Subject: [dhcwg] dhcwg archives

From: "David W. Hankins" <[email-masked]>
Date: Thu, 21 Feb 2008 11:53:45 -0800

I was going to link the archive entry of Simon's post over to one
of our mailing lists as a heads up, and noticed the archive entry for
this post:

http://www.ietf.org/mail-archive/web/dhcwg/current/msg08320.html

Is missing everything in Simon's post from his quote of 2131 on.  To
experiment (and save space on the archive), I will attempt to make the
below full quote of Simon's message disappear from the archive entry
of this message, a priori.

From my Inbox to yours:

----- Forwarded message from Simon Kelley <[email-masked]> -----

Date: Thu, 21 Feb 2008 11:20:59 +0000
From: Simon Kelley <[email-masked]>
To: [email-masked]
Subject: [dhcwg] Source address in Vista DHCP packets.

I've just had some tcpdump output sent to me by someone who is having
problems getting Windows Vista to work with dnsmasq. Vista is emitting
DHCP packets which look like this. There's not enough information to be
sure if they are DISCOVER or REQUEST packets (and what flavour of
REQUEST), but my guess is that they are DISCOVER.

Client Ethernet Address: 00:17:c4:10:9a:3c [|bootp]
17:36:50.527538 IP (tos 0x0, ttl 128, id 442, offset 0, flags [none],
length: 328) 169.254.194.239.68 > 255.255.255.255.67: BOOTP/DHCP,
Request from 00:17:c4:10:9a:3c, length: 300, xid:0xe014ef8f, secs:768,
flags: [Broadcast] (0x8000)

Note that the source address in the IP header is 169.254.194.239 which
is in the APIPA range. I suspect that this is the cause of the problem,
(a badly configured firewall to dumping these packets before they get to
the DHCP server because of their source address), but that is not point
of this post. I think this behaviour is a standards violation.

From RFC 2131:
   DHCP messages broadcast by a client prior to that client obtaining
   its IP address must have the source address field in the IP header
   set to 0.

It looks like the Microsoft DHCP client violates this if DHCP has timed
out at some point and an APIPA address has been selected. Further
attempts at DHCP then have a wrong source address.

So: questions.

1) Has anyone else seen this? Can you clarify the circumstances under
which it occurs?

2) Is this really a standards violation?

3) If it is, does anyone have experience of the best way to report it as
bug to Microsoft?

Cheers,

Simon.

_______________________________________________
dhcwg mailing list
[email-masked]
http://www.ietf.org/mailman/listinfo/dhcwg

----- End forwarded message -----

-- 
Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
Why settle for the lesser evil?	 https://secure.isc.org/store/t-shirt/
-- 
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
_______________________________________________
dhcwg mailing list
[email-masked]
http://www.ietf.org/mailman/listinfo/dhcwg