Monitor Linux Hosts with NRPE¶
The Nagios Remote Plugin Executor (NRPE) allows your Nagios Enterprise Monitoring Server to communicate with the Linux machines on your server to determine things like free disk space, CPU load, and detect possible issues that a simple ping can’t determine.
There are countless instructions online to download tar.gz files and install manually, or use a PPA to install via apt-get, but NEMS includes a helpful installer that will configure everything for you.
Do not install the NRPE plugin via software repositories as these are abandoned and lack some important functionality.
To install the needed NRPE client on Debian / Ubuntu / other Debian-based Linux operating systems (as root):
wget -O - https://raw.githubusercontent.com/Cat5TV/nems-admin/master/build/047-nrpe | bash
Please note: Rudimentary support for RPM-based distros is included, but may not work. Please consider RPM support as experimental, and report your findings (especially your solutions or pull requests) so I can improve it.
Next, we just have to tell NRPE that it’s allowed to communicate with our Nagios server. On the client system, open the file /usr/local/nagios/etc/nrpe.cfg
Find the line that reads:
Now there are a few ways we can allow our server. First (and most obvious) is to add its IP address like this:
Where 192.168.0.5 is our Nagios/NEMS server.
Alternatively we can tell NRPE that it’s allowed to communicate with any local system:
Now, save the file and restart NRPE as follows:
systemctl restart nrpe
If you have a software firewall running on your Linux machine, setup an exception for your NEMS server IP to gain access through TCP ports 5666 and 12489.
And there we have it! Your NEMS Server can now check your Linux machine at a deeper level using check_nrpe.