shorewall_code/Shorewall-docs/OPENVPN.html
teastep c2ccd7fd3d Shorewall 1.4.8
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2003-12-02 23:51:46 +00:00

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<title>OpenVPN Tunnels</title>
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<h1 style="text-align: center;">OpenVPN Tunnels<br>
</h1>
<p>OpenVPN is a robust and highly configurable VPN (Virtual Private
Network) daemon which can be used to securely link two or more private
networks using an encrypted tunnel over the internet. OpenVPN is an
Open Source project and is <a
href="http://openvpn.sourceforge.net/license.html">licensed under the
GPL</a>. OpenVPN can be downloaded from <a
href="http://openvpn.sourceforge.net/">http://openvpn.sourceforge.net/</a>.<br>
</p>
<p>OpenVPN support was added to Shorewall in version 1.3.14.<br>
</p>
<h2>Bridging two Masqueraded Networks</h2>
<p>Suppose that we have the following situation:</p>
<p align="center"><img border="0" src="images/TwoNets1.png" width="745"
height="427"> </p>
<p align="left">We want systems in the 192.168.1.0/24 subnetwork to be
able to communicate with the systems in the 10.0.0.0/8 network. This is
accomplished through use of the /etc/shorewall/tunnels file and the
/etc/shorewall/policy file and OpenVPN.</p>
<p align="left">While it was possible to use the Shorewall start and
stop script to start and stop OpenVPN, I decided to use the init script
of OpenVPN to start and stop it.</p>
<p align="left">On each firewall, you will need to declare a zone to
represent the remote subnet. We'll assume that this zone is called
'vpn' and declare it in /etc/shorewall/zones on both systems as follows.</p>
<blockquote>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><strong>ZONE</strong></td>
<td><strong>DISPLAY</strong></td>
<td><strong>COMMENTS</strong></td>
</tr>
<tr>
<td>vpn</td>
<td>VPN</td>
<td>Remote Subnet</td>
</tr>
</tbody>
</table>
</blockquote>
<p align="left">On system A, the 10.0.0.0/8 will comprise the <b>vpn</b>
zone.
In /etc/shorewall/interfaces:</p>
<blockquote>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>ZONE</b></td>
<td><b>INTERFACE</b></td>
<td><b>BROADCAST</b></td>
<td><b>OPTIONS</b></td>
</tr>
<tr>
<td>vpn</td>
<td>tun0</td>
<td><br>
</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
</blockquote>
<p align="left">In /etc/shorewall/tunnels on system A, we need the
following:</p>
<blockquote>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>TYPE</b></td>
<td><b>ZONE</b></td>
<td><b>GATEWAY</b></td>
<td><b>GATEWAY ZONE</b></td>
</tr>
<tr>
<td>openvpn</td>
<td>net</td>
<td>134.28.54.2</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
</blockquote>
<p>This entry in /etc/shorewall/tunnels opens the firewall so that
OpenVPN traffic on the default port 5000/udp will be accepted to/from
the remote gateway. If you change the port used by OpenVPN to 7777, you
can define&nbsp;/etc/shorewall/tunnels like this:<br>
</p>
<blockquote>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>TYPE</b></td>
<td><b>ZONE</b></td>
<td><b>GATEWAY</b></td>
<td><b>GATEWAY ZONE</b></td>
</tr>
<tr>
<td>openvpn:7777</td>
<td>net</td>
<td>134.28.54.2</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
</blockquote>
<p>This is the OpenVPN config on system A:</p>
<blockquote>
<p></p>
</blockquote>
<blockquote>
<p>dev tun<br>
local 206.162.148.9<br>
remote 134.28.54.2<br>
ifconfig 192.168.99.1 192.168.99.2<br>
up ./route-a.up<br>
tls-server<br>
dh dh1024.pem<br>
ca ca.crt<br>
cert my-a.crt<br>
key my-a.key<br>
comp-lzo<br>
verb 5<br>
</p>
</blockquote>
<p>Similarly, On system B the 192.168.1.0/24 subnet will comprise the <b>vpn</b>
zone. In /etc/shorewall/interfaces:</p>
<blockquote>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>ZONE</b></td>
<td><b>INTERFACE</b></td>
<td><b>BROADCAST</b></td>
<td><b>OPTIONS</b></td>
</tr>
<tr>
<td>vpn</td>
<td>tun0</td>
<td>192.168.1.255</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
</blockquote>
<p>In /etc/shorewall/tunnels on system B, we have:</p>
<blockquote>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>TYPE</b></td>
<td><b>ZONE</b></td>
<td><b>GATEWAY</b></td>
<td><b>GATEWAY ZONE</b></td>
</tr>
<tr>
<td>openvpn</td>
<td>net</td>
<td>206.191.148.9</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
</blockquote>
<p>And in the&nbsp;OpenVPN config on system B:</p>
<blockquote>
<p>dev tun<br>
local 134.28.54.2<br>
remote 206.162.148.9<br>
ifconfig 192.168.99.2 192.168.99.1<br>
up ./route-b.up<br>
tls-client<br>
ca ca.crt<br>
cert my-b.crt<br>
key my-b.key<br>
comp-lzo<br>
verb 5<br>
</p>
</blockquote>
<p align="left">You will need to allow traffic between the "vpn" zone
and the "loc" zone on both systems -- if you simply want to admit all
traffic in both directions, you can use the policy file:</p>
<blockquote>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><strong>SOURCE</strong></td>
<td><strong>DEST</strong></td>
<td><strong>POLICY</strong></td>
<td><strong>LOG LEVEL</strong></td>
</tr>
<tr>
<td>loc</td>
<td>vpn</td>
<td>ACCEPT</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>vpn</td>
<td>loc</td>
<td>ACCEPT</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
</blockquote>
<p>On both systems, restart Shorewall and start OpenVPN. The systems in
the two masqueraded subnetworks can now talk to each other.</p>
<p><font size="2">Updated 2/4/2003 - <a href="support.htm">Tom Eastep</a></font>
<small>and Simon Mater</small><br>
</p>
<p><font size="2"> </font></p>
<p><font face="Trebuchet MS"><a href="copyright.htm"><font size="2">Copyright</font>
<EFBFBD> <font size="2">2003 Thomas M. Eastep. and Simon Mater<br>
</font></a></font></p>
<br>
<br>
<br>
<br>
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