forked from extern/shorewall_code
9ee03db521
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@964 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
324 lines
8.4 KiB
XML
324 lines
8.4 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
|
<article id="IPIP">
|
|
<!--$Id$-->
|
|
|
|
<articleinfo>
|
|
<title>GRE and IPIP Tunnels</title>
|
|
|
|
<authorgroup>
|
|
<author>
|
|
<firstname>Tom</firstname>
|
|
|
|
<surname>Eastep</surname>
|
|
</author>
|
|
</authorgroup>
|
|
|
|
<pubdate>2003-02-22</pubdate>
|
|
|
|
<copyright>
|
|
<year>2001</year>
|
|
|
|
<year>2002</year>
|
|
|
|
<year>2003</year>
|
|
|
|
<holder>Thomas M. Eastep</holder>
|
|
</copyright>
|
|
|
|
<legalnotice>
|
|
<para>Permission is granted to copy, distribute and/or modify this
|
|
document under the terms of the GNU Free Documentation License, Version
|
|
1.2 or any later version published by the Free Software Foundation; with
|
|
no Invariant Sections, with no Front-Cover, and with no Back-Cover
|
|
Texts. A copy of the license is included in the section entitled
|
|
<quote><ulink url="GnuCopyright.htm">GNU Free Documentation License</ulink></quote>.</para>
|
|
</legalnotice>
|
|
</articleinfo>
|
|
|
|
<warning>
|
|
<para>GRE and IPIP Tunnels are insecure when used over the internet; use
|
|
them at your own risk</para>
|
|
</warning>
|
|
|
|
<para>GRE and IPIP tunneling with Shorewall can be used to bridge two
|
|
masqueraded networks.</para>
|
|
|
|
<para>The simple scripts described in the <citetitle><ulink
|
|
url="http://ds9a.nl/lartc">Linux Advanced Routing and Shaping HOWTO</ulink></citetitle>
|
|
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>/).</para>
|
|
|
|
<section>
|
|
<title>Bridging two Masqueraded Networks</title>
|
|
|
|
<para>Suppose that we have the following situation:</para>
|
|
|
|
<graphic fileref="images/TwoNets1.png" />
|
|
|
|
<para>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.</para>
|
|
|
|
<para>The <quote>tunnel</quote> 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>).</para>
|
|
|
|
<para>In the /etc/shorewall/tunnel script, set the <quote>tunnel_type</quote>
|
|
parameter to the type of tunnel that you want to create.</para>
|
|
|
|
<example>
|
|
<title>/etc/shorewall/tunnel</title>
|
|
|
|
<programlisting>tunnel_type=gre</programlisting>
|
|
</example>
|
|
|
|
<para>On each firewall, you will need to declare a zone to represent the
|
|
remote subnet. We'll assume that this zone is called <quote>vpn</quote>
|
|
and declare it in /etc/shorewall/zones on both systems as follows.</para>
|
|
|
|
<table>
|
|
<title>/etc/shorewall/zones system A & B</title>
|
|
|
|
<tgroup cols="3">
|
|
<thead>
|
|
<row>
|
|
<entry align="center">ZONE</entry>
|
|
|
|
<entry align="center">DISPLAY</entry>
|
|
|
|
<entry align="center">COMMENTS</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry>vpn</entry>
|
|
|
|
<entry>VPN</entry>
|
|
|
|
<entry>Remote Subnet</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>On system A, the 10.0.0.0/8 will comprise the <emphasis role="bold">vpn</emphasis>
|
|
zone. In /etc/shorewall/interfaces:</para>
|
|
|
|
<table>
|
|
<title>/etc/shorewall/interfaces system A</title>
|
|
|
|
<tgroup cols="4">
|
|
<thead>
|
|
<row>
|
|
<entry align="center">ZONE</entry>
|
|
|
|
<entry align="center">INTERFACE</entry>
|
|
|
|
<entry align="center">BROADCAST</entry>
|
|
|
|
<entry align="center">OPTIONS</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry>vpn</entry>
|
|
|
|
<entry>tosysb</entry>
|
|
|
|
<entry>10.255.255.255</entry>
|
|
|
|
<entry></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>In /etc/shorewall/tunnels on system A, we need the following:</para>
|
|
|
|
<table>
|
|
