Cisco Security Agent (CSA) is an endpoint intrusion prevention system made originally by Okena (formerly named StormWatch Agent), which was bought by Cisco Systems in 2003. The software is rule-based and examines system activity and network traffic, determining which behaviors are normal and which may indicate an attack. CSA was offered as a replacement for Cisco IDS Host Sensor, which was announced end-of-life on 21 February 2003.