How to add Linux Host to Nagios Monitoring Server in CentOS 7

Nagios plugins and NRPE are available for Cent OS 7 and RHEL in EPEL repository (Extra Packages for Enterprise Linux).
Setup EPEL repository: follow tutorial How to install EPEL repository on Centos7

Step 1: Run the following command to install NRPE and Nagios plugins:

[root@linuxcnf ~]# yum install nagios-plugins nrpe

Step 2: Configure NRPE to allow communication with Nagios Server:

Open NRPE configuration file /etc/nagios/nrpe.cfg and add the Nagios server in allowed_hosts:

[root@linuxcnf ~]# vi /etc/nagios/nrpe.cfg …………. allowed_hosts=127.0.0.1,192.168.43.15 [root@linuxcnf ~]#

Save the file and exit.

Step 3: Start NRPE service and enable on OS boot up:

[root@linuxcnf ~]# service nrpe start Redirecting to /bin/systemctl start nrpe.service [root@linuxcnf ~]# chkconfig nrpe on Note: Forwarding request to 'systemctl enable nrpe.service'. [root@linuxcnf ~]#

Step 4: Adding the host to the Nagios Server:

Now configure the host on Nagios server to check the remote host status. Open below file and paste the below into the file

[root@linuxcnf ~]# vi /usr/local/nagios/etc/servers/host.cfg ………… define host{         use                          linux-server                    host_name               Server-Name         alias                        Server-Name         address                   192.168.43.16         contacts                  nagiosadmin         } define service{         use                         generic-service         host_name              Server-Name         service_description PING         check_command     check-host-alive         } [root@linuxcnf ~]#

Save the file and exit.

Step 5: Check syntax errors (pre-flight check) and Restart NRPE service: Now restart NRPE to reflect the changes:

[root@linuxcnf ~]# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/servers/host.cfg …… Total Warnings: 0 Total Errors:   0 Things look okay - No serious problems were detected during the pre-flight check [root@linuxcnf ~]# service nagios reload Reloading nagios configuration (via systemctl):            [  OK  ] [root@linuxcnf ~]#

Configuration is done. Now the host status is available on Nagios admin portal.