Prefacing this by saying that I am fairly new to all of this.
In order to communicate with my hosts I have been experimenting with both the check_nscp_api command as well as nrpe but I have/had my issues with those two. I believe nrpe is also somewhat insecure - if not even deprecated.
I was wanting to try out the icinga agent again. I suppose it needs to be kept up-to-date? And I was wondering what the best and easiest approach would be, as manually updating and checking for updates is a bit unrealistic.