Ganglia is a scalable distributed monitoring system for high-performance computing systems such as clusters and grids. It is based on a hierarchical design targeted at federations of clusters. Ganglia is currently in use on over 500 clusters around the world and has scaled to handle clusters with 2000 nodes.
Modem.pl is a small script that scrapes the Web interface of a Motorola SURFboard cable modem for various status conditions like signal strength and signal to noise ratio. The results are sent to STDOUT where they can be easily piped into a log file. The modem values are also checked for reasonable operating ranges. If the modem values are outside of reasonable operating ranges, results are also sent to STDERR. When run from a cron job, modem.pl can be used to monitor the condition of the cable service and notify someone before conditions cause service interruptions.
System Local Audit Daemon can run standalone or managed by systems like IBM-Tivoli, HP-OpenView, or Nessus to perform local security checks. It runs on the target hosts and enables them to call security tools like John the Ripper, Tiger, Tripwire, or a virus scanner via a unified XML interface. It is part of the BOSS Project.
The WebReboot Plugin for Nagios is a suite of commands that can be used within Nagios to monitor a server and take corrective action if necessary via the WebReboot line of products. For example, the plugin can be used to alert you if a host is powered down, versus simply not responding to network requests. Likewise, it can be used to reboot a server if a host fails to respond to ping, or to shut down a server when a critical temperature threshold is exceeded. The commands can be mixed-and-matched with all existing Nagios commands, maximizing total network coverage.
simena-io is a Linux tool written in Perl and designed to show ethernet interface statistics in bits/second and packets/second in real time. It requires at least Linux kernel 2.2 and Perl 5. It does not require a root account. There is only one command parameter: the refresh rate in seconds. If no parameter is provided, simena-io will refresh every 2 seconds by default. Detailed documentation can be obtained by running "perldoc simena-io".