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464 lines
14 KiB
HTML
464 lines
14 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>Shorewall Squid Usage</title>
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<meta http-equiv="content-type"
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content="text/html; charset=ISO-8859-1">
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<meta name="author" content="Tom Eastep">
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</head>
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<body>
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<table cellpadding="0" cellspacing="0" border="0" width="100%"
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bgcolor="#3366ff">
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<tbody>
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<tr>
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<td valign="middle" width="33%" bgcolor="#3366ff"><a
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href="http://www.squid-cache.org/"><img src="images/squidnow.gif"
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alt="" width="88" height="31" hspace="4"> </a><br>
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</td>
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<td valign="middle" height="90" align="center" width="34%">
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<h1><font color="#ffffff"><b>Using Shorewall with Squid</b></font></h1>
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<h1> </h1>
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</td>
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<td valign="middle" height="90" width="33%" align="right"><a
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href="http://www.squid-cache.org/"><img src="images/cache_now.gif"
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alt="" width="100" height="31" hspace="4"> </a><br>
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</td>
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</tr>
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</tbody>
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</table>
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<br>
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This page covers Shorewall configuration to use with <a
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href="http://www.squid-cache.org/">Squid </a>running as a <u><b>Transparent
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Proxy</b></u>. If you are running Shorewall 1.3, please see <a
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href="1.3/Shorewall_Squid_Usage.html">this documentation</a>.<br>
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<br>
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<img border="0" src="images/j0213519.gif" width="60" height="60"
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alt="Caution" align="middle"> Please observe the
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following general requirements:<br>
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<br>
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<b><img src="images/BD21298_3.gif" alt="" width="13" height="13">
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</b>In all cases, Squid should be configured to run
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as a transparent proxy as described at <a
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href="http://tldp.org/HOWTO/mini/TransparentProxy.html">http://tldp.org/HOWTO/mini/TransparentProxy.html</a>.<br>
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<b><br>
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</b><b><img src="images/BD21298_3.gif" alt="" width="13" height="13">
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</b>The following instructions mention
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the files /etc/shorewall/start and /etc/shorewall/init -- if you don't
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have those files, siimply create them.<br>
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<br>
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<b><img src="images/BD21298_3.gif" alt="" width="13" height="13"> </b>
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When the Squid server is in the DMZ zone or in the local zone, that
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zone must be defined ONLY by its interface -- no /etc/shorewall/hosts
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file entries. That is because the packets being routed to the Squid
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server still have their original destination IP addresses.<br>
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<br>
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<b><img src="images/BD21298_3.gif" alt="" width="13" height="13"> </b>
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You must have iptables installed on your Squid server.<br>
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<br>
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<b><img src="images/BD21298_3.gif" alt="" width="13" height="13"> </b>
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If you run a Shorewall version earlier than 1.4.6, you must have NAT
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and MANGLE enabled in your /etc/shorewall/conf file<br>
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<br>
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<b><font color="#009900">
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NAT_ENABLED=Yes<br>
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</font></b> <font color="#009900"><b>MANGLE_ENABLED=Yes</b></font><br>
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<br>
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Three different configurations are covered:<br>
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<ol>
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<li><a href="Shorewall_Squid_Usage.html#Firewall">Squid
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running on the Firewall.</a></li>
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<li><a href="Shorewall_Squid_Usage.html#Local">Squid running in the
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local network</a></li>
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<li><a href="Shorewall_Squid_Usage.html#DMZ">Squid running in the DMZ</a></li>
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</ol>
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<h2><a name="Firewall"></a>Squid Running on the Firewall</h2>
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You want to redirect all local www connection requests
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EXCEPT those to your own http server (206.124.146.177) to a Squid
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transparent proxy running on the firewall
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and listening on port 3128. Squid will of course require access
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to remote web servers.<br>
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<br>
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In /etc/shorewall/rules:<br>
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<br>
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<blockquote>
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<table border="1" cellpadding="2" style="border-collapse: collapse;">
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<tbody>
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<tr>
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<td><b>ACTION</b></td>
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<td><b>SOURCE</b></td>
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<td><b>DEST</b></td>
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<td><b> PROTO</b></td>
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<td><b>DEST<br>
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PORT(S)</b></td>
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<td><b>SOURCE<br>
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PORT(S)</b></td>
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<td><b>ORIGINAL<br>
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DEST</b></td>
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</tr>
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<tr>
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<td>REDIRECT</td>
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<td>loc</td>
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<td>3128</td>
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<td>tcp</td>
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<td>www</td>
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<td> -<br>
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</td>
