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<h1><font color="#ffffff"><b>Using Shorewall with Squid</b></font></h1>
<h1> </h1>
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This page covers Shorewall configuration to use with <a
href="http://www.squid-cache.org/">Squid </a>running as a <a
href="#Transparent">Transparent
Proxy</a> or as a <a href="#Manual">Manual Proxy</a>.<br>
<br>
If you are running Shorewall 1.3, please see <a
href="1.3/Shorewall_Squid_Usage.html">this documentation</a>.<br>
<h1><a name="Transparent"></a>Squid as a Transparent Proxy<br>
</h1>
<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://tldp.org/HOWTO/mini/TransparentProxy.html">http://tldp.org/HOWTO/mini/TransparentProxy.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 iptables installed on your Squid server.<br>
<br>
<b><img src="images/BD21298_3.gif" alt="" width="13" height="13"> </b>
If you run a Shorewall version earlier than 1.4.6, 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 (transparent) 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>
There may be a requirement to exclude additional destination
hosts or networks from being redirected. For example, you might also
want
requests destined for 130.252.100.0/24 to not be routed to Squid.<br>
<br>
If you are running Shorewall version 1.4.5 or later, you may just add
the additional hosts/networks to the ORIGINAL DEST column in your
REDIRECT rule:<br>
<br>
<div style="margin-left: 40px;">
<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>!206.124.146.177,130.252.100.0/24</td>
</tr>
</tbody>
</table>
</div>
<br>
If you are running a Shorewall version earlier than 1.4.5, you must add
a manual rule in /etc/shorewall/start:<br>
<blockquote>
<pre>run_iptables -t nat -I loc_dnat -p tcp --dport www -d 130.252.100.0/24 -j RETURN<br></pre>
</blockquote>
To exclude additional hosts or networks, just add additional
similar rules.<br>
<h2><a name="Local"></a>Squid (transparent) 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>
<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>If you are running Shorewall 1.4.1 or Shorewall 1.4.1a, please
upgrade to Shorewall 1.4.2 or later.<br>
<br>
</li>
<li>If you are running Shorewall 1.4.2 or later, then in
/etc/shorewall/interfaces:<br>
<br>
<table cellpadding="2" cellspacing="0" border="1">
<tbody>
<tr>
<td valign="top">ZONE<br>
</td>
<td valign="top">INTERFACE<br>
</td>
<td valign="top">BROADCAST<br>
</td>
<td valign="top">OPTIONS<br>
</td>
</tr>
<tr>
<td valign="top">loc<br>
</td>
<td valign="top">eth1<br>
</td>
<td valign="top">detect<br>
</td>
<td valign="top"><b>routeback</b><br>
</td>
</tr>
</tbody>
</table>
<br>
</li>
<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>
</li>
<br>
<li>Alternativfely, if you are running Shorewall 1.4.0 you can have
the following policy in place of the above rule:<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 on<br></b></font></pre>
</blockquote>
<blockquote> </blockquote>
<h2><a name="DMZ"></a>Squid (transparent) 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 mangle -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>
</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">loc<br>
</td>
<td valign="top">dmz<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>
<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 on<br></b></font></pre>
</blockquote>
<blockquote> </blockquote>
<h1><a name="Manual"></a>Squid as a Manual Proxy</h1>
Assume that Squid is running in zone SZ and listening on port SP; all
web sites that are to be accessed through Squid are in the 'net' zone.
Then for each zone Z that needs access to the Squid server:<br>
<br>
<div style="margin-left: 40px;">
<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">Z<br>
</td>
<td valign="top">SZ<br>
</td>
<td valign="top">tcp<br>
</td>
<td valign="top">SP<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top">ACCEPT<br>
</td>
<td valign="top">SZ<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>
</div>
<br>
Example:<br>
<br>
<div style="margin-left: 40px;">Squid on the firewall listening on port
8080 with access from the 'loc' zone:<br>
<br>
<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">loc<br>
</td>
<td valign="top">$FW<br>
</td>
<td valign="top">tcp<br>
</td>
<td valign="top">8080<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top">ACCEPT<br>
</td>
<td valign="top">$FW<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>
</div>
<p><font size="-1">Updated 1017/2003 - <a href="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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