fix some typos

git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@2178 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
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judas_iscariote 2005-05-26 21:53:40 +00:00
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<?xml version = '1.0' encoding = 'UTF-8'?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<article id="Shorewall_Squid_Usage" >
<!--$Id$-->
<articleinfo>
<!--$Id$--> <articleinfo>
<title>Using Shorewall with Squid</title>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Eastep</surname>
</author>
</authorgroup>
<pubdate>2005-05-19</pubdate>
<copyright>
<year>2003-2005</year>
<holder>Thomas M. Eastep</holder>
</copyright>
<legalnotice>
<para>Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version
1.2 or any later version published by the Free Software Foundation; with
no Invariant Sections, with no Front-Cover, and with no Back-Cover
Texts. A copy of the license is included in the section entitled
<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
License</ulink></quote>.</para>
<quote>
<ulink url="GnuCopyright.htm" >GNU Free Documentation
License</ulink>
</quote>.</para>
</legalnotice>
</articleinfo>
<para>This page covers Shorewall configuration to use with <ulink
url="http://www.squid-cache.org">Squid</ulink> running as a Transparent
<para>This page covers Shorewall configuration to use with <ulink url="http://www.squid-cache.org" >Squid</ulink> running as a Transparent
Proxy or as a Manual Proxy.</para>
<warning>
<para>This documentation assumes that you are running Shorewall 2.0.0 or
later.</para>
</warning>
<section>
<title>Squid as a Transparent Proxy</title>
<important>
<para>This section gives instructions for transparent proxying of HTTP.
HTTPS (normally TCP port 443) <emphasis role="bold" >cannot</emphasis> be
proxied transparently (stop and think about it for a minute; if HTTPS
could be transparently proxied, then how secure would it be?).</para>
</important>
<caution>
<para>Please observe the following general requirements:</para>
<itemizedlist>
<listitem>
<para>In all cases, Squid should be configured to run as a transrent
proxy as described at <ulink
url="http://www.tldp.org/HOWTO/mini/TransparentProxy.html">http://www.tldp.org/HOWTO/mini/TransparentProxy.html</ulink>.</para>
proxy as described at <ulink url="http://www.tldp.org/HOWTO/mini/TransparentProxy.html" >http://www.tldp.org/HOWTO/mini/TransparentProxy.html</ulink>.</para>
</listitem>
<listitem>
<para>Depending on your distribution, other Squid configuration
changes may be required. These changes typically consist of:</para>
<orderedlist>
<listitem>
<para>Adding an ACL that represents the clients on your local
network.</para>
<para>Example:</para>
<programlisting>ACL my_networks src 192.168.1.0/24 192.168.2.0/24</programlisting>
</listitem>
<listitem>
<para>Allowing HTTP access to that ACL.</para>
<para>Example:</para>
<programlisting>http_access allow my_networks</programlisting>
</listitem>
</orderedlist>
<para>See your distribution's Squid documenation and <ulink
url="http://www.squid-cache.org/">http://www.squid-cache.org/</ulink>
<para>See your distribution's Squid documenation and <ulink url="http://www.squid-cache.org/" >http://www.squid-cache.org/</ulink>
for details.</para>
<para>It is a good idea to get Squid working as a <link
linkend="Manual">manual proxy</link> first before you try
<para>It is a good idea to get Squid working as a <link linkend="Manual" >manual proxy</link> first before you try
transparent proxying.</para>
</listitem>
<listitem>
<para>The following instructions mention the files
/etc/shorewall/start and /etc/shorewall/init -- if you don't have
those files, siimply create them.</para>
</listitem>
<listitem>
<para>When the Squid server is in the DMZ zone or in the local zone,
that zone must be defined ONLY by its interface -- no
@ -108,13 +80,11 @@
