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<td valign="middle" width="33%" bgcolor="#400169"><a
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<td valign="middle" height="90" align="center" width="34%"><font
color="#ffffff"><b><big><big><big><big>Using Shorewall with Squid</big></big></big></big></b></font><br>
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This page covers Shorewall configuration to use with <a
href="http://www.squid-cache.org/">Squid </a>running as a <u><b>Transparent
Proxy</b></u>. <br>
<a href="#DMZ"></a><br>
<img border="0" src="images/j0213519.gif" width="60" height="60"
alt="Caution" align="middle">
Please observe the following general requirements:<br>
<br>
<b><img src="images/BD21298_3.gif" alt="" width="13" height="13">
</b>In all cases, Squid should be configured to run
as a transparent proxy as described at <a
href="http://www.tldp.org/HOWTO/mini/TransparentProxy-4.html">http://www.tldp.org/HOWTO/mini/TransparentProxy-4.html</a>.<br>
<b><br>
</b><b><img src="images/BD21298_3.gif" alt="" width="13" height="13">
</b>The following instructions mention the files /etc/shorewall/start
and /etc/shorewall/init -- if you don't have those files, siimply create
them.<br>
<br>
<b><img src="images/BD21298_3.gif" alt="" width="13" height="13">
</b> When the Squid server is in the DMZ zone or in
the local zone, that zone must be defined ONLY by its interface -- no /etc/shorewall/hosts
file entries. That is because the packets being routed to the Squid server
still have their original destination IP addresses.<br>
<br>
<b><img src="images/BD21298_3.gif" alt="" width="13" height="13">
</b> You must have iproute2 (<i>ip </i>utility) installed
on your firewall.<br>
<br>
<b><img src="images/BD21298_3.gif" alt="" width="13" height="13">
</b> You must have iptables installed on your Squid
server.<br>
<br>
<b><img src="images/BD21298_3.gif" alt="" width="13" height="13">
</b> You must have NAT and MANGLE enabled in your /etc/shorewall/conf
file<br>
<br>
<b><font color="#009900"> NAT_ENABLED=Yes<br>
</font></b> <font color="#009900"><b>MANGLE_ENABLED=Yes</b></font><br>
<br>
Three different configurations are covered:<br>
<ol>
<li><a href="Shorewall_Squid_Usage.html#Firewall">Squid running on the
Firewall.</a></li>
<li><a href="Shorewall_Squid_Usage.html#Local">Squid running in the
local network</a></li>
<li><a href="Shorewall_Squid_Usage.html#DMZ">Squid running in the DMZ</a></li>
</ol>
<h2><a name="Firewall"></a>Squid Running on the Firewall</h2>
You want to redirect all local www connection requests EXCEPT
those to your own
http server (206.124.146.177)
to a Squid transparent
proxy running on the firewall and listening on port 3128. Squid
will of course require access to remote web servers.<br>
<br>
In /etc/shorewall/rules:<br>
<br>
<blockquote>
<table border="1" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>ACTION</b></td>
<td><b>SOURCE</b></td>
<td><b>DEST</b></td>
<td><b> PROTO</b></td>
<td><b>DEST<br>
PORT(S)</b></td>
<td><b>SOURCE<br>
PORT(S)</b></td>
<td><b>ORIGINAL<br>
DEST</b></td>
</tr>
<tr>
<td>REDIRECT</td>
<td>loc</td>
<td>3128</td>
<td>tcp</td>
<td>www</td>
<td> -<br>
</td>
<td>!206.124.146.177</td>
</tr>
<tr>
<td>ACCEPT</td>
<td>fw</td>
<td>net</td>
<td>tcp</td>
<td>www</td>
<td> <br>
</td>
<td> <br>
</td>
</tr>
</tbody>
</table>
<br>
</blockquote>
<h2><a name="Local"></a>Squid Running in the local network</h2>
You want to redirect all local www connection requests to a Squid
transparent proxy
running in your local zone at 192.168.1.3 and listening on port 3128.
Your local interface is eth1. There may also be a web server running on 192.168.1.3.
It is assumed that web access is already enabled from the local zone to the
internet.<br>
<p><font color="#ff0000"><b>WARNING: </b></font>This setup may conflict with
other aspects of your gateway including but not limited to traffic shaping
and route redirection. For that reason, <b>I don't recommend it</b>.<br>
</p>
<ul>
<li>On your firewall system, issue the following command<br>
</li>
</ul>
<blockquote>
<pre><b><font color="#009900">echo 202 www.out >> /etc/iproute2/rt_tables</font></b><br></pre>
</blockquote>
<ul>
<li>In /etc/shorewall/init, put:<br>
</li>
</ul>
<blockquote>
<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>
</blockquote>
<ul>
<li>In /etc/shorewall/rules:<br>
<br>
<table border="1" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>ACTION</b></td>
<td><b>SOURCE</b></td>
<td><b>DEST</b></td>
<td><b> PROTO</b></td>
<td><b>DEST<br>
PORT(S)</b></td>
<td><b>SOURCE<br>
PORT(S)</b></td>
<td><b>ORIGINAL<br>
DEST</b></td>
</tr>
<tr>
<td>ACCEPT<br>
</td>
<td>loc</td>
<td>loc<br>
</td>
<td>tcp</td>
<td>www</td>
<td> <br>
</td>
<td><br>
</td>
</tr>
</tbody>
</table>
<br>
</li>
<li>Alternativfely, you can have the following policy:<br>
<br>
<table cellpadding="2" cellspacing="0" border="1">
<tbody>
<tr>
<td valign="top"><b>SOURCE<br>
</b></td>
<td valign="top"><b>DESTINATION<br>
</b></td>
<td valign="top"><b>POLICY<br>
</b></td>
<td valign="top"><b>LOG LEVEL<br>
</b></td>
<td valign="top"><b>BURST PARAMETERS<br>
</b></td>
</tr>
<tr>
<td valign="top">loc<br>
</td>
<td valign="top">loc<br>
</td>
<td valign="top">ACCEPT<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
</li>
<li>In /etc/shorewall/start add:<br>
</li>
</ul>
<blockquote>
<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>
</blockquote>
<ul>
<li>On 192.168.1.3, arrange for the following command to be executed
after networking has come up<br>
<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>
</li>
</ul>
<blockquote> If you are running RedHat on the server, you can simply execute
the following commands after you have typed the iptables command above:<br>
</blockquote>
<blockquote>
<blockquote> </blockquote>
<pre><font color="#009900"><b>iptables-save > /etc/sysconfig/iptables</b></font><font
color="#009900"><b><br>chkconfig --level 35 iptables start<br></b></font></pre>
</blockquote>
<blockquote> </blockquote>
<h2><a name="DMZ"></a>Squid Running in the DMZ (This is what I do)</h2>
You have a single Linux system in your DMZ with IP address 192.0.2.177.
