forked from extern/shorewall_code
338 lines
8.2 KiB
XML
338 lines
8.2 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="OPENVPN">
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<articleinfo>
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<title>OpenVPN 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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<author>
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<firstname>Simon</firstname>
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<surname>Mater</surname>
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</author>
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</authorgroup>
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<pubdate>2003-02-04</pubdate>
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<copyright>
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<year>2003</year>
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<holder>Thomas M. Eastep</holder>
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<holder>Simon Mater</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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<para>OpenVPN is a robust and highly configurable VPN (Virtual Private
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Network) daemon which can be used to securely link two or more private
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networks using an encrypted tunnel over the internet. OpenVPN is an Open
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Source project and is <ulink
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url="http://openvpn.sourceforge.net/license.html">licensed under the GPL</ulink>.
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OpenVPN can be downloaded from <ulink url="http://openvpn.sourceforge.net/">http://openvpn.sourceforge.net/</ulink>.</para>
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<para>OpenVPN support was added to Shorewall in version 1.3.14.</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 and the
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/etc/shorewall/policy file and OpenVPN.</para>
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<para>While it was possible to use the Shorewall start and stop script to
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start and stop OpenVPN, I decided to use the init script of OpenVPN to
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start and stop it.</para>
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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 'vpn' and
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declare it in /etc/shorewall/zones on both systems as follows.</para>
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<table>
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<title>/etc/shorewall/zones system A & B</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>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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</table>
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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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<table>
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<title>etc/shorewall/interfaces 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">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></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 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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<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>openvpn</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>This entry in /etc/shorewall/tunnels opens the firewall so that
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OpenVPN traffic on the default port 5000/udp will be accepted to/from the
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remote gateway. If you change the port used by OpenVPN to 7777, you can
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define /etc/shorewall/tunnels like this:</para>
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<table>
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<title>/etc/shorewall/tunnels port 7777</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>openvpn:7777</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>This is the OpenVPN config on system A:</para>
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<programlisting>dev tun
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local 206.162.148.9
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remote 134.28.54.2
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ifconfig 192.168.99.1 192.168.99.2
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up ./route-a.up
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tls-server
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dh dh1024.pem
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ca ca.crt
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cert my-a.crt
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key my-a.key
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comp-lzo
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verb 5</programlisting>
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<para>Similarly, On system B the 192.168.1.0/24 subnet will comprise the
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<emphasis role="bold">vpn</emphasis> zone. In /etc/shorewall/interfaces:</para>
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<table>
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<title>/etc/shorewall/interfaces 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">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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</table>
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<para>In /etc/shorewall/tunnels on system B, we 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>openvpn</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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</tbody>
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</tgroup>
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</table>
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<para>And in the OpenVPN config on system B:</para>
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<programlisting>dev tun
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local 134.28.54.2
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remote 206.162.148.9
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ifconfig 192.168.99.2 192.168.99.1
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up ./route-b.up
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tls-client
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ca ca.crt
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cert my-b.crt
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key my-b.key
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comp-lzo
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verb 5</programlisting>
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<para>You will need to allow traffic between the "vpn" zone and
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the "loc" zone on both systems -- if you simply want to admit all
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traffic in both directions, you can use the policy file:</para>
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<table>
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<title>/etc/shorewall/policy system A & 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">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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</table>
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<para>On both systems, restart Shorewall and start OpenVPN. The systems in
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the two masqueraded subnetworks can now talk to each other.</para>
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</section>
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||
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</article>
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