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That probably means you have an "XU" account which is for facility users for LCLS systems.  XU accounts do not have access to central computing systems (they do not have a valid shell on central computing systems – the "DO NOT use..." message comes from a special "use-NOT" shell).  If your status has changed from a facility users to a staff/faculty user, then you can request to have your group changed from XU to something else, so you have access to central computing systems, such as FastX.  You can contact ithelp@slac.stanford.edu for help changing your account status and getting a valid shell for central computing systems.

Connecting to FastX using your Web Browser

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