Jovan StosicNagios /ˈnɑːɡiːoʊs/, now known as Nagios Core, is a free and open-source computer–software application that monitors systems, networks and infrastructure. Nagios offers monitoring and alerting services for servers, switches, applications and services. It alerts users when things go wrong and alerts them a second time when the problem has been resolved.
Ethan Galstad and a group of developers originally wrote Nagios as NetSaint. As of 2015 they actively maintain both the official and unofficial plugins. Nagios is a recursive acronym: “Nagios Ain’t Gonna Insist On Sainthood” – “sainthood” makes reference to the original name NetSaint, which changed in response to a legal challenge by owners of a similar trademark. “Agios” (or “hagios”) also transliterates the Greek word άγιος, which means “saint”.
Nagios was originally designed to run under Linux, but it also runs well on other Unix variants. It is free software licensed under the terms of the GNU General Public License version 2 as published by the Free Software Foundation.