shorewall_code/Shorewall-docs2/UPnP.xml

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  <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>