Naemon - Networks, Applications and Event Monitor, a Nagios fork

Naemon is the new monitoring suite that aims to be fast, stable and innovative while giving you a clear view of the state of your network and applications. The Naemon core is a network monitoring tool based on the Nagios 4 core, but with many bug fixes, new features, and performance enhancements. If you today use Nagios, you should switch to Naemon to get bugfixes, new features, and performance enhancements.