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560 lines
18 KiB
XML
560 lines
18 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 IPv6 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>2008</year>
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<year>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 4.3 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>
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<title>Overview</title>
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<para>Beginning with Shorewall 4.2.4, support for firewalling IPv6 is
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included as part of Shorewall.</para>
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<section>
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<title>Prerequisites</title>
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<para>In order to use Shorewall with IPv6, your firewall must meet the
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following prerequisites:</para>
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<orderedlist>
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<listitem>
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<para><ulink url="FAQ.htm#faq80a">Kernel 2.6.24 or
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later</ulink>.</para>
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</listitem>
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<listitem>
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<para>Iptables 1.4.0 or later (1.4.1.1 is strongly
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recommended)</para>
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</listitem>
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<listitem>
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<para>If you wish to include DNS names in your IPv6 configuration
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files, you must have Perl 5.10 and must install the Perl Socket6
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library.</para>
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</listitem>
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</orderedlist>
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</section>
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<section>
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<title>Packages</title>
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<para>Shorewall IPv6 support introduced two new packages:</para>
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<orderedlist>
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<listitem>
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<para>Shorewall6. This package provides
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<filename>/sbin/shorewall6</filename> which is the IPv6 equivalent
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of <filename>/sbin/shorewall</filename>.
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<filename>/sbin/shorewall</filename> only handles IPv4 while
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<filename>/sbin/shorewall6</filename> handles only IPv6.. Shorewall6
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depends on Shorewall. The Shorewall6 configuration is stored in
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<filename class="directory">/etc/shorewall6</filename>.</para>
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</listitem>
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<listitem>
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<para>Shorewall6 Lite. This package is to IPv6 what Shorewall Lite
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is to IPv4. The package stores its configuration in <filename
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class="directory">/etc/shorewall6-lite</filename>. As with Shorewall
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Lite, Shorewall6 Lite usually requires no configuration changes on
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the firewall system.</para>
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</listitem>
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</orderedlist>
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</section>
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<section>
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<title>IPv4/IPv6 Interaction</title>
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<para>IP connections are either IPv4 or IPv6; there is no such thing as
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a mixed IPv4/6 connecton. IPv4 connections are controlled by Shorewall
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(or Shorewall-lite); IPv6 connections are controlled by Shorewall6 (or
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Shorewall6-lite). Starting and stopping the firewall for one address
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family has no effect on the other address family.</para>
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<para>As a consequence, there is very little interaction between
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Shorewall and Shorewall6.</para>
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<section>
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<title>DISABLE_IPV6</title>
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<para>An obvious area where the configuration of Shorewall affects
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Shorewall6 is the DISABLE_IPV6 setting in
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<filename>/etc/shorewall/shorewall.conf</filename>. When configuring
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Shorewall6, you will want to set DISABLE_IPV6=No and restart Shorewall
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or Shorewall-lite.</para>
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</section>
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<section>
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<title>TC_ENABLED</title>
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<para>Another area where their configurations overlap is in traffic
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shaping; the <filename>tcdevices</filename> and tcclasses files do
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exactly the same thing in both Shorewall and Shorewall6. Consequently,
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you will have TC_ENABLED=Internal in Shorewall or in Shorewall6 and
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TC_ENABLED=No in the other product. Also, you will want CLEAR_TC=No in
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the configuration with TC_ENABLED=No.</para>
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<para>Regardless of which product has TC_ENABLED=Internal:</para>
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<itemizedlist>
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<listitem>
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<para>IPv4 packet marking is controlled by
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/etc/shorewall/tcrules</para>
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</listitem>
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<listitem>
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<para>IPv6 packet marking is controlled by
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/etc/shorewall6/tcrules</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>KEEP_RT_TABLES</title>
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<para>Multi-ISP users will need to be aware of this one. When there
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are entries in the providers file, Shorewall normally installs a
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modified <filename>/etc/iproute2/rt_tables</filename> during
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<command>shorewall start</command> and <command>shorewall
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restart</command> and restores a default file during
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<command>shorewall stop</command>. Setting KEEP_RT_TABLES=Yes in
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<ulink url="manpages/shorewall.conf.html">shorewall.conf</ulink>(5)
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stops Shorewall (Shorewall lite) from modifying
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<filename>/etc/iproute2/rt_tables</filename>.</para>
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<para>Shorewall6 is also capable of modifying
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<filename>/etc/iproute2/rt_tables</filename> in a similar way.</para>
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<para>Our recommendation to Multi-ISP users is to:</para>
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<itemizedlist>
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<listitem>
