Nagios NRPE agent on a Nagios XI server

[xlin125]

When installing Nagios XI, a Nagios NRPE agent is also installed on the same server. What this Nagios NRPE agent will and can do on a Nagios XI server? If this Nagios XI agent is stopped or disabled, what is the impact to the Nagios XI? Just wanted to clarify ....... Thanks!

[kyang]

The NRPE agent stands for (Nagios Remote Plugin Executor). It's basically the middleman that sends checks to a remote server that also has NRPE & Nagios plugins.
Then it sends back that information to your XI and does so for whichever time interval you set it for.

If this Nagios XI agent is stopped or disabled, what is the impact to the Nagios XI?

Do you mean if the NRPE agent is stopped or disabled? If so, Nagios XI still runs perfectly fine.
You just won't be able to remotely check/monitor another server.

I hope this helps answers your questions! Let us know!

[xlin125]

Thanks to kyang!

Yes, I stopped the NRPE agent on the Nagios XI server. I noticed the Nagios XI still works fine, however, I see the Nagios XI is still able to remotely check/monitor another server that runs a Nagios NRPE agent. What is missing? Thanks!

[xlin125]

Is that true that the NRPE agent is installed on a Nagios XI so that if this Nagios XI needs to be monitored by another Nagios XI, this another Nagios XI can check and monitor this Nagios XI by sending check_nrpe requests to the NRPE agent running on this Nagios XI? In this case, this Nagios XI just acts like a Nagios managed host. Thanks!

[kyang]

Yes, I stopped the NRPE agent on the Nagios XI server. I noticed the Nagios XI still works fine, however, I see the Nagios XI is still able to remotely check/monitor another server that runs a Nagios NRPE agent. What is missing? Thanks!

Could you verify that it's stopped and post the output? (Not sure if you are running NRPE under xinetd or as a standalone daemon) (that is why there are two commands if one doesn't work choose the other one thanks!)

Code: Select all

service xinetd status

OR

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service nrpe status

Could you also send the output of this.

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ps -ef | grep xinetd

OR

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ps -ef | grep nrpe

It's probably a good idea to read our documentation if you haven't already.
https://assets.nagios.com/downloads/nag ... e/NRPE.pdf

[xlin125]

I ran "service xinetd stop" to stop xinetd.

# service xinetd status
xinetd is stopped
# ps -ef|grep xinetd
root 7369 19895 0 21:12 pts/0 00:00:00 grep xinetd
# grep 127.0.0.1 /etc/xinetd.d/nrpe
only_from = 127.0.0.1
# /usr/local/nagios/libexec/check_nrpe -H 127.0.0.1
connect to address 127.0.0.1 port 5666: Connection refused
connect to host 127.0.0.1 port 5666: Connection refused#

[kyang]

NRPE under xinetd seems to be off.

You say that remote checks are still happening? Could you screenshot it?

I see the Nagios XI is still able to remotely check/monitor another server that runs a Nagios NRPE agent

I must have missed it, but have you turned off the NRPE agent on the remote server?

[xlin125]

My original question is that if the Nagios NRPE agent on a Nagios XI is stopped (e.g., via "service xinetd stop"), what would be the impact to the Nagios XI, or what functions (s) the Nagios XI would lose or this Nagios can not do? For testing purpose, I stopped the Nagios NRPE agent on a Nagios XI, and I observed that the Nagios XI still ran fine, and was still able to remotely check/monitor (via check_nrpe) another server that had Nagios NRPE agent running. Note that the Nagios NRPE agent on another server (not Nagios XI) is running, not stopped in this case. The focus on this discussion is the Nagios NRPE agent on a Nagios XI, and the impact, if any, to the monitoring capability for a Nagios XI, if its NRPE agent is stopped.

As I mentioned before, if a Nagios XI needs to be monitored by another Nagios XI via NRPE agent, another Nagios XI can check and monitor this Nagios XI by sending check_nrpe requests to the NRPE agent running on this Nagios XI. In this case, this Nagios XI just acts like a Nagios managed host. So if Nagios NRPE agent is stopped on this Nagios XI, the NRPE agent would not respond to the check_nrpe requests from another Nagios XI, therefore it can not be monitored by another Nagios XI via check_nrpe.

[kyang]

Thanks for a good explanation.

There should not be any impact other than, the remote host/services checks will be returned as critical if XI cannot reach the remote host for checks.

As I mentioned before, if a Nagios XI needs to be monitored by another Nagios XI via NRPE agent, another Nagios XI can check and monitor this Nagios XI by sending check_nrpe requests to the NRPE agent running on this Nagios XI. In this case, this Nagios XI just acts like a Nagios managed host. So if Nagios NRPE agent is stopped on this Nagios XI, the NRPE agent would not respond to the check_nrpe requests from another Nagios XI, therefore it can not be monitored by another Nagios XI via check_nrpe.

Yes, you are correct. NRPE on another XI won't be able to check the "XI" that has NRPE turned off.

Overall, yes you can turn off NRPE on XI, and it should not impact anything as you have seen already.

[xlin125]

Thanks @kyang!