Chapter 1. Introduction to SSH

Many people today have multiple computer accounts. If you're a reasonably savvy user, you might have a personal account with an Internet service provider (ISP), a work account on your employer's local network, and one or more PCs at home. You might also have permission to use other accounts owned by family members or friends.

If you have multiple accounts, it's natural to want to make connections between them. For instance, you might want to copy files between computers over a network, log into one account remotely from another, or transmit commands to a remote computer for execution. Various programs exist for these purposes, such as ftp and rcp for file transfers, telnet and rlogin for remote logins, and rsh for remote execution of commands.