"Client is not authorized to connect to server"

Usually a trio of messages, e.g.:

        Xlib:  connection to "stehekin:0.0" refused by server
        Xlib:  Client is not authorized to connect to server
        Error: Can't open display: stehekin:0

Make sure your .Xauthority file on the client side has an entry for the X server you want to use. Or, use the xhost command to force the server to accept clients. See man pages for xauth andxhost.