SecureNAT ISA Server not functioning

  • From: "Hatton, Chris - SAL" <Chris.Hatton@xxxxxxxxxxxxx>
  • To: "'isalist@xxxxxxxxxxxxx'" <isalist@xxxxxxxxxxxxx>
  • Date: Mon, 9 Aug 2004 10:53:46 +1200

Hi All,


I have here an interesting problem that I have encountered with SBS2000.


Server is running two nic cards and a router.


1 external nic has router plugged in directly.







2 nic is the Local Network: 


GW: Nothing



LAT: - 255


Problem is that the server cannot connect to any winsock applications via
SecureNat, the web browser works with the web proxy, but for the likes of
exchange server/telnet or antivirus updates it will fails to connect. The
computers on the private lan work faultlessly with or without the firewall


However if I put the external network card in the lat entry -, the server sees it as local and works fine, but then it defeats
the purpose of securing the LAT, and the lan clients will require the
firewall client.


Looked under the IPEXD..... files from the ISA Server logs, it says that it
has blocked at port 25, so I opened up a packet filter to allow
outbound access SMTP for the external nic, but still doesn't work.


This seems pretty straight forward stuff, but I feel that I have maybe
overlooked something?? Anyone with any ideas?






Chris Hatton 

Information Systems Engineer 

CAUTION - This message may contain privileged and confidential 
information intended only for the use of the addressee named above.
If you are not the intended recipient of this message you are hereby 
notified that any use, dissemination, distribution or reproduction 
of this message is prohibited. If you have received this message in 
error please notify Safe Air Ltd immediately. Any views expressed 
in this message are those of the individual sender and may not 
necessarily reflect the views of Safe Air.
For more information on the Safe Air Group, visit us online

Other related posts: