I'm just now looking at this:

www.flukenetworks.com/TryAirCheck<http://www.flukenetworks.com/TryAirCheck>

Thinking it might be useful...



From: Jeff Steward [mailto:jstew...@gmail.com]
Sent: Tuesday, October 19, 2010 11:09 AM
To: NT System Admin Issues
Subject: Re: Update: Group Policy Problems Over Wireless

http://www.sans.org/reading_room/whitepapers/auditing/wifi-backtrack_2038

Here is a whitepaper on using the free backtrack bootable CD to audit and map 
your wireless network or hire someone to do it.  I took the SANS 'Assessing and 
Securing Wireless Networks' course a few years back and it was well worth the 
money.  Of course, your head may explode by the end of the course :-)

The short answer is to use 3 channels and double up on the pair of APs that are 
furthest apart.  YMMV.

-Jeff Steward
On Tue, Oct 19, 2010 at 10:36 AM, John Hornbuckle 
<john.hornbuc...@taylor.k12.fl.us<mailto:john.hornbuc...@taylor.k12.fl.us>> 
wrote:
The theory behind auto seems good... Listen for a channel that's not noisy, 
then use it. But I get what you're saying--there may not be interference on a 
particular channel when the WAP boots, but that doesn't mean there won't be 
later.

The trouble is that we have 4 WAPs in close proximity. If I should only use 
those 3 channels, what's my best approach?


-----Original Message-----
From: Glen Johnson [mailto:gjohn...@vhcc.edu<mailto:gjohn...@vhcc.edu>]
Sent: Tuesday, October 19, 2010 9:23 AM
To: NT System Admin Issues
Subject: RE: Update: Group Policy Problems Over Wireless

We just had a Cisco site survey done for our wireless and he said "never set 
them to auto" for the channel.

Plot the waps on a map and manually configure the channels to 1 6 or 11 for 
minimum overlap. IE, waps on the same channel need to be separated to prevent 
interference.  We had previously had ours set to auto and following his advise 
helped quite a bit.

His explanation is that, when configured for auto, the wap listens when it 
boots and selects the least busy channel.

That may be good at boot time but could change significantly later on.

Also, if a wap chooses any channel other than 1, 6 or 11, it can cause 
interference with on other channels.

With these 3 channels selected, you get 3 non-overlapping channels.

Any other channel will overlap with 2 of the above.



________________________________
From: John Hornbuckle 
[john.hornbuc...@taylor.k12.fl.us<mailto:john.hornbuc...@taylor.k12.fl.us>]
Sent: Tuesday, October 19, 2010 8:50 AM
To: NT System Admin Issues
Subject: Update: Group Policy Problems Over Wireless

No firm resolution on this yet, but possibly a bit of progress.

I kept thinking about the problems we were having in this lab. The computers 
are the same computers we had in the lab last year, and last year we didn't 
have these problems. So, what changed? Two things: we replaced the WAPs that 
serve the lab with newer models, and more WAPs were installed in that area of 
the building.

So I got to thinking that maybe the issue was an incompatibility between 
Broadcom NICs and the new WAPs, or an issue caused by too many WAPs being in 
the same vicinity. But we have another lab in a different area of the building 
that has the exact same WAPs and the exact same computers-but no problems. So 
that left the latter possibility-lots of WAPs stepping on one another's toes-as 
the prime culprit.

The WAPs are Cisco/Linksys, and they all default to the same channel. I changed 
the ones in the area that was having the problem to "auto," but that didn't 
seem to really help. So next I forced the WAPs that serve the lab to "g" rather 
than "b/g/n." As moment, everything is working fine. My tech and I will be 
watching throughout the week, and if things are still working after a few days 
we'll consider the issue resolved.


John


From: John Hornbuckle 
[mailto:john.hornbuc...@taylor.k12.fl.us<mailto:john.hornbuc...@taylor.k12.fl.us>]
Subject: Group Policy Problems Over Wireless

Short version:
Is there a trick to improving group policy processing when accessing the 
network wirelessly?


Long version:
We have a lab with machines that have Broadcom wireless NICs in them. Vista OS, 
connecting to Server 2008 R2 DC.

I'm trying to deploy a piece of software to these machines via Group Policy. I 
have things setup so that if the machine is a member of a certain group, the 
software is deployed. Unfortunately, it only worked correctly on one of the 
machines-on all the rest, the software isn't being deployed.

So I connect to any of the machines that didn't get the software, and run 
gpresult. It doesn't show me that those machines are members of the group that 
gets the software. But I know they are; I've confirmed in ADUC on the DC. 
They're just not picking up group membership.

Looking at the event log for events that happen around startup, I see things 
that make me think group policy processing is trying to happen prior to the 
wireless network being initialized. Things like:

Event ID 5719 (There are currently no logon servers available to service the 
logon request.) Event ID 129 (NtpClient was unable to set a domain peer to use 
as a time source because of discovery error.) Event ID 1129 (The processing of 
Group Policy failed because of lack of network connectivity to a domain 
controller.)
Connectivity to the DC is fine once you get the [Ctrl] + [Alt] + [Del] window. 
You can log in (including as someone who has never logged into the machine 
before), ping the DC, browse to 
\\domain\syvol<file:///\\domain\syvol<file:///\\domain\syvol%3cfile:\domain\syvol>>,
 and so on. It's just that at that point, group policy processing seems to have 
given up. My machines aren't figuring out that they've been added to a new 
group.

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