Re: Windows Updates and Cisco Clean Access

[Jim Lawson <jtl+educause () UVM EDU>]

Martin,

We ran into the same problem here at UVM when implementing NetReg.
There are a list of DNS names by which Microsoft provides access to
Windows Update, but they are frequently CNAMEs which point to various
ISPs which get rotated.  I ended up writing a script which re-generates
the list of DNS names and IP addresses that are allowed based upon the
result of certain DNS queries.  We do this for other sites besides
Windows Update, such as Trend Micro's "Housecall" (which helps in
cleaning up virus-infected machines in the unregistered subnets.)

I'd be happy to share the list of names with you if it would help.  I
have to admit that I'm kind of surprised that CCA/Perfigo doesn't
already do this, though.

Flagg, Martin D. wrote:
> We are implementing Cisco Clean Access (formally Perfigo).  It has gone
> really well but we keep coming up with problems with Windows Update, it
> fails because CCA is blocking the IP.  When this happens, I use a
> sniffer and add the new IP address that Microsoft is using and then it
> works, until they change address's again.  Cisco says use the Host
> setting allowing requests that end in "update.microsoft.com".  This does
> not always work.
>
> I am really at a loss because it works for 95% of the machines but I can
> not afford to have 5% of the students in my office when they get back
> from the summer.
>
> Any Ideas?
>
> Martin Flagg
> Hiram College

--
Jim Lawson
Technical Support Group, Computing & Information Technology
University of Vermont
Burlington, VT USA