Problem: Nagios Checks reporting undefined command

nagios
ucs-4
nrpe

#1

Problem

In the Nagios frontend the service checks reporting NRPE: Command '<COMMAND>' not defined.

Reason

Most likely the file permissions are wrong as you can see as follows

root@ucs-backup:~# ls -la /etc/nagios/nrpe.univention.d/
insgesamt 80K
drw-r--r-- 2 root nogroup 4,0K Mär 20 17:37 .
drwxr-xr-x 9 root root    4,0K Apr  3 17:17 ..
-rw------ 1 root nogroup  391 Mär  7  2018 UNIVENTION_DISK_ROOT.cfg
-rw------- 1 root nogroup  380 Mär  7  2018 UNIVENTION_DNS.cfg
-rw------- 1 root nogroup  396 Mär  7  2018 UNIVENTION_JOINSTATUS.cfg
...
-rw------- 1 root nogroup  379 Okt 25 18:07 UNIVENTION_SWAP.cfg
-rw------- 1 root nogroup  390 Feb 16  2017 UNIVENTION_WINBIND.cfg

Solution

Correct the file permissions of the respective folder and the command config’s inside. The config files must be readable and the folder must also be executable, which means accessible.

root@ucs-backup:~# chmod +r -R /etc/nagios/nrpe.univention.d
root@ucs-backup:~# chmod +x /etc/nagios/nrpe.univention.d

They must look like

root@ucs-backup:~# ls -la /etc/nagios/nrpe.univention.d/
insgesamt 80K
drwxr-xr-x 2 root nogroup 4,0K Mär 20 17:37 .
drwxr-xr-x 9 root root    4,0K Apr  3 17:17 ..
-rw-r--r-- 1 root nogroup  391 Mär  7  2018 UNIVENTION_DISK_ROOT.cfg
-rw-r--r-- 1 root nogroup  380 Mär  7  2018 UNIVENTION_DNS.cfg
-rw-r--r-- 1 root nogroup  396 Mär  7  2018 UNIVENTION_JOINSTATUS.cfg
...
-rw-r--r-- 1 root nogroup  379 Okt 25 18:07 UNIVENTION_SWAP.cfg
-rw-r--r-- 1 root nogroup  390 Feb 16  2017 UNIVENTION_WINBIND.cfg