A java PCAP and DPI library
Graphical network monitoring and documentation tool
ICMP-based network bandwidth measurement tool
Scalable, distributed monitoring system for high-performance computing
Zenoss - Intelligent IT Operations Management
IP Monitor notifies you when your public IP address changes
Intelligently block brute-force attacks by aggregating system logs
Daemonlogger is a packet logger and soft tap developed by Martin Roes
netflow collecting and processing tools
Open source tool to monitor your servers and websites