ISC DHCP server always ACKs DHCPREQUESTs without checking the server identier

[David W. Hankins]

On Fri, Feb 23, 2007 at 01:50:02PM +0200, Jordan Gordeev wrote:
> I am using the ISC DHCP server version 3.0.5. Most of the DHCP clients 
> on my network have host declarations with fixed adresses. I have noticed 
> that the server  sends DHCPACK messages to clients requesting (via 
> DHCPREQUEST) leases from other DHCP server. I have looked at the source 
> code and have noticed that the server identier in DHCPREQUEST messages 
> is not used. I'm wondering why the server behaves like that.

I suspect the answer to this question is lost to the mists of
time.

I don't think rfc2131 ever goes straight on record that the
server MUST drop packets with other servers' identifiers (even
if it did, it would only apply to REQUEST's got from clients
in SELECTING state, as that's the only state the client is
supposed to provide the server-id).

It would be not quite trivial to do so in ISC DHCP since it's
possible that the administrator might have configured a server-id
in a scope for the client.

By the time we've built enough scope from the client, we're
already well into handling...


So I suspect that the original author (Ted) looked at the
complexities involved, and the meager rewards, and decided not
to complicate the server on this point.

-- 
ISC Training!  http://www.isc.org/training/  training at isc.org
Washington DC area, April 16-20 2007.  DNS & BIND, DDNS & DHCP.
-- 
David W. Hankins	"If you don't do it right the first time,
Software Engineer		you'll just have to do it again."
Internet Systems Consortium, Inc.	-- Jack T. Hankins