shorewall_code/STABLE/documentation/VPN.htm
2002-12-28 15:38:03 +00:00

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<title>VPN</title>
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<h1 align="center"><font color="#ffffff">VPN</font></h1>
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<p>It is often the case that a system behind the firewall needs to be able
to access a remote network through Virtual Private Networking (VPN). The
two most common means for doing this are IPSEC and PPTP. The basic setup
is shown in the following diagram:</p>
<p align="center"><img border="0" src="images/VPN.png" width="568"
height="796">
</p>
<p align="left">A system with an RFC 1918 address needs to access a remote
network through a remote gateway. For this example, we will assume that
the local system has IP address 192.168.1.12 and that the remote gateway
has IP address 192.0.2.224.</p>
<p align="left">If PPTP is being used, there are no firewall requirements
beyond the default loc-&gt;net ACCEPT policy. There is one restriction however:
Only one local system at a time can be connected to a single remote gateway
unless you patch your kernel from the 'Patch-o-matic' patches available
at <a href="http://www.netfilter.org">http://www.netfilter.org</a>. </p>
<p align="left">If IPSEC is being used then only one system may connect to
the remote gateway and there are firewall configuration requirements as
follows:</p>
<blockquote>
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<td height="38"><u><b>ACTION</b></u></td>
<td height="38"><u><b>SOURCE</b></u></td>
<td height="38"><u><b>DESTINATION</b></u></td>
<td height="38"><u><b>PROTOCOL</b></u></td>
<td height="38"><u><b>PORT</b></u></td>
<td height="38"><u><b>CLIENT<br>
PORT</b></u></td>
<td height="38"><u><b>ORIGINAL<br>
DEST</b></u></td>
</tr>
<tr>
<td height="19">DNAT</td>
<td height="19">net:192.0.2.224</td>
<td height="19">loc:192.168.1.12</td>
<td height="19">50</td>
<td height="19"><EFBFBD></td>
<td height="19"><EFBFBD></td>
<td height="19"><EFBFBD></td>
</tr>
<tr>
<td height="19">DNAT</td>
<td height="19">net:192.0.2.224</td>
<td height="19">loc:192.168.1.12</td>
<td height="19">udp</td>
<td height="19">500</td>
<td height="19"><EFBFBD></td>
<td height="19"><EFBFBD></td>
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</blockquote>
<p>If you want to be able to give access to all of your local systems to
the remote network, you should consider running a VPN client on your firewall.
As starting points, see <a
href="http://www.shorewall.net/Documentation.htm#Tunnels"> http://www.shorewall.net/Documentation.htm#Tunnels</a>
or <a href="http://www.shorewall.net/PPTP.htm">http://www.shorewall.net/PPTP.htm</a>.</p>
<p><font size="2">Last modified 12/21/2002 - <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">2002 Thomas M. Eastep.</font></a></font></p>
<p><EFBFBD></p>
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