check_pf has been installed to %%PREFIX%%/libexec/nagios.

check_pf needs read permission to the pf(4) pseudo-device, i.e. /dev/pf.

Assuming check_pf will be run by user `nagios', the following will work:

	# chmod 640 /dev/pf
	# chgrp nagios /dev/pf

To make sure the change persists across reboots, add the following
to /etc/devfs.conf:

	# nrpe2/nagios needs to be able to read statistics
	own     pf    root:nagios
	perm    pf    0640
	
Please refer to the online documentation for additional information.

https://github.com/kian/nagios-pf-plugin/