shorewall_code/docs/blacklisting_support.xml

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  <articleinfo>
    <title>Shorewall Blacklisting/Whitelisting Support</title>

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

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

    <pubdate><?dbtimestamp format="Y/m/d"?></pubdate>

    <copyright>
      <year>2002-2006</year>

      <year>2010</year>

      <year>2011</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>

  <caution>
    <para><emphasis role="bold">This article applies to Shorewall 4.4 and
    later. If you are running a version of Shorewall earlier than Shorewall
    4.3.5 then please see the documentation for that
    release.</emphasis></para>
  </caution>

  <section id="Intro">
    <title>Introduction</title>

    <para>Shorewall supports two different types of blacklisting; rule-based,
    static and dynamic. The BLACKLIST option in /etc/shorewall/shorewall.conf
    controls the degree of blacklist filtering.</para>

    <para>The BLACKLIST option lists the Netfilter connection-tracking states
    that blacklist rules are to be applied to (states are NEW, ESTABLISHED,
    RELATED, INVALID, NOTRACK). The BLACKLIST option supersedes the
    BLACKLISTNEWONLY option:</para>

    <orderedlist>
      <listitem>
        <para>BLACKLISTNEWONLY=No -- All incoming packets are checked against
        the blacklist. New blacklist entries can be used to terminate existing
        connections.</para>
      </listitem>

      <listitem>
        <para>BLACKLISTNEWONLY=Yes -- The blacklists are only consulted for
        new connection requests. Blacklists may not be used to terminate
        existing connections.</para>
      </listitem>
    </orderedlist>

    <important>
      <para>For automatic blacklisting based on exceeding defined threshholds,
      see <ulink url="Events.html">Events</ulink>.</para>
    </important>
  </section>

  <section>
    <title>Rule-based Blacklisting</title>

    <para>Beginning with Shorewall 4.4.25, the preferred method of
    blacklisting and whitelisting is to use the blrules file (<ulink
    url="manpages/shorewall-blrules.html">shorewall-blrules</ulink> (5)).
    There you have access to the DROP, ACCEPT, REJECT and WHITELIST actions,
    standard and custom macros as well as standard and custom actions. See
    <ulink url="manpages/shorewall-rules.html">shorewall-blrules</ulink> (5)
    for details.</para>

    <para>Example:</para>

    <programlisting>#ACTION         SOURCE                  DEST                    PROTO   DPORT

WHITELIST       net:70.90.191.126       all
DROP            net                     all                     udp     1023:1033,1434,5948,23773
DROP            all                     net                     udp     1023:1033
DROP            net                     all                     tcp     57,1433,1434,2401,2745,3127,3306,3410,4899,5554,5948,6101,8081,9898,23773
DROP            net:221.192.199.48      all
DROP            net:61.158.162.9        all
DROP            net:81.21.54.100        all                     tcp     25
DROP            net:84.108.168.139      all                             
DROP            net:200.55.14.18        all
</programlisting>

    <para>Beginning with Shorewall 4.4.26, the <command>update</command>
    command supports a <option>-b</option> option that causes your legacy
    blacklisting configuration to use the blrules file.</para>
  </section>

  <section>
    <title>Dynamic Blacklisting</title>

    <para>Beginning with Shorewall 4.4.7, dynamic blacklisting is enabled by
    setting DYNAMIC_BLACKLIST=Yes in <filename>shorewall.conf</filename>.
    Prior to that release, the feature is always enabled.</para>

    <para>Once enabled, dynamic blacklisting doesn't use any configuration
    parameters but is rather controlled using /sbin/shorewall[-lite] commands.
    <emphasis role="bold">Note</emphasis> that <emphasis
    role="bold">to</emphasis> and <emphasis role="bold">from</emphasis> may
    only be specified when running <emphasis role="bold">Shorewall 4.4.12 or
    later</emphasis>.</para>

    <itemizedlist>
      <listitem>
        <para>drop [to|from] <emphasis>&lt;ip address list&gt;</emphasis> -
        causes packets from the listed IP addresses to be silently dropped by
        the firewall.</para>
      </listitem>

      <listitem>
        <para>reject [to|from]<emphasis>&lt;ip address list&gt;</emphasis> -
        causes packets from the listed IP addresses to be rejected by the
        firewall.</para>
      </listitem>

      <listitem>
        <para>allow [to|from] <emphasis>&lt;ip address list&gt;</emphasis> -
        re-enables receipt of packets from hosts previously blacklisted by a
        <emphasis>drop</emphasis> or <emphasis>reject</emphasis>
        command.</para>
      </listitem>

      <listitem>
        <para>save - save the dynamic blacklisting configuration so that it
        will be automatically restored the next time that the firewall is
        restarted.</para>

        <para><emphasis role="bold">Update:</emphasis> Beginning with
        Shorewall 4.4.10, the dynamic blacklist is automatically retained over
        <command>stop/start</command> sequences and over
        <command>restart</command> and <emphasis
        role="bold">reload</emphasis>.</para>
      </listitem>

      <listitem>
        <para>show dynamic - displays the dynamic blacklisting
        configuration.</para>
      </listitem>

      <listitem>
        <para>logdrop [to|from] <emphasis>&lt;ip address list&gt;</emphasis> -
        causes packets from the listed IP addresses to be dropped and logged
        by the firewall. Logging will occur at the level specified by the
        BLACKLIST_LOGLEVEL setting at the last [re]start (logging will be at
        the 'info' level if no BLACKLIST_LOGLEVEL was given).</para>
      </listitem>

      <listitem>
        <para>logreject [to|from}<emphasis>&lt;ip address list&gt;</emphasis>
        - causes packets from the listed IP addresses to be rejected and
        logged by the firewall. Logging will occur at the level specified by
        the BLACKLIST_LOGLEVEL setting at the last [re]start (logging will be
        at the 'info' level if no BLACKLIST_LOGLEVEL was given).</para>
      </listitem>
    </itemizedlist>
  </section>
</article>