Getting a GUI on the BladeCenter



  • Echoing a Display from the login node to the user machine.
  • Case 1) Logging in from a Linux box.
  • Case 2) Logging in from a Windows box.

  • (Case 1) Logging in from a Linux box.
    Having logged into the blade center, check that the command line entry

    >echo $DISPLAY

    returns

    >localhost:16:0

    "16" is likely to be some other small positive integer, where every new ssh login will give a different integer. Then verify that

    >xclock &

    on the command line produces an xclock window (sometimes this small window appears behind your other open windows so look around a bit). If $DISPLAY does not echo as hoped and no xclock window pops, the best option is to reconfigure your ssh to forward X traffic. Or get the "putty" for Unix and follow the directions in the Windows section below.

    Another less secure option is to log out of Blade Center and type on the command line of your local machine

    >xhost + login1.hpc.ncsu.edu >xhost + login2.hpc.ncsu.edu

    It is also possible that you will (Redhat) have to go to System Settings --> Security Level and lower the level of the firewall.

    On the local machine >echo $DISPLAY and find typically that DISPLAY is 0.0. Find your local IP address, e.g. 152.4.3.112 perhaps by viewing the file /etc/hosts. Then on logging in again to henry2, type on the command line

    >setenv DISPLAY 152.4.3.112

    Then try

    >xclock &

    again. Since the command "xhost +" and a decrease in the firewall level both increase system vulnerability, a cautious user might prefer to resign himself to using a command line interface instead of a GUI.

  • Case 2) Logging in from a Windows box.

    Having logged into henry2, verify that the command line command

    >echo $DISPLAY

    returns something like "localhost:16.0". The particular number 16 could be some other small positive integer. If so, verify that

    >xclock &

    command pops up a small xterminal clock on your screen. If this doesn't work, logging in with a putty window and using the X-Win32 program should work. There are explicit instructions at

    http://www.eos.ncsu.edu/software/xwin32/

    X-Win32 is available to all current NC State faculty, staff, and students. An open source option is X/Cygwin.

    In the case of putty, the DISPLAY variable is forwarded only if X11 forwarding in enabled on the client machine putty program. Go to Connection->SSH->Tunnels and check the box "Enable X11 forwarding". Make sure X-Win32 is already running before again logging into henry2. ~