OpenNMS is the first enterprise-grade network management platform developed using the open source model. The three main functional areas of OpenNMS are service polling, which monitors services on the network and reports on their "service level"; data collection from the remote systems via SNMP in order to measure the performance of the network; and a system for event management and notifications.
fping is a ping-like program which uses the Internet Control Message Protocol (ICMP) echo request to determine if a target host is responding. fping differs from ping in that you can specify any number of targets on the command line, or specify a file containing the lists of targets to ping. Instead of sending pings to one target until it times out or replies, fping will send out a ping packet and move on to the next target in a round-robin fashion.
di is a disk information utility that displays everything that df does and more. It features the ability to display your disk usage in whatever format you prefer. It also checks the user and group quotas, so that the user sees the space available for their use, not the system wide disk space. It is designed to be highly portable across many platforms and is great for heterogenous networks.
lm_sensors provides essential tools for monitoring the temperatures, voltages, and fans of Linux systems with hardware monitoring devices. It contains a library for sensors access (libsensors), a command-line tool for sensor reporting (sensors), and a daemon (sensord). It also contains scripts for sensor hardware identification and fan speed control.
Snort is a network intrusion detection and prevention system. It is the most widely deployed technology of its kind in the world. It performs detection using a variety of methods including rules-based detection, anomaly detection, and heuristic analysis of network traffic. Its rules language is open source and available to the public as well.
Angel is a simple yet useful tool to monitor the services on your network. Technically speaking, it's a Perl program that runs every 'n' minutes (usually fired from your cron) and calls different perl subprograms (referred to as "plugins" from now on) to do the actual testing. It will then generate an HTML table containing the status of your network.
SNMP Monitor is a Tcl extension for monitoring static variables in routers or other agents using SNMP to access MIBs. The SNMP (Simple Network Management Protocol) uses polling or traps to communicate with the agent and the monitor equipment. MIBs are management information bases containing a wide range of interesting variables to be monitored.
The Emu10k1 Driver for Linux supports Creative Labs' Emu10K1 chip, which is found in SoundBlaster Live! cards. It supports full duplex sound, two sound devices (dsp, dsp1), OSS compatibility, AC97, sndstat, MIDI, a Joystick interface and more than one EMU10k1 board in one computer. It does not yet support SMP.