
|
|
|
|
<tgroup cols="4">
|
|
|
|
|
<thead>
|
|
|
|
|
<row>
|
|
|
|
|
<entry align="center">SOURCE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">DEST</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">POLICY</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">LOG LEVEL</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</thead>
|
|
|
|
|
|
|
|
|
|
<tbody>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>loc</entry>
|
|
|
|
|
|
|
|
|
|
<entry>vpn1</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn1</entry>
|
|
|
|
|
|
|
|
|
|
<entry>loc</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
|
|
|
|
|
<row>
|
|
|
|
|
<entry>loc</entry>
|
|
|
|
|
|
|
|
|
|
<entry>vpn2</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn2</entry>
|
|
|
|
|
|
|
|
|
|
<entry>loc</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<para>On systems B and C, you will need to allow traffic between the
|
|
|
|
|
"vpn" zone and the "loc" zone -- if you simply want to
|
|
|
|
|
admit all traffic in both directions, you can use the following policy
|
|
|
|
|
file entries on all three gateways:</para>
|
|
|
|
|
|
|
|
|
|
<table>
|
|
|
|
|
<title>/etc/shorewall/policy system B & C</title>
|
|
|
|
|
|
|
|
|
|
<tgroup cols="4">
|
|
|
|
|
<thead>
|
|
|
|
|
<row>
|
|
|
|
|
<entry align="center">SOURCE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">DEST</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">POLICY</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">LOG LEVEL</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</thead>
|
|
|
|
|
|
|
|
|
|
<tbody>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>loc</entry>
|
|
|
|
|
|
|
|
|
|
<entry>vpn</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn</entry>
|
|
|
|
|
|
|
|
|
|
<entry>loc</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<para>Once you have the Shorewall entries added, restart Shorewall on each
|
|
|
|
|
gateway (type shorewall restart); you are now ready to configure the
|
|
|
|
|
tunnels in <ulink url="http://www.xs4all.nl/%7Efreeswan/">FreeS/WAN</ulink>.</para>
|
|
|
|
|
|
|
|
|
|
<note>
|
|
|
|
|
<para>to allow traffic between the networks attached to systems B and C,
|
|
|
|
|
it is necessary to simply add two additional entries to the
|
|
|
|
|
/etc/shorewall/policy file on system A.</para>
|
|
|
|
|
|
|
|
|
|
<table>
|
|
|
|
|
<title>/etc/shorewall/policy system A</title>
|
|
|
|
|
|
|
|
|
|
<tgroup cols="4">
|
|
|
|
|
<thead>
|
|
|
|
|
<row>
|
|
|
|
|
<entry align="center">SOURCE</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">DEST</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">POLICY</entry>
|
|
|
|
|
|
|
|
|
|
<entry align="center">LOG LEVEL</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</thead>
|
|
|
|
|
|
|
|
|
|
<tbody>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn1</entry>
|
|
|
|
|
|
|
|
|
|
<entry>vpn2</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
|
|
|
|
|
<row>
|
|
|
|
|
<entry>vpn2</entry>
|
|
|
|
|
|
|
|
|
|
<entry>vpn1</entry>
|
|
|
|
|
|
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
|
|
|
|
|
|
<entry></entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
</note>
|
|
|
|
|
|
|
|
|
|
<note>
|
|
|
|
|
<para>If you find traffic being rejected/dropped in the OUTPUT chain,
|
|
|
|
|
place the names of the remote VPN zones as a comma-separated list in the
|
|
|
|
|
GATEWAY ZONE column of the /etc/shorewall/tunnels file entry.</para>
|
|
|
|
|
</note>
|
|
|
|
|
</section>
|
|
|
|
|
|
|
|
|
|
<section>
|
|
|
|
|
<title>Mobile System (Road Warrior)</title>
|
|
|
|
|
|
|
|
|
|
<para>Suppose that you have a laptop system (B) that you take with you
|
|
|
|
|
when you travel and you want to be able to establish a secure connection
|
|
|
|
|
back to your local network.</para>
|
|
|
|
|
|
|
|
|
|
<graphic fileref="images/Mobile.png" />
|
|
|
|
|
|
|
|
|
|
<example>
|
|
|
|
|
<title>Road Warrior VPN</title>
|
|
|
|
|
|
|
|
|
|
<para>You need to define a zone for the laptop or include it in your
|
|
|
|
|
local zone. In this example, we'll assume that you have created a
|
|
|
|
|
zone called "vpn" to represent the remote host.</para>
|
|
|
|
|
|
|
|
|
|
<para><table><title>/etc/shorewall/zones local</title><tgroup cols="3"><thead><row><entry
|
|
|
|
|
align="center">ZONE</entry><entry align="center">DISPLAY</entry><entry
|
|
|
|
|
align="center">COMMENTS</entry></row></thead><tbody><row><entry>vpn</entry><entry>VPN</entry><entry>Remote
|
|
|
|
|
Subnet</entry></row></tbody></tgroup></table></para>
|
|
|
|
|
|
|
|
|
|
<para>In this instance, the mobile system (B) has IP address 134.28.54.2
|
|
|
|
|
but that cannot be determined in advance. In the /etc/shorewall/tunnels
|
|
|
|
|
file on system A, the following entry should be made:</para>
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<para><table><title>/etc/shorewall/tunnels system A</title><tgroup
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cols="4"><thead><row><entry align="center">TYPE</entry><entry
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align="center">ZONE</entry><entry align="center">GATEWAY</entry><entry
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align="center">GATEWAY ZONE</entry></row></thead><tbody><row><entry>ipsec</entry><entry>net</entry><entry>0.0.0.0/0</entry><entry>vpn</entry></row></tbody></tgroup></table></para>
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<para><note><para>the GATEWAY ZONE column contains the name of the zone
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corresponding to peer subnetworks. This indicates that the gateway
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system itself comprises the peer subnetwork; in other words, the remote
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gateway is a standalone system.</para></note></para>
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<para>You will need to configure /etc/shorewall/interfaces and establish
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your "through the tunnel" policy as shown under the first
