2003-02-21 23:22:19 +01:00
|
|
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<html>
|
|
|
|
|
|
<head>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<meta http-equiv="Content-Type"
|
|
|
|
|
|
content="text/html; charset=windows-1252">
|
|
|
|
|
|
<title>GRE/IPIP Tunnels</title>
|
|
|
|
|
|
<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
|
|
|
|
|
|
<meta name="ProgId" content="FrontPage.Editor.Document">
|
2002-08-13 22:45:21 +02:00
|
|
|
|
</head>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<body>
|
|
|
|
|
|
<h1 style="text-align: center;">GRE and IPIP Tunnels<br>
|
|
|
|
|
|
</h1>
|
|
|
|
|
|
<h3><font color="#ff6633">Warning: </font>GRE and IPIP Tunnels are
|
|
|
|
|
|
insecure when used over the internet; use them at your own risk</h3>
|
|
|
|
|
|
<p>GRE and IPIP tunneling with Shorewall can be used to bridge two
|
|
|
|
|
|
masqueraded networks.</p>
|
|
|
|
|
|
<p>The simple scripts described in the <a href="http://ds9a.nl/lartc">Linux
|
|
|
|
|
|
Advanced Routing and Shaping HOWTO</a> work fine with Shorewall.
|
|
|
|
|
|
Shorewall also includes a tunnel script for automating tunnel
|
|
|
|
|
|
configuration. If you have installed the RPM, the tunnel script may be
|
|
|
|
|
|
found in the Shorewall documentation directory (usually
|
|
|
|
|
|
/usr/share/doc/shorewall-<version>/).</p>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<h2>Bridging two Masqueraded Networks</h2>
|
|
|
|
|
|
<p>Suppose that we have the following situation:</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<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, the
|
|
|
|
|
|
/etc/shorewall/policy file and the /etc/shorewall/tunnel script that is
|
|
|
|
|
|
included with Shorewall.</p>
|
|
|
|
|
|
<p align="left">The 'tunnel' script is not installed in /etc/shorewall
|
|
|
|
|
|
by default -- If you install using the tarball, the script is included
|
|
|
|
|
|
in the tarball; if you install using the RPM, the file is in your
|
|
|
|
|
|
Shorewall documentation directory (normally
|
|
|
|
|
|
/usr/share/doc/shorewall-<version>).</p>
|
|
|
|
|
|
<p align="left">In the /etc/shorewall/tunnel script, set the
|
|
|
|
|
|
'tunnel_type' parameter to the type of tunnel that you want to create.</p>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<p align="left">Example:</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<blockquote>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<p align="left">tunnel_type=gre</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</blockquote>
|
|
|
|
|
|
<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>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<table border="2" cellpadding="2" style="border-collapse: collapse;">
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<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>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
</table>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</blockquote>
|
|
|
|
|
|
<p align="left">On system A, the 10.0.0.0/8 will comprise the <b>vpn</b>
|
|
|
|
|
|
zone.
|
2003-07-16 20:59:33 +02:00
|
|
|
|
In /etc/shorewall/interfaces:</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<blockquote>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<table border="2" cellpadding="2" style="border-collapse: collapse;">
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<tbody>
|
|
|
|
|
|
<tr>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<td><b>ZONE</b></td>
|
|
|
|
|
|
<td><b>INTERFACE</b></td>
|
|
|
|
|
|
<td><b>BROADCAST</b></td>
|
|
|
|
|
|
<td><b>OPTIONS</b></td>
|
|
|
|
|
|
</tr>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<tr>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<td>vpn</td>
|
|
|
|
|
|
<td>tosysb</td>
|
|
|
|
|
|
<td>10.255.255.255</td>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<td> </td>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
</tr>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</tbody>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
</table>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</blockquote>
|
|
|
|
|
|
<p align="left">In /etc/shorewall/tunnels on system A, we need the
|
|
|
|
|
|
following:</p>
|
|
|
|
|
|
<blockquote>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<table border="2" cellpadding="2" style="border-collapse: collapse;">
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<tbody>
|
|
|
|
|
|
<tr>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<td><b>TYPE</b></td>
|
|
|
|
|
|
<td><b>ZONE</b></td>
|
|
|
|
|
|
<td><b>GATEWAY</b></td>
|
|
|
|
|
|
<td><b>GATEWAY ZONE</b></td>
|
|
|
|
|
|
</tr>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<tr>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<td>ipip</td>
|
|
|
|
|
|
<td>net</td>
|
|
|
|
|
|
<td>134.28.54.2</td>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<td> </td>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
</tr>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</tbody>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
