Novell has decided to release the source code for its Linux security offering, AppArmor.

AppArmor secures Web servers and e-mail and instant-messaging systems against network-based attacks from hackers, Trojans and viruses. Novell acquired it with the purchase of Immunix last May and it now ships with SuSE Linux.

SuSE is a distant second in the enterprise Linux market behind Red Hat and 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.

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.”

The CTO of Tresys Technology, Frank Mayer, disagrees though. "The glory of SELinux is that it can scale to any level, up or down," he argued.

Developers for AppArmor, which will be available via a GNU General Public Licence, will be able to download code and exchange enhancements at and Novell Forge. Ungashick said he hopes that developers will take AppArmor and create versions that work on non-SuSE flavors of Linux.

He also predicted that developers could contribute templates and profiles that could be used by security managers to easily customize security settings.

But making AppArmor’s code freely available doesn’t necessarily make it easier for hackers to find holes in Linux, said Gordon Haff, an analyst at Illuminata. "Attacks aren’t done by analysing source code, they are usually based on script-driven penetration."