Configuring NRPE client CentOS7

[tgriep]

It might be a sudo permission problem causing the plugin from running so add the following line to the /etc/sudoers file.

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nagios ALL=NOPASSWD: /usr/local/nagios/libexec/check_services

You may need to change the command in the nrpe.cfg file from

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command[check_services]=/usr/local/nagios/libexec/check_services -p $ARG1$

to

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command[check_services]=sudo /usr/local/nagios/libexec/check_services -p $ARG1$

Verify that the nagios user has access to the plugin and it's folders.


If the check_services plugin is in the /usr/lib64/nagios/plugins/ folder, I suggest updating the commands to point to that folder.

Then, restart the NRPE agent and test it again.

[rferebee]

It doesn't seem to be configured that way on my other Log Server (the one that's working).

Is there a way to just give the nagios account access to the entire libexec directory? Because, in theory, wouldn't you have to add a line for every single check in that directory so the nagios account can run it?

[tgriep]

Depending on the server, sometimes you have to allow the nagios user account sudo access if there are other security software but lets see what the differences between the servers.

I think I found the issue, the agent is not enabled to accept arguments.
Edit the /etc/nagios/nrpe.cfg file and change this from

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dont_blame_nrpe=0

to

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dont_blame_nrpe=1

Save the file and restart the NRPE agent.
Test it out and let us know how it works out.

[rferebee]

I made the change you suggested. It did not resolve the issue.

[tgriep]

I was hoping that would fix it but the next thing to do it to remove the existing NRPE agent from the server and install the agent from the Nagios site.

When I see NRPE running like this on a server

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/usr/sbin/nrpe -c /etc/nagios/nrpe.cfg -f

That means it was installed by an RPM package from someone else and sometimes they do not compile it with the ability to accept arguments.

I suggest removing the RPM install of the NRPE agent and install this one.

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https://assets.nagios.com/downloads/nagiosxi/agents/linux-nrpe-agent.tar.gz

Documentation for installing it.
https://assets.nagios.com/downloads/nag ... _Agent.pdf

That will compile the NRPE agent to accept Arguments.
Also, the agent will change a bit. It will run as the nagios user and not the nrpe user and the agent and plugins will be in the /usr/local/nagios folder and sub folders.

Or, option 2 is to hard code the command in the existing nrpe config file like this.

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command[check_services]=/usr/local/nagios/libexec/check_services -p elasticsearch

[rferebee]

Here's the thing. I installed the NRPE client myself using the Nagios instructions.

[tgriep]

What I feel is happening is that the Binary install of the NRPE agent is still running and that is causing the new install from running as they both cannot be running at the same time.
Make sure the other copy is removed or disabled from starting and that will allow the new one to run.

[rferebee]

Would you be able to tell me how to do that?

I'm sorry, I'm not very Linux savvy. Before I started working with Nagios I had little to no Linux experience.

[tgriep]

Run this command as root on the Centos7 server.

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yum list installed |grep nrpe

You should see something like this

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nrpe.x86_64                             3.2.1-8.el7                    @epel

That means that the nrpe binary package is installed.

To stop it, run this

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systemctl stop nrpe

To remove it, run this

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yum remove nrpe

Then check to see if the compiled version is installed, the following commands should show valid output.

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ls -l /etc/xinetd.d/nrpe
ls -l /usr/local/nagios/bin/nrpe
ls -l /usr/local/nagios/etc/nrpe.cfg

If they are all there, edit this file

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/etc/xinetd.d/nrpe

Verify that is is set like this (Replace xxx.xxx.xxx.xxx with the IP address of the Nagios server)

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service nrpe
{
    disable         = no
    per_source      = 25
    socket_type     = stream
    port            = 5666
    wait            = no
    user            = nagios
    group           = nagios
    server          = /usr/local/nagios/bin/nrpe
    server_args     = -c /usr/local/nagios/etc/nrpe.cfg --inetd
    only_from       = 127.0.0.1 xxx.xxx.xxx.xxx
    log_on_success  =
}

Restart xinetd

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service xinetd restart

Then to test it, run this from the nagios server. (Replace xxx.xxx.xxx.xxx with the IP address of the Remote Centos 7 server)

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/usr/local/nagios/libexec/check_nrpe -H xxx.xxx.xxx.xxx

You should see the version of the NRPE agent.

[rferebee]

Ok, I did all that.

I got the NRPE version (v3.2.1) returned from the CentOS 7 server on the Nagios XI box, but the check is still telling me "CHECK_NRPE: No output returned from daemon."