Basic Client Use

Contents:

Running Example
Remote Terminal Sessions with ssh
Adding Complexity to the Example
Authentication by Cryptographic Key
The SSH Agent
Connecting Without a Password or Passphrase
Miscellaneous Clients
Summary
SSH is a simple idea, but it has many complex parts. This chapter is designed to get you started with SSH quickly. We cover the basics of SSH's most immediately useful features: We also introduce authentication with cryptographic keys, a more secure alternative to ordinary passwords. Advanced uses of client programs, such as multiple keys, client configuration files, and TCP port forwarding, will be covered in later chapters.We use SSH1 and SSH2 (and occasionally OpenSSH) for all examples. If the syntax differs among the products, we'll discuss each of them.

A Running Example

Suppose you're out of town on a business trip and want to read your email, which sits on a Unix machine belonging to your ISP, shell.isp.com. A friend at a nearby university agrees to let you log into her Unix account on the machine local.university.edu, and then remotely log into yours. For the remote login you could use the telnet or rlogin programs, but as we've seen, this connection between the machines is insecure. (No doubt some subversive college student would grab your password and turn your account into a renegade web server for pirated software and Ani DiFranco MP3s.) Fortunately, both your friend's Unix machine and your ISP's have an SSH product installed.In the example running through the chapter, we represent the shell prompt of the local machine, local.university.edu, as a dollar sign ($) and the prompt on shell.isp.com as shell.isp.com>.