Re: problems with KB951746

Agreed. But in this case it's moot. The issue persists even if both
firewalls are bypassed.

--

GaryK


"Cliff Galiher" <cgaliher@xxxxxxxxx> wrote in message
news:hIadnXIUU8UcpjvVnZ2dnUVZ_j6dnZ2d@xxxxxxxxxxxxxx
Depends on how aggressive the firewall is with its intrusion prevention
measures. Blocking legitimate IP addresses responding on ports the
firewall doesn't expect will cause problems. And three or more people
using the net will cause the firewall to block IPs more rapidly. Never
*assume* that the problem isn't somewhere. Test and verify...test and
verify... :)

-Cliff

"Gary Karasik" <gkarasik@xxxxxxx> wrote in message
news:u7%23gyc0$IHA.3756@xxxxxxxxxxxxxxxxxxxxxxx
Also, if this were a firewall issue, I think it would be there all the
time, not just when the system is under load.

--

GaryK


"Cliff Galiher" <cgaliher@xxxxxxxxx> wrote in message
news:I5OdnRWuYKkGijvVnZ2dnUVZ_uqdnZ2d@xxxxxxxxxxxxxx
Gary,

I doubt the patch, or SBS, is the problem here. What I suspect is
happening is that the patch is doing what it is supposed to do. But one
of the things the patch does is cause the source port to be randomized.
If your firewall is not configured to allow DNS traffic from a random
source port then your recursive DNS requests are being stopped at the
firewall...and you'll get the symptoms you describe. It is also
possible, but less likely, that your ISP's DNS servers are misconfigured
and are unable to reply on odd source ports.

So this is where I'd start....look at your network perimeter and see if
you can verify there is a firewall issue.
Then, if you are CONFIDENT that you are okay there and the speed issue
remains, reconfigure SBS (CEICW) and point it to another DNS server that
is known to be patched and working (openDNS is a good option here).

Let me know if that helps,

-Cliff

I'm fairly confident you'll be able to fix the issue from there.
"Gary Karasik" <gkarasik@xxxxxxx> wrote in message
news:%236rvj2y$IHA.5660@xxxxxxxxxxxxxxxxxxxxxxx
Hi,

I can't decide how to proceed with getting this problem solved. Wien
the server-side DNS-vulnerability patch (951746) is installed, all my
SBS2K3 systems are exhibiting the same problem: extremely show internet
access when the system is under load, meaning when three or more
clients are trying to access the internet at once.

With the patch uninstalled everything returns to normal. This is not
resolved by reserving ports as one fix suggests.

The problem seems to be that DNS can't resolve quickly when the patch
is installed. Sometimes it is so slow that the system times out. I've
tried different forwarders, different DNS servers, and root hints only.
If the patch is installed, nothing helps.

Someone has posted a message about this in the SBS private forum, but
he isn't getting much help.

My indecision stems from the fact that no symptoms show if there is no
load, so if I call CSS after hours I can't show them any symptoms, and
I don't want to load the patch during a work day because access is so
slow that client work slows to a virtual standstill, the remote
branches connections to Exchange server stop responding, and local
clients can't do any work that involves the internet.

I think I'm just going to have to live with this and hope that MS comes
up with a fix for someone else and I hear about it.

Maybe someone here can suggest an approach, because I'm stumped as to
how to proceed.

--

GaryK









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Relevant Pages

  • Re: problems with KB951746
    ... Blocking legitimate IP addresses responding on ports the firewall doesn't expect will cause problems. ... What I suspect is happening is that the patch is doing what it is supposed to do. ... It is also possible, but less likely, that your ISP's DNS servers are misconfigured and are unable to reply on odd source ports. ...
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