question about DHCPACK log entries

David W. Hankins David_Hankins at
Thu Mar 1 22:30:03 UTC 2007

On Thu, Mar 01, 2007 at 04:00:18PM -0600, Tim Peiffer wrote:
>         /* RFC2131 states the server SHOULD unciast to ciaddr.
>          * There are two wrinkles - relays, and when ciaddr is zero.
>          * There's actually no mention of relays at all in rfc2131 in
>          * regard to DHCPINFORM, except to say we might get packets from
>          * clients via them.  Note: relays unicast to clients to the
>          * "yiaddr" address, which servers are forbidden to set when
>          * answering an inform.
>          *
>          * The solution: If ciaddr is zero, and giaddr is set, go via the
>          * relay with the broadcast flag set to help the relay (with no
>          * yiaddr and very likely no chaddr, it will have no idea where to
>          * send the packet).
>          *
>          * If the ciaddr is zero and giaddr is not set, go via the source
>          * IP address (but you are permitted to barf on their shoes).
>          *
>          * If ciaddr is not zero, send the packet there always.
>          */

It should be noted that this comment is from the DHCPINFORM processing
function, not from the DHCPREQUEST processing function.  DHCPACK is
used in two places this way.

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