Official site of the SPECTER intrusion detection system.
The Cisco Secure Intrusion Detection System is an enterprise-scale, real-time, system designed to detect, report, and terminate unauthorized activity throughout a network.
"Clue-Gathering Tools for Network and Security Managers" from which an IDS can be built. Source code freely available.
A comprehensive host based security assessment and intrusion detection tool, S2 identifies and reports exploitable system weaknesses.
NGSEC is a security company with two main focuses: ngProducts (set of security solutions ranging firewalls, and IDS) and ngServices (penetration tests, source code auditing, software and development).
LT Auditor+ enables administrators to track network activity and alerts users about intrusions through email or paging.
Offers change management and auditing solutions which provide regulatory compliance, network security, and system availability.
eTrust is Computer Associates solution intended to incorporate a comprehensive network intrusion management and prevention system, real-time session monitoring, and Internet web filtering.
Unified Access Communications has developed a Linux-based intrusion detection system with an easy to use graphical interface.
CyberTrace is an active network monitoring tool that identifies suspecious network traffic. Features include the ability to flags connections by priority and review/replay traffic sessions.