Nagios remote host monitoring not visible in nagios URL

Hi,I had installed nagios and remote host monitoring from url http://www.tecmint.com/how-to-add-linux-host-to-nagios-monitoring-server/comment-page-15/#comment-639491.

All the steps executes successfully but i am not able to see my remote host in nagios url.

Please help me out

Firstly, have you added correct IP address of your remote Linux host in hosts.cfg file? And also have you placed correct services to monitor in services.cfg file.

Secondly, are you allowed Nagios Server IP address in remote server Nrpe.cfg file under xinetd directory?

Thirdly, are you opened 5666 port on remote Linux server, so that Nagois can communicate?

If all above are done then make sure you have installed Nrpe plugin correctly under remote Linux host…

@dvrkittu When requesting such help it would be nice to provide some additional error messages or logs that you may obtain. This can really help troubleshoot your issue.

Thanks Ravi and Marin T !!

Its showing now in nagios web ,after re-checking all the steps but encountered new problem.
In nagios web the remote machine status is "No output on stdout) stderr: Could not resolve hostname XXX.XX.XX.XXX Name or service not known "

troubleshooting steps did:
1.Checked in the “commands.cfg” ,that it is hostaddress only.
2.Log file entry "[1439029914] SERVICE NOTIFICATION: nagiosadmin;tecmint;Current Users;WARNING;not
ify-service-by-email;(No output on stdout) stderr: Could not resolve hostname
XXX.XX.XX.XXX : Name or service not known
"
3. As I am using ec2 instance ,so wherever we need to mention IP address - public or private we can keep?

Thanks In advance

Did your remote Linux host reachable from Nagios Monitoring server? Have opened port 5666 on both machines? Have placed correct IP address in hosts.cfg file?

Can your NRPE plugin communicating with remote NRPE plugin on port 5666?

Can you cross check with netstat command that nrpe listening on Port 5666 on both machines…

yes I had placed the IP address in host.cfg.I had opened ports in security groups as I am using AWS EC2 instance.

Could you please help for checking remote Linux host reachable from Nagios Monitoring server

Below the output from remote host:
[root@ip- ~]# netstat -at | grep nrpe
tcp6 0 0 [::]:nrpe [::]:* LISTEN

whereas in nagios server there is no output with “netstat -at | grep nrpe”

This means your NRPE is not working, you need to cross check nrpe installation and also you correctly configured nrpe under xinetd service…can you post the output of following command on the remote Linux host…

# telnet localhost 5666

Thanks Ravi !!!

below the out:
Trying ::1…
Connected to localhost.
Escape character is ‘^]’.

Now can do a same test from Nagios Monitoring Server to remote Linus host?

# telnet remotelinuxip 5666

If its able to communicate then both nrpe plugins working correctly…

Now confirm that both Nrpe handshake properly working by running following command on Nagios server…

# /usr/local/nagios/libexec/check_nrpe -H remotelinuxip

You should get Nrpe version…

telnet remotelinuxip 5666 output:

Trying remoteIP…
Connected to remote IP.
Escape character is ‘^]’

/usr/local/nagios/libexec/check_nrpe -H remoteIP
.NRPE v2.15(output got)

Please guide me

Then you need to only cross check your hosts.cfg file and services.cfg file and also make sure you added both file locations to nagios.cfg file…or if you don’t know how to do just send me these three files at admin@tecmint.com, i will modify and resend to you…

Thanks Ravi !!

I did cross check all the files in hosts.cfg ,services,cfg and nagios.cfg everything seems to be fine.
But to be on same page I had mailed to admin@tecmint.com.

Please suggest me

Finally all set !!

re-installed all the thing and its working fine now.

Also able to monitor the httpd (running in remote machie) in nagios web

Thank You Ravi

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