Next patches:
 - Relay v4:
   * I kept the patching of the first 67 (index 8)

   * BTW the cast to short in ntohs() calls is
    not correct (fixed them around modified code)

   * I added a #error in other PF code (NDLI, NIT, etc)

   * missing trailing ']' in "[-p <port> | -rp <relay-port>"

  - Relay v6:
   * changed {up, down}_intf into {up, down}done

   * I am not convinced by the else before the break
    which matches more than needed but I don't believe
    it can harm so I didn't try to fix it.
   (down_intf++; in you patch)

   * changed "ipv6-relay-port" in "relay-source-port"
    and 90 in 135 and I reordered entries to increasing codes.

   * 547 -> htons(547) (compare to client_port)

   * relay-port -> relay-source-port in message

I updated the manual page.