X2Go

CLASSE uses X2Go as the preferred GUI remote access tool. X2Go is a fully open source, actively developed project to support the remote execution of X applications, including full linux graphical desktops. It uses an open-source (and updated) version of the NoMachine NX protocol and is a replacment for freenx.

X2Go is not meant to be used with temporary CLASSE accounts (i.e. accounts that begin with "x_"). Instead, please ask your CLASSE sponsor to request a permanent CLASSE account for you by filling out the NewUserForm.

The X2Go server is currently available on all CLASSE Linux boxes, so directly using your Linux workstation for remote access is recommended. If you do not have a designated Linux desktop or workstation, you can use lnx201.classe.cornell.edu.

Installation on personal computers.

Download the client installer from https://wiki.x2go.org/doku.php/download:start .

Creating a new desktop session, or launch a specific application.

• Run the X2Go client on your desktop.
• Create a new session with “session | new session…”.
• Assign a session name.
• As 'host name' give the name of the machine, the session you want to connect to, is running on.
• As 'user name' give your account on the remote machine.
• Choose your desired 'session type'
  • For a full desktop session, we highly recommned you choose Xfce.
  • For a much lighter-weight (and probably faster) experience, we recommend you choose Terminal. This will open a terminal, from which you can type any command and launch any graphical or console application.
  • To launch an application on the CLASSE Grid Farm, select Single Application, and by the Command enter:

    python /nfs/opt/CLASSE_GRID/CLASSE_GRID.py

    For more on the CLASSE Grid script, please see WindowsRemoteLinuxScript
• Press 'OK' to save the session.

Remote access to physical desktop

With X2Go, it is possible to access the physical desktop (the desktop at CLASSE you see when sitting in front of your computer) remotely as follows:

• Run the X2Go client on your desktop.
• Create a new session with “session | new session…”.
• Assign a session name.
• As 'host name' give the name of the machine, the session you want to connect to, is running on. Please be sure to use the full hostname of your computer, including the ".classe.cornell.edu".
• As 'user name' give your account on the remote machine.
• As 'session type' choose 'X2Go/X11 Desktop Sharing' or 'connection to local desktop' (depending on the version of your client).
• Press 'OK' to save the session.

If you'd like to let someone else access your desktop remotely, you must first start X2Go Desktop Sharing.

• open a terminal
• type:

  x2godesktopsharing --activate-desktop-sharing &

When someone else makes a "X2Go/X11 Desktop Sharing" or "connection to local desktop" using X2Go to your machine, they can then select your local desktop. You must first "Grant access" using the popup before the user will successfully connect. If you receive a "Policy Kit Agent" popup after granting access, simply click on "Cancel."

Display Size

The one major shortcoming to X2Go's screen sharing feature is that there's no option to scale the display. So, the display you run X2Go on must be the same size or larger than the display of the computer you are connecting to. If this isn't possible (either by reducing the monitors or display size of the desktop at CLASSE, or by increasing the monitors or display of your computer at home), you can resize the desktop to match your home display as follows:

• start a "X2Go/X11 Desktop Sharing" or “Connection to local desktop” session to your computer at CLASSE
• open a terminal, and type “xrandr” to view available resolutions
• select a resolution that matches or is smaller than your home computer’s display
• type “xrandr -s 1920x1080” (for example) to switch to your desired resolution
  • alternatively or in addition, you could disable the second monitor using something like xrandr --output DP-3 --off
• resize the window on your home display to match the selected resolution.
  • If you're trying for a full screen display, you may want to hide the taskbar on the computer you are sitting in front of.
• And when you’re done (or if you added a monitor or increased the resolution of your home computer), you can always revert to the original resolution using “xrandr -s …”.
  • and/or to re-enable the second display, something like xrandr --output DP-3 --right-of DP-2

As an alternative to X2Go, please see ZoomRemoteControl for using Zoom to control a desktop at CLASSE.

