This was tested on a CentOS 7.
This might have TWO possible causes
- nrpe service is down
use service nrpe status to test it.
You might wanna see ‘section’ Add NRPE to service bellow, to activate nrpe as a service.
- firewall on nrpe machine is blocking it
Some important files/directories
nrpe.cfg – /etc/nagios/nrpe.cfg
nagios/nrpe plugins folder – /usr/lib64/nagios/plugins/
logs – /var/log/messages
My nrpe.cfg, in a CentOS 7, is located at /etc/nagios/nrpe.cfg
In a default nrpe installation log is disabled!
You might want to enable it for better debug of the issues… Go to and enable it.
nrpe debug mode
Yah!, the default installation will came also with debug disabled.
We want it enabled to see more information while we try to use service nrpe status for example.
Server address… it might confuse you!
Server address ISN’T the NAGIOS’s ip address. It’s the actual external IP address of the current machine! allowed_hosts it’s actually it!
Lets check out the status of 5666 port.
netstat -an |grep 5666
If you don’t see any result… this probably means that nrpe is down!
See the ‘section’ Add NRPE to service bellow.
Open PORT on the firewall
sudo firewall-cmd --permanent --zone=public --add-port=5666/tcp firewall-cmd --reload
Add NRPE to service – this will lunch nrpe on reboots –
sudo systemctl enable nrpe.service sudo systemctl start nrpe.service