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Remote Access via Secure Shell (ssh)

Secure Shell (ssh) provides remote access to CAE lab facilities, similar to traditional telnet and ftp services. The primary difference is that ssh encrypts all its traffic, effectively eliminating the possibility of unauthorized individuals eavesdropping or rerouting connections elsewhere.

SSH can also provide encrypted "tunnels" for all sorts of otherwise unencrypted network programs (POP and IMAP email, X Window System clients, etc).

Free SSH Programs for Various Computers

The following programs are recommended for CAE Laboratory users. Each of them supports the current ssh protocols and also allows tunnelling of both X Window System graphics and generic network traffic.

SSH Example

In its simplest form, SSH is as easy to use as telnet. We'll show an example with PuTTY, realizing that other SSH clients will differ slightly in details.

Here, we enter the name of the remote host we wish to connect to (ch208m.cae.tntech.edu) in the Host Name box. We set the Protocol button to SSH and click the Open button at the bottom of the dialog.

Putty Screenshot: Configuration Dialog

The first time you connect to a particular computer via SSH, you should receive a warning similar to this one. In order to ensure the security of your connection, SSH programs exchange identifying keys to each other -- PuTTY is warning you that the remote computer is sending an unrecognized key, and prompts you to decide whether to continue connecting or not.

Putty Screenshot: Security Alert

If you see this warning on a later connection to the same computer, one of the following has happened:

  1. You have reinstalled the operating system on your own computer, causing it to forget the remote computer's identity.
  2. The remote computer's operating system has been reinstalled, and we forgot to make a backup of the computer's identity before the reinstallation.
  3. Someone has replaced the remote computer, or is redirecting your connection elsewhere.

Assuming possibility 1 isn't true, call Joel Seber at x3734 or Mike Renfro at x3601 to check on possibility 2. Possibility 3 could result in your sending your username and password to an unauthorized entity, allowing others a chance to break into your account, remove or modify your files, etc.

Upon verifying the remote computer's identity, you'll be asked to enter your username and password. If successful, you'll be at a Unix shell prompt and can start working.

Putty Screenshot: Logged In

If you want to automate this process, you can make a shortcut on your Windows desktop similar to the one shown here.

Putty Shortcut

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