The document provides an overview of several open source intrusion detection tools, including Snort, Suricata, Bro, Kismet, OSSEC, Samhain, and OpenDLP. It discusses the types of detection each tool performs, such as signature-based detection for Snort and Suricata, and behavior analysis for Bro. It also outlines advantages of each tool, such as Suricata's ability to use hardware acceleration and multi-threading. Finally, it recommends the Security Onion distribution for testing various open source IDS tools together.