OSSEC HIDS1.6

OSSEC HIDS is an Open Source Host-based Intrusion Detection System. OSSEC performs log analysis, integrity checking, rootkit detection, real-time alerting and active response.

Intrusion Detection is the process or techniques used to detect attacks on a specific network, system or application. Most intrusion detection tools not only detect attacks, but also software misuse, policy violations and other forms of inappropriate activities.

A Host-based IDS performs intrusion detection from within the systems you want to protect. Some of these tools perform log analysis, others spyware detection, while others perform virus detection.