Athena Dialup Service -- SSH

SSH is a popular program used to securely connect between UNIX machines. It does not generally use Kerberos, although later versions include that as an option.

Generally, ssh involves users generating public/private key pairs and using them to authenticate: however, on the dialups, the sshd will ask you for your password instead. (The reason for this is that you need to get Kerberos tickets to be able to do things like read your files and incorporate your mail, and you can't get tickets without typing your password.)

To use ssh to connect to the dialups, just do:


If your username on the machine you're connecting from is not the same as your Athena username, you'll need to use the -l option:

      ssh -l cmvest

The first time you connect, ssh will tell you:

      Host key not found from the list of known hosts.
      Are you sure you want to continue connecting (yes/no)? 

Type `yes'. It will respond:

      Host '' added to the list of known hosts.
      cmvest's password:

Type your password now. (ssh always encrypts your connection, so it's safe to type it here.)

If you connect to x.dialup, it will arrange to have your X connection go through the encrypted ssh connection so that you can securely run X applications remotely. (If you connect to a non-X dialup, your client will probably try to negotiate this option anyway, and print an error when the dialup doesn't allow it to.)

For secure file transfer, use scp, which works like rcp:

      scp localfilename
      scp localfilename

or, if you need to specify a different username:

      scp localfilename

What if I can't install an ssh client on my machine

You can use MindTerm SSH to connect to securely, if your browser includes Java support (please use this page instead if you are using Netscape on a Macintosh.) You should use Netscape version 4.06 or higher for best results.

Where can I get ssh?

Refer to for more information about ssh resources and programs available at MIT.

I'm incredibly paranoid! How do I know that someone isn't spoofing me into accepting the wrong host key the first time I connect?

Theoretically, someone could trick you into accepting a false key the first time you try to connect to one of the dialups, and use this to capture your password. The odds of this are extremely, extremely low, but in case you're concerned about it, here is a copy of the host keys, PGP-signed by Jeff Schiller:


This is the SSHv1 host public key:

1024 37

This is the SSHv2 DSA host public key:


This is the SSHv2 RSA host public key:


Version: GnuPG v1.0.7 (GNU/Linux)


This page last updated: $Date: 2005/06/18 07:13:19 $ GMT by $Author: jweiss $.