Using jenkins-cli to connect slave to master

[uscen...@gmail.com]

I used cloudbees for a bit with multiple on premise executors. To connect the nodes we added the ssh key to our cloudbees account and then ran the following command from the node machine:

java -jar jenkins-cli.jar -s https://test1234.ci.cloudbees.com on-premise-executor -fsroot /usr/share/jenkins -labels osx -name osx1

Now I want to create a similar setup but without cloudbees.

Where does the ssh-key need to be added?

Is the command on-premise-executor only available for the cloudbees jenkins-cli.jar? Or is the command part of all jenkins projects?