Once configured NSClient++ in windows server if you have received an error, could not fetch information from the Nagios server (Linux).

solution :

You need to check the  "allowed_hosts" line in configuration file nsclient.ini. Just add the Nagios server IP (for example

C:\Program Files\NSClient++\nsclient.ini

allowed_hosts =

Also, you can view the debug logs, add the below lines in nsclient.ini file and restart the nsclient service.

file name = nsclient.log
level = debug