  <varlistentry>
  <term><emphasis remap='B'>listen-udp</emphasis></term>
  <listitem>
<para>Whether the pluto IKE daemon should listen on the standard
UDP ports of <emphasis remap='B'>500</emphasis> and <emphasis
remap='B'>4500</emphasis>. The value "yes" means to listen on these
ports, and is the default. This should almost never be disabled. In the
rare case where it is known that only ever TCP or non-standard UDP ports
will be used, this option can disable the standard UDP ports. Connections
can specify their own non-standard port using leftikeport=.
</para>
  </listitem>
  </varlistentry>
