Sourcefire develops network security and information management systems. The company entered the intrusion prevention services (IPS) market in 2004 with the introduction of its 3D (for discover, determine, and defend) software product suite. The product line is built upon Snort, an open-source intrusion detection engine. It targets government agencies and large enterprises in the finance, health care, manufacturing, and technology industries; customers have included PricewaterhouseCoopers, Scientific-Atlanta, SAIC, and Ernst & Young. Entities affiliated with Sierra Ventures and New Enterprise Associates hold stakes in Sourcefire of 29% and 18%, respectively.