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shorewall_code/docs/IPv6Support.xml
Tom Eastep 0d1d2c881f Documentation updates on top of those by Tuomo Soini 
Signed-off-by: Tom Eastep <teastep@shorewall.net>
2016-02-16 14:14:40 -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 IPv6 Support</title>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Eastep</surname>
</author>
</authorgroup>
<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
<copyright>
<year>2008</year>
<year>2009</year>
<year>2016</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 4.3 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>
<title>Overview</title>
<para>Beginning with Shorewall 4.2.4, support for firewalling IPv6 is
included as part of Shorewall.</para>
<section>
<title>Prerequisites</title>
<para>In order to use Shorewall with IPv6, your firewall must meet the
following prerequisites:</para>
<orderedlist>
<listitem>
<para><ulink url="FAQ.htm#faq80a">Kernel 2.6.24 or
later</ulink>.</para>
</listitem>
<listitem>
<para>Iptables 1.4.0 or later (1.4.1.1 is strongly
recommended)</para>
</listitem>
<listitem>
<para>If you wish to include DNS names in your IPv6 configuration
files, you must have Perl 5.10 and must install the Perl Socket6
library.</para>
</listitem>
</orderedlist>
</section>
<section>
<title>Packages</title>
<para>Shorewall IPv6 support introduced two new packages:</para>
<orderedlist>
<listitem>
<para>Shorewall6. This package provides
<filename>/sbin/shorewall6</filename> which is the IPv6 equivalent
of <filename>/sbin/shorewall</filename>.
<filename>/sbin/shorewall</filename> only handles IPv4 while
<filename>/sbin/shorewall6</filename> handles only IPv6.. Shorewall6
depends on Shorewall. The Shorewall6 configuration is stored in
<filename class="directory">/etc/shorewall6</filename>.</para>
</listitem>
<listitem>
<para>Shorewall6 Lite. This package is to IPv6 what Shorewall Lite
is to IPv4. The package stores its configuration in <filename
class="directory">/etc/shorewall6-lite</filename>. As with Shorewall
Lite, Shorewall6 Lite usually requires no configuration changes on
the firewall system.</para>
</listitem>
</orderedlist>
</section>
<section>
<title>IPv4/IPv6 Interaction</title>
<para>IP connections are either IPv4 or IPv6; there is no such thing as
a mixed IPv4/6 connecton. IPv4 connections are controlled by Shorewall
(or Shorewall-lite); IPv6 connections are controlled by Shorewall6 (or
Shorewall6-lite). Starting and stopping the firewall for one address
family has no effect on the other address family.</para>
<para>As a consequence, there is very little interaction between
Shorewall and Shorewall6.</para>
<section>
<title>DISABLE_IPV6</title>
<para>An obvious area where the configuration of Shorewall affects
Shorewall6 is the DISABLE_IPV6 setting in
<filename>/etc/shorewall/shorewall.conf</filename>. When configuring
Shorewall6, you will want to set DISABLE_IPV6=No and restart Shorewall
or Shorewall-lite.</para>
</section>
<section>
<title>TC_ENABLED</title>
<para>Another area where their configurations overlap is in traffic
shaping; the <filename>tcdevices</filename> and tcclasses files do
exactly the same thing in both Shorewall and Shorewall6. Consequently,
you will have TC_ENABLED=Internal in Shorewall or in Shorewall6 and
TC_ENABLED=No in the other product. Also, you will want CLEAR_TC=No in
the configuration with TC_ENABLED=No.</para>
<para>Regardless of which product has TC_ENABLED=Internal:</para>
<itemizedlist>
<listitem>
<para>IPv4 packet marking is controlled by /etc/shorewall/mangle
(Shorewall 4.6.0 and later) or by /etc/shorewall/tcrules</para>
</listitem>
<listitem>
<para>IPv6 packet marking is controlled by /etc/shorewall6/mangle
(Shorewall 4.6.0 and later) or by /etc/shorewall6/tcrules</para>
</listitem>
</itemizedlist>
</section>
<section>
<title>KEEP_RT_TABLES</title>
<para>Multi-ISP users will need to be aware of this one. When there
are entries in the providers file, Shorewall normally installs a
modified <filename>/etc/iproute2/rt_tables</filename> during
<command>shorewall start</command> and <command>shorewall
restart</command> and restores a default file during
<command>shorewall stop</command>. Setting KEEP_RT_TABLES=Yes in
<ulink url="manpages/shorewall.conf.html">shorewall.conf</ulink>(5)
stops Shorewall (Shorewall lite) from modifying
<filename>/etc/iproute2/rt_tables</filename>.</para>
<para>Shorewall6 is also capable of modifying
<filename>/etc/iproute2/rt_tables</filename> in a similar way.</para>
<para>Our recommendation to Multi-ISP users is to:</para>
<itemizedlist>
<listitem>
<para>Select the same names for similar providers.</para>
</listitem>
<listitem>
<para>Set KEEP_RT_TABLES=No in <ulink
url="manpages/shorewall.conf.html">shorewall.conf</ulink>(5) and
set KEEP_RT_TABLES=Yes in <ulink
url="manpages6/shorewall6.conf.html">shorewall6.conf</ulink>(5).</para>
</listitem>
</itemizedlist>
<para>These setting allow Shorewall to control the contents of
<filename>/etc/iproute2/rt_tables</filename>.</para>
</section>
<section>
<title>6TO4</title>
<para>If you are using a 6to4 tunnel for your IPv6 connectivity, you
