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331 lines
15 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
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<article>
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<!--$Id$-->
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<articleinfo>
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<title>Shorewall Traffic Accounting</title>
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<authorgroup>
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<author>
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<firstname>Tom</firstname>
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<surname>Eastep</surname>
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</author>
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</authorgroup>
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<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
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<copyright>
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<year>2003-2009</year>
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<holder>Thomas M. Eastep</holder>
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</copyright>
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<legalnotice>
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<para>Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License, Version
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1.2 or any later version published by the Free Software Foundation; with
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no Invariant Sections, with no Front-Cover, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled
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<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
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License</ulink></quote>.</para>
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</legalnotice>
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</articleinfo>
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<caution>
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<para><emphasis role="bold">This article applies to Shorewall 4.0 and
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later. If you are running a version of Shorewall earlier than Shorewall
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4.0.0 then please see the documentation for that
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release</emphasis>.</para>
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</caution>
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<section id="Basics">
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<title>Accounting Basics</title>
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<para>Shorewall accounting rules are described in the file
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<filename><filename>/etc/shorewall/accounting</filename></filename>. By
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default, the accounting rules are placed in a chain called
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<quote>accounting</quote> and can thus be displayed using
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<quote>shorewall[-lite] show -x accounting</quote>. All traffic passing
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into, out of, or through the firewall traverses the accounting chain
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including traffic that will later be rejected by interface options such as
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<quote>tcpflags</quote> and <quote>maclist</quote>.</para>
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<para>The columns in the accounting file are described in <ulink
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url="manpages/shorewall-accounting.html">shorewall-accounting</ulink> (5)
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and <ulink
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url="manpages6/shorewall6-accounting.html">shorewall6-accounting</ulink>
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(5).</para>
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<para>In all columns except ACTION and CHAIN, the values <quote>-</quote>,
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<quote>any</quote> and <quote>all</quote> are treated as
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wild-cards.</para>
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<para>The accounting rules are evaluated in the Netfilter
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<quote>filter</quote> table. This is the same environment where the
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<quote>rules</quote> file rules are evaluated and in this environment,
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DNAT has already occurred in inbound packets and SNAT has not yet occurred
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on outbound packets.</para>
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<para>Accounting rules are not stateful -- each rule only handles traffic
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in one direction. For example, if eth0 is your Internet interface, and you
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have a web server in your DMZ connected to eth1, then to count HTTP
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traffic in both directions requires two rules:</para>
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<programlisting> #ACTION CHAIN SOURCE DESTINATION PROTOCOL DEST SOURCE
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# PORT PORT
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DONE - eth0 eth1 tcp 80
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DONE - eth1 eth0 tcp - 80</programlisting>
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<para>Associating a counter with a chain allows for nice reporting. For
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example:</para>
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<programlisting> #ACTION CHAIN SOURCE DESTINATION PROTOCOL DEST SOURCE
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# PORT PORT
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web:COUNT - eth0 eth1 tcp 80
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web:COUNT - eth1 eth0 tcp - 80
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web:COUNT - eth0 eth1 tcp 443
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web:COUNT - eth1 eth0 tcp - 443
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DONE web</programlisting>
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<para>Now <command>shorewall show web</command> (or
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<command>shorewall-lite show web</command> for Shorewall Lite users) will
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give you a breakdown of your web traffic:</para>
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<programlisting> [root@gateway shorewall]# shorewall show web
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Shorewall-1.4.6-20030821 Chain web at gateway.shorewall.net - Wed Aug 20 09:48:56 PDT 2003
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Counters reset Wed Aug 20 09:48:00 PDT 2003
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Chain web (4 references)
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pkts bytes target prot opt in out source destination
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11 1335 tcp -- eth0 eth1 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
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18 1962 tcp -- eth1 eth0 0.0.0.0/0 0.0.0.0/0 tcp spt:80
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0 0 tcp -- eth0 eth1 0.0.0.0/0 0.0.0.0/0 tcp dpt:443
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0 0 tcp -- eth1 eth0 0.0.0.0/0 0.0.0.0/0 tcp spt:443
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29 3297 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
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[root@gateway shorewall]#</programlisting>
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<para>Here is a slightly different example:</para>
