This KB article addresses the following NRPE error or variants of this error:
UNKNOWN: No Handler For That Command
No handler for command:
Unknown command(s):
Assumed Knowledge
The following KB article contains an explanation of how NRPE works and may need to be referenced to completely understand the problem and solution that is provided here:
NRPE - Agent and Plugin Explained
In addition to this, NSClient++ must be correctly installed and configured, please refer to the following KB article on enabling the NRPE listener in NSClient++:
Documentation - Enabling The NRPE Listener In NSClient++ 0.4.x
Troubleshooting The Error
This is usually caused by a missing or incorrectly spelled handler (external alias) in the remote host's C:\Program Files\NSClient++\nsclient.ini file.
Check the spelling of the check_nrpe command for the service check in Nagios XI (the name of the command after the "-c"). It should match the spelling of the external alias in the nsclient config file. For example:
[/settings/external scripts/alias]
alias_cpu = checkCPU warn=80 crit=90 time=5m time=1m time=30s
In the example above, the "alias_cpu" is the handler and therefore the service check in Nagios XI should specify the check_nrpe command as "alias_cpu".
Final Thoughts
For any support related questions please visit the Nagios Support Forums at:
http://support.nagios.com/forum/
Article ID: 627
Created On: Mon, Jul 17, 2017 at 3:25 AM
Last Updated On: Mon, Jul 17, 2017 at 3:25 AM
Authored by: tlea
Online URL: https://support.nagios.com/kb/article/nrpe-unknown-no-handler-for-that-command-627.html