What the heck is SSH?
Secure Shell, sometimes referred to as Secure Socket Shell, is a protocol which allows you to connect securely to a remote computer or a server by using a text-based interface.
System and network administrators use this protocol the most, as well as anyone who needs to manage a computer remotely in a highly secure manner.
How Does SSH Work?
In order to establish an SSH connection, you need two components: a client and the corresponding server-side component. An SSH client is an application you install on the computer which you will use to connect to another computer or a server. The client uses the provided remote host information to initiate the connection and if the credentials are verified, establishes the encrypted connection.
On the server’s side, there is a component called an SSH daemon that is constantly listening to a specific TCP/IP port for possible client connection requests.
Once a client initiates a connection, the SSH daemon will respond with the software and the protocol versions it supports and the two will exchange their identification data.
If the provided credentials are correct, SSH creates a new session for the appropriate environment.
OpenSSH is an open-source SSH tool— widely used for Linux distributions— Installing OpenSSH is relatively easy.
Note that Ubuntu does not have an SSH server installed by default.
