Re: ISC dhcpd and Vista clients

Scott Silva <ssilva@xxxxxxxxxxxx> · Thu, 31 Jul 2008 12:02:14 -0700

on 7-31-2008 10:37 AM James N. Smith spake the following:

-----Original Message-----
From: centos-bounces@xxxxxxxxxx [mailto:centos-bounces@xxxxxxxxxx] On Behalf
Of Scott Silva
Sent: Thursday, July 31, 2008 1:20 PM
To: centos@xxxxxxxxxx
Subject:  Re: ISC dhcpd and Vista clients

on 7-31-2008 10:06 AM Glenn spake the following:
At 12:52 PM 7/31/2008, you wrote:
on 7-30-2008 11:20 PM Paul Bijnens spake the following:
Scott Silva wrote:
on 7-30-2008 2:53 PM Paul Bijnens spake the following:
Scott Silva wrote:
Has anyone had good luck serving dhcp addresses to Vista clients 
that work reliably?

I have a test system and I can't seem to find out how to properly 
get dhcpd to always respond with broadcast instead of unicast 
since Vista won't honor unicast dhcp packets.
My Vista (my wife's actually) has no problems with unicast dhcp 
packets.

Stock dhcpd server in CentOS 5, and Vista Home. Worked without any 
special config.

Are you sure that is the problem?
Not sure, but it is one of the suggested problems I see in many 
google searches. There are registry edits that help, but I don't 
want to have to do a bunch of edits when we get stuck with a hundred 
Vista machines. I have plenty of time, for now, to experiment. There 
are posts that say the subnet needs to be authoritative, but mine 
is. What happens is that the Vista system will not route outside the 
local subnet for more than 5 or 10 minutes.
Do you mean that you do get an IP-number and default gateway from the
dhcp server, but after 5 to 10 minutes, the default route setting gets
lost?
To me that would mean that the dhcp is working fine, but something 
else kicks in after that time that messes up the dhcp settings.  Any 
additional firewall software on the laptop, like Norton etc.
Or can you relate the loss of routing to an action on the dhcp server,
like lease renewing etc.
I think I am going to have to spend some more time on this. Maybe with 
a sniffer and some patience. The laptop just had Vista Ultimate 
because that is the version we acquired for testing, and our standard 
McAfee virus scanner. I will have to toss together a VM machine and 
try different combos of stuff. As a matter of fact I have a VM loaded 
on my laptop that I was playing with at home as it runs fine there. 
That way the only difference will be the change in  location. It is 
just dog slow, but for this test it doesn't matter that much.

I'll have to look at the troubled machine and see if I can detect 
problems in the routing tables and such. I just have to figure out if 
the same commands do what I want between Vista and XP, or if I need to 
do some reading.

My recent reading has lead me to believe that Windows Vista comes with 
IPV6 enabled by default and can really generate some traffic if you do 
not turn it off and possibly cause problems if your network 
infrastructure does not support it. Is that possibly a problem?

Cheers,
Glenn
I turned off IPv6 on that machine, but since it is in our other office, I 
won't get back to it until tomorrow to poke it some more.

I'm not sure if this is related.  I am running a Linksys WRVS4400N router
(which has Linux based firmware) for my DHCP.  I am noticing that my one
vista machine is having a difficult time with the DHCP.  I haven't solved it
yet but what I have seen is that the problem appears to be with the lease
times and renewal.  When my IP addressing fails on the Vista machine and I
check the lease table on the router I note that the machine appears on the
list but has a MUCH shorter lease time remaining than the XP machines.  As I
take this machine in and out of the house a good bit I run across this
problem every few days.  Rebooting the router has been my only recourse
until recently.

I moved to a new firmware and also maxed out the lease time on the DHCP
service.  You might want to increase the lease time on your CentOS DHCP
server and see if it effects the situation. 

Wish I could be of more help, but I'm just starting to troubleshoot the
problem.  The one thing I know for sure is that it seems isolated to only
Vista clients.  I do not know if the Linksys firmware is using the same
version of ISC DHCPD that CentOS.

Regards,
James
Many of the articles point to the fact that Vista, by the will of the 
Microsoft demons, changed how it deals with the broadcast flag in dhcp packets.

Quote:

CAUSE
This issue occurs because of a difference in design between Windows Vista and 
Microsoft Windows XP Service Pack 2 (SP2). Specifically, in Windows XP SP2, 
the BROADCAST flag in DHCP discovery packets is set to 0 (disabled). In 
Windows Vista, the BROADCAST flag in DHCP discovery packets is not disabled. 
Therefore, some routers and some non-Microsoft DHCP servers cannot process the 
DHCP discovery packets.

Microsofts answer is that Vista is right and the rest of the world is wrong 
(typical), but if you want it to work you have to regedit every affected 
machine and change something.

That is unacceptable in a business environment, IMHO.

The other answer is to get ISC dhcpd to honor the broadcast flag, and 
broadcast all packets instead of unicasting the answer packets. That I can't 
find a setting for.

--
MailScanner is like deodorant...
You hope everybody uses it, and
you notice quickly if they don't!!!!

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