shorewall_code/Shorewall-docs/6to4.htm
2003-07-16 18:59:33 +00:00

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<title>6to4 Tunnels</title>
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<h1 align="center"><font color="#ffffff">6to4 Tunnels</font></h1>
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<h3>The 6to4 tunnel documentation is provided by Eric de Thouars.<br>
</h3>
<h3><font color="#ff6633">Warning: </font>The 6to4 tunnel feature of Shorewall
only facilitates IPv6 over IPv4 tunneling. It does not provide any IPv6
security measures.</h3>
<p>6to4 tunneling with Shorewall can be used to connect your IPv6 network
to another IPv6 network over an IPv4 infrastructure</p>
<p>More information on Linux and IPv6 can be found in the <a
href="http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO">Linux IPv6 HOWTO</a>.
Details on how to setup a 6to4 tunnels are described in the section <a
href="http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/configuring-ipv6to4-tunnels.html">Setup
of 6to4 tunnels</a>.</p>
<h2>Connecting two IPv6 Networks</h2>
<p>Suppose that we have the following situation:</p>
<p align="center"> <img border="0" src="images/TwoIPv6Nets1.png"
width="745" height="427" alt="">
</p>
<p align="left">We want systems in the 2002:100:333::/64 subnetwork to be
able to communicate with the systems in the 2002:488:999::/64 network. This
is accomplished through use of the /etc/shorewall/tunnels file and the "ip"
utility for network interface and routing configuration.</p>
<p align="left">Unlike GRE and IPIP tunneling, the /etc/shorewall/policy,
/etc/shorewall/interfaces and /etc/shorewall/zones files are not used. There
is no need to declare a zone to represent the remote IPv6 network. This
remote network is not visible on IPv4 interfaces and to iptables. All that
is visible on the IPv4 level is an IPv4 stream which contains IPv6 traffic.
Separate IPv6 interfaces and ip6tables rules need to be defined to handle
this traffic. </p>
<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>6to4</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 IPv6
encapsulation protocol (41) will be accepted to/from the remote gateway.</p>
<p>Use the following commands to setup system A:</p>
<blockquote>
<p>&gt;ip tunnel add tun6to4 mode sit ttl 254 remote 134.28.54.2<br>
&gt;ip link set dev tun6to4 up<br>
&gt;ip addr add 3ffe:8280:0:2001::1/64 dev tun6to4<br>
&gt;ip route add 2002:488:999::/64 via 3ffe:8280:0:2001::2</p>
</blockquote>
<p>Similarly, 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>6to4</td>
<td>net</td>
<td>206.191.148.9</td>
<td><EFBFBD></td>
</tr>
</tbody>
</table>
</blockquote>
<p>And use the following commands to setup system B:</p>
<blockquote>
<p>&gt;ip tunnel add tun6to4 mode sit ttl 254 remote 206.191.148.9<br>
&gt;ip link set dev tun6to4 up<br>
&gt;ip addr add 3ffe:8280:0:2001::2/64 dev tun6to4<br>
&gt;ip route add 2002:100:333::/64 via 3ffe:8280:0:2001::1</p>
</blockquote>
<p>On both systems, restart Shorewall and issue the configuration commands
as listed above. The systems in both IPv6 subnetworks can now talk to each
other using IPv6.</p>
<p><font size="2">Updated 5/18/2003 - <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 and Eric de Thouars.</font></a></p>
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