SSH, The Secure Shell: The Definitive Guide, 2nd Edition

Overview of SSH Features

So, what can SSH do? Let’s run through some examples that demonstrate the major features of SSH, such as secure remote logins , secure file copying, and secure invocation of remote commands.

1.4.1 Secure Remote Logins

Suppose you have login accounts on several computers on the Internet. Common programs like telnet let you log into one computer from another, say, from your home PC to your web hosting provider, or from one office computer to another. Unfortunately, telnet and similar programs transmit your username and password in plain text over the Internet, where a malicious third party can intercept them.^[4] Additionally, your entire telnet session is readable by a network snooper.

Terminology: Networking

Local computer ( local host, local machine)

A computer on which you are logged in and, typically, running an SSH client.

Remote computer (remote host, remote machine)

A second computer you connect to via your local computer. Typically, the remote computer is running an SSH server and is accessed via an SSH client. As a degenerate case, the local and remote computers can be the same machine.

Local user

A user logged into a local computer.

Remote user

A user logged into a remote computer.

Server

An SSH server program.

Server machine

A computer running an SSH server program. We sometimes simply write “server” for the server machine when the context makes clear (or irrelevant) the distinction between the running SSH server program and its host machine.

Client

An SSH client ...