forked from extern/shorewall_code
292 lines
7.1 KiB
XML
292 lines
7.1 KiB
XML
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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="GenericTunnels">
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<!--$Id$-->
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<articleinfo>
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<title>Generic 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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<pubdate>2003-08-09</pubdate>
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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
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<quote><ulink url="GnuCopyright.htm">GNU Free Documentation License</ulink></quote>.</para>
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</legalnotice>
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</articleinfo>
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<para>Shorewall includes built-in support for a wide range of VPN solutions.
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If you have need for a tunnel type that does not have explicit support, you
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can generally describe the tunneling software using <quote>generic tunnels</quote>.</para>
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<section>
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<title>Bridging two Masqueraded Networks</title>
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<para>Suppose that we have the following situation:</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 subnetwork to be able to
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communicate with the systems in the 10.0.0.0/8 network. This is
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accomplished through use of the /etc/shorewall/tunnels file, the
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/etc/shorewall/policy file and the /etc/shorewall/tunnel script that is
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included with Shorewall.</para>
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<para>Suppose that you have tunneling software that uses two different
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protocols:</para>
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<orderedlist numeration="loweralpha">
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<listitem>
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<para>TCP port 1071</para>
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</listitem>
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<listitem>
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<para>GRE (Protocol 47)</para>
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</listitem>
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<listitem>
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<para>The tunnel interface on system A is <quote>tun0</quote> and the
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tunnel interface on system B is also <quote>tun0</quote>.</para>
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</listitem>
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</orderedlist>
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<para>On each firewall, you will need to declare a zone to represent the
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remote subnet. We'll assume that this zone is called <quote>vpn</quote>
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and declare it in /etc/shorewall/zones on both systems as follows.</para>
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<informaltable>
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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>vpn</entry>
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<entry>VPN</entry>
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<entry>Remote Subnet</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<para>On system A, the 10.0.0.0/8 will comprise the <emphasis role="bold">vpn</emphasis>
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zone. In /etc/shorewall/interfaces:</para>
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<informaltable>
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<tgroup cols="4">
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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">INTERFACE</entry>
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<entry align="center">BROADCAST</entry>
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<entry align="center">OPTIONS</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>vpn</entry>
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<entry>tun0</entry>
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<entry>10.255.255.255</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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</informaltable>
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<para>In /etc/shorewall/tunnels on system A, we need the following:</para>
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<informaltable>
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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>generic:tcp:1071</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>generic:47</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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</informaltable>
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<para>These entries in /etc/shorewall/tunnels, opens the firewall so that
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TCP port 1071 and the Generalized Routing Encapsulation Protocol (47) will
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be accepted to/from the remote gateway.</para>
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<informaltable>
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<tgroup cols="4">
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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">INTERFACE</entry>
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<entry align="center">BROADCAST</entry>
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<entry align="center">OPTIONS</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>vpn</entry>
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<entry>tun0</entry>
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<entry>192.168.1.255</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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</informaltable>
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<para>In /etc/shorewall/tunnels on system B, we have:</para>
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<informaltable>
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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>generic:tcp:1071</entry>
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<entry>net</entry>
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<entry>206.191.148.9</entry>
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<entry></entry>
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</row>
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<row>
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<entry>generic:47</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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</informaltable>
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<para>You will need to allow traffic between the <quote>vpn</quote> zone
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and the <quote>loc</quote> zone on both systems -- if you simply want to
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admit all traffic in both directions, you can use the policy file:</para>
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<informaltable>
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<tgroup cols="4">
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<thead>
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<row>
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<entry align="center">SOURCE</entry>
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<entry align="center">DEST</entry>
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<entry align="center">POLICY</entry>
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<entry align="center">LOG LEVEL</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>loc</entry>
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<entry>vpn</entry>
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<entry>ACCEPT</entry>
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<entry></entry>
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</row>
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<row>
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<entry>vpn</entry>
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<entry>loc</entry>
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<entry>ACCEPT</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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</informaltable>
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<para>On both systems, restart Shorewall and start your VPN software on
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each system. The systems in the two masqueraded subnetworks can now talk
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to each other</para>
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</section>
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</article>
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