SSH

SSH allows you to connect to a shell on a remote computer.

Example:

[user@localhost ~]$ ssh username@yourserver

SCP

You can also use scp to securely transfer files.

Example:

[user@localhost ~]$ scp examplefile yourusername@yourserver:/home/yourusername/

This example sends examplefile from the directory you're currently in to /home/yourusername/ on yourserver