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shorewall_code/docs/ipsets.xml
Tom Eastep 3277bd991b Update ipset doc for 5.0
Signed-off-by: Tom Eastep <teastep@shorewall.net>
2016-02-18 09:10:41 -08:00

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
<article>
<!--$Id$-->
<articleinfo>
<title>Shorewall and Ipsets</title>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Eastep</surname>
</author>
</authorgroup>
<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
<copyright>
<year>2005</year>
<year>2008</year>
<year>2010</year>
<year>2015</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
4.4.0 then please see the documentation appropriate for your
version.</emphasis></para>
</caution>
<section id="Ipsets">
<title>What are Ipsets?</title>
<para>Ipsets are an extension to Netfilter/iptables that are available in
<ulink url="http://xtables-addons.sourceforge.net/">xtables-addons</ulink>
if they are not available in your current distribution. Instructions for
installing xtables-addons may be found in the <ulink
url="Dynamic.html">Dynamic Zones article</ulink>.</para>
<para>Ipset allows you to create one or more named sets of addresses then
use those sets to define Netfilter/iptables rules. Possible uses of ipsets
include:</para>
<orderedlist>
<listitem>
<para>Blacklists. Ipsets provide an efficient way to represent large
sets of addresses and you can maintain the lists without the need to
restart or even refresh your Shorewall configuration.</para>
</listitem>
<listitem>
<para>Zone definition. Using the /etc/shorewall/hosts file, you can
<ulink url="Dynamic.html">define a zone based on the (dynamic)
contents of an ipset</ulink>. Again, you can then add or delete
addresses to the ipset without restarting Shorewall.</para>
</listitem>
</orderedlist>
<para>See the ipsets site (URL above) for additional information about
ipsets.</para>
</section>
<section id="Support">
<title>Shorewall Support for Ipsets</title>
<para>Support for ipsets was introduced in Shorewall version 2.3.0. In
most places where a host or network address may be used, you may also use
the name of an ipset prefaced by "+".</para>
<para>Example: "+Mirrors"</para>
<para>When using Shorewall, the names of ipsets are restricted as
follows:</para>
<itemizedlist>
<listitem>
<para>They must begin with a letter (after the '+').</para>
</listitem>
<listitem>
<para>They must be composed of letters, digits, dashes ("-") or
underscores ("_").</para>
</listitem>
</itemizedlist>
<para>To generate a negative match, prefix the "+" with "!" as in
"!+Mirrors".</para>
<para>Example 1: Blacklist all hosts in an ipset named "blacklist"</para>
<para><filename>/etc/shorewall/blrules</filename><programlisting>#ACTION SOURCE DEST PROTO DPORT
DROP net:+blacklist</programlisting></para>
<para>Example 2: Allow SSH from all hosts in an ipset named "sshok:</para>
<para><filename>/etc/shorewall/rules</filename><programlisting>#ACTION SOURCE DEST PROTO DPORT
ACCEPT net:+sshok $FW tcp 22</programlisting></para>
<para>The name of the ipset can be optionally followed by a
comma-separated list of flags enclosed in square brackets ([...]). Each
flag is either <emphasis role="bold">src</emphasis> or <emphasis
role="bold">dst</emphasis> and specifies whether it is the SOURCE address
or port number or the DESTINATION address or port number that should be
matched. The number of flags must be appropriate for the type of ipset. If
no flags are given, Shorewall assumes that the set takes a single flag and
will select the flag based on the context. For example, in the blacklist
file and when the ipset appears in the SOURCE column of the rules file,
<emphasis role="bold">src</emphasis> is assumed. If the ipset appears in
the DEST column of the rules file, <emphasis role="bold">dst</emphasis> is
