Nagios - installing custom plugin on Windows 7 that executes and sends back data to the server - plugins

Question

I have setup Nagios 4 core on ubuntu machine and I have installed NSClient++ on windows 7 machine. For the out-of-box monitoring like CPU, memory , etc. everything works.
I also have written an EXE in .Net that gathers some metrics on the windows machine and the hope is that NSClient on the windows machine would execute this EXE and marshal these output back to the server. The problem is that I don't know how to install the plug in. Do you install it on the server? On the client? Both? If so where? Needless to say that ubuntu (where the nagios server is) shouldn't try to execute the .net EXE.
When I look at the configuration files on the server, I see that the nagios server uses Check_NT for communicating with the NSclient. We have a syntax like Check_nt!blah. Will I need to use the same syntax when executing my .Net EXE which is not part of the core?
I hardly found any detailed documentation as how to install a windows plugin and have the server and client talk to each other. So either it is extremely easy or extremely complicated. I also looked at some YouTube videos ...there is nothing there for the problem that I"m facing.
Any help is appreciated. Thanks all!

Answer 1

You'll want to define it as an NRPE check on your monitor, then define the check using the same name # NSClient++ on Windows. The NSClient++ configuration has a section for NRPE handlers, just for this (source: op5 kb):
[NRPE Handlers]
The nrpe handlers provide a way to execute any custom plugin/check command on the monitored Windows server. In this section you configure all the commands that should be available.
Adding a custom NRPE command to NSClient++ follow this syntax:
command[my_custom]=c:\mycustomdir\my_prog.exe
To test the check from your monitoring system you can use NRPE from the CLI to call my_custom:
./check_nrpe -H 10.0.0.1 -c my_custom
And then define the service in your Nagios config like so:
define service{
use generic-service
host_name windowshost
service_description CPU Load
check_command check_nrpe!my_custom
}
You may need to do some extra work to format the output correctly. In BASH, exit 1 and exit 0 are commonly used to indicate state, IE: OK/Critical (source), and you may find it easier to augment your EXE's output with some simple scripting like that.