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<para>Select the same names for similar providers.</para>
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</listitem>
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<listitem>
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<para>Set KEEP_RT_TABLES=No in <ulink
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url="manpages/shorewall.conf.html">shorewall.conf</ulink>(5) and
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set KEEP_RT_TABLES=Yes in <ulink
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url="manpages6/shorewall6.conf.html">shorewall6.conf</ulink>(5).</para>
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</listitem>
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</itemizedlist>
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<para>These setting allow Shorewall to control the contents of
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<filename>/etc/iproute2/rt_tables</filename>.</para>
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</section>
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<section>
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<title>6TO4</title>
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<para>If you are using a 6to4 tunnel for your IPv6 connectivity, you
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need an entry in
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<filename>/etc/shorewall/tunnels</filename>.<programlisting>#TYPE ZONE GATEWAY GATEWAY
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# ZONE
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6to4 net
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#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting></para>
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</section>
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</section>
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</section>
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<section>
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<title>Shorewall6 Differences from Shorewall</title>
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<para>Configuring and operating Shorewall6 is very similar to configuring
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Shorewall with some notable exceptions:</para>
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<variablelist>
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<varlistentry>
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<term>No NAT</term>
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<listitem>
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<para>In Shorewall6, there is no NAT of any kind (Netfilter6 doesn't
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support any form of NAT). Most people consider this to be a giant
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step forward.</para>
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<para>When an ISP assigns you an IPv6 address, you are actually
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assigned an IPv6 <firstterm>prefix</firstterm> (similar to a
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subnet). A 64-bit prefix defines a subnet with 4 billion hosts
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squared (the size of the IPv4 address space squared). Regardless of
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the length of your prefix, you get to assign local addresses within
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that prefix.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Default Zone Type</term>
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<listitem>
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<para>The default zone type in Shorewall6 is
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<firstterm>ipv6</firstterm>. It is suggested that you specify
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<emphasis role="bold">ipv6</emphasis> in the TYPE column of
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<filename>/etc/shorewall6/zones</filename> and a type of <emphasis
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role="bold">ipv4</emphasis> in
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<filename>/etc/shorewall/zones</filename>; that way, if you run the
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wrong utility on a configuration, you will get an instant
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error.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Interface Options</term>
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<listitem>
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<para>The following interface options are available in
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<filename>/etc/shorewall6/interfaces</filename>:</para>
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<variablelist>
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<varlistentry>
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<term>blacklist</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>bridge</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>dhcp</term>
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<listitem>
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<para>Interface is assigned by IPv6 DHCP or the firewall hosts
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an IPv6 DHCP server on the interface.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>maclist</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>nosmurfs</term>
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<listitem>
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<para>Checks the source IP address of packets arriving on the
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interface and drops packets whose SOURCE address is:</para>
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<itemizedlist>
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<listitem>
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<para>An IPv6 multicast address</para>
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</listitem>
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<listitem>
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<para>The subnet-router anycast address for any of the
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global unicast addresses assigned to the interface.</para>
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</listitem>
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<listitem>
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<para>An RFC 2526 anycast address for any of the global
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unicast addresses assigned to the interface.</para>
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</listitem>
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</itemizedlist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>optional</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>routeback</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>sourceroute[={0|1}]</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>tcpflags</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>mss=<replaceable>mss</replaceable></term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>forward[={0|1}]</term>
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<listitem>
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<para>Override the setting of IP_FORWARDING in shorewall6.conf
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with respect to how the system behaves on this interface. If
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1, behave as a router; if 0, behave as a host.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Host Options</term>
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<listitem>
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<para>The following host options are available in<filename>
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/etc/shorewall6/hosts</filename>:</para>
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<variablelist>
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<varlistentry>
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<term>blacklist</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>maclist</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>routeback</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>tcpflags</term>
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<listitem>
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<para>Same as in Shorewall</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Specifying Addresses</term>
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<listitem>
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<para>Anywhere that an address or address list follows a colon
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(":"), the address or list may be enclosed in angled brackets
