Running Graphical Applications on GAUL from Home

Sometimes, it is useful to run graphical programs on the GAUL network from your Windows computer at home. For instance, you may be working on an assignment that uses a Graphical User Interface (GUI) and wish to test your code on the GAUL UNIX servers, but do not wish to come into the university to do so.

To facilitate this, you must have an X server running on your Windows system, and must connect to GAUL using a special SSH feature known as X forwarding. This tutorial will demonstrate how to run graphical applications on GAUL from your Windows computer.

Section 0: Prerequisites

Before completing this tutorial, make sure you have first completed the following tutorials:

Section 1: Creating a PuTTY Profile with X Forwarding Enabled

In this section, you will create a profile in PuTTY that will allow you to login to the GAUL network with X forwarding enabled. You can use this profile to login whenever you need to work remotely with graphical applications running on a UNIX server in the network.

  1. Start PuTTY by double-clicking the putty.exe file that you downloaded in the Installing and Configuring PuTTY tutorial.
  2. In the Session pane, enter the following details:
    • Host name (or IP address): obelix.gaul.csd.uwo.ca
    • Port: 22
    • Connection type: SSH

  3. Select the Data node in the left pane, under the Connection heading. In the Auto-login username field, enter your GAUL username (this is typically the same as your UWO email address — without the @uwo.ca).

  4. Select the SSH node in the left pane, under the Connection heading. Ensure that the Preferred SSH protocol version is set to 2.

  5. Expand the SSH node in the left pane, and select the X11 node. Check the Enable X11 forwarding checkbox.

  6. Select the Session node again in the left pane, and enter obelix-xforwarding in the Saved Sessions field.

  7. Click Save to save the connection for later use. You should now see obelix-xforwarding listed in the stored sessions list.

  8. In the future, when you need to establish an SSH connection to the GAUL network which will allow you to run graphical applications remotely, you can simply double-click the obelix-xforwarding profile you created from the stored sessions list.

Section 2: Running Graphical Applications Remotely

In this section, you will establish a remote connection to the primary GAUL compute server, obelix. From there, you will execute a graphical application on obelix, which will display on your Windows computer.

  1. Start Xming by clicking Start > All Programs > Xming > Xming.
  2. If this is your first time starting Xming, you may receive a Windows Security Alert. If so, be sure to check the Public networks checkbox, and click Allow access to allow Xming access to the Internet.

  3. Xming does not have a graphical user interface, but instead runs as a service in the background. You can verify that it is running by checking to see if the Xming icon is listed in the system tray, in the bottom right corner of the screen.

  4. If it is not already running, start PuTTY by double-clicking the putty.exe file that you downloaded in the Installing and Configuring PuTTY tutorial.
  5. In the stored sessions list, double-click the obelix-xforwarding profile you created in Section 1.

  6. If this is the first time you are connecting to GAUL from PuTTY, you will receive a security warning concerning the server's host key. This is normal, and you should click Yes.

  7. When prompted, enter your GAUL password, and press Enter. Note that, for security purposes, you will not see the password characters that you are typing. You should have received your password via email when you took your first Computer Science course. Click here if you do not remember your password or are having difficulty logging in. If problems persist, fill out a problem report to notify the Systems Group of your account issues.

  8. After logging in, try running a graphical program on obelix, such as prticket.

    If your X server and X forwarding are configured properly, you should see the prticket window appear on your screen after a few seconds. Note that you can expect some delays when working with remote graphical applications since all the graphical information needed to display them on your screen needs to be transferred over the Internet, from obelix to your system.


Section 3: Troubleshooting

If the prticket application did not display on your screen in Section 2, all is not lost. This section discusses several techniques that may help you to get things working.

  1. Try setting your DISPLAY variable on obelix using one of the following commands (depending on the shell you are using):

    set DISPLAY=obelix:1.0
    export DISPLAY=obelix:1.0
    

    Once you have done so, try executing prticket again, and wait a few seconds to see if it displays on your screen.


  2. Verify that Xming is started, as discussed in the Installing and Configuring Xming tutorial.
  3. Verify that you are using the obelix-xforwarding profile created in Section 1, and verify that the Enable X11 forwarding checkbox is enabled for this profile on the Connection > SSH > X11 node in the left pane in PuTTY.

  4. If remote graphical applications still will not display on your system after performing the above steps — or applications are displaying, but they do not display properly — try reinstalling Xming, but instead of downloading and installing the Xming package, download and install the Xming-mesa package. For a refresher on installing Xming, see the Installing and Configuring Xming tutorial (remember to choose the Xming-mesa package instead of Xming!)