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<td>!206.124.146.177</td>
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</tr>
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<tr>
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<td>ACCEPT</td>
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<td>fw</td>
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<td>net</td>
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<td>tcp</td>
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<td>www</td>
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<td> <br>
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</td>
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<td> <br>
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</td>
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</tr>
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</tbody>
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</table>
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<br>
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</blockquote>
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There may be a requirement to exclude additional destination
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hosts or networks from being redirected. For example, you might also
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want
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requests destined for 130.252.100.0/24 to not be routed to Squid. In
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that
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case, you must add a manual rule in /etc/shorewall/start:<br>
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<blockquote>
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<pre>run_iptables -t nat -I loc_dnat -p tcp --dport www -d 130.252.100.0/24 -j RETURN<br></pre>
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</blockquote>
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To exclude additional hosts or networks, just add additional
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similar rules.<br>
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<h2><a name="Local"></a>Squid Running in the local network</h2>
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You want to redirect all local www connection requests to a Squid
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transparent proxy running in your local zone at 192.168.1.3 and
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listening
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on port 3128. Your local interface is eth1. There may also be a web
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server running on 192.168.1.3. It is assumed that web access is already
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enabled from the local zone to the internet..<br>
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<ul>
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<li>On your firewall system, issue the following command<br>
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</li>
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</ul>
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<blockquote>
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<pre><b><font color="#009900">echo 202 www.out >> /etc/iproute2/rt_tables</font></b><br></pre>
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</blockquote>
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<ul>
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<li>In /etc/shorewall/init, put:<br>
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</li>
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</ul>
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<blockquote>
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<pre><b><font color="#009900">if [ -z "`ip rule list | grep www.out`" ] ; then<br> ip rule add fwmark 202 table www.out<br> ip route add default via 192.168.1.3 dev eth1 table www.out<br> ip route flush cache<br> echo 0 > /proc/sys/net/ipv4/conf/eth1/send_redirects<br>fi<br></font></b></pre>
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</blockquote>
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<ul>
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<li>If you are running Shorewall 1.4.1 or Shorewall 1.4.1a, please
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upgrade to Shorewall 1.4.2 or later.<br>
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<br>
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</li>
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<li>If you are running Shorewall 1.4.2 or later, then in
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/etc/shorewall/interfaces:<br>
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<br>
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<table cellpadding="2" cellspacing="0" border="1">
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<tbody>
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<tr>
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<td valign="top">ZONE<br>
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</td>
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<td valign="top">INTERFACE<br>
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</td>
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<td valign="top">BROADCAST<br>
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</td>
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<td valign="top">OPTIONS<br>
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</td>
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</tr>
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<tr>
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<td valign="top">loc<br>
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</td>
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<td valign="top">eth1<br>
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</td>
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<td valign="top">detect<br>
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</td>
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<td valign="top"><b>routeback</b><br>
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</td>
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</tr>
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</tbody>
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</table>
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<br>
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</li>
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<li>In /etc/shorewall/rules:<br>
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<br>
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<table border="1" cellpadding="2" style="border-collapse: collapse;">
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<tbody>
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<tr>
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<td><b>ACTION</b></td>
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<td><b>SOURCE</b></td>
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<td><b>DEST</b></td>
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<td><b> PROTO</b></td>
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<td><b>DEST<br>
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PORT(S)</b></td>
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<td><b>SOURCE<br>
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PORT(S)</b></td>
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<td><b>ORIGINAL<br>
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DEST</b></td>
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</tr>
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<tr>
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<td>ACCEPT<br>
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</td>
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<td>loc</td>
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<td>loc<br>
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</td>
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<td>tcp</td>
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<td>www</td>
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<td> <br>
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</td>
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<td><br>
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</td>
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</tr>
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</tbody>
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</table>
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</li>
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<br>
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<li>Alternativfely, if you are running Shorewall 1.4.0 you can have
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the following policy in place of the above rule:<br>
