ISA 2004 includes a rich SDK with several extensibility mechanisms that allow third parties to integrate their specialized solutions on top of the ISA platform. In this article, the author explores the application filter extensibility mechanism, which enables you to add high-level application layer filtering capabilities to ISA Server and to provide rich content filtering solutions. He also highlights the new features of the ISA Server 2004 SDK, then moves on to describe how to develop a basic application filter that monitors all data going through the ISA Server, and how to integrate a filter into the ISA Server management console to create a seamless interface experience for your users.
Head on over to http://msdn.microsoft.com/msdnmag/issues/04/03/ISAServer2004/default.aspx for details on how to create your own application filters for ISA firewalls.
Thomas W Shinder, M.D.
MVP -- ISA Firewalls