Monitoring local services on a remote machine with NRPE

In this recipe, we'll learn how to install and run an NRPE (Nagios Remote Plugin Executor) server on a target host, roma.example.net. We'll use this to check the load average on that host with the check_load plugin.

The plugins for these checks will be executed on the target server by the NRPE daemon, but the results will be returned to our Nagios Core monitoring server, olympus.example.net. This requires installing the check_nrpe plugin on the monitoring server and the full Nagios Plugins set (but not Nagios Core itself) on the target server.

This is a reasonably long and in-depth recipe as it involves installing a total of three software packages on two servers.

Getting ready

You will need a monitoring server with Nagios Core 4.0 or newer installed. You should also have a UNIX-like target host that you intend to monitor that can run the NRPE daemon. Most modern UNIX-like systems including Linux and BSD should be able to do...