Can Dhcp client receive messages on a different port than 68?

[Glenn Satchell]

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>Date: Wed, 19 Jul 2006 05:20:43 -0700 (PDT)
>From: Lilian JS <lilianjs at yahoo.com>
>Subject: Can Dhcp client receive messages on a different port than 68?
>To: dhcp-users at isc.org
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>Hello!
>
>RFC says that client should send to server port 67 and
>server should send to client port 68. I would like to
>know whether the client can receive on another
>port?..And if the client can, will it be
>inter-operable with the other servers out there? Does
>the server always send to the default client port, or
>on the port from which the client message came?
>
>Thanks & Regards,
>Lilian.
>
Hi Lilian

The dhclient man page says that dhclient has a -p port option:

     If the DHCP client should listen  and  transmit  on  a  port
     other than the standard (port 68), the -p flag may used.  It
     should be followed by the  udp  port  number  that  dhclient
     should  use.   This is mostly useful for debugging purposes.
     If a different port is specified for the client to listen on
     and transmit on, the client will also use a different desti-
     nation port - one greater  than  the  specified  destination
     port.

Whether the server replies to this or the default is a function of the
server. The corresponding section of the dhcpd man page says:

     If dhcpd should listen on a port  other  than  the  standard
     (port  67),  the -p flag may used.  It should be followed by
     the udp port number on which dhcpd should listen.   This  is
     mostly useful for debugging purposes.

No mention of the reply port, so maybe this is something for you to
test?

regards,
-glenn