Then you need to have the Nagios plugin in /usr/lib/nagios/plugins
on the monitoring server or even better in $OMD_ROOT/local/lib/nagios/plugins
of the checkmk site.
In the ruleset “Integrate Nagios Plugin” create a rule that has the command line of the Nagios plugin (including the path if installed in /usr/lib/nagios/plugins
). That’s all.