</table>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</blockquote>
|
|
|
|
|
|
<p>This entry in /etc/shorewall/tunnels, opens the firewall so that the
|
|
|
|
|
|
IP encapsulation protocol (4) will be accepted to/from the remote
|
|
|
|
|
|
gateway.</p>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<p>In the tunnel script on system A:</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<blockquote>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<p>tunnel=tosysb<br>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
myrealip=206.161.148.9 (for GRE tunnel only)<br>
|
|
|
|
|
|
myip=192.168.1.1<br>
|
|
|
|
|
|
hisip=10.0.0.1<br>
|
|
|
|
|
|
gateway=134.28.54.2<br>
|
|
|
|
|
|
subnet=10.0.0.0/8</p>
|
|
|
|
|
|
</blockquote>
|
|
|
|
|
|
<p>Similarly, On system B the 192.168.1.0/24 subnet will comprise the <b>vpn</b>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
zone. In /etc/shorewall/interfaces:</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<blockquote>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<table border="2" cellpadding="2" style="border-collapse: collapse;">
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<tbody>
|
|
|
|
|
|
<tr>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<td><b>ZONE</b></td>
|
|
|
|
|
|
<td><b>INTERFACE</b></td>
|
|
|
|
|
|
<td><b>BROADCAST</b></td>
|
|
|
|
|
|
<td><b>OPTIONS</b></td>
|
|
|
|
|
|
</tr>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<tr>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<td>vpn</td>
|
|
|
|
|
|
<td>tosysa</td>
|
|
|
|
|
|
<td>192.168.1.255</td>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<td> </td>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
</tr>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</tbody>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
</table>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</blockquote>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<p>In /etc/shorewall/tunnels on system B, we have:</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<blockquote>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<table border="2" cellpadding="2" style="border-collapse: collapse;">
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<tbody>
|
|
|
|
|
|
<tr>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<td><b>TYPE</b></td>
|
|
|
|
|
|
<td><b>ZONE</b></td>
|
|
|
|
|
|
<td><b>GATEWAY</b></td>
|
|
|
|
|
|
<td><b>GATEWAY ZONE</b></td>
|
|
|
|
|
|
</tr>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<tr>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
<td>ipip</td>
|
|
|
|
|
|
<td>net</td>
|
|
|
|
|
|
<td>206.191.148.9</td>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<td> </td>
|
2003-07-16 20:59:33 +02:00
|
|
|
|
</tr>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</tbody>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
</table>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</blockquote>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<p>And in the tunnel script on system B:</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<blockquote>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
<p>tunnel=tosysa<br>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
myrealip=134.28.54.2 (for GRE tunnel only)<br>
|
|
|
|
|
|
myip=10.0.0.1<br>
|
|
|
|
|
|
hisip=192.168.1.1<br>
|
|
|
|
|
|
gateway=206.191.148.9<br>
|
|
|
|
|
|
subnet=192.168.1.0/24</p>
|
|
|
|
|
|
</blockquote>
|
|
|
|
|
|
<p>You can rename the modified tunnel scripts if you like; be sure that
|
|
|
|
|
|
they are secured so that root can execute them. </p>
|
|
|
|
|
|
<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>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
<table border="2" cellpadding="2" style="border-collapse: collapse;">
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<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> </td>
|
|
|
|
|
|
</tr>
|
|
|
|
|
|
<tr>
|
|
|
|
|
|
<td>vpn</td>
|
|
|
|
|
|
<td>loc</td>
|
|
|
|
|
|
<td>ACCEPT</td>
|
|
|
|
|
|
<td> </td>
|
|
|
|
|
|
</tr>
|
|
|
|
|
|
</tbody>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
</table>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
</blockquote>
|
|
|
|
|
|
<p>On both systems, restart Shorewall and run the modified tunnel
|
|
|
|
|
|
script with
|
|
|
|
|
|
the "start" argument on each system. The systems in the two masqueraded
|
|
|
|
|
|
subnetworks
|
2003-07-16 20:59:33 +02:00
|
|
|
|
can now talk to each other</p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<p><font size="2">Updated 2/22/2003 - <a href="support.htm">Tom Eastep</a>
|
2003-02-21 23:22:19 +01:00
|
|
|
|
</font></p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<p><a href="copyright.htm"><font size="2">Copyright</font> <20> <font
|
2003-02-21 23:22:19 +01:00
|
|
|
|
size="2">2001, 2002, 2003Thomas M. Eastep.</font></a></p>
|
2003-12-03 00:51:46 +01:00
|
|
|
|
<br>
|
|
|
|
|
|
<br>
|
2002-08-13 22:45:21 +02:00
|
|
|
|
</body>
|
2003-01-14 18:18:42 +01:00
|
|
|
|
</html>
|
