You need to run X11. It can be found in the “Utilities” folder under “Applications”.

This application will load a terminal window. Type the following command in the terminal window:

ssh -X [username]@[server name]

or, to enable trusted X11 forwarding

ssh -Y [username]@[server name]

If you cannot find X11, it may not be installed on your machine. Please email helpdesk@math.purdue.edu and request that it be installed.