mirror of
https://gitlab.com/shorewall/code.git
synced 2024-12-12 01:10:52 +01:00
f3790a541b
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@507 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
249 lines
7.1 KiB
HTML
249 lines
7.1 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
||
<html>
|
||
<head>
|
||
|
||
<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">
|
||
</head>
|
||
<body>
|
||
|
||
<table border="0" cellpadding="0" cellspacing="0"
|
||
style="border-collapse: collapse;" bordercolor="#111111" width="100%"
|
||
id="AutoNumber1" bgcolor="#400169" height="90">
|
||
<tbody>
|
||
<tr>
|
||
<td width="100%">
|
||
<h1 align="center"><font color="#ffffff">GRE and IPIP Tunnels</font></h1>
|
||
</td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
</table>
|
||
|
||
<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>
|
||
|
||
<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, 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>
|
||
|
||
<p align="left">Example:</p>
|
||
|
||
<blockquote>
|
||
<p align="left">tunnel_type=gre</p>
|
||
</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>
|
||
<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>tosysb</td>
|
||
<td>10.255.255.255</td>
|
||
<td><EFBFBD></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>ipip</td>
|
||
<td>net</td>
|
||
<td>134.28.54.2</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
</table>
|
||
</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>
|
||
|
||
<p>In the tunnel script on system A:</p>
|
||
|
||
<blockquote>
|
||
<p>tunnel=tosysb<br>
|
||
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>
|
||
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>tosysa</td>
|
||
<td>192.168.1.255</td>
|
||
<td><EFBFBD></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>ipip</td>
|
||
<td>net</td>
|
||
<td>206.191.148.9</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p>And in the tunnel script on system B:</p>
|
||
|
||
<blockquote>
|
||
<p>tunnel=tosysa<br>
|
||
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>
|
||
<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><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>vpn</td>
|
||
<td>loc</td>
|
||
<td>ACCEPT</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
</table>
|
||
</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 can now talk to each other</p>
|
||
|
||
<p><font size="2">Updated 2/22/2003 - <a href="support.htm">Tom Eastep</a>
|
||
</font></p>
|
||
|
||
<p><a href="copyright.htm"><font size="2">Copyright</font> <20> <font
|
||
size="2">2001, 2002, 2003Thomas M. Eastep.</font></a></p>
|
||
<br>
|
||
</body>
|
||
</html>
|