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<table cellpadding="2" cellspacing="0" border="1">
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<tbody>
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<tr>
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<td valign="top"><b>SOURCE<br>
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</b></td>
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<td valign="top"><b>DESTINATION<br>
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</b></td>
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<td valign="top"><b>POLICY<br>
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</b></td>
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<td valign="top"><b>LOG LEVEL<br>
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</b></td>
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<td valign="top"><b>BURST PARAMETERS<br>
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</b></td>
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</tr>
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<tr>
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<td valign="top">loc<br>
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</td>
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<td valign="top">loc<br>
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</td>
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<td valign="top">ACCEPT<br>
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</td>
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<td valign="top"><br>
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</td>
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<td valign="top"><br>
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</td>
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</tr>
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</tbody>
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</table>
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<br>
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</li>
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<li>In /etc/shorewall/start add:<br>
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</li>
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</ul>
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<blockquote>
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<pre><font color="#009900"><b>iptables -t mangle -A PREROUTING -i eth1 -s ! 192.168.1.3 -p tcp --dport 80 -j MARK --set-mark 202</b></font><br></pre>
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</blockquote>
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<ul>
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<li>On 192.168.1.3, arrange for the following command to be executed
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after networking has come up<br>
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<pre><b><font color="#009900">iptables -t nat -A PREROUTING -i eth0 -d ! 192.168.1.3 -p tcp --dport 80 -j REDIRECT --to-ports 3128</font></b><br></pre>
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</li>
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</ul>
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<blockquote> If you are running RedHat on the server, you can simply
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execute the following commands after you have typed the iptables
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command above:<br>
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</blockquote>
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<blockquote>
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<blockquote> </blockquote>
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<pre><font color="#009900"><b>iptables-save > /etc/sysconfig/iptables</b></font><font
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color="#009900"><b><br>chkconfig --level 35 iptables on<br></b></font></pre>
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</blockquote>
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<blockquote> </blockquote>
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<h2><a name="DMZ"></a>Squid Running in the DMZ (This is what I do)</h2>
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You have a single Linux system in your DMZ with IP address 192.0.2.177.
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You want to run both a web server and Squid on that system. Your DMZ
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interface is eth1 and your local interface is eth2.<br>
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<ul>
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<li>On your firewall system, issue the following command<br>
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</li>
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</ul>
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<blockquote>
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<pre><font color="#009900"><b>echo 202 www.out >> /etc/iproute2/rt_tables</b></font><br></pre>
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</blockquote>
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<ul>
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<li>In /etc/shorewall/init, put:<br>
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</li>
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</ul>
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<blockquote>
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<pre><font color="#009900"><b>if [ -z "`ip rule list | grep www.out`" ] ; then<br> ip rule add fwmark 202 table www.out<br> ip route add default via 192.0.2.177 dev eth1 table www.out<br> ip route flush cache<br>fi</b></font><br></pre>
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</blockquote>
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<ul>
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<li> Do<b> one </b>of the following:<br>
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<br>
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A) In /etc/shorewall/start add<br>
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</li>
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</ul>
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<blockquote>
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<pre><b><font color="#009900"> iptables -t mangle -A PREROUTING -i eth2 -p tcp --dport 80 -j MARK --set-mark 202</font></b><br></pre>
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</blockquote>
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<blockquote>B) Set MARK_IN_FORWARD_CHAIN=No in
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/etc/shorewall/shorewall.conf and add the following entry in
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/etc/shorewall/tcrules:<br>
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</blockquote>
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<blockquote>
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<blockquote>
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<table cellpadding="2" border="1" cellspacing="0">
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<tbody>
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<tr>
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<td valign="top">MARK<br>
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</td>
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<td valign="top">SOURCE<br>
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</td>
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<td valign="top">DESTINATION<br>
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</td>
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<td valign="top">PROTOCOL<br>
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</td>
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<td valign="top">PORT<br>
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</td>
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<td valign="top">CLIENT PORT<br>
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</td>
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</tr>
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<tr>
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<td valign="top">202<br>
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</td>
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<td valign="top">eth2<br>
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</td>
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<td valign="top">0.0.0.0/0<br>
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</td>
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<td valign="top">tcp<br>
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</td>
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<td valign="top">80<br>
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</td>
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<td valign="top">-<br>
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</td>
