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ISA 2004 not forwarding requests to particular site

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arbrctb

IS-IT--Management
Apr 9, 2010
1
GB
Hello,

We are currently experiencing problems connecting to a particular website
from our SBS 2003 box, which is running a dual-NIC configuration with ISA
2004. On attempting to access the site, ISA returns a connection timeout page
to Internet Explorer.

We have been able to access the site in the past and we have not recently
changed the ISA configuration.

We've tried accessing it by entering the IP directly to eliminate DNS lookup
errors - this does not work, and running a traceroute shows that our request
gets stopped at the our SBS server. Have also tried disabling web caching
and compression and making sure the connection limit is at 160.

On looking at real-time ISA logs, a request to the IP address is
successfully initiated, then successfully closed, with no bytes tranferred.
There are no errors reported at all. Looking at the logs from the last 7
days, when the site was previously accessible, there are 2 isolated errors:
"A connection was abortively closed after one of the peers sent a RST
segment." and "A non-SYN packet was dropped because it was sent by a source
that does not have an established connection with the ISA Server computer."
We can't reproduce these errors, though, and are not sure if they are
relevant.

The site is accessible from computers outside of our network with no
problems! We have also looked at the web server logs at the other end and no
connection is being made to the site at all. ISA does not seem to be
forwarding the requests.

This problem affects all traffic on all protocols and ports to this particular IP! It's as if it's been blacklisted.

Any suggestions on this one? We are really stuck and have no idea what to
try next.


Any help would be much appreciated.

Adrian
 
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