Nagios Support Forum

You need something listening on port 25 to accept mail. Postfix is one such program, sendmail is another. If you stopped postfix, then nothing is listening and therefore, no mail can be sent to that machine. You need to fix your postfix configuration and get that running before anything related to N...

An easy "cheat" is to use escalation rules to only alert after it's happened a few times in a row.

5. Nagios installation This step is most likely your problem. Did it actually complete properly? Is nagios running? Is Apache running? It looks mostly like Apache doesn't know about the /nagios directory, which implies that Apache has not been restarted since the configuration changes done during N...

something is blocking network traffic such as an outage It's really hard to tell, but you can at least try this from the command line on your Nagios box: $ telnet 37.202.5.178 25 If you get a "Trying 37.202.5.178..." message, then you can't connect. (You may not have the telnet command in...

Are there any concise recommendations on using Nagios on specific hypervisors/virtualization technologies for optimal performance?

The answer to your question is "no, there are no concise recommendations."

Correct. No NTP server installed means that there is no NTP server to query to see if it's running or if it's running too far ahead/behind its source clock. If you're not running NTP server on a box, there is no reason to install it just to monitor it. An NTP client or Windows Time client will sync ...

Well, the nice thing about AWS is the free tier. Google's new cloud compute doesn't have one. Neither does Rackspace. And don't get me started on Azure. AWS's EC2 is a nice intro to cloud-based computing, and it's quite well suited for running a modestly medium-sized Nagios instance.

Come to Nagios World Conference 2014 in St. Paul and sit in on my talk on using Nagios Core on AWS boxes. But seriously, you can get away with a very small instance - Nagios doesn't take that much - but it will all depend on what you're monitoring. And if you're cloud-basing your server, then you ma...