Naemon is an application, system and network monitoring application.
It can escalate problems by email, pager or any other medium. It is
also useful for incident or SLA reporting. It is originally a fork
of Nagios, but with extended functionality, stability and performance.

It is written in C and is designed as a background process,
intermittently running checks on various services that you specify.

The actual service checks are performed by separate "plugin" programs
which return the status of the checks to Naemon. The plugins are
compatible with Nagios, and can be found in the monitoring-plugins package.

Naemon ships the Thruk gui with extended reporting and dashboard features.