[Nagiosplug-help] NRPE: Unable to read output

Brian Tomjack btomjack at suretytek.com
Tue Feb 17 21:32:09 CET 2009

Well i think this is the right place for this, since it seems plugin 
related to me.

Here is the setup, my nagios server is on the same network, behind the 
core router. The server i am trying to monitor is behind an outlying 
firewall. I have configured both to work over port 5666 and have opened 
the appropriate firewall port to the remote host.

I know that nagios i working fine because it has several hundred other 
hosts on it all working fine. and i know that nrpe must be (mostly) 
working ok on the remote host in question because the check_load via 
nrpe is working fine to that remote host.

My problem is that when the nagios server checks the mailq on the remote 
host it gets back:
[root at ns1 ~]# /usr/local/nagios/libexec/check_nrpe -H 
remote.server.ip.address -c check_mailq
NRPE: Unable to read output

on the remote host, in the nrpe config:
command[check_mailq]="sudo /usr/local/nagios/libexec/check_mailq -w 120 
-c 175"

from the remote host /etc/sudousers:
nagios ALL=NOPASSWD: /usr/local/nagios/libexec/check_mailq

now, on the remote host, i can run it manually and get:
[nagios at ns1 ~]$ sudo /usr/local/nagios/libexec/check_mailq -w 120 -c 175
CRITICAL: mailq is 194 (threshold c = 175)|unsent=194;120;175;0

and finally, on the remote host. if i configure it to allow requests 
from and run the nrpe command i get this:
[nagios at ns1 ~]$ /usr/local/nagios/libexec/check_nrpe -H -c 
NRPE: Unable to read output

(the same result as when run from the nagios server)

so im stumped. the plugin is working on the remote host, and nrpe is 
working because i can execute the check_load via nrpe from the nagios 
server to the remote host and it works just fine. its only when i run 
the check_mailq via nrpe do i get a output read error. the nagios server 
is a fedora server, the remote host is a centos server. im not sure what 
else to check on so any suggestions are appreciated, as this is the only 
machine that i am having problems monitoring the mailq on.


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