Configure Nagios remote machine with NRPE plugin on ubuntu 16.04

Introduction

NRPE stand for Nagios Remote Plugin Executor, Which nagios’s agent and allow to monitoring nagios’s client machine services and applications like Apache, mysql, redis, solr, Jenkins etc.

Requirement

Root permission access.
Basic knowledge of linux commands.

In this blog we are going to configure nagios remote machine using NRPE plugin uisng ubuntu 16.04 and we must have running nagios server in a same network.

Nagios client side installation and configuration:-

Step 1: Installation of Nagios Plugins

You need login as root user in your nagios’s client machine and need to install required packages by following the commands.

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

Step 2: Nagios server ip configuration on NRPE Agent

To allow nagios server to access the remote machine you need to edit the /etc/nagios/nrpe.cfg file by using given commands.

nano /etc/nagios/nrpe.cfg

Add the Nagios servers IP address, separated by comma like below.

allowed_hosts=192.168.1.10

Save and exit from the nano editor.

Step 3: Verifying Nagios Checks

To get status of machine CPU, Memory, Disk Spcace, Totoal Process, and more, We need to verify the all pre configure nagios check is working file for that we need to opwn the nrpe.cfg config file using following commands and check the nrpe commands.

to check monitoring check you need to move /usr/lib/nagios/plugins/ and test some nrpe commands by following the command.

./check_procs -w 200 -c 250

here w for warning and c for critical status for nagios alerts and after execute the commands you will get output of the checks like that.

PROCS OK: 190 processes | procs=189;200;250;0;

After that you need to restart the nrpe service and enable nrpe service on boot.

systemctl restart nagios-nrpe-server
systemctl enable nagios-nrpe-server
ufw allow 5666/tcp

Your client side nagios host configuration is completed.

Step 4: Server-side nagios configuration for remote machine

Login to your nagios-server with root privileges and edit the nagios main config file located in /usr/local/nagios/etc/nagios.cfg and add the nagios-client server directory or uncomment it.

nano /usr/local/nagios/etc/nagios.cfg

and uncommet the following lines.

cfg_dir=/usr/local/nagios/etc/servers

You need to create a configuration directory.

mkdir /usr/local/nagios/etc/servers

Step 5: Configure Nagios Server

Now it’s time to configure the Nagios server to monitor the remote client machine, and You’ll need to create a command definition in Nagios object configuration file to use the check_nrpe plugin. Open the commands.cfg file.

nano /usr/local/nagios/etc/objects/commands.cfg

Paste the follwoing configuration.

# .check_nrpe. command definition
define command{
command_name check_nrpe
command_line /usr/lib/nagios/plugins/check_nrpe -H $HOSTADDRESS$ -t 30 -c $ARG1$
}

Save and exit.

Step 6: Configure remote nagios client

Open the configuration file.

nano /usr/local/nagios/etc/servers/client.cfg

Paste the following configurtion.

define host{
                          
            use                     linux-server           
            host_name               client       
            alias                   client           
            address                 10.10.10.11

                                  
}                                 
                                  
define hostgroup{                 
                                  
            hostgroup_name          linux-server           
            alias                   Linux Servers           
            members                 client
}                                 
                                  
define service{                   
                                  
            use                     local-service           
            host_name               client           
            service_description     SWAP Uasge           
            check_command           check_nrpe!check_swap                         
                                  
}                                 
                                  
define service{                   
                                  
            use                     local-service           
            host_name               client         
            service_description     Root / Partition           
            check_command           check_nrpe!check_root                         
                                  
}                                 
                                  
define service{                   
                                  
            use                     local-service           
            host_name               client         
            service_description     Current Users           
            check_command           check_nrpe!check_users                       
                                  
}                                 
                                  
define service{                   
                                  
            use                     local-service           
            host_name               client         
            service_description     Total Processes           
            check_command           check_nrpe!check_total_procs                 
                                  
}                                 
                                  
define service{                   
                                  
            use                     local-service           
            host_name               client         
            service_description     Current Load           
            check_command           check_nrpe!check_load

}

Save and exit from nano editor.

Step 6: Verify Nagios for any errors

Execute the follwing command check error with nagios.

 /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Step 7: Restart the Nagios server

To get new changes we need to restart the nagios server by using the following command.

systemctl restart nagios

Now open the browser with http://localhost/nagios and you should get this screen.

Now nagios nrpe client is successful configured.