SSH
Short for Secure Shell is a network protocol that allows establishing a secure connections between a local and a remote computer. SSH provides confidentiality and integrity of data exchanged between the two computers using encryption and message authentication codes . SSH is typically used to log into a remote machine and execute commands, but it also supports tunneling and forwarding arbitrary TCP ports. It can transfer files using the associated SFTP or SCP protocols. The default SSH server listening port number 22.