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("<" and ">") to improve readability.</para>
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<para>Example (<filename>/etc/shorewall6/rules</filename>):</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST
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# PORT(S)
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ACCEPT net $FW:<2002:ce7c:92b4::3> tcp 22</programlisting>
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<para>When the colon is preceeded by an interface name,
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<emphasis>the angle brackets are required</emphasis>. This is true
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even when the address is a MAC address in Shorewall format.</para>
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<para>Example (<filename>/etc/shorewall6/rules</filename>):</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST
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# PORT(S)
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ACCEPT net:wlan0:<2002:ce7c:92b4::3> tcp 22</programlisting>
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<para>Beginning with Shorewall 4.4.6 and 4.5.4, square brackets ("["
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and "]") may also be used.</para>
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<para>Example (<filename>/etc/shorewall6/rules</filename>):</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST
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# PORT(S)
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ACCEPT net:wlan0:[2002:ce7c:92b4::3] tcp 22</programlisting>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Stopped State</term>
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<listitem>
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<para>When Shorewall6 or Shorewall6 Lite is in the stopped state,
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the following traffic is still allowed.</para>
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<itemizedlist>
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<listitem>
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<para>Traffic with a multicast destination IP address
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(ff00::/8).</para>
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</listitem>
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<listitem>
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<para>Traffic with a link local source address
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(ff800::/8)</para>
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</listitem>
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<listitem>
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<para>Traffic with a link local destination address.</para>
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</listitem>
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</itemizedlist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Multi-ISP</term>
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<listitem>
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<para>The Linux IPv6 stack does not support balancing (multi-hop)
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routes. Hence, neither the <option>balance</option> option in <ulink
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url="manpages6/shorewall6-providers.html">shorewall6-providers</ulink>(5)
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nor USE_DEFAULT_RT=Yes in <ulink
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url="manpages6/shorewall.conf.html">shorewall6.conf</ulink>(5) is
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supported.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>/sbin/shorewall6 and /sbin/shorewall6-lite Commands</term>
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<listitem>
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<para>Several commands supported by
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<filename>/sbin/shorewall</filename> and
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<filename>/sbin/shorewall-lite</filename> are not supported by
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<filename>/sbin/shorewall6</filename> and
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<filename>/sbin/shorewall6-lite</filename>:</para>
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<itemizedlist>
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<listitem>
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<para>hits</para>
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</listitem>
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<listitem>
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<para>ipcalc</para>
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</listitem>
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<listitem>
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<para>iprange</para>
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</listitem>
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</itemizedlist>
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<para></para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Macros</term>
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<listitem>
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<para>The Shorewall6 package depends on Shorewall-common for
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application macros. Only certain address-family specific macros such
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as macro.AllowICMPs are included in Shorewall6. As a consequence,
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/usr/share/shorewall/ is included in the default Shorewall6
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CONFIG_PATH.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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|
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<section>
|
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<title>Installing IPv6 Support</title>
|
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|
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<para>You will need at least the following packages:</para>
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|
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<itemizedlist>
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<listitem>
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<para>Shorewall 4.3.5 or later.</para>
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</listitem>
|
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|
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<listitem>
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<para>Shorewall6 4.3.5 or later.</para>
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</listitem>
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</itemizedlist>
|
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|
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<para>You may also with to install Shorewall6-lite 4.3.5 or later on your
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remote firewalls to allow for central IPv6 firewall administration.</para>
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</section>
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<section>
|
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<title>More information about IPv6</title>
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|
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<para>I strongly suggest that you read the<ulink
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url="http://tldp.org/HOWTO/Linux+IPv6-HOWTO/"> Linux IPv6 HOWTO</ulink>.
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The <ulink url="6to4.htm">6to4 Tunnels</ulink> page also includes
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instructions for setting up your first IPv6 environment.</para>
|
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|
|
<para>In addition to the Linux IPv6 HOWTO, I have found the following two
|
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books to be useful:</para>
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|
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<itemizedlist>
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<listitem>
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<para><emphasis>IPv6 Essentials</emphasis>, Silvia Hagen, 2002,
|
|
O'Reilly Media, Inc, ISBN 0-596-00125-8.</para>
|
|
|
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<para>O'Reilly published a second edition of this book in 2006.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para><emphasis>IPV6 Theory, Protocol, and Practice</emphasis>, Second
|
|
Edition, Pete Loshin, 2004, Morgan-Kaufmann Publishers, IBSN
|
|
1-55860-820-9</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</section>
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</article>
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