need an entry in
<filename>/etc/shorewall/tunnels</filename>.<programlisting>#TYPE ZONE GATEWAY GATEWAY_ZONE
6to4 net</programlisting></para>
</section>
</section>
</section>
<section>
<title>Shorewall6 Differences from Shorewall</title>
<para>Configuring and operating Shorewall6 is very similar to configuring
Shorewall with some notable exceptions:</para>
<variablelist>
<varlistentry>
<term>No NAT</term>
<listitem>
<para>In Shorewall6, there is no NAT of any kind (Netfilter6 doesn't
support any form of NAT). Most people consider this to be a giant
step forward.</para>
<para>When an ISP assigns you an IPv6 address, you are actually
assigned an IPv6 <firstterm>prefix</firstterm> (similar to a
subnet). A 64-bit prefix defines a subnet with 4 billion hosts
squared (the size of the IPv4 address space squared). Regardless of
the length of your prefix, you get to assign local addresses within
that prefix.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Default Zone Type</term>
<listitem>
<para>The default zone type in Shorewall6 is
<firstterm>ipv6</firstterm>. It is suggested that you specify
<emphasis role="bold">ipv6</emphasis> in the TYPE column of
<filename>/etc/shorewall6/zones</filename> and a type of <emphasis
role="bold">ipv4</emphasis> in
<filename>/etc/shorewall/zones</filename>; that way, if you run the
wrong utility on a configuration, you will get an instant
error.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Interface Options</term>
<listitem>
<para>The following interface options are available in
<filename>/etc/shorewall6/interfaces</filename>:</para>
<variablelist>
<varlistentry>
<term>blacklist</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>bridge</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>dhcp</term>
<listitem>
<para>Interface is assigned by IPv6 DHCP or the firewall hosts
an IPv6 DHCP server on the interface.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>maclist</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>nosmurfs</term>
<listitem>
<para>Checks the source IP address of packets arriving on the
interface and drops packets whose SOURCE address is:</para>
<itemizedlist>
<listitem>
<para>An IPv6 multicast address</para>
</listitem>
<listitem>
<para>The subnet-router anycast address for any of the
global unicast addresses assigned to the interface.</para>
</listitem>
<listitem>
<para>An RFC 2526 anycast address for any of the global
unicast addresses assigned to the interface.</para>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
<varlistentry>
<term>optional</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>routeback</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>sourceroute[={0|1}]</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>tcpflags</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>mss=<replaceable>mss</replaceable></term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>forward[={0|1}]</term>
<listitem>
<para>Override the setting of IP_FORWARDING in shorewall6.conf
with respect to how the system behaves on this interface. If
1, behave as a router; if 0, behave as a host.</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
<varlistentry>
<term>Host Options</term>
<listitem>
<para>The following host options are available in<filename>
/etc/shorewall6/hosts</filename>:</para>
<variablelist>
<varlistentry>
<term>blacklist</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>maclist</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>routeback</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
<varlistentry>
<term>tcpflags</term>
<listitem>
<para>Same as in Shorewall</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
<varlistentry>
<term>Specifying Addresses</term>
<listitem>
<para>Shorewall follows the usual convention of distinguishing IPv6
address by enclosing them in square brackets ("[" and "]").</para>
<para>Anywhere that an address or address list follows a colon
(":"), the address or list may be enclosed in square brackets to
improve readability.</para>
<para>Example (<filename>/etc/shorewall6/rules</filename>):</para>
<programlisting>#ACTION SOURCE DEST PROTO DPORT
?SECTION NEW
ACCEPT net $FW:[2002:ce7c:92b4::3] tcp 22</programlisting>
<para>When the colon is preceeded by an interface name,
<emphasis>the angle brackets are required</emphasis>. This is true
even when the address is a MAC address in Shorewall format.</para>
<para>Example (<filename>/etc/shorewall6/rules</filename>):</para>
<programlisting>#ACTION SOURCE DEST PROTO DPORT
?SECTION NEW
ACCEPT net:wlan0:[2002:ce7c:92b4::3] $FW tcp 22</programlisting>
<para>Prior to Shorewall 4.5.4, angled brackets ("&lt;" and "&gt;")
were used. While these are still accepted, their use is deprecated
in favor of square brackets.</para>
<para>Example (<filename>/etc/shorewall6/rules</filename>):</para>
<programlisting>#ACTION SOURCE DEST PROTO DPORT
SECTION NEW
ACCEPT net:wlan0:&lt;2002:ce7c:92b4::3&gt; $FW tcp 22</programlisting>
<para>Prior to Shorewall 4.5.9, network addresses were required to
be enclosed in either angle brackets or square brackets (e.g.
