Monitor just about anything that runs on electricity.
What Is A Plugin?
Plugins are standalone extensions to Nagios Core that make it possible to monitor anything and everything with Core.
Plugins process command-line arguments, perform a specific check, and then return the results to Nagios Core. They can be compiled binaries (written in C, C++, etc) or executable scripts (shell, Perl, PHP, etc).
In addition to the official Nagios plugins, you can find thousands of other plugins for monitoring all types of hardware, services, metrics, and applications at Nagios Exchange.
Official Nagios Plugins
There are roughly 50 plugins that are considered the “official” Nagios plugins.
Official Nagios plugins are developed and maintained by the official Nagios Plugins team. The scope of the official Nagios plugins distribution includes plugin libraries that are used by both both official and additional plugins. The information contained below on this page generally applies to the official Nagios plugins.
There are over 3,000 third party Nagios plugins that have been developed by hundreds of Nagios community members that allow you to monitor just about anything that runs on electricity.
Information on Nagios Plugins can be found below
Nagios-Plugins.org | Plugin API | Plugin Development Guidelines | Nagios Plugins Documentation