What is ssh?

"ssh" stands for "secure shell". This software permits end-to-end encryption of remote sessions (i.e. it replaces telnet or rsh), as well as more sophisticated authentication methods, and some pretty fancy port forwarding and X-session forwarding. In this page, we'll discuss only the regular encryption function; if you need help with anything fancier, ask in the help newsgroup. Also, you may find the ssh FAQ to be useful.

The benefits of encrypting your connection are two-fold: first, it prevents anyone from "sniffing" your traffic (including your password!), and second, it defeats "session hijacking" attacks.

In order to have an encrypted session with ssh, you need both ends of the connection to understand ssh. Alcor runs the ssh server software (protocol version 1), and also provides ssh client software which you can use if you are connecting from Alcor to a remote machine which runs an ssh server.

Using ssh to connect to Alcor

However, the more frequent case will be Alcor users connecting to Alcor from home through an ISP. You are responsible for setting up ssh at your end. If you have a shell account with your ISP, check with them first, since they may already have ssh, or may be willing to install it for you.

If you have an "internet" account with your ISP, you'll have to set up ssh on your home machine. Here are some of your options (a more recent list is available in the ssh FAQ part 2):

• Unix or Linux:

  • If you're running Linux or another flavour of Unix, you can use the free client software available from SSH Communications Security Ltd. in Finland, or from a Canadian mirror at achilles.net. Make sure you get the latest version 1, not version 2 (which Alcor does not support).
  • Another organization which provides free client software for various Unixes is OpenBSD.

• Mac:

  • If you've got a Mac, you may buy a copy of the F-Secure ssh client software (protocol version 1) from DataFellows. In this province (Quebec), you can get this software directly from RIQ.

  • Alternatively, take a look at the free niftytelnet-1.1-ssh-r2.

• Windows:

  • A great (and free) ssh client for Win32 platforms (i.e., Windows 95, 98, 2000, ME, NT, and NT4, and Windows 3.1 with 32-bit extensions, but not bare 3.1 or 3.0) is PuTTY. (One note about PuTTY - when it first starts up the default protocol is Telnet. Make sure you select the "SSH" button before connecting.)

  • Another free ssh client, for Windows 95 or Windows NT, is TeraTerm software with its ssh extensions. We have additional notes on how to obtain and install it.

  • If you're running an earlier version of Windows, you can use the commercial program F-Secure SSH Tunnel & Terminal for Windows from DataFellows. In this province (Quebec), you can get this software directly from RIQ. (This program is also available for Windows 95 or Windows NT.)

  • If you're running Windows 95, 98, or NT, you can also use SecureCRT from Van Dyke Technologies; you can get a 30-day evaluation copy, and the product costs $us99 (half price for students). Our testers found it particularly easy to install. Note that downloading this software requires answering a munitions-export quiz, which begins at http://secure.vandyke.com/download/SecureCRT/.

  • Another commercial product for newer Windows releases is Kermit 95.

• DOS:

  • We're not aware of any product for the DOS environment, but if you find out about one, please let us know.

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Copyright, © 2003, Concordia University, (IITS). Author: Anne Bennett Credits: Sheila Ettinger Maintained by: webdoc@alcor.concordia.ca Last update: 2002/06/13 -- Sheila Ettinger