[2001:470:b:787::/64]). Beginning with Shorewall 4.5.9, the more
common representation that places the VLSM outside the brackets is
accepted and preferred (e.g., [2001:470:b:787::]/64).</para>
<para>Beginning with Shorewall 4.5.14, the rules compiler translates
"&lt;" and "&gt;" to "[" and "]" respectively before parsing. So
square brackets may appear in error messages even when angled
brackets were used.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Stopped State</term>
<listitem>
<para>When Shorewall6 or Shorewall6 Lite is in the stopped state,
the following traffic is still allowed.</para>
<itemizedlist>
<listitem>
<para>Traffic with a multicast destination IP address
(ff00::/8).</para>
</listitem>
<listitem>
<para>Traffic with a link local source address
(ff800::/8)</para>
</listitem>
<listitem>
<para>Traffic with a link local destination address.</para>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
<varlistentry>
<term>Multi-ISP</term>
<listitem>
<para>The Linux IPv6 stack does not support balancing (multi-hop)
routes. Thehe <option>balance</option> and <option>fallback</option>
options in <ulink
url="manpages6/shorewall6-providers.html">shorewall6-providers</ulink>(5)
and USE_DEFAULT_RT=Yes in <ulink
url="manpages6/shorewall.conf.html">shorewall6.conf</ulink>(5) are
supported, but at most one provider can have the
<option>balance</option> option and at most one provider can have
the <option>fallback</option> option.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>/sbin/shorewall6 and /sbin/shorewall6-lite Commands</term>
<listitem>
<para>Several commands supported by
<filename>/sbin/shorewall</filename> and
<filename>/sbin/shorewall-lite</filename> are not supported by
<filename>/sbin/shorewall6</filename> and
<filename>/sbin/shorewall6-lite</filename>:</para>
<itemizedlist>
<listitem>
<para>hits</para>
</listitem>
<listitem>
<para>ipcalc</para>
</listitem>
<listitem>
<para>iprange</para>
</listitem>
</itemizedlist>
<para/>
</listitem>
</varlistentry>
<varlistentry>
<term>Macros</term>
<listitem>
<para>The Shorewall6 package depends on Shorewall for application
macros. Only certain address-family specific macros such as
macro.AllowICMPs are included in Shorewall6. As a consequence,
/usr/share/shorewall/ is included in the default Shorewall6
CONFIG_PATH.</para>
</listitem>
</varlistentry>
</variablelist>
</section>
<section>
<title>Installing IPv6 Support</title>
<para>You will need at least the following packages:</para>
<itemizedlist>
<listitem>
<para>Shorewall 4.3.5 or later.</para>
</listitem>
<listitem>
<para>Shorewall6 4.3.5 or later.</para>
</listitem>
</itemizedlist>
<para>You may also with to install Shorewall6-lite 4.3.5 or later on your
remote firewalls to allow for central IPv6 firewall administration.</para>
</section>
<section>
<title>More information about IPv6</title>
<para>I strongly suggest that you read the<ulink
url="http://tldp.org/HOWTO/Linux+IPv6-HOWTO/"> Linux IPv6 HOWTO</ulink>.
The <ulink url="6to4.htm">6to4 Tunnels</ulink> page also includes
instructions for setting up your first IPv6 environment.</para>
<para>In addition to the Linux IPv6 HOWTO, I have found the following two
books to be useful:</para>
<itemizedlist>
<listitem>
<para><emphasis>IPv6 Essentials</emphasis>, Silvia Hagen, 2002,
O'Reilly Media, Inc, ISBN 0-596-00125-8.</para>
<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>
</article>
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