home overview research resources outreach & training outreach & training visitors center visitors center search search

Secure Shell Tutorial

SSH is a program that runs on your personal computer (e.g. PC, Macintosh, or UNIX workstation) and is used to login to a remote computer system, much in the same way that telnet has been used in the past for the same purpose. The big difference between telnet and SSH, however, is that SSH provides significantly enhanced security for your login session.

SSH is the now the de facto standard for remote computer logins, with an estimated three million users in 80 countries. It solves the most important security problem on the Internet: hackers stealing passwords. Typical applications of SSH include remote access to computer resources over the Internet, secure file transfers, and remote system administration.

SSH provides an encrypted communications path between two untrusted hosts over a potentially insecure network and thus prevents user's passwords and other sensitive data from being transmitted across the network in clear-text form. SSH is available on virtually all computer platforms: Macintosh, Microsoft Windows, Unix, Linux, etc. You can learn more about SSH and the secure communications protocol it uses from this online article by Galvin Peter or this list of SSH Frequently Asked Questions. You'll also find links in these documents to SSH client programs that run on virtually every kind of workstation.

As of February 21, 2001 the Computer Graphics Laboratory supports both version 1 and version 2 of the SSH protocol.

If you use Microsoft Windows, you can visit OAAIS Licensed Software to download the Secure Shell SSH application. Follow the documentation link for instructions on installation and use.

If you use a Macintosh running OS X, then things are really easy as the standard OS X "ssh" application implements the SSH protocol. This is a command-line only application that is most easily invoked from the standard OS X "Terminal" appliction. In the Finder, go to Applications->Utilities->Terminal, then in a terminal window just type "ssh HOSTNAME," with the word HOSTNAME substituted by the name of the computer system you want to access, e.g. plato.cgl.ucsf.edu.

And there's even a version of SSH that's written in java and can be run from a web browser such as Netscape's Navigator or Microsoft's Internet Explorer. Just access this URL to try it out.

On host plato you can find out more about SSH by consulting the on-line SSH manual page (or type "man ssh" at a plato command prompt).