I’ve seen several people complain about the ISA firewall suddenly stop accepting incoming connections to the Web Proxy Listener for unknown reasons. There are a number of possible causes for this problem, but one of them might be covered by the following scenario:

If one of the following conditions is true, Internet Security and Acceleration (ISA) Server may not listen for Web proxy requests on the network adaptor or IP address:

• You add or enable a network adaptor in ISA Server 2004 configuration settings.
• You remove an IP address from a network adaptor and then add the same IP address again.
• You find that ISA event ID 14148 is logged with an error code 0×80072740 in the event log. This event indicates that ISA cannot bind its socket to the Listing IP and Port because there may be another service that is already using this port.
• After you experience a network disconnect on ISA, you cannot connect to the ISA listeners. For example, Web proxy requests fail

If this sounds like you, then check out KB article 891992 at http://support.microsoft.com/kb/891992/en-us

HTH,

Tom

Thomas W Shinder, M.D., MCSE
Sr. Consultant / Technical Writer
Prowess Consulting www.prowessconsulting.com
PROWESS CONSULTING documentation | integration | virtualization
Email: tshinder@isaserver.org
MVP — Forefront Edge Security (ISA/TMG/IAG)