How to Install NRPE on Ubuntu 18.04 & 16.04 LTS

NRPE (Nagios Remote Plugin Executor) is used for executing Nagios plugins on remote client systems. In previous article we had described about installation of Nagios Server on Ubuntu operating system. This article will help you to install NRPE on Ubuntu 18.04 LTS, 16.04 LTS & LinuxMint 19/18 systems.

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• How to Monitor Remote Linux System with Nagios
• How to Monitor Remote Linux System over SSH

Step 1 – Install NRPE on Ubuntu

NRPE packages are available under the default repositories on Ubuntu systems. Open a terminal and run the following command to install:

sudo apt update
sudo apt install nagios-nrpe-server nagios-plugins

Here nagios-nrpe-server package install service on system and nagios-plugins provides monitoring scripts, which is called with NRPE client on request of Nagios server.

Step 2 – Configure NRPE

In NRPE configuration, first we need to nrpe to which nagios servers it accepts requests, For example your Nagios server IP is 192.168.1.100, then add this IP to allowed hosts list. Edit NRPE configuration file /etc/nagios/nrpe.cfg and make the necessary changes like below:

sudo nano /etc/nagios/nrpe.cfg

 allowed_hosts=127.0.0.1, 192.168.1.100

We can allow multiple Nagios servers by a comma-separated list.

Next, restart NRPE service. Now it is ready to listen to requests from Nagios server

sudo /etc/init.d/nagios-nrpe-server restart

Step 3 – Verify Connection

Let’s verify the connection between the Nagios server and NRPE client machine. Login to your Nagios server and check the Nagios server can communicate with NRPE service properly.

Use check_nrpe command on the Nagios server under the plugins directory. The command will be like as below here 192.168.1.11 is the IP address of client machine.

check_nrpe -H 192.168.1.11

NRPE v2.15

The output “NRPE v2.15” shows that the Nagios server successfully communicated with NRPE.

Step 4 – Add Check Commands in NRPE

All the services check commands with the nagios plugins packages, which is by default installed in /usr/lib/nagios/plugins/ for 32 bit systems. Default installation adds few commands in configuration file. Add more commands as per your requirements like below

vim /etc/nagios/nrpe.cfg

command[check_users]=/usr/lib/nagios/plugins/check_users -w 5 -c 10
command[check_load]=/usr/lib/nagios/plugins/check_load -w 15,10,5 -c 30,25,20
command[check_hda1]=/usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /dev/hda1
command[check_zombie_procs]=/usr/lib/nagios/plugins/check_procs -w 5 -c 10 -s Z
command[check_total_procs]=/usr/lib/nagios/plugins/check_procs -w 150 -c 200

Step 5 – Manage NRPE Service

Use the following commands to start, stop or restart NRPE service. Each time we make any changes in the configuration file required to restart service

sudo /etc/init.d/nagios-nrpe-server stop
sudo /etc/init.d/nagios-nrpe-server start
sudo /etc/init.d/nagios-nrpe-server restart