routed to the Squid server still have their original destination IP
addresses.</para>
</listitem>
<listitem>
<para>You must have iptables installed on your Squid server.</para>
</listitem>
</itemizedlist>
</caution>
<caution>
<para>In the instructions below, only TCP Port 80 is opened from the
system running Squid to the internet. If your users require browsing
@ -123,304 +93,267 @@
must open those ports as well.</para>
</caution>
</section>
<section>
<title>Configurations</title>
<para>Three different configurations are covered:</para>
<simplelist>
<member>Squid (transparent) Running on the Firewall</member>
<member>Squid (transparent) Running in the local Network</member>
<member>Squid (transparent) Running in a DMZ</member>
</simplelist>
<section id="Firewall" >
<title>Squid (transparent) Running on the Firewall</title>
<para>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.</para>
<para>In <filename>/etc/shorewall/rules</filename>:</para>
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S) SOURCE ORIGINAL
# PORT(S) DEST
REDIRECT loc 3128 tcp www - !206.124.146.177
ACCEPT fw net tcp www</programlisting>
<para>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.</para>
<para>If needed, you may just add the additional hosts/networks to the
ORIGINAL DEST column in your REDIRECT rule.</para>
<para><filename>/etc/shorewall/rules</filename>:<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S) SOURCE ORIGINAL
<para>
<filename>/etc/shorewall/rules</filename>:<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S) SOURCE ORIGINAL
# PORT(S) DEST
REDIRECT loc 3128 tcp www - !206.124.146.177,130.252.100.0/24</programlisting></para>
REDIRECT loc 3128 tcp www - !206.124.146.177,130.252.100.0/24</programlisting>
</para>
</section>
<section id="Local" >
<title>Squid (transparent) Running in the local network</title>
<para>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.</para>
<para>If you are running a Shorewall version earlier than 2.3.2 OR your
kernel and/or iptables do not have <ulink
url="Shorewall_and_Routing.html#RouteTarget">ROUTE target
kernel and/or iptables do not have <ulink url="Shorewall_and_Routing.html#RouteTarget" >ROUTE target
support</ulink> then:</para>
<orderedlist>
<listitem>
<para>On your firewall system, issue the following command</para>
<programlisting><command>echo 202 www.out &gt;&gt; /etc/iproute2/rt_tables</command></programlisting>
<programlisting>
<command>echo 202 www.out >> /etc/iproute2/rt_tables</command>
</programlisting>
</listitem>
<listitem>
<para>Create <filename>/etc/shorewall/addroutes</filename> as
follows:</para>
<programlisting>
<command>#!/bin/sh
<programlisting><command>#!/bin/sh
if [ -z "`ip rule list | grep www.out`" ] ; then
if [ -z &quot;`ip rule list | grep www.out`&quot; ] ; then
ip rule add fwmark 0xCA table www.out # Note 0xCA = 202
ip route add default via 192.168.1.3 dev eth1 table www.out
ip route flush cache
echo 0 &gt; /proc/sys/net/ipv4/conf/eth1/send_redirects
fi</command></programlisting>
echo 0 > /proc/sys/net/ipv4/conf/eth1/send_redirects
fi</command>
</programlisting>
</listitem>
<listitem>
<para>Make <filename>/etc/shorewall/addroutes </filename>executable
via:</para>
<programlisting><command>chmod +x /etc/shorewall/addroutes</command></programlisting>
<programlisting>
<command>chmod +x /etc/shorewall/addroutes</command>
</programlisting>
</listitem>
<listitem>
<para>In /etc/shorewall/init, put:</para>
<programlisting><command>run_and_save_command "/etc/shorewall/addroutes"</command></programlisting>
<programlisting>
<command>run_and_save_command &quot;/etc/shorewall/addroutes&quot;</command>
</programlisting>
</listitem>
</orderedlist>
<para>If you are running Shorewall 2.3.2 or later:</para>
<orderedlist>
<listitem>
<para>Add this entry to your /etc/shorewall/providers file.</para>
<programlisting>#NAME NUMBER MARK DUPLICATE INTERFACE GATEWAY OPTIONS
