I had my first encounter with Nagios today. I set up a server, it monitors itself, I configured a Windows server to be monitored successfully (in the same LAN). Then I configured a remote Ubuntu machine at home (via WAN), setup NRPE and I can monitor services successfully.
The main problem is that Tactical overview shows the remote Ubuntu machine (host) as down with error (Host Check Timed Out). How can I solve this?