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<programlisting> #ACTION CHAIN SOURCE DESTINATION PROTOCOL DEST SOURCE
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# PORT PORT
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web - eth0 eth1 tcp 80
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web - eth1 eth0 tcp - 80
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web - eth0 eth1 tcp 443
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web - eth1 eth0 tcp - 443
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COUNT web eth0 eth1
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COUNT web eth1 eth0</programlisting>
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<para>Now <command>shorewall show web</command> (or
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<command>shorewall-lite show web</command> for Shorewall Lite users)
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simply gives you a breakdown by input and output:</para>
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<programlisting> [root@gateway shorewall]# shorewall show accounting web
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Shorewall-1.4.6-20030821 Chains accounting web at gateway.shorewall.net - Wed Aug 20 10:27:21 PDT 2003
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Counters reset Wed Aug 20 10:24:33 PDT 2003
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Chain accounting (3 references)
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pkts bytes target prot opt in out source destination
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8767 727K web tcp -- eth0 eth1 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
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0 0 web tcp -- eth0 eth1 0.0.0.0/0 0.0.0.0/0 tcp dpt:443</programlisting>
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<programlisting>
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11506 13M web tcp -- eth1 eth0 0.0.0.0/0 0.0.0.0/0 tcp spt:80
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0 0 web tcp -- eth1 eth0 0.0.0.0/0 0.0.0.0/0 tcp spt:443
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Chain web (4 references)
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pkts bytes target prot opt in out source destination
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8767 727K all -- eth0 eth1 0.0.0.0/0 0.0.0.0/0
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11506 13M all -- eth1 eth0 0.0.0.0/0 0.0.0.0/0
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[root@gateway shorewall]#</programlisting>
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<para>Here's how the same example would be constructed on an HTTP server
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with only one interface (eth0).</para>
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<caution>
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<para>READ THE ABOVE CAREFULLY -- IT SAYS <emphasis
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role="bold">SERVER</emphasis>. If you want to account for web browsing,
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you have to reverse the rules below.</para>
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</caution>
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<programlisting> #ACTION CHAIN SOURCE DESTINATION PROTOCOL DEST SOURCE
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# PORT PORT
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web - eth0 - tcp 80
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web - - eth0 tcp - 80
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web - eth0 - tcp 443
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web - - eth0 tcp - 443
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COUNT web eth0
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COUNT web - eth0</programlisting>
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<para>Note that with only one interface, only the SOURCE (for input rules)
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or the DESTINATION (for output rules) is specified in each rule.</para>
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<para>Here's the output:</para>
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<programlisting> [root@mail shorewall]# shorewall show accounting web Shorewall-1.4.7
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Chains accounting web at mail.shorewall.net - Sun Oct 12 10:27:21 PDT 2003
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Counters reset Sat Oct 11 08:12:57 PDT 2003
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Chain accounting (3 references)
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pkts bytes target prot opt in out source destination
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8767 727K web tcp -- eth0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
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11506 13M web tcp -- * eth0 0.0.0.0/0 0.0.0.0/0 tcp spt:80
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0 0 web tcp -- eth0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:443
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0 0 web tcp -- * eth0 0.0.0.0/0 0.0.0.0/0 tcp spt:443
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Chain web (4 references)
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pkts bytes target prot opt in out source destination
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8767 727K all -- eth0 * 0.0.0.0/0 0.0.0.0/0
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11506 13M all -- * eth0 0.0.0.0/0 0.0.0.0/0
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[root@mail shorewall]#</programlisting>
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<para>For an example of integrating Shorewall Accounting with MRTG, see
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<ulink
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url="http://www.nightbrawler.com/code/shorewall-stats/">http://www.nightbrawler.com/code/shorewall-stats/</ulink>.</para>
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</section>
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<section id="Bridge">
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<title>Accounting with Bridges</title>
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<para>The structure of the accounting rules changes slightly when there
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are <ulink url="bridge-Shorewall-perl.html">bridges</ulink> defined in the
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Shorewall configuration. Because of the restrictions imposed by Netfilter
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in kernel 2.6.21 and later, output accounting rules must be segregated
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from forwarding and input rules. To accomplish this separation,
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Shorewall-perl creates two accounting chains:</para>
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<itemizedlist>
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<listitem>
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<para><emphasis role="bold">accounting</emphasis> - for input and
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forwarded traffic.</para>
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</listitem>
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<listitem>
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<para><emphasis role="bold">accountout</emphasis> - for output
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traffic.</para>
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</listitem>
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</itemizedlist>
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<para>If the CHAIN column contains <quote>-</quote>, then:</para>
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<itemizedlist>
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<listitem>
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<para>If the SOURCE column in a rule includes the name of the firewall
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zone (e.g., $FW), then the default chain to insert the rule into is