Squid 1 202 - eth1 192.168.1.3 -</programlisting>
</listitem>
</orderedlist>
<para>Regardless of your Shorewall version, you need the
following:</para>
<orderedlist>
<listitem>
<para>In <filename>/etc/shorewall/start</filename> add:</para>
<programlisting><command>iptables -t mangle -A PREROUTING -i eth1 -s ! 192.168.1.3 -p tcp --dport 80 -j MARK --set-mark 202</command></programlisting>
<programlisting>
<command>iptables -t mangle -A PREROUTING -i eth1 -s ! 192.168.1.3 -p tcp --dport 80 -j MARK --set-mark 202</command>
</programlisting>
</listitem>
<listitem>
<para>In
<filename><filename>/etc/shorewall/interfaces</filename></filename>:</para>
<filename>
<filename>/etc/shorewall/interfaces</filename>
</filename>:</para>
<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
loc eth1 detect <emphasis role="bold">routeback</emphasis> </programlisting>
loc eth1 detect <emphasis role="bold" >routeback</emphasis>
</programlisting>
</listitem>
<listitem>
<para>In /etc/shorewall/rules:</para>
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
ACCEPT loc loc tcp www</programlisting>
<orderedlist numeration="loweralpha" >
<listitem>
<para>Alternativfely, you can have the following policy in place
<para>Alternatively, you can have the following policy in place
of the above rule.</para>
<para><filename>/etc/shorewall/policy</filename></para>
<para>
<filename>/etc/shorewall/policy</filename>
</para>
<programlisting>#SOURCE DESTINATION POLICY
loc loc ACCEPT</programlisting>
</listitem>
</orderedlist>
</listitem>
<listitem>
<para>On 192.168.1.3, arrange for the following command to be
executed after networking has come up</para>
<programlisting><command>iptables -t nat -A PREROUTING -i eth0 -d ! 192.168.1.3 -p tcp --dport 80 -j REDIRECT --to-ports 3128</command></programlisting>
<programlisting>
<command>iptables -t nat -A PREROUTING -i eth0 -d ! 192.168.1.3 -p tcp --dport 80 -j REDIRECT --to-ports 3128</command>
</programlisting>
<para>If you are running RedHat on the server, you can simply
execute the following commands after you have typed the iptables
command above:</para>
<programlisting><command>iptables-save &gt; /etc/sysconfig/iptables
chkconfig --level 35 iptables on</command></programlisting>
<programlisting>
<command>iptables-save > /etc/sysconfig/iptables
chkconfig --level 35 iptables on</command>
</programlisting>
</listitem>
</orderedlist>
</section>
<section id="DMZ" >
<title>Squid (transparent) Running in the DMZ</title>
<para>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.</para>
<para>If you are running a Shorewall version earlier than 2.3.2 OR your
kernel and/or iptables do not have <ulink
url="Shorewall_and_Routing.html#RouteTarget">ROUTE target
kernel and/or iptables do not have <ulink url="Shorewall_and_Routing.html#RouteTarget" >ROUTE target
support</ulink> then:</para>
<orderedlist>
<listitem>
<para>On your firewall system, issue the following command</para>
<programlisting><command>echo 202 www.out &gt;&gt; /etc/iproute2/rt_tables</command></programlisting>
<programlisting>
<command>echo 202 www.out >> /etc/iproute2/rt_tables</command>
</programlisting>
</listitem>
<listitem>
<para>Create <filename>/etc/shorewall/addroutes</filename> as
follows:</para>
<programlisting>
<command>#!/bin/sh
<programlisting><command>#!/bin/sh
if [ -z "`ip rule list | grep www.out`" ] ; then
if [ -z &quot;`ip rule list | grep www.out`&quot; ] ; then
ip rule add fwmark 0xCA table www.out # Note 0xCA = 202
ip route add default via 192.168.1.3 dev eth1 table www.out
ip route flush cache
echo 0 &gt; /proc/sys/net/ipv4/conf/eth1/send_redirects
fi</command></programlisting>
echo 0 > /proc/sys/net/ipv4/conf/eth1/send_redirects
fi</command>
</programlisting>
</listitem>
<listitem>
<para>Make <filename>/etc/shorewall/addroutes</filename> executable
via:</para>
<programlisting><command>chmod +x /etc/shorewall/addroutes</command></programlisting>