<title>/etc/shorewall/tunnels system A</title>
|
|
|
|
<tgroup cols="4">
|
|
<thead>
|
|
<row>
|
|
<entry align="center">TYPE</entry>
|
|
|
|
<entry align="center">ZONE</entry>
|
|
|
|
<entry align="center">GATEWAY</entry>
|
|
|
|
<entry align="center">GATEWAY ZONE</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry>ipip</entry>
|
|
|
|
<entry>net</entry>
|
|
|
|
<entry>134.28.54.2</entry>
|
|
|
|
<entry></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>This entry in /etc/shorewall/tunnels, opens the firewall so that the
|
|
IP encapsulation protocol (4) will be accepted to/from the remote gateway.</para>
|
|
|
|
<para>In the tunnel script on system A:</para>
|
|
|
|
<example>
|
|
<title>tunnel script on system A</title>
|
|
|
|
<programlisting>tunnel=tosysb
|
|
myrealip=206.161.148.9 (for GRE tunnel only)
|
|
myip=192.168.1.1
|
|
hisip=10.0.0.1
|
|
gateway=134.28.54.2
|
|
subnet=10.0.0.0/8
|
|
</programlisting>
|
|
</example>
|
|
|
|
<para>Similarly, On system B the 192.168.1.0/24 subnet will comprise the
|
|
<emphasis role="bold">vpn</emphasis> zone. In /etc/shorewall/interfaces:</para>
|
|
|
|
<table>
|
|
<title>/etc/shorewall/interfaces system B</title>
|
|
|
|
<tgroup cols="4">
|
|
<thead>
|
|
<row>
|
|
<entry align="center">ZONE</entry>
|
|
|
|
<entry align="center">INTERFACE</entry>
|
|
|
|
<entry align="center">BROADCAST</entry>
|
|
|
|
<entry align="center">OPTIONS</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry>vpn</entry>
|
|
|
|
<entry>tosysa</entry>
|
|
|
|
<entry>192.168.1.255</entry>
|
|
|
|
<entry></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>In /etc/shorewall/tunnels on system B, we have:</para>
|
|
|
|
<table>
|
|
<title>/etc/shorewall/tunnels system B</title>
|
|
|
|
<tgroup cols="4">
|
|
<thead>
|
|
<row>
|
|
<entry align="center">TYPE</entry>
|
|
|
|
<entry align="center">ZONE</entry>
|
|
|
|
<entry align="center">GATEWAY</entry>
|
|
|
|
<entry align="center">GATEWAY ZONE</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry>ipip</entry>
|
|
|
|
<entry>net</entry>
|
|
|
|
<entry>206.191.148.9</entry>
|
|
|
|
<entry></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>And in the tunnel script on system B:</para>
|
|
|
|
<example>
|
|
<title>tunnel script on system B</title>
|
|
|
|
<programlisting>tunnel=tosysa
|
|
myrealip=134.28.54.2 (for GRE tunnel only)
|
|
myip=10.0.0.1
|
|
hisip=192.168.1.1
|
|
gateway=206.191.148.9
|
|
subnet=192.168.1.0/24</programlisting>
|
|
</example>
|
|
|
|
<para>You can rename the modified tunnel scripts if you like; be sure that
|
|
they are secured so that root can execute them.</para>
|
|
|
|
<para>You will need to allow traffic between the <quote>vpn</quote> zone
|
|
and the <quote>loc</quote> zone on both systems -- if you simply want to
|
|
admit all traffic in both directions, you can use the policy file:</para>
|
|
|
|
<table>
|
|
<title>/etc/shorewall/policy system A & B</title>
|
|
|
|
<tgroup cols="4">
|
|
<thead>
|
|
<row>
|
|
<entry align="center">SOURCE</entry>
|
|
|
|
<entry align="center">DEST</entry>
|
|
|
|
<entry align="center">POLICY</entry>
|
|
|
|
<entry align="center">LOG LEVEL</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry>loc</entry>
|
|
|
|
<entry>vpn</entry>
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
<entry></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>vpn</entry>
|
|
|
|
<entry>loc</entry>
|
|
|
|
<entry>ACCEPT</entry>
|
|
|
|
<entry></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>On both systems, restart Shorewall and run the modified tunnel
|
|
script with the <quote>start</quote> argument on each system. The systems
|
|
in the two masqueraded subnetworks can now talk to each other</para>
|
|
</section>
|
|
</article> |