assumed. Note that by using <emphasis role="bold">[dst]</emphasis> in the
blacklist file, you can coerce the rule into matching the destination IP
address rather than the source.</para>
<para>Beginning with Shorewall 4.4.14, multiple source or destination
matches may be specified by placing multiple set names in '+[...]' (e.g.,
+[myset,myotherset]). When so enclosed, the set names need not be prefixed
with a plus sign.</para>
<para>Shorewall can save/restore your ipset contents with certain
restrictions:</para>
<orderedlist>
<listitem>
<para>You must set SAVE_IPSETS=Yes in <ulink
url="manpages/shorewall.conf.html">shorewall.conf</ulink> (5).</para>
</listitem>
<listitem>
<para>You cannot use an ipset in <ulink
url="manpages/shorewall-stoppedulres.html">shorewall-stoppedrules</ulink>
(5) (<ulink
url="manpages/shorewall-routestopped.html">shorewall-routestopped</ulink>
(5)).</para>
</listitem>
<listitem>
<para>The <command>restore</command> command cannot restore ipset
contents saved by the <command>save</command> command unless the
firewall is first stopped.</para>
</listitem>
</orderedlist>
<para>Beginning with Shorewall 4.6.4, you can save selective ipsets by
setting SAVE_IPSETS to a comma-separated list of ipset names. You can also
restrict the group of sets saved to ipv4 sets by setting
SAVE_IPSETS=ipv4.</para>
<para>With Shorewall 4.6.4, the SAVE_IPSETS option may specify a list of
ipsets to be saved. When such a list is specified, only those ipsets
together with the ipsets supporting dynamic zones are saved. Shorewall6
support for the SAVE_IPSETS option was also added in 4.6.4. When
SAVE_IPSETS=Yes in <ulink
url="manpages6/shorewall6.conf.html">shorewall6.conf(5)</ulink>, only ipv6
ipsets are saved. For Shorewall, if SAVE_IPSETS=ipv4 in <ulink
url="manpages/shorewall.conf.html">shorewall.conf(5)</ulink>, then only
ipv4 ipsets are saved. Both features require ipset version 5 or
later.</para>
<para>Although Shorewall can save the definition of your ipsets and
restore them when Shorewall starts, in most cases you must use the ipset
utility to initially create and load your ipsets. The exception is that
Shorewall will automatically create an empty iphash ipset to back each
dynamic zone.</para>
</section>
<section>
<title>Shorewall6 and Shorewall-init Support for Ipsets</title>
<para>Ipset support in Shorewall6 was added in Shorewall 4.4.21.</para>
<para>Beginning with Shorewall 4.6.4, SAVE_IPSETS is available in <ulink
url="manpages6/shorewall6.conf.html">shorewall6-conf(5)</ulink>. When set
to Yes, the ipv6 ipsets will be saved. You can also save selective ipsets
by setting SAVE_IPSETS to a comma-separated list of ipset names.</para>
<para>Prior to Shorewall 4.6.4, SAVE_IPSETS=Yes in <ulink
url="manpages/shorewall.conf.html">shorewall.conf(5)</ulink> won't work
correctly because it saves both IPv4 and IPv6 ipsets. To work around this
issue, Shorewall-init is capable restoring ipset contents during 'start'
and saving them during 'stop'. To direct Shorewall-init to save/restore
ipset contents, set the SAVE_IPSETS option in
/etc/sysconfig/shorewall-init (/etc/default/shorewall-init on Debian and
derivatives). The value of the option is a file name where the contents of
the ipsets will be save to and restored from. Shorewall-init will create
any necessary directories during the first 'save' operation.</para>
<para>If you configure Shorewall-init to save/restore ipsets, be sure to
set SAVE_IPSETS=No in shorewall.conf and shorewall6.conf.</para>
<para>If you configure SAVE_IPSETS in <ulink
url="manpages/shorewall.conf.html">shorewall.conf(5)</ulink> and/or <ulink
url="manpages6/shorewall6.conf.html">shorewall6.conf(5)</ulink> then do
not set SAVE_IPSETS in shorewall-init.</para>
</section>
</article>