"Clue-Gathering Tools for Network and Security Managers" from which an IDS can be built. Source code freely available.

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).

NIKSUN is the recognized worldwide leader in developing and deploying a complete range of network performance monitoring, security surveillance and forensic analysis tools serving a wide range of protocols and interfaces, ranging from Ethernet and Gigabit Ethernet to OC-3. Our products are the only network appliances that continuously capture and analyze LAN, MAN and WAN traffic at Gigabit rates in a single platform.

An appliance that plugs into existing network infrastructure and locates computers compromised by worms, DoS attacks and spyware.

Real-time network sensor-based Intrusion Detection System (IDS). Based on snort, features include live signature updates and custom signature creation.

Information security specialists providing penetration testing, vulnerability assessment, application security audit and intrusion detection implementation services

Extends the capabilities of conventional security systems to help manage threats more efficiently and effectively. Includes a wide array of intrusion detection and analysis tools for Windows servers.

Manufacturer of Network Scout, a behavior-based perimeter intrusion preventation system.

Provides "Spider" integrated network security appliance with over 10 security functions in one platform including IDS/IPS, a vulnerability scanner, risk analysis, Web content filter, SPAM and virus filter, Wireless security, firewall and VPN.

Manufacturer of Intrusion Detection/Prevention appliances. Features include Layer 2 network bridge operation, an integrated hardware/software solution, and automatic attack signature updating.

Manufacturer of server security products intended to safeguard HTTP transactions, identify and protect against web server vulnerabilities.

Official site of the SPECTER intrusion detection system.

REACT is a network abuse monitoring and tracking service which provides real time data to track and control abusive hosts on your network.

Monitors, detects and prevents intrusions of malware into Microsoft Windows platforms.

Host Intrusion Prevention Systems (HIPS) that stop mass attacks and targeted attacks before they impact hosts, applications and data.