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example above.</para>
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</example>
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</section>
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<section>
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<title>Dynamic RoadWarrior Zones</title>
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<para>Beginning with Shorewall release 1.3.10, you can define multiple VPN
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zones and add and delete remote endpoints dynamically using
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/sbin/shorewall. In /etc/shorewall/zones:</para>
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<table>
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<title>/etc/shorewall/zones</title>
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<tgroup cols="3">
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<thead>
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<row>
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<entry align="center">ZONE</entry>
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<entry align="center">DISPLAY</entry>
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<entry align="center">COMMENTS</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>vpn1</entry>
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<entry>VPN-1</entry>
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<entry>First VPN Zone</entry>
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</row>
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<row>
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<entry>vpn2</entry>
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<entry>VPN-2</entry>
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<entry>Second VPN Zone</entry>
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</row>
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<row>
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<entry>vpn3</entry>
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<entry>VPN-3</entry>
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<entry>Third VPN Zone</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>In /etc/shorewall/tunnels:</para>
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<table>
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<title>/etc/shorewall/tunnels</title>
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<tgroup cols="4">
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<thead>
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<row>
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<entry align="center">TYPE</entry>
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<entry align="center">ZONE</entry>
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<entry align="center">GATEWAY</entry>
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<entry align="center">GATEWAY ZONE</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>ipsec</entry>
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<entry>net</entry>
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<entry>0.0.0.0/0</entry>
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<entry>vpn1,vpn2,vpn3</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>When Shorewall is started, the zones vpn[1-3] will all be empty and
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Shorewall will issue warnings to that effect. These warnings may be safely
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ignored. FreeS/Wan may now be configured to have three different Road
|
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|
Warrior connections with the choice of connection being based on X-509
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|
certificates or some other means. Each of these connectioins will utilize
|
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|
a different updown script that adds the remote station to the appropriate
|
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|
zone when the connection comes up and that deletes the remote station when
|
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the connection comes down. For example, when 134.28.54.2 connects for the
|
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vpn2 zone the 'up' part of the script will issue the command":</para>
|
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|
|
<programlisting>/sbin/shorewall add ipsec0:134.28.54.2 vpn2</programlisting>
|
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|
|
<para>and the 'down' part will:</para>
|
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|
|
<programlisting>/sbin/shorewall delete ipsec0:134.28.54.2 vpn2</programlisting>
|
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|
<section>
|
|
|
|
|
<title>Limitations of Dynamic Zones</title>
|
|
|
|
|
|
|
|
|
|
<para>If you include a dynamic zone in the exclude list of a DNAT rule,
|
|
|
|
|
the dynamically-added hosts are not excluded from the rule.</para>
|
|
|
|
|
|
|
|
|
|
<example>
|
|
|
|
|
<title>dyn=dynamic zone</title>
|
|
|
|
|
|
|
|
|
|
<para><informaltable><tgroup cols="7"><thead><row><entry
|
|
|
|
|
align="center">ACTION</entry><entry align="center">SOURCE</entry><entry
|
|
|
|
|
align="center">DESTINATION</entry><entry align="center">PROTOCOL</entry><entry
|
|
|
|
|
align="center">PORT(S)</entry><entry align="center">CLIENT PORT(S)</entry><entry
|
|
|
|
|
align="center">ORIGINAL DESTINATION</entry></row></thead><tbody><row><entry>DNAT</entry><entry>z!dyn</entry><entry>loc:192.168.1.3</entry><entry>tcp</entry><entry>80</entry><entry></entry><entry></entry></row></tbody></tgroup></informaltable></para>
|
|
|
|
|
|
|
|
|
|
<para>Dynamic changes to the zone <emphasis role="bold">dyn</emphasis>
|
|
|
|
|
will have no effect on the above rule.</para>
|
|
|
|
|
</example>
|
|
|
|
|
</section>
|
|
|
|
|
</section>
|
|
|
|
|
</article>
|
