York University Computer Science and Engineering

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SSH Support

Technical Database >> User Guide >> Login and Remote Access

The preferred protocol for connecting to the department from your home ISP or from another remote computer is SSH or Secure Shell. This protocol provides for the encryption of traffic in transit making it very difficult (and in most cases, nigh impossible) for a third party to snoop or listen in.

We operate ssh servers on our time-sharing servers. SSH clients must be used to access the Computer Science time-sharing servers from outside the department. Telnet and rlogin protocols may not be used when connecting to departmental machines from outside the department. Local users (i.e. computers within the department) can still use telnet, rlogin, rsh, and similar protocols.

There are a number of available ssh clients for Unix, Windows and Macintosh. An online list of these clients is available at http://en.wikipedia.org/wiki/Comparison_of_SSH_clients. The clients we recommend are:

Java SSH Applet Notes

The Java SSH Applet is provided as a convenience when accessing the department's computers from remote machines which do not have readily available SSH support, but do have a Java-enabled web browser.

You can get a copy of the applet (including the source code) on the Java Telnet App Site.

SSH From One Host To Another Without Entering A Password

By default, you will be able to connect by SSH from any tech-supported departmental Unix machine to any other tech-supported departmental Unix machine without requiring a password.

If you would like to be able to connect to a non-tech-supported SSH server without entering a password, you will need to carry out a simple two-step process yourself.

First, run 'ssh-keygen' on one of the departmental Unix hosts:

% ssh-keygen -t rsa -N ""
Generating public/private rsa key pair.
Enter file in which to save the key (/cs/home/jas/.ssh/id_rsa):

Hit "ENTER" to create the public key file, .ssh/id_rsa.pub and the private key file .ssh/id_rsa.

On the system that you would like to login to, you will now need to append the contents of the newly created .ssh/id_rsa.pub file to the .ssh/authorized_keys file. If the file does not exist, create it. Now, you will be able to ssh to your host from any departmental Unix system without requiring a password.