<programlisting>
<command>chmod +x /etc/shorewall/addroutes</command>
</programlisting>
</listitem>
<listitem>
<para>In <filename>/etc/shorewall/init</filename>, put:</para>
<programlisting><command>run_and_save_command "/etc/shorewall/addroutes"</command></programlisting>
<programlisting>
<command>run_and_save_command &quot;/etc/shorewall/addroutes&quot;</command>
</programlisting>
</listitem>
</orderedlist>
<para>If you are running Shorewall 2.3.2 or later:</para>
<orderedlist>
<listitem>
<para>Add this entry in
<filename>/etc/shorewall/providers</filename>:</para>
</listitem>
</orderedlist>
<blockquote>
<programlisting>#NAME NUMBER MARK DUPLICATE INTERFACE GATEWAY OPTIONS
Squid 1 202 - eth1 192.0.2.177 -
</programlisting>
</blockquote>
<para>Regardless of your Shorewall version, you need the
following:</para>
<orderedlist>
<listitem>
<para>Do <emphasis role="bold" >one</emphasis> of the
following:</para>
<orderedlist numeration="loweralpha" >
<listitem>
<para>In <filename>/etc/shorewall/start</filename> add</para>
<programlisting><command>iptables -t mangle -A PREROUTING -i eth2 -p tcp --dport 80 -j MARK --set-mark 202</command></programlisting>
<programlisting>
<command>iptables -t mangle -A PREROUTING -i eth2 -p tcp --dport 80 -j MARK --set-mark 202</command>
</programlisting>
</listitem>
<listitem>
<para>Set MARK_IN_FORWARD_CHAIN=No in
<filename>/etc/shorewall/shorewall.conf</filename> and add the
following entry in
<filename>/etc/shorewall/tcrules</filename>:</para>
<programlisting>#MARK SOURCE DESTINATION PROTOCOL PORT
202 eth2 0.0.0.0/0 tcp 80</programlisting>
</listitem>
<listitem>
<para>Add the following entry in
<filename>/etc/shorewall/tcrules</filename>:</para>
<programlisting>#MARK SOURCE DESTINATION PROTOCOL PORT
202:P eth2 0.0.0.0/0 tcp 80</programlisting>
</listitem>
</orderedlist>
</listitem>
<listitem>
<para>In <filename>/etc/shorewall/rules</filename>, you will
need:</para>
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
ACCEPT loc dmz tcp 80
ACCEPT dmz net tcp 80</programlisting>
</listitem>
<listitem>
<para>On 192.0.2.177 (your Web/Squid server), arrange for the
following command to be executed after networking has come up</para>
<programlisting><command>iptables -t nat -A PREROUTING -i eth0 -d ! 192.0.2.177 -p tcp --dport 80 -j REDIRECT --to-ports 3128</command></programlisting>
<programlisting>
<command>iptables -t nat -A PREROUTING -i eth0 -d ! 192.0.2.177 -p tcp --dport 80 -j REDIRECT --to-ports 3128</command>
</programlisting>
<para>If you are running RedHat/Fedora on the server, you can simply
execute the following commands after you have typed the iptables
command above:</para>
<programlisting><command>iptables-save &gt; /etc/sysconfig/iptables
chkconfig --level 35 iptables on</command></programlisting>
<programlisting>
<command>iptables-save > /etc/sysconfig/iptables
chkconfig --level 35 iptables on</command>
</programlisting>
</listitem>
</orderedlist>
</section>
</section>
<section id="Manual" >
<title>Squid as a Manual Proxy</title>
<para>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
<quote>net</quote> zone. Then for each zone Z that needs access to the
Squid server.</para>
<para><filename>/etc/shorewall/rules</filename>:</para>
<para>
<filename>/etc/shorewall/rules</filename>:</para>
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
ACCEPT Z SZ tcp SP
ACCEPT SZ net tcp 80,443</programlisting>
<example>
<title>Squid on the firewall listening on port 8080 with access from the
<quote>loc</quote> zone:</title>
<para><filename>/etc/shorewall/rules:</filename><programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
<para>
<filename>/etc/shorewall/rules:</filename>
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
ACCEPT loc fw tcp 8080
ACCEPT fw net tcp 80,443</programlisting></para>
ACCEPT fw net tcp 80,443</programlisting>
</para>
</example>
</section>
</article>