Nagios Support Forum

Hello!
I'm running nagios 3.5.1 servers on 2 boxes independently to check the same hosts in the same network via NRPE (2 nagios servers just this week for some testing, later on will be just one )
Nagios (both nagios-servers) checks wether service is running or not on a host using check_ps.sh plugin. This plugin has a parameter "-p name-of-the-service" and returns OK if service is running or CRITICAL if not.

in nrpe.cfg on the host I have a line

command[check_ps]=/usr/lib64/nagios/plugins/check_ps.sh -p smg
where smg - name of the service (process) I'm monitoring

on both nagios servers I vave the same lines in commands.cfg

define command{
command_name check_ps.sh
command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c "check_ps" -t 300
}

on one nagios server everything is just fine. The service is down on the host for approximately 2 weeks and I have web-interface indication and alarms about, as it should be.
on the other nagios web-interface - the service goes up and down and the same is recorded in logs. Just a small example of logs underneath.

12-08-2014 20:45:11 12-08-2014 20:53:11 0d 0h 8m 0s SERVICE OK (HARD) OK - Process: smg, User: root, CPU: 7.0%, RAM: 0.0%, Start: 20:45, CPU Time: 0 min
12-08-2014 20:53:11 12-08-2014 20:54:11 0d 0h 1m 0s SERVICE CRITICAL (HARD) CRITICAL - Process is not running!
12-08-2014 20:54:11 12-08-2014 20:56:11 0d 0h 2m 0s SERVICE OK (HARD) OK - Process: smg, User: root, CPU: 3.0%, RAM: 0.0%, Start: 20:54, CPU Time: 0 min
12-08-2014 20:56:11 12-08-2014 21:36:11 0d 0h 40m 0s SERVICE CRITICAL (HARD) CRITICAL - Process is not running!
12-08-2014 21:36:11 12-08-2014 21:43:11 0d 0h 7m 0s SERVICE OK (HARD) OK - Process: smg, User: root, CPU: 12.0%, RAM: 0.0%, Start: 21:36, CPU Time: 0 min
12-08-2014 21:43:11 12-08-2014 21:44:11 0d 0h 1m 0s SERVICE CRITICAL (HARD) CRITICAL - Process is not running!
12-08-2014 21:44:11 12-08-2014 21:46:11 0d 0h 2m 0s SERVICE OK (HARD) OK - Process: smg, User: root, CPU: 3.0%, RAM: 0.0%, Start: 21:44, CPU Time: 0 min
12-08-2014 21:46:11 12-08-2014 22:24:11 0d 0h 38m 0s SERVICE CRITICAL (HARD) CRITICAL - Process is not running!

I have figured out that if I call ./check_ps.sh in CLI without any parameters it always returns OK status, exactly as you can see in logs.
If I call it with parameter, it gives me the right return - Process is not running.

I assume that periodically NRPE calls script without parameter and do not understand why. And it's strange that it's true for requests coming from one particular nagios-server
Can I check this assumption somehow ? Any ideas about?

Thank you

On the remote server with the issue can you enable debug logging in the nrpe config. Restart nrpe and then the results should end up in /var/log/messages

Thank you, Box293!
Let me add my notes for people who may read these posts.
It's not enough to add debug=1 in nrpe.cfg (at least on CentOS 6.4)
to see debugging messages, do next

Edit /etc/rsyslog.conf
Find:
*.info;mail.none;authpriv.none;cron.none /var/log/messages
Change to:
*.info;mail.none;authpriv.none;cron.none;daemon.debug /var/log/messages

Now restart rsyslog and nrpe:

$ /etc/init.d/rsyslog restart
$ /etc/init.d/nrpe restart

we can close the tread, I believe

Thanks, we'll go ahead and close this thread. Thanks.