Ossec - OSSEC is an Open Source Host-based Intrusion Detection System.
SecurityOnion - Security Onion is a free and open source Linux distribution for intrusion detection, enterprise security monitoring, and log management.
Samhain - The Samhain host-based intrusion detection system (HIDS) provides file integrity checking and log...
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Tripwire - Open Source Tripwire software is a security and data integrity tool useful for monitoring and...
Suricata - Suricata is a high performance Network IDS, IPS and Network Security Monitoring engine.