The Network UPS Tools repository
A Swiss army knife for your daily Linux network plumbing
Performance Co-Pilot
Free open source tool for real-time PC hardware sensor monitoring
SQL operating system instrumentation and monitoring framework
High performance ping tool
Ncurses-based monitoring application for wireless network devices
Nagios Open Source network monitoring software - The Standard In ITM
Open Source Monitoring System for performance and availability.
VoIP SIP and SKINNY quality analyzer and packet / audio recording tool
ICMP-based network bandwidth measurement tool
Intelligently block brute-force attacks by aggregating system logs
Powerful, open-source network protocol analyzer
Manage and interpret IPMI systems with common a software tool
Network Load Balancer and Application Security