Subject: Re: dhcpd(8) _cannot_ be completely disabled on an interface
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: gabriel rosenkoetter <>
List: tech-net
Date: 01/07/2002 16:32:11
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Mon, Jan 07, 2002 at 04:03:43PM -0500, der Mouse wrote:
> Yes - or at least, _someone_ needs to know it, and only DHCP has it.
> I saw a list message saying that it's already present in the DHCP
> payload, though.  (No idea what the Right Thing to do is if that's
> different from the Ethernet sender MAC address.)

This smells of DoS, but I think it's a necessary evil. I mean, if
you have an link-level repeater, won't it show up as the source MAC
address for anything on the other side trying to contact a DHCP
server? In that case, you definitely want the MAC address in the
payload, not the outermost one on the packet you received...

Also, not so sure that it's a useful DoS to send DHCP responses to
an unsuspecting "victim". Don't know how dhcpd behaves if it recieves
a new connection from a machine it has already serviced. Seems like
it would be the same as if the machine had unexpectedly dropped off
the network, and the old lease would still be valid in most cases,
so not much would change.

gabriel rosenkoetter

Content-Type: application/pgp-signature
Content-Disposition: inline

Version: GnuPG v1.0.6 (NetBSD)
Comment: For info see