AppArmor secures Web servers and e-mail and instant-messaging systems against network-based attacks from hackers, Trojans and viruses. AppArmor, which Novell acquired when it bought Portland, Ore.-based security vendor Immunix last May, is now shipping with SUSE Linux 10.0, Novell's community Linux distribution and Novell's SUSE Linux Enterprise Server 9 Service Pack 3.

Novell plans to release a public beta version of SUSE Linux Enterprise Server 10 next month.

SUSE, a distant second in the enterprise Linux market behind the offerings of Raleigh, N.C.-based Red Hat, actually turns off security features installed in the current Linux kernel via the open-source Security Enhanced Linux, or SELinux. Created by the National Security Agency, SELinux has a mandatory access control system that lets developers and administrators fine-tune access rights. SELinux has been integrated into the core Linux kernel since 2004, with Version 2.6.

Charles Ungashick, Novell's director of product marketing, said AppArmor can scale to multiple machines and is easier to administer than SELinux. 'With SELinux, you have to write a lot of low-level code at the lowest level of the OS,' he said. 'It is difficult for mere mortals to implement.'

Not so, says Frank Mayer, chief technology officer at Tresys Technology LLC, a Columbia, Md.-based consulting firm that has contributed heavily to the SELinux code. He said that the current version of Red Hat's Linux includes SELinux-based security tools with easy-to-use graphical user interfaces.