Nagios Support Forum

and that was the problem!
When I changed, in the host definition of the localhost.cfg in /usr/local/nagios/etc/objects, the address from the default 127.0.0.1 to my node's address it started running correctly.
Thank you all for your help!!!

Forgive my Joison I'm not sure what do you mean exactly?

Thank you Box293. I'm getting the same error. UNKNOWN localhost - Hostname info not available. Likely invalid hostname

Thank you for your reply but unfortunately it's not that. Any other suggestion to try please?

I'm trying to use check_multiple_metrics.sh and I'm getting UNKNOWN localhost - Hostname info not available. Likely invalid hostname My nagios.log and /var/log/messages [1446798122] SERVICE NOTIFICATION: nagiosadmin;localhost;Check Multiple Metrics;UNKNOWN;notify-service-by-email;UNKNOWN localhost -...