Nagios is an open source software for system and network monitoring. Nagios can see the activity of a host and its services, and provides a warning/alert if something bad happens on the server. Nagios can run on Linux operating systems. At this time we are using Ubuntu 15.04 for the installation.
Original URL: https://www.howtoforge.com/tutorial/how-to-install-nagios-on-ubuntu-15-04/