forked from extern/shorewall_code
279 lines
11 KiB
XML
279 lines
11 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 Blacklisting/Whitelisting Support</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>2002-2006</year>
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<year>2010</year>
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<year>2011</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 4.4 and
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later. If you are running a version of Shorewall earlier than Shorewall
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4.3.5 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="Intro">
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<title>Introduction</title>
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<para>Shorewall supports two different types of blacklisting; rule-based,
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static and dynamic. The BLACKLIST option in /etc/shorewall/shorewall.conf
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controls the degree of blacklist filtering.</para>
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<para>The BLACKLIST option lists the Netfilter connection-tracking states
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that blacklist rules are to be applied to (states are NEW, ESTABLISHED,
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RELATED, INVALID, NOTRACK). The BLACKLIST option supersedes the
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BLACKLISTNEWONLY option:</para>
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<orderedlist>
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<listitem>
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<para>BLACKLISTNEWONLY=No -- All incoming packets are checked against
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the blacklist. New blacklist entries can be used to terminate existing
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connections.</para>
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</listitem>
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<listitem>
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<para>BLACKLISTNEWONLY=Yes -- The blacklists are only consulted for
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new connection requests. Blacklists may not be used to terminate
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existing connections.</para>
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</listitem>
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</orderedlist>
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<important>
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<para>For automatic blacklisting based on exceeding defined threshholds,
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see <ulink url="Events.html">Events</ulink>.</para>
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</important>
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</section>
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<section>
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<title>Rule-based Blacklisting</title>
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<para>Beginning with Shorewall 4.4.25, the preferred method of
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blacklisting and whitelisting is to use the blrules file (<ulink
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url="manpages/shorewall-blrules.html">shorewall-blrules</ulink> (5)).
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There you have access to the DROP, ACCEPT, REJECT and WHITELIST actions,
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standard and custom macros as well as standard and custom actions. See
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<ulink url="manpages/shorewall-blrules.html">shorewall-blrules</ulink> (5)
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for details.</para>
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<para>Example:</para>
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<programlisting>#ACTION SOURCE DEST PROTO DPORT
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WHITELIST net:70.90.191.126 all
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DROP net all udp 1023:1033,1434,5948,23773
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DROP all net udp 1023:1033
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DROP net all tcp 57,1433,1434,2401,2745,3127,3306,3410,4899,5554,5948,6101,8081,9898,23773
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DROP net:221.192.199.48 all
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DROP net:61.158.162.9 all
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DROP net:81.21.54.100 all tcp 25
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DROP net:84.108.168.139 all
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DROP net:200.55.14.18 all
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</programlisting>
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<para>Beginning with Shorewall 4.4.26, the <command>update</command>
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command supports a <option>-b</option> option that causes your legacy
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blacklisting configuration to use the blrules file.</para>
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</section>
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<section>
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<title>Chain-based Dynamic Blacklisting</title>
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<para>Beginning with Shorewall 4.4.7, dynamic blacklisting is enabled by
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setting DYNAMIC_BLACKLIST=Yes in <filename>shorewall.conf</filename>.
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Prior to that release, the feature is always enabled.</para>
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<para>Once enabled, dynamic blacklisting doesn't use any configuration
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parameters but is rather controlled using /sbin/shorewall[-lite] commands.
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<emphasis role="bold">Note</emphasis> that <emphasis
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role="bold">to</emphasis> and <emphasis role="bold">from</emphasis> may
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only be specified when running <emphasis role="bold">Shorewall 4.4.12 or
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later</emphasis>.</para>
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<itemizedlist>
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<listitem>
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<para>drop [to|from] <emphasis><ip address list></emphasis> -
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causes packets from the listed IP addresses to be silently dropped by
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the firewall.</para>
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</listitem>
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<listitem>
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<para>reject [to|from]<emphasis><ip address list></emphasis> -
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causes packets from the listed IP addresses to be rejected by the
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firewall.</para>
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</listitem>
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<listitem>
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<para>allow [to|from] <emphasis><ip address list></emphasis> -
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re-enables receipt of packets from hosts previously blacklisted by a
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<emphasis>drop</emphasis> or <emphasis>reject</emphasis>
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command.</para>
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</listitem>
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<listitem>
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<para>save - save the dynamic blacklisting configuration so that it
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will be automatically restored the next time that the firewall is
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restarted.</para>
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<para><emphasis role="bold">Update:</emphasis> Beginning with
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Shorewall 4.4.10, the dynamic blacklist is automatically retained over
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<command>stop/start</command> sequences and over
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<command>restart</command> and <emphasis
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role="bold">reload</emphasis>.</para>
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</listitem>
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<listitem>
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<para>show dynamic - displays the dynamic blacklisting
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configuration.</para>
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</listitem>
