Nagios Error: could not fetch information from server

Check nsclient++ ini file on PC ** Check Nagios IP "allowed" ** Restart Nsclient++ service The most logical first step is to re-verify the Nagios server config file. Check to make sure DNS resolution is correct. Second, take a look at the NSC.log on the client system. In my case, I saw: 2009-03-30 10:52:23: error:.\NSClientListener.cpp:307: Unauthorized access from: ************* Well, that could definitely be a problem. My fault this time was in editing the NSC.ini after installation. The allowed_hosts line of: allowed_hosts=**************** needed to be like: allowed_hosts=***********/23