shorewall_code/Shorewall-docs/User_defined_Actions.xml

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  <articleinfo>
    <title>User-defined Actions</title>

    <authorgroup>
      <author>
        <firstname>Tom</firstname>

        <surname>Eastep</surname>
      </author>
    </authorgroup>

    <pubdate>2003-12-09</pubdate>

    <copyright>
      <year>2001</year>

      <year>2002</year>

      <year>2003</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>
    </legalnotice>
  </articleinfo>

  <para>Prior to Shorewall version 1.4.9, rules in /etc/shorewall/rules were
  limited to those defined by Netfilter (ACCEPT, DROP, REJECT, etc.).
  Beginning with Shorewall version 1.4.9, users may use sequences of these
  elementary operations to define more complex actions.</para>

  <para>To define a new action:</para>

  <orderedlist>
    <listitem>
      <para>Add a line to /etc/shorewall/actions that names your new action.
      Action names must be valid shell variable names as well as valid
      Netfilter chain names. It is recommended that the name you select for a
      new action begins with with a capital letter; that way, the name
      won&#39;t conflict with a Shorewall-defined chain name.</para>
    </listitem>

    <listitem>
      <para>Once you have defined your new action name (ActionName), then copy
      /etc/shorewall/action.template to /etc/shorewall/action.ActionName (for
      example, if your new action name is <quote>Foo</quote> then copy
      /etc/shorewall/action.template to /etc/shorewall/action.foo).</para>
    </listitem>

    <listitem>
      <para>Now modify the new file to define the new action.</para>
    </listitem>
  </orderedlist>

  <para>Columns in the action.template file are as follows:</para>

  <itemizedlist>
    <listitem>
      <para>TARGET - Must be ACCEPT, DROP, REJECT, LOG, QUEUE or
      &#60;action&#62; where &#60;action&#62; is a previously-defined action.
      The TARGET may optionally be followed by a colon (<quote>:</quote>) and
      a syslog log level (e.g, REJECT:info or ACCEPT:debugging). This causes
      the packet to be logged at the specified level. You may also specify
      ULOG (must be in upper case) as a log level.This will log to the ULOG
      target for routing to a separate log through use of ulogd
      (http://www.gnumonks.org/projects/ulogd).</para>
    </listitem>

    <listitem>
      <para>SOURCE - Source hosts to which the rule applies. A comma-separated
      list of subnets and/or hosts. Hosts may be specified by IP or MAC
      address; mac addresses must begin with <quote>~</quote> and must use
      <quote>-</quote> as a separator.</para>

      <para>Alternatively, clients may be specified by interface name. For
      example, eth1 specifies a client that communicates with the firewall
      system through eth1. This may be optionally followed by another colon (<quote>:</quote>)
      and an IP/MAC/subnet address as described above (e.g.,
      eth1:192.168.1.5).</para>
    </listitem>

    <listitem>
      <para>DEST - Location of Server. Same as above with the exception that
      MAC addresses are not allowed.</para>

      <para>Unlike in the SOURCE column, you may specify a range of up to 256
      IP addresses using the syntax &#60;first ip&#62;-&#60;last ip&#62;.</para>
    </listitem>

    <listitem>
      <para>PROTO - Protocol - Must be <quote>tcp</quote>, <quote>udp</quote>,
      <quote>icmp</quote>, a number, or <quote>all</quote>.</para>
    </listitem>

    <listitem>
      <para>DEST PORT(S) - Destination Ports. A comma-separated list of Port
      names (from /etc/services), port numbers or port ranges; if the protocol
      is <quote>icmp</quote>, this column is interpreted as the destination
      icmp-type(s).</para>

      <para>A port range is expressed as &#60;low port&#62;:&#60;high
      port&#62;.</para>

      <para>This column is ignored if PROTOCOL = all but must be entered if
      any of the following ields are supplied. In that case, it is suggested
      that this field contain <quote>-</quote>.</para>

      <para>If your kernel contains multi-port match support, then only a
      single Netfilter rule will be generated if in this list and the CLIENT
      PORT(S) list below:</para>

      <orderedlist>
        <listitem>
          <para>There are 15 or less ports listed.</para>
        </listitem>

        <listitem>
          <para>No port ranges are included.</para>
        </listitem>
      </orderedlist>

      <para>Otherwise, a separate rule will be generated for each port.</para>
    </listitem>

    <listitem>
      <para>RATE LIMIT - You may rate-limit the rule by placing a value in
      this column:</para>

      <para><programlisting>     &#60;rate&#62;/&#60;interval&#62;[:&#60;burst&#62;]</programlisting>where
      &#60;rate&#62; is the number of connections per &#60;interval&#62; (<quote>sec</quote>
      or <quote>min</quote>) and &#60;burst&#62; is the largest burst
      permitted. If no &#60;burst&#62; is given, a value of 5 is assumed.
      There may be no whitespace embedded in the specification.</para>

      <para><programlisting>     Example: 10/sec:20</programlisting></para>
    </listitem>
  </itemizedlist>

  <para>Example:</para>

  <para><emphasis role="bold">/etc/shorewall/actions:</emphasis></para>

  <para><programlisting>     LogAndAccept</programlisting><emphasis
  role="bold">/etc/shorewall/action.LogAndAccept</emphasis><programlisting>     LOG:info
     ACCEPT</programlisting></para>
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