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</tr>
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</tbody>
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</table>
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</blockquote>
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C) Run Shorewall 1.3.14 or later and add the following entry
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in /etc/shorewall/tcrules:<br>
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</blockquote>
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<blockquote>
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<blockquote>
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<table cellpadding="2" border="1" cellspacing="0">
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<tbody>
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<tr>
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<td valign="top">MARK<br>
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</td>
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<td valign="top">SOURCE<br>
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</td>
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<td valign="top">DESTINATION<br>
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</td>
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<td valign="top">PROTOCOL<br>
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</td>
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<td valign="top">PORT<br>
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</td>
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<td valign="top">CLIENT PORT<br>
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</td>
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</tr>
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<tr>
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<td valign="top">202:P<br>
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</td>
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<td valign="top">eth2<br>
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</td>
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<td valign="top">0.0.0.0/0<br>
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</td>
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<td valign="top">tcp<br>
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</td>
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<td valign="top">80<br>
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</td>
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<td valign="top">-<br>
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</td>
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</tr>
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</tbody>
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</table>
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</blockquote>
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</blockquote>
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<ul>
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<li>In /etc/shorewall/rules, you will need:</li>
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</ul>
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<blockquote>
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<table cellpadding="2" border="1" cellspacing="0">
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<tbody>
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<tr>
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<td valign="top">ACTION<br>
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</td>
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<td valign="top">SOURCE<br>
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</td>
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<td valign="top">DEST<br>
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</td>
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<td valign="top">PROTO<br>
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</td>
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<td valign="top">DEST<br>
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PORT(S)<br>
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</td>
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<td valign="top">CLIENT<br>
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PORT(2)<br>
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</td>
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<td valign="top">ORIGINAL<br>
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DEST<br>
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</td>
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</tr>
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<tr>
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<td valign="top">ACCEPT<br>
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</td>
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<td valign="top">loc<br>
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</td>
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<td valign="top">dmz<br>
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</td>
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<td valign="top">tcp<br>
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</td>
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<td valign="top">80<br>
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</td>
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<td valign="top"><br>
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</td>
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<td valign="top"><br>
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</td>
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</tr>
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<tr>
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<td valign="top">ACCEPT<br>
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</td>
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<td valign="top">dmz<br>
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</td>
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<td valign="top">net<br>
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</td>
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<td valign="top">tcp<br>
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</td>
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<td valign="top">80<br>
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</td>
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<td valign="top"><br>
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</td>
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<td valign="top"><br>
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</td>
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</tr>
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</tbody>
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</table>
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<br>
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</blockquote>
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<ul>
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<li>On 192.0.2.177 (your Web/Squid server), arrange for the following
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command to be executed after networking has come up<br>
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<pre><font color="#009900"><b>iptables -t nat -A PREROUTING -i eth0 -d ! 192.0.2.177 -p tcp --dport 80 -j REDIRECT --to-ports 3128</b></font><br></pre>
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</li>
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</ul>
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<blockquote> If you are running RedHat on the server, you can simply
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execute the following commands after you have typed the iptables
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command above:<br>
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</blockquote>
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<blockquote>
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<blockquote> </blockquote>
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<pre><font color="#009900"><b>iptables-save > /etc/sysconfig/iptables</b></font><font
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color="#009900"><b><br>chkconfig --level 35 iptables on<br></b></font></pre>
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</blockquote>
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<blockquote> </blockquote>
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<p><font size="-1"> Updated 8/9/2003 - <a href="support.htm">Tom Eastep</a>
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</font></p>
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<a href="copyright.htm"><font size="2">Copyright</font> © <font
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size="2">2003 Thomas M. Eastep.</font></a><br>
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