NSClient++with Nagios Core

[pcfx]

Hi,
im using Nagios Core 4 and installed the check_nrpe plugin from nrpe v.3.0.1.
Nagios Core is running on Ubuntu Server and the NSClient++ on Windows Server 2012.
Basically i can compile nrpe with/without ssl support and i can install NSClient++ in legacy mode or secure mode (with certification or cert. + authentication). Is this correct?
Also as far as i read check_nt is unencrypted. I want to use at least some encryption between the check_nrpe plugin and the NSClient++.
I've already tried to generate some certs with openssl, link them in the config file of NSClient but it did not work. I always get ssl handshake failed error.
I sniffed the network traffic between the two machines while nsclient.ini was set to "insecure = true" but i could not sniff some plain commands.
Is check_nrpe already using some default encryption? Is there a easy way to encrypt the communication if not?

[avandemore]

This document says XI but it largely applies to your situation:

https://assets.nagios.com/downloads/nag ... utions.pdf

Have you considered NCPA as an agent? It's one we maintain so it's easier to help with something like that.

https://www.nagios.org/ncpa/help.php
https://www.nagios.org/ncpa/#downloads