You want to run both a web server and Squid on that system. Your DMZ interface
is eth1 and your local interface is eth2.<br>
<ul>
<li>On your firewall system, issue the following command<br>
</li>
</ul>
<blockquote>
<pre><font color="#009900"><b>echo 202 www.out >> /etc/iproute2/rt_tables</b></font><br></pre>
</blockquote>
<ul>
<li>In /etc/shorewall/init, put:<br>
</li>
</ul>
<blockquote>
<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>
</blockquote>
<ul>
<li> Do<b> one </b>of the following:<br>
<br>
A) In /etc/shorewall/start add<br>
</li>
</ul>
<blockquote>
<pre><b><font color="#009900"> iptables -t nat -A PREROUTING -i eth2 -p tcp --dport 80 -j MARK --set-mark 202</font></b><br></pre>
</blockquote>
<blockquote>B) Set MARK_IN_FORWARD_CHAIN=No in /etc/shorewall/shorewall.conf
and add the following entry in /etc/shorewall/tcrules:<br>
</blockquote>
<blockquote>
<blockquote>
<table cellpadding="2" border="1" cellspacing="0">
<tbody>
<tr>
<td valign="top">MARK<br>
</td>
<td valign="top">SOURCE<br>
</td>
<td valign="top">DESTINATION<br>
</td>
<td valign="top">PROTOCOL<br>
</td>
<td valign="top">PORT<br>
</td>
<td valign="top">CLIENT PORT<br>
</td>
</tr>
<tr>
<td valign="top">202<br>
</td>
<td valign="top">eth2<br>
</td>
<td valign="top">0.0.0.0/0<br>
</td>
<td valign="top">tcp<br>
</td>
<td valign="top">80<br>
</td>
<td valign="top">-<br>
</td>
</tr>
</tbody>
</table>
</blockquote>
C) Run Shorewall 1.3.14 or later and add the following entry in /etc/shorewall/tcrules:<br>
</blockquote>
<blockquote>
<blockquote>
<table cellpadding="2" border="1" cellspacing="0">
<tbody>
<tr>
<td valign="top">MARK<br>
</td>
<td valign="top">SOURCE<br>
</td>
<td valign="top">DESTINATION<br>
</td>
<td valign="top">PROTOCOL<br>
</td>
<td valign="top">PORT<br>
</td>
<td valign="top">CLIENT PORT<br>
</td>
</tr>
<tr>
<td valign="top">202:P<br>
</td>
<td valign="top">eth2<br>
</td>
<td valign="top">0.0.0.0/0<br>
</td>
<td valign="top">tcp<br>
</td>
<td valign="top">80<br>
</td>
<td valign="top">-<br>
</td>
</tr>
</tbody>
</table>
</blockquote>
<br>
</blockquote>
<ul>
<li>In /etc/shorewall/rules, you will need:</li>
</ul>
<blockquote>
<table cellpadding="2" border="1" cellspacing="0">
<tbody>
<tr>
<td valign="top">ACTION<br>
</td>
<td valign="top">SOURCE<br>
</td>
<td valign="top">DEST<br>
</td>
<td valign="top">PROTO<br>
</td>
<td valign="top">DEST<br>
PORT(S)<br>
</td>
<td valign="top">CLIENT<br>
PORT(2)<br>
</td>
<td valign="top">ORIGINAL<br>
DEST<br>
</td>
</tr>
<tr>
<td valign="top">ACCEPT<br>
</td>
<td valign="top">dmz<br>
</td>
<td valign="top">net<br>
</td>
<td valign="top">tcp<br>
</td>
<td valign="top">80<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
</blockquote>
<ul>
<li>On 192.0.2.177 (your Web/Squid server), arrange for the following
command to be executed after networking has come up<br>
<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>
</li>
</ul>
<blockquote> If you are running RedHat on the server, you can simply execute
the following commands after you have typed the iptables command above:<br>
</blockquote>
<blockquote>
<blockquote> </blockquote>
<pre><font color="#009900"><b>iptables-save > /etc/sysconfig/iptables</b></font><font
color="#009900"><b><br>chkconfig --level 35 iptables start<br></b></font></pre>
</blockquote>
<blockquote> </blockquote>
<p><font size="-1"> Updated 1/23/2003 - <a
href="file:///home/teastep/Shorewall-docs/support.htm">Tom Eastep</a>
</font></p>
<a
href="copyright.htm"><font size="2">Copyright</font> © <font
size="2">2003 Thomas M. Eastep.</font></a><br>
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