Nagios Support Forum

Posted: **Wed Dec 12, 2018 6:51 am**

I have set up Nagios® Core™ 4.3.4 and configured to monitor a linux box using NRPE and Windows machine using NSClient++.

I have defined the host in a cfg file and service checks for Hard disk usage and PING in another cfg file. Initially the host check command was also a PING and it correctly indicated that the Host was "UP" and all services were "OK". I have changed the host check_command to query the NRPE version installed:

Code: Select all

define host {
        host_name                       XXX-XXXX
        alias                           XXX-XXXX
        [b]check_command                   check_nrpe!check_nrpeversion[/b]
        max_check_attempts              5
        check_interval                  0.08
        retry_interval                  0.08
        check_period                    24x7
        contacts                        nagiosadmin
        icon_image                      nrpe.png
        statusmap_image                 nrpe.png
}

but now Nagios indicates the host is "DOWN" (even though this is not the case and all service are still "OK"). How can I fix this?

For the Windows machine this work ok i.e. my cfg file has the following:

Code: Select all

define host {
    host_name               XXXXXXX
[b]    check_command           check_nscpp!CLIENTVERSION[/b]
    max_check_attempts      5
    check_interval          0.08
    retry_interval          0.08
    check_period            24x7
    contacts                nagiosadmin
    icon_image              nscpp.png
    statusmap_image         nscpp.png
}

and the host is indicated as "UP" with status information: "NSClient++ 0.5.2.35 2018-01-28 "

Posted: **Wed Dec 12, 2018 1:22 pm**

Strictly speaking, you shouldn't actually need to call a specific remote NRPE command to get the version info back. check_nrpe can do that natively:

Code: Select all

[root@capra_nag linux-nrpe-agent]# /usr/local/nagios/libexec/check_nrpe -H 127.0.0.1
NRPE v3.2.1
[root@capra_nag linux-nrpe-agent]# echo $?
0

And it should always return "OK" unless the remote NRPE server is down:

Code: Select all

[root@capra_nag linux-nrpe-agent]# systemctl stop xinetd
[root@capra_nag linux-nrpe-agent]# /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
[root@capra_nag linux-nrpe-agent]# echo $?
2

So you'd really just create a new check_nrpe command definition on the Nagios Core end of things (maybe call it check_nrpe_host?) which only accepts the $HOSTADDRESS$ to plug into -H and no other args.

If you still require additional troubleshooting, can you share the check_nrpeversion command definition from your nrpe.cfg file on the remote machine? Also, the versions of your check_nrpe plugin and remote NRPE server.

Posted: **Thu Dec 13, 2018 2:39 pm**

I would tend to agree, I would make a check_nrpe_version command like so

Code: Select all

define command {
    command_name    check_nrpe
    command_line    $USER1$/check_nrpe -H $HOSTADDRESS$ -t 30
}

Then modify your host to just be as follows:

Code: Select all

define host {
        host_name                       XXX-XXXX
        alias                           XXX-XXXX
        check_command                   check_nrpe_version
        max_check_attempts              5
        check_interval                  0.08
        retry_interval                  0.08
        check_period                    24x7
        contacts                        nagiosadmin
        icon_image                      nrpe.png
        statusmap_image                 nrpe.png
}

Nagios Support Forum

Linux Host check_command for NRPE version

Linux Host check_command for NRPE version

Re: Linux Host check_command for NRPE version

Re: Linux Host check_command for NRPE version