Icinga is a fork of the Nagios monitoring solution. It is a program that will monitor hosts and services on your network, and to email or page you when a problem arises or is resolved. Icinga runs on a Unix server as a background or daemon 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 Icinga.
This package contains those plugins.