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shorewall_code/STABLE/documentation/IPIP.htm
teastep 48719a6621 Initial revision 
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@182 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
2002-08-07 14:28:04 +00:00

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<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">
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<body background="_themes/radial/radbkgnd.gif" bgcolor="#FFFFFF" text="#000000" link="#6666FF" vlink="#993333" alink="#66CCCC"><!--mstheme--><font face="arial, Arial, Helvetica">
<h1 align="center"><!--mstheme--><font face="times new roman, Times New Roman, Times" color="#666666">GRE and IPIP Tunnels<!--mstheme--></font></h1>
<h3><!--mstheme--><font face="times new roman, Times New Roman, Times" color="#666666"><font color="#FF6633">Warning: </font>GRE and IPIP Tunnels are insecure when used
over the internet; use them at your own risk<!--mstheme--></font></h3>
<p>GRE and IPIP tunneling with Shorewall requires iproute2 and can be used to bridge two masqueraded networks.&nbsp;GRE
tunnels were introduced in shorewall version 1.2.0_Beta2.</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-&lt;version&gt;/).</p>
<h2><!--mstheme--><font face="times new roman, Times New Roman, Times" color="#666666">Bridging two Masqueraded Networks<!--mstheme--></font></h2>
<p>Suppose that we have the following situation:</p>
<p align="center"><img border="0" src="images/TwoNets1.jpg" width="651" height="394"></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-&lt;version&gt;).</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 system A, the 10.0.0.0/8 will comprise the <b>gw</b> zone. In
/etc/shorewall/interfaces:</p>
<blockquote>
<!--mstheme--></font><table border="2" cellpadding="2" style="border-collapse: collapse" bordercolordark="#666666" bordercolorlight="#CCCCCC">
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>ZONE</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>INTERFACE</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>BROADCAST</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>OPTIONS</b><!--mstheme--></font></td>
</tr>
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica">gw<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">tosysb<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">10.255.255.255<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">&nbsp;<!--mstheme--></font></td>
</tr>
</table><!--mstheme--><font face="arial, Arial, Helvetica">
</blockquote>
<p align="left">In /etc/shorewall/tunnels on system A, we need the following:</p>
<blockquote>
<!--mstheme--></font><table border="2" cellpadding="2" style="border-collapse: collapse" bordercolordark="#666666" bordercolorlight="#CCCCCC">
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>TYPE</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>ZONE</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>GATEWAY</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>GATEWAY ZONE</b><!--mstheme--></font></td>
</tr>
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica">ipip<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">net<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">134.28.54.2<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">&nbsp;<!--mstheme--></font></td>
</tr>
</table><!--mstheme--><font face="arial, Arial, Helvetica">
</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>gw</b>
zone. In /etc/shorewall/interfaces:</p>
<blockquote>
<!--mstheme--></font><table border="2" cellpadding="2" style="border-collapse: collapse" bordercolordark="#666666" bordercolorlight="#CCCCCC">
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>ZONE</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>INTERFACE</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>BROADCAST</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>OPTIONS</b><!--mstheme--></font></td>
</tr>
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica">gw<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">tosysa<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">192.168.1.255<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">&nbsp;<!--mstheme--></font></td>
</tr>
</table><!--mstheme--><font face="arial, Arial, Helvetica">
</blockquote>
<p>In /etc/shorewall/tunnels on system B, we have:</p>
<blockquote>
<!--mstheme--></font><table border="2" cellpadding="2" style="border-collapse: collapse" bordercolordark="#666666" bordercolorlight="#CCCCCC">
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>TYPE</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>ZONE</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>GATEWAY</b><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><b>GATEWAY ZONE</b><!--mstheme--></font></td>
</tr>
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica">ipip<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">net<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">206.191.148.9<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">&nbsp;<!--mstheme--></font></td>
</tr>
</table><!--mstheme--><font face="arial, Arial, Helvetica">
</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 &quot;gw&quot; zone and
the &quot;loc&quot; zone on both systems -- if you simply want to admit all traffic
in both directions, you can use the policy file:</p>
<blockquote>
<!--mstheme--></font><table border="2" cellpadding="2" style="border-collapse: collapse" bordercolordark="#666666" bordercolorlight="#CCCCCC">
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><strong>SOURCE</strong><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><strong>DEST</strong><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><strong>POLICY</strong><!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica"><strong>LOG LEVEL</strong><!--mstheme--></font></td>
</tr>
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica">loc<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">gw<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">ACCEPT<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">&nbsp;<!--mstheme--></font></td>
</tr>
<tr>
<td><!--mstheme--><font face="arial, Arial, Helvetica">gw<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">loc<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">ACCEPT<!--mstheme--></font></td>
<td><!--mstheme--><font face="arial, Arial, Helvetica">&nbsp;<!--mstheme--></font></td>
</tr>
</table><!--mstheme--><font face="arial, Arial, Helvetica">
</blockquote>
<p>On both systems, restart Shorewall and
run the modified tunnel script with the &quot;start&quot; argument on each
system. The systems in the two masqueraded subnetworks can now talk to each
other</p>
<p><font size="2">Updated 5/18/2002 - <a href="support.htm">Tom
Eastep</a> </font></p>
<p><font face="Trebuchet MS"><a href="copyright.htm"><font size="2">Copyright</font>
<EFBFBD> <font size="2">2001, 2002 Thomas M. Eastep.</font></a></font></p>
<!--mstheme--></font></body>
</html>
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