### Setting up Check Plugins

On its own Icinga 2 does not know how to check external services. The
[Nagios Plugins Project](https://www.nagios-plugins.org/) provides an extensive
set of *plugins* which can be used by Icinga 2 to check whether services are
working properly.

The recommended way of installing these standard plugins is to use your
distribution's package manager. For your convenience here is a list of package
names for some of the more popular operating systems/distributions:

OS/Distribution | Package Name   | Installation Path
----------------|----------------|---------------------------
RHEL/CentOS     | nagios-plugins | /usr/lib/nagios/plugins
Debian          | nagios-plugins | /usr/lib/nagios/plugins
FreeBSD         | nagios-plugins | /usr/local/libexec/nagios
OS X (MacPorts) | nagios-plugins | /opt/local/libexec

Depending on which directory your plugins are installed into you may need to
update the *plugindir* macro in your Icinga 2 configuration. This macro is used
by the service templates contained in the Icinga Template Library to determine
where to find the plugin binaries.