  <varlistentry>
  <term><emphasis remap='B'>nat_keepalive</emphasis></term>
  <listitem>
<para>whether to send any NAT-T keep-alives. These 1 byte packets 
are send to prevent the NAT router from closing its port when there is
not enough traffic on the IPsec connection. Acceptable values are:
<emphasis remap='B'>yes</emphasis> (the deault) and
<emphasis remap='B'>no</emphasis>. This per-conn option takes precedence
over the global (config setup) <emphasis remap='I'>force_keepalive=</emphasis> option.
</para>
  </listitem>
  </varlistentry>