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<listitem>
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<para>logdrop [to|from] <emphasis><ip address list></emphasis> -
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causes packets from the listed IP addresses to be dropped and logged
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by the firewall. Logging will occur at the level specified by the
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BLACKLIST_LOGLEVEL setting at the last [re]start (logging will be at
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the 'info' level if no BLACKLIST_LOGLEVEL was given).</para>
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</listitem>
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<listitem>
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<para>logreject [to|from}<emphasis><ip address list></emphasis>
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- causes packets from the listed IP addresses to be rejected and
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logged by the firewall. Logging will occur at the level specified by
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the BLACKLIST_LOGLEVEL setting at the last [re]start (logging will be
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at the 'info' level if no BLACKLIST_LOGLEVEL was given).</para>
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</listitem>
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</itemizedlist>
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</section>
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<section>
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<title>Ipset-based Dynamic Blacklisting</title>
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<para>Beginning with Shorewall 5.0.8, it is possible to use an ipset to
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hold blacklisted addresses. The DYNAMIC_BLACKLIST option was expanded
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to:</para>
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<para><emphasis role="bold">DYNAMIC_BLACKLIST=</emphasis>{<emphasis
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role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>||<emphasis
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role="bold">ipset</emphasis>[<emphasis
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role="bold">-only</emphasis>][<replaceable>,option</replaceable>[,...]][:[<replaceable>setname</replaceable>][:<replaceable>log_level</replaceable>|:l<replaceable>og_tag</replaceable>]]]}</para>
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<para>When <option>ipset</option> or <option>ipset-only</option> is
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specified, the <command>shorewall blacklist</command> command is used to
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blacklist a single host or a network. The <command>allow</command> command
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is used to remove entries from the ipset. The name of the set
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(<replaceable>setname</replaceable>) and the level
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(<replaceable>log_level</replaceable>), if any, at which blacklisted
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traffic is to be logged may also be specified. The default set name is
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SW_DBL4 and the default log level is <option>none</option> (no logging).
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If <option>ipset-only</option> is given, then chain-based dynamic
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blacklisting is disabled just as if DYNAMIC_BLACKLISTING=No had been
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specified.</para>
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<para>Possible <replaceable>option</replaceable>s are:</para>
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<variablelist>
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<varlistentry>
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<term>src-dst</term>
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<listitem>
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<para>Normally, only packets whose source address matches an entry
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in the ipset are dropped. If <option>src-dst</option> is included,
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then packets whose destination address matches an entry in the ipset
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are also dropped.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>disconnect</option></term>
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<listitem>
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<para>The <option>disconnect</option> option was added in Shorewall
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5.0.13 and requires that the conntrack utility be installed on the
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firewall system. When an address is blacklisted using the
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<command>blacklist</command> command, all connections originating
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from that address are disconnected. if the <option>src-dst</option>
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option was also specified, then all connections to that address are
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also disconnected.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>timeout</option>=<replaceable>seconds</replaceable></term>
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<listitem>
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<para>Added in Shorewall 5.0.13. Normally, Shorewall creates the
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dynamic blacklisting ipset with timeout 0 which means that entries
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are permanent. If you want entries in the set that are not accessed
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for a period of time to be deleted from the set, you may specify
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that period using this option. Note that the
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<command>blacklist</command> command can override the ipset's
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timeout setting.</para>
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<important>
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<para>Once the dynamic blacklisting ipset has been created,
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changing this option setting requires a complete restart of the
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firewall; <command>shorewall restart</command> if RESTART=restart,
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otherwise <command>shorewall stop && shorewall
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start</command></para>
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</important>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>When ipset-based dynamic blacklisting is enabled, the contents of
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the blacklist will be preserved over
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<command>stop</command>/<command>reboot</command>/<command>start</command>
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sequences if SAVE_IPSETS=Yes, SAVE_IPSETS=ipv4 or if
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<replaceable>setname</replaceable> is included in the list of sets to be
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saved in SAVE_IPSETS.</para>
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</section>
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<section>
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<title>BLACKLIST Policy and Action</title>
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<para>Beginning with Shorewall 5.1.1, it is possible to specify BLACKLIST
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in the POLICY column of <ulink
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url="manpages/shorewall-policy.html">shorewall-policy</ulink>(5) when
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ipset-based dynamic blacklisting is being used. When a packet is disposed
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of via the BLACKLIST policy, the packet's sender is added to the dynamic
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blacklist ipset and the packet is dropped.</para>
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<para>Also available beginning with Shorewall 5.1.1 is a BLACKLIST action
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for use in the rules file, macros and filter table actions. Execute the
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<command>shorewall show action BLACKLIST</command> command for
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details.</para>
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</section>
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</article>
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