nrpe-server - A Nagios NRPE Server
./nrpe-server --conf ./nrpe-server.conf --pid /var/run/pid --listen 127.0.0.1 --port 5666
This is a simple perl implementation of the nagios-nrpe server you can see SYNOPSIS for how to start it.
After it is started it will listen on a given port (either by config or on the commandline) and run checks as defined in your config.
NOTE: Options set on the commandline can overwrite options defined in the config file.