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There are two ways to connect from a Macintosh or PC to a UNIX machine.
Which connection method you choose will depend on what you want to accomplish,
what services are available on the remote host, and whether you require
graphics to be displayed. You can use a text-only connection (also
referred to as a tty, command line, or terminal interface) or a graphical
(X-windows) connection.
SSH secure shell is used to connect to Research Computing systems
for command line connections. All communication with the remote host is
encrypted with a very secure algorithm based on public key cryptography. The
advantage to this is that network traffic can pass through an untrusted channel
without danger of being decoded.
For X-Windows (graphical) access, the user must run a
program called an X Server on their desktop computer, which
interprets and displays the graphical output of programs running on the remote
UNIX system. The X Server may initiate programs using the mechanisms of command
line logins, or it may use a protocol called XDMCP. Using
XDMCP allows the remote user to see a screen display similar to what would be
displayed on a local display on the UNIX system, with the window management
provided by the UNIX system. XDMCP is often disabled or restricted to local
access only because of poor security. X-Windows connections can be
"tunneled" through an encrypted channel if used in conjunction with
SSH, providing a completely secure graphical connection (at some cost
in performance).
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