A second beta of Microsoft's ISA Server 2004, code-named "Stringray," has made its way into the hands of a select group of testers.

Stringray represents a major update of the server's architecture and is designed to ward off the latest worms and Internet attacks. The software augments existing security infrastructure and includes an enterprise firewall, overhauled virtual private networking and a Web cache solution.

According to the Microsoft, ISA Server 2004 is a "must consider" for "any company that puts network security at a premium," and fits snuggly into the company's vaunted "securing the perimeter" strategy.

Microsoft's firewall adds packet filtering and stateful inspection with the capacity for application-layer security.

In addition to gating in network assets, Stingray incorporates new tools to deploy and secure VPN access to private corporate networks.

Microsoft Chairman Bill Gates unveiled Stringray in his opening keynote at COMDEX 2003. Redmond intends to market the solution to businesses of all sizes, with a final release is due out by the end of 2004.