DHCP client nonstandard behavior

[David W. Hankins]

On Wed, Jan 21, 2009 at 01:45:57PM +0100, Christian Treczoks wrote:
> for one point: The RFCs state that the clients sender address is to be 
> 0.0.0.0 and the recipient address should be 255.255.255.255. This is ok 
> for the initial DISCOVER and REQUEST packets,

That is all they are required for.  When the client has an no valid
lease binding, it does not have an IP address to use (hence 0.0.0.0),
and does not know the server's IP addresses (hence sending to
the limited broadcast).

Once the client has a valid configuration, it uses its own source IP
address, and generally (exception: REBINDING, I think maybe release
as well but check the RFC on that one) unicasts its messages to the
server-identifier provided in its binding.

Note that the server will unciast replies directly back to the client,
but should not track the IP source address.  So the actual IP source
address is irrelevant so long as the bootp headers are correct.  You
can let the OS pick 'an appropriate source address' as it pleases.

-- 
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
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