Nagios Support Forum

Posted: **Wed Jun 06, 2018 6:08 am**

Node service is running on remote Linux host and I have to monitor the node service from Nagios server. I have crated my script [check_node]

But I am getting this error NRPE: unable to read output.

Added this command in my nre.cfg file.

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command[check_node]=/usr/local/nagios/libexec/node_check $ARG1$

added command in command.cfg file.

#'check_node' command definition

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define command{
       command_name    check_node
       command_line    $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
       }

Added service in linux_servers.cfg.

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define service{
        use                        local-service         ; Name of service template to use
        host_name                  Sales-Demo
        service_description        Node Service
        check_command          check_nrpe!check_node
        contact_groups             Nagios
        notification_options       w,u,c,r
        notification_interval      10
        notification_period        24x7
        }

I checked the permission of my script as well both the sides on Nagios server and remote host also.

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-rwxr-xr-x 1 root root 340 Jun  5 21:07 check_node

I have gone through the remote host nrpe.log also i am getting below mentioned error in the log file.

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[1528212140] Host address is in allowed_hosts
[1528212141] Host 10.10.100.35 is asking for command 'check_node' to be run...
[1528212141] Running command: /usr/local/nagios/libexec/check_node
[1528212141] WARNING: my_system() seteuid(0): Operation not permitted

Can someone suggest me on this.? Thanks in advance.

Posted: **Wed Jun 06, 2018 6:42 am**

Does your script "/usr/local/nagios/libexec/node_check" run correctly when you run it as the nrpe/nagios user?

i.e.

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su nagios /usr/local/nagios/libexec/node_check

or

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su nrpe /usr/local/nagios/libexec/node_check

dependent on if your nrpe-daemon runs as nagios or nrpe.

Do you have se-linux enabled? If yes try to disable it and test again.
I do not know how you script looks like, but it looks like it is calling some command/script that has the suid-bit set and the user nagios/nrpe is not allowed to execute this command/script.

Posted: **Wed Jun 06, 2018 10:47 am**

My check_node script

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#!/bin/bash

#Mentioned valid service name
service=node

#Checking for service pid value
pid=`ps -ef | grep -v grep | grep -i $service | wc -l`

case $pid in
[2]*)

echo "OK -$service is running" 
exit 0
;;

[0]*)

echo "CRITICAL -$service is not running"
exit 2
;;

[1]*)

echo "WARNING -$service Please check the service"
exit 1
;;

esac

I tried with this option because nrpe is running as nagios user but still I am getting same problem.

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su nagios /usr/local/nagios/libexec/node_check

I am using Ubuntu 16.04 LTS and by default se-linux wouldn't be enable on this. Same process I have followed to monitor python service and it's working fine. I don't know why It's not working for this.? I just changed service name in my script instead of node before that it was python .

But that works fine. Please help I have to finish this task today itself at any coast.

Posted: **Wed Jun 06, 2018 2:23 pm**

So what is the output of this command

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su nagios -c /usr/local/nagios/libexec/node_check

how about as root

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/usr/local/nagios/libexec/node_check

Posted: **Wed Jun 06, 2018 11:03 pm**

scottwilkerson I tried both the commands as you suggested but it didn't workout for me.

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su nagios -c /usr/local/nagios/libexec/node_check

Output of this command is NRPE:Unable to read output

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/usr/local/nagios/libexec/node_check

Output of this command is NRPE:Unable to read output

I am getting same error with both the commands no changes in output. @scottwilkerson If you remembered I have followed same steps to monitor my python service that time it worked fine. I am following same steps here to monitor node but getting error.

Please suggest something here I will wait for your reply @scottwilkerson.

Posted: **Thu Jun 07, 2018 9:03 am**

I meant run them on the machine by themselves, NOT through NRPE

Posted: **Thu Jun 07, 2018 9:39 am**

I ran this command on remote Linux host as well as Nagios server also it gives me same output.

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su nagios -c /usr/local/nagios/libexec/node_check
Password: 
su: Authentication failure

Then I ran this command on Nagios sever it gives me correct output.

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bash /usr/local/nagios/libexec/check_node 
OK -node is running

Same when I am running on remote host it doesn't give any output.

Posted: **Thu Jun 07, 2018 9:50 am**

how about

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sudo su nagios -c /usr/local/nagios/libexec/node_check

Posted: **Thu Jun 07, 2018 9:54 am**

It doesn't gives any output when I run on remote Linux machine.

Getting error when I run on Nagios server.

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 sudo su nagios -c /usr/local/nagios/libexec/node_check
bash: /usr/local/nagios/libexec/node_check: No such file or directory

Posted: **Thu Jun 07, 2018 10:04 am**

Ravikimt wrote:It doesn't gives any output when I run on remote Linux machine.

This means there is something in the plugin that the nagios user can't run.

If the output of the plugin is blank, then you would get the error you see from NRPE.

For debugging purposes, I would add the following above your case statement to see what the value of PID is as your case doesn't have a default echo:

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echo $pid

Then run again as the nagios user

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sudo su nagios -c /usr/local/nagios/libexec/node_check

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