Mac OS X

For detailed Mac OS X instructions, please see MacX2Go

Debugging

For a list of debugging procedures, see X2GoDebugging

Application Notes

Xterm - Recommended

1. Go to Session preferences
   1. select menu Session
   2. select item New session..
2. Under Session type
   1. select Single Application
   2. change the command to xterm.
3. click on ok

Icewm or Xfce (Full Linux Desktop) - if needed

Please see IceWM or Xfce Startup for more general information on using IceWM or Xfce. Xfce provides more desktop features than IceWM does.

Either IceWM or Xfce must be used if you want to run more than one graphical desktop at once. Gnome and KDE are only usable for one session at a time, no matter which CLASSE computer they're running on. So if you want to run X2Go to or from another computer while you are already logged into your Linux desktop (for example), it's important that you configure an X2Go session to start either the IceWM or Xfce desktop

Note:after selecting Logout in an Xfce sesstion, you may need to select Terminate at the bottom right of the X2Go window.

For more information about Xfce, see https://www.xfce.org/about

For more information on using IceWM, please see MultipleSessions and IceWM.

Resize Desktop

To resize the desktop:

1. click in the lower-right corner of the window and drag to desired size for either IceWM or Xfce.
2. To relocate the IceWM task bar
   1. click on the "Start" menu in the lower-left hand corner
   2. click on the "triangle" icon to the right of "Logout ..."
   3. click on "Restart Icewm."

Three button mouse emulation in Windows

1. on X2Go start screen select menu item Options->Settings
2. select tab X-Server settings
3. choose "use custom X-Server"
   1. set executable path to point to vcxsrv.exe installed as part of X2Go
   2. add command line option -emulate3buttons
4. restart X2Go

Mathematica

To run mathematica from X2Go, use

mathematica -mesa

.

Troubleshooting

Trouble logging in

1. Occasionally X2Go sessions will not terminate properly and can prevent you from logging back in. When this happens, ssh into the system you are trying to connect to and kill all of your processes.

   1. ps -fu $USER

      • will show all of your processes. Once you're sure you want to kill all of them, execute:

   2. killall -HUP -u $USER

      or

      pkill -9 -u $USER

      • This will also kill the ssh session you are logged in with, so you should log back in and use "ps -fu $USER" again to make sure everything is killed.
2. If you are still unable to use X2Go reliably, see RemoteLinux for instructions on using VNC. While the setup is a bit more involved, most users find VNC to be more reliable and as responsive as X2Go.

CLASSE Temporary Accounts

If you have a temporary CLASSE account and have not logged into lnx201.classe.cornell.edu before, you will get an error saying "Connection failed: Could not chdir to home directory /tmp/x_XXXXXX: No such file or directory". To fix this error, log into lnx201 via SSH (ssh [username]@lnx201.classe.cornell.edu), which automatically creates the temporary account home directory.

IceWM or Xfce task bar

Note: if IceWM's or Xfce's task bar is not visible in X2Go 's window,

1. select the bottom edge of the X2go session's desktop window
2. drag it down.
3. release it.
4. The taskbar should then appear

Tab key not working with Xfce.

When using the Xfce desktop, users may notice that the tab key does not work. This is due to a bug in Xfce sending a super key modifier with the command. See Xfce bug 10760

To fix this,

• Open the Xfce Application Menu > Settings > Window Manager
• Click on the Keyboard Tab
• Clear the Switch window for same application setting

Apple Keyboards with Gnome

Apple keyboards don't work with the gnome desktop. Xfce is recommended (and see X2Go above)

Font errors on Windows

If you're trying to load newin or other programs from a Personal (Not CLASSE Managed) Windows computer and get a font warning, you need to download fonts.zip attached to this page and extract it in your X2Go Xserver fonts directory. This is usually C:\Program Files (x86)\x2goclient\VcXsrv\fonts

Advanced Users

• If you installed to a non-standard location, look for the VcXSrv\fonts directory inside your X2go installation directory.
• If you're using an external X Server on Windows, you need to put the fonts in that X Server's fonts directory.