In this lesson you will learn how easy it is to add a node to Jenkins. But what is most importantly I will explain the ssh public private keys thingy.
It is important to understand that jenkins master is the one who initiates connection (in ssh connection scenarios). So private keys are stored on Jenkins master; public key is copied to node using ssh-copy-id command.
Nodes/Agents don't need to have any jenkins software installed. Nodes need only to have java installed as prerequisite. Ssh software is usually already installed.