You want to monitor open ports on Windows clients through UCS Nagios.
check_tcp delivered by Nagios. It’s parameters are well documented.
For testing purposes you can start the check by
/usr/lib/nagios/plugins/check_tcp -H HOST -p PORT
Replace HOST and PORT accordingly:
To integrate this check into Nagios see documentation.
Note: You can only monitor a single port with this check. To monitor multiple ports you have to create multiple checks in Nagios.