Feisty intrusion-detection vendor Sourcefire Inc. will use the $11 million in venture capital it announced last week to keep itself afloat until it can turn a profit and expand from its well-known Snort software into network-based intrusion-prevention technology.

The creators of Snort, an open-source intrusion-detection software, founded Sourcefire in 2001. The company will try to build on its foundation of 40,000 Snort users now that it has added enterprise-class manageability and support to its intrusion-detection system. In December, the company introduced versions of its Intrusion Management System for speeds above gigabit. And it plans to extend its technology to stop as well as spot network-based attacks.

Now it faces the classic challenge of any company with open-source roots: converting its users into paying customers.