The Nagios daemon which run checks on remote machines in NRPE (Nagios Remote Plugin Executor). It allows you to run Nagios plugins on other machines remotely. You can monitor remote machine metrics such as disk usage, CPU load etc. It can also check metrics of remote windows machines through some windows agent addons.
Let us see how to install and configure NRPE step by step on client machine which needs to be monitored.
Step 1 − Run below command to install NRPE on the remote linux machine to be monitored.
sudo apt-get install nagios-nrpe-server nagios-plugins
Step 2 − Now, create a host file inside the server directory, and put all the necessary definitions for the host.
sudo gedit /usr/local/nagios/etc/servers/ubuntu_host.cfg
# Ubuntu Host configuration file define host { use linux-server host_name ubuntu_host alias Ubuntu Host address 192.168.1.10 register 1 } define service { host_name ubuntu_host service_description PING check_command check_ping!100.0,20%!500.0,60% max_check_attempts 2 check_interval 2 retry_interval 2 check_period 24x7 check_freshness 1 contact_groups admins notification_interval 2 notification_period 24x7 notifications_enabled 1 register 1 } define service { host_name ubuntu_host service_description Check Users check_command check_local_users!20!50 max_check_attempts 2 check_interval 2 retry_interval 2 check_period 24x7 check_freshness 1 contact_groups admins notification_interval 2 notification_period 24x7 notifications_enabled 1 register 1 } define service { host_name ubuntu_host service_description Local Disk check_command check_local_disk!20%!10%!/ max_check_attempts 2 check_interval 2 retry_interval 2 check_period 24x7 check_freshness 1 groups admins notification_interval 2 notification_period 24x7 notifications_enabled 1 register 1 } define service { host_name ubuntu_host service_description Check SSH check_command check_ssh max_check_attempts 2 check_interval 2 retry_interval 2 check_period 24x7 check_freshness 1 contact_groups admins notification_interval 2 notification_period 24x7 notifications_enabled 1 register 1 } define service { host_name ubuntu_host service_description Total Process check_command check_local_procs!250!400!RSZDT max_check_attempts 2 check_interval 2 retry_interval 2 check_period 24x7 check_freshness 1 contact_groups admins notification_interval 2 notification_period 24x7 notifications_enabled 1 register 1 }
Step 3 − Run the command shown below for the verification of configuration file.
sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Step 4 − Restart NRPE, Apache and Nagios if there are no errors.
service nagios-nrpe-server restart service apache2 restart service nagios restart
Step 5 − Open your browser and go to Nagios web interface. You can see the host which needs to be monitored has been added to Nagios core service. Similarly, you can add more hosts to be monitored by Nagios.