We are running a Firewall because of computer security. Because of that, user at remote location can connect only one machine shell.ima.umn.edu which is our a login server with ssh.
Once you've logged in at any IMA computer system, there are several utilities which allow you to open an interactive session or otherwise access other workstation and remote workstations on the network. The recommended utilities are slogin and ssh, the ``secure shell'' remote login programs. These programs work nearly identically to the older rlogin and rsh utilities, but with improved features. One of the advantages of using ssh is that it automatically sets your DISPLAY variable properly and transmits all X Window related traffic over a cryptographically secured channel. If ssh is not able to make a secured connection, it will attempt to fall back on the less secure rsh protocol. See the man pages for further details.