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2.3. Configuration
• 1. First, create a host configuration file for server02. Unless otherwise specified, run all these commands on server01. In a terminal enter:
sudo cp /etc/nagios3/conf.d/localhost_nagios2.cfg
/etc/nagios3/conf.d/server02.cfg
In the above and following command examples, replace "server01", "server02" 172.18.100.100, and 172.18.100.101 with the host names and IP addresses of your servers.
2. Next, edit /etc/nagios3/conf.d/server02.cfg:
define host{
use generic-host ; Name of host template to use
host_name server02
alias Server 02
address 172.18.100.101
}
# check DNS service. define service {
use generic-service
host_name server02
service_description DNS
check_command check_dns!172.18.100.101
}
3. Restart the nagios daemon to enable the new configuration:
sudo systemctl restart nagio3.service
• 1. Now add a service definition for the MySQL check by adding the following to /etc/nagios3/conf.d/ services_nagios2.cfg:
# check MySQL servers. define service {
hostgroup_name mysql-servers service_description MySQL
check_command check_mysql_cmdlinecred!nagios!secret!$HOSTADDRESS use generic-service
notification_interval 0 ; set > 0 if you want to be renotified
}
2. A mysql-servers hostgroup now needs to be defined. Edit /etc/nagios3/conf.d/ hostgroups_nagios2.cfg adding:
# MySQL hostgroup. define hostgroup {
hostgroup_name mysql-servers
alias MySQL servers
members localhost, server02
}
3. The Nagios check needs to authenticate to MySQL. To add a nagios user to MySQL enter:
mysql -u root -p -e "create user nagios identified by 'secret';"
The nagios user will need to be added all hosts in the mysql-servers hostgroup.
4. Restart nagios to start checking the MySQL servers.
sudo systemctl restart nagios3.service
• 1. Lastly configure NRPE to check the disk space on server02.
On server01 add the service check to /etc/nagios3/conf.d/server02.cfg:
# NRPE disk check. define service {
use generic-service
host_name server02 service_description nrpe-disk
check_command check_nrpe_1arg!check_all_disks!172.18.100.101
}
2. Now on server02 edit /etc/nagios/nrpe.cfg changing:
allowed_hosts=172.18.100.100
And below in the command definition area add:
command[check_all_disks]=/usr/lib/nagios/plugins/check_disk -w 20% -c 10% -e
3. Finally, restart nagios-nrpe-server:
sudo systemctl restart nagios-nrpe-server.service
4. Also, on server01 restart nagios:
sudo systemctl restart nagios3.service
You should now be able to see the host and service checks in the Nagios CGI files. To access them point a browser to http://server01/nagios3. You will then be prompted for the nagiosadmin username and password.