This is the recommended configuration file for the Windows monitoring client.
SecureSchool, ISBossBox, LibraryDoor
To put this in place, simply download the attached zip file, then put the NSClient.ini in the directory with the client (typically C:\Program Files\NSClient++), replacing the file that is there. After the file is there, open it with Notepad and find the line "allowed_hosts=xxx.xxx.xxx.xxx". Change the IP address listed to the IP of your SecureSchool appliance.
Once you save and close the file, go to the control panel and restart the "NSClient++" service.