shorewall_code/Shorewall-docs2/UPnP.xml
2005-05-28 04:59:08 +00:00

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<article>
<!--$Id$-->
<articleinfo>
<title>Shorewall and UPnP</title>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Eastep</surname>
</author>
</authorgroup>
<pubdate>2005-05-16</pubdate>
<copyright>
<year>2005</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>
<section>
<title>UPnP</title>
<para>In Shorewall 2.2.4, support was added for UPnP (Universal Plug and
Play) using linux-igd (<ulink
url="http://linux-igd.sourceforge.net">http://linux-igd.sourceforge.net</ulink>).
UPnP is required by a number of popular applications including MSN
IM.</para>
<warning>
<para>From a security architecture viewpoint, UPnP is a disaster. It
assumes that:</para>
<orderedlist numeration="loweralpha">
<listitem>
<para>All local systems and their users are completely
trustworthy.</para>
</listitem>
<listitem>
<para>No local system is infected with any worm or trojan.</para>
</listitem>
</orderedlist>
<para>If either of these assumptions are not true then UPnP can be used
to totally defeat your firewall and to allow incoming connections to
arbitrary local systems on any port whatsoever. In short: USE
UPnP<emphasis> </emphasis> <emphasis role="bold">AT YOUR OWN
RISK.</emphasis></para>
</warning>
<warning>
<para>The linux-igd project appears to be inactive and the web site does
not display correctly on any open source browser that I've tried.
Building and installing linux-igd is not for the faint of heart. You
must download the source from CVS and be prepared to do quite a bit of
fiddling with the include files from libupnp (which is required to build
and/or run linux-igd).</para>
</warning>
<warning>
<para>Before building liunx-igd, you must apply all patches found at
<ulink
url="http://shorewall.net/pub/shorewall/contrib/linux-igd">http://shorewall.net/pub/shorewall/contrib/linux-igd</ulink>.</para>
</warning>
<para></para>
</section>
<section>
<title>linux-igd Configuration</title>
<para>In /etc/upnpd.conf, you will want:</para>
<programlisting>insert_forward_rules = yes
prerouting_chain_name = UPnP
forward_chain_name = forwardUPnP</programlisting>
</section>
<section>
<title>Shorewall Configuration</title>
<para>In <filename>/etc/shorewall/interfaces</filename>, you need the
'upnp' option on your external interface.</para>
<para>Example:</para>
<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
net eth1 detect dhcp,routefilter,norfc1918,tcpflags,<emphasis
role="bold">upnp</emphasis></programlisting>
<para>If your fw-&gt;loc policy is not ACCEPT then you need this
rule:</para>
<programlisting>#ACTION SOURCE DEST
allowoutUPnP fw loc</programlisting>
<note>
<para>To use 'allowoutUPnP', your iptables and kernel must support the
'owner match' feature (see the output of "shorewall show
capabilities").</para>
</note>
<para>If your loc-&gt;fw policy is not ACCEPT then you need this
rule:</para>
<programlisting>#ACTION SOURCE DEST
allowinUPnP loc fw</programlisting>
<para>You MUST have this rule:</para>
<programlisting>#ACTION SOURCE DEST
forwardUPnP net loc</programlisting>
<para>You must also ensure that you have a route to 224.0.0.0/4 on your
internal (local) interface as described in the linux-igd
documentation.</para>
</section>
</article>