/0</code> represents all
       IPv4 addresses, and <code class="literal">::0/0</code> represents
       all IPv6 addresses.
       To specify a single host, use a mask length of 32 for IPv4 or
       128 for IPv6.  In a network address, do not omit trailing zeroes.
      </p><p>
       An entry given in IPv4 format will match only IPv4 connections,
       and an entry given in IPv6 format will match only IPv6 connections,
       even if the represented address is in the IPv4-in-IPv6 range.
      </p><p>
  