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<emphasis role="bold">accountout</emphasis> only.</para>
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</listitem>
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<listitem>
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<para>Otherwise, if the DEST in the rule is <emphasis
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role="bold">any</emphasis> or <emphasis role="bold">all</emphasis> or
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0.0.0.0/0, then the rule is added to both <emphasis
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role="bold">accounting</emphasis> and <emphasis
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role="bold">accountout</emphasis>.</para>
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</listitem>
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<listitem>
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<para>Otherwise, the rule is added to <emphasis
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role="bold">accounting</emphasis> only.</para>
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</listitem>
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</itemizedlist>
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</section>
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<section id="Collectd">
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<title>Integrating Shorewall Accounting with Collectd</title>
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<para>Sergiusz Pawlowicz has written a nice article that shows how to
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integrate Shorewall Accounting with collectd to produce nice graphs of
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traffic activity. The article may be found at <ulink
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url="http://collectd.org/wiki/index.php/Plugin:IPTables">http://collectd.org/wiki/index.php/Plugin:IPTables</ulink>.</para>
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</section>
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<section id="perIP">
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<title>Per-IP Accounting</title>
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<para>Shorewall 4.4.17 added support for per-IP accounting using the
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ACCOUNT target. That target is only available when xtables-addons is
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installed. This support has been successfully tested with xtables-addons
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1.32 on:</para>
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<itemizedlist>
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<listitem>
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<para>Fedora 14</para>
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</listitem>
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<listitem>
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<para>Debian Squeeze</para>
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</listitem>
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</itemizedlist>
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<para>and xtables-addons Version 1.21 on:</para>
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<itemizedlist>
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<listitem>
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<para>Debian Lenny</para>
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</listitem>
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</itemizedlist>
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<para>Information about xtables-addons installation may be found at <ulink
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url="Dynamic.html#xtables-addons">here</ulink>.</para>
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<para>Per-IP accounting is configured in <ulink
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url="manpages/shorewall-accounting.html">shorewall-accounting</ulink> (5)
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(it is currently not supported in IPv6). In the ACTION column,
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enter:</para>
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<simplelist>
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<member><emphasis
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role="bold">ACCOUNT(</emphasis><replaceable>table</replaceable>,<replaceable>network</replaceable><emphasis
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role="bold">)</emphasis></member>
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</simplelist>
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<para>where</para>
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<simplelist>
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<member><replaceable>table</replaceable> is the name of an accounting
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table (you choose the name). All rules specifying the same table will
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have their per-IP counters accumulated in that table.</member>
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<member><replaceable>network</replaceable> is an IPv4 network in CIDR
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notation. The network can be as large as a /8 (class A).</member>
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</simplelist>
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<para>One nice feature of per-IP accounting is that the counters survive
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<command>shorewall restart</command>. This has a downside, however. If you
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change the network associated with an accounting table, then you must
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<command>shorewall stop; shorewall start</command> to have a successful
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restart (counters will be cleared).</para>
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<para>Example: Suppose your WAN interface is eth0 and your LAN interface
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is eth1 with network 172.20.1.0/24. To account for all traffic between the
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WAN and LAN interfaces:</para>
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<programlisting>#ACTION CHAIN SOURCE DEST ...
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ACCOUNT(net-loc,172.20.1.0/24) - eth0 eth1
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ACCOUNT(net-loc,172.20.1.0/24) - eth1 eth0</programlisting>
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<para>This will create a <emphasis role="bold">net-loc</emphasis> table
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for counting packets and bytes for traffic between the two
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interfaces.</para>
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<para>The table is dumped using the <command>iptaccount</command> utility
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(part of xtables-addons):</para>
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<programlisting><command>iptaccount [-f] -l net-loc</command></programlisting>
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<para>For each local IP address with non-zero counters, the packet and
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byte count for both incoming traffic (IP is DST) and outgoing traffic (IP
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is SRC) are listed. The -f option causes the table to be flushed (reset
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all counters to zero) after printing.</para>
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<para>For a command synopsis:</para>
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<programlisting><command>iptaccount --help</command></programlisting>
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</section>
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</article>
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