Two machines running a server and a client running respectively can be connected securely via ssh. ssh user@serverIP example: ssh tom@203.159.11.42 Every time a user logs in to the server user have to provide password for getting into the server.Whereas passwordless authentication using the public key is considered more secure while loggin to a remote server. For that the following steps should be followed: 1. Generate public/private rsa key pair: ssh-keygen -t rsa When password is asked just hit a "ENTER" to leave it empty 2.Now use ssh to create a directory ~/.ssh as user (e.g. "tom") on server(e.g. 203.159.11.42). ssh tom@203.159.11.42 -p .ssh 3.Copy key to remote server cat .ssh/id_rsa.pub | ssh tom@203.159.11.42 'cat >> .ssh/authorized_keys' After finishing these three steps, login to the remote server with ssh will not require password.