2002-12-28 16:38:03 +01:00
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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2002-09-16 19:04:56 +02:00
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2002-12-28 16:38:03 +01:00
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<meta http-equiv="Content-Language" content="en-us">
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<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
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<meta name="ProgId" content="FrontPage.Editor.Document">
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content="text/html; charset=windows-1252">
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<title>VPN</title>
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2002-09-16 19:04:56 +02:00
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</head>
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2002-12-28 16:38:03 +01:00
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<body>
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<table border="0" cellpadding="0" cellspacing="0"
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style="border-collapse: collapse;" bordercolor="#111111" width="100%"
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id="AutoNumber1" bgcolor="#400169" height="90">
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<tbody>
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2002-09-16 19:04:56 +02:00
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<tr>
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2002-12-28 16:38:03 +01:00
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<td width="100%">
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<h1 align="center"><font color="#ffffff">VPN</font></h1>
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</tbody>
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</table>
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<p>It is often the case that a system behind the firewall needs to be able
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to access a remote network through Virtual Private Networking (VPN). The
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two most common means for doing this are IPSEC and PPTP. The basic setup
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is shown in the following diagram:</p>
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<p align="center"><img border="0" src="images/VPN.png" width="568"
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height="796">
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</p>
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<p align="left">A system with an RFC 1918 address needs to access a remote
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network through a remote gateway. For this example, we will assume that
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the local system has IP address 192.168.1.12 and that the remote gateway
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has IP address 192.0.2.224.</p>
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<p align="left">If PPTP is being used, there are no firewall requirements
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beyond the default loc->net ACCEPT policy. There is one restriction however:
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Only one local system at a time can be connected to a single remote gateway
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unless you patch your kernel from the 'Patch-o-matic' patches available
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at <a href="http://www.netfilter.org">http://www.netfilter.org</a>. </p>
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<p align="left">If IPSEC is being used then only one system may connect to
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the remote gateway and there are firewall configuration requirements as
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follows:</p>
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<blockquote>
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<table border="1" cellpadding="2" style="border-collapse: collapse;"
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bordercolor="#111111" id="AutoNumber2" height="98">
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<tbody>
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<tr>
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<td height="38"><u><b>ACTION</b></u></td>
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<td height="38"><u><b>SOURCE</b></u></td>
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<td height="38"><u><b>DESTINATION</b></u></td>
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<td height="38"><u><b>PROTOCOL</b></u></td>
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<td height="38"><u><b>PORT</b></u></td>
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<td height="38"><u><b>CLIENT<br>
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PORT</b></u></td>
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<td height="38"><u><b>ORIGINAL<br>
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DEST</b></u></td>
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</tr>
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<tr>
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<td height="19">DNAT</td>
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<td height="19">net:192.0.2.224</td>
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<td height="19">loc:192.168.1.12</td>
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<td height="19">50</td>
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<td height="19"><EFBFBD></td>
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<td height="19"><EFBFBD></td>
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<td height="19"><EFBFBD></td>
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</tr>
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<tr>
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<td height="19">DNAT</td>
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<td height="19">net:192.0.2.224</td>
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<td height="19">loc:192.168.1.12</td>
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<td height="19">udp</td>
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<td height="19">500</td>
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<td height="19"><EFBFBD></td>
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<td height="19"><EFBFBD></td>
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</tr>
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</tbody>
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2002-09-16 19:04:56 +02:00
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</table>
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2002-12-28 16:38:03 +01:00
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</blockquote>
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<p>If you want to be able to give access to all of your local systems to
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the remote network, you should consider running a VPN client on your firewall.
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As starting points, see <a
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href="http://www.shorewall.net/Documentation.htm#Tunnels"> http://www.shorewall.net/Documentation.htm#Tunnels</a>
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or <a href="http://www.shorewall.net/PPTP.htm">http://www.shorewall.net/PPTP.htm</a>.</p>
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<p><font size="2">Last modified 12/21/2002 - <a href="support.htm">Tom Eastep</a></font></p>
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<p><font face="Trebuchet MS"><a href="copyright.htm"> <font size="2">Copyright</font>
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<EFBFBD> <font size="2">2002 Thomas M. Eastep.</font></a></font></p>
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<p><EFBFBD></p>
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<br>
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2002-09-16 19:04:56 +02:00
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</body>
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</html>
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