X11 Forwarding for the Stats Servers

The graphical versions of the stats programs on the SCS machines use a system called X or X11 to do the graphical display. For this to work on your desktop, you must be running an X package on the desktop. When you run X-based applications on the SCS hosts, those applications will make forwarding connections from the SCS hosts to the X server on your desktop.

For example, if you have X11 forwarding enabled and you run the xstata command on one of the SCS machines, a graphical Stata window will appear on your local desktop. You can use it as if it were running on your computer, though all data will still be in your AFS space or on the disk of the SCS machine you're using to run the program.

How to do this depends on what kind of computer you're using. See below for use on Windows, Mac (OSX), and Linux/UNIX desktops.

Windows PCs

To use X11 forwarding on Windows, you must have an X11 package installed and must properly configure your communications to forward the X connection.

X11 Packages for Windows

There are a number of packages for X11 on Windows. This is not a complete list, but describes the most popular usage at U-M.

Exceed/Hummingbird Exceed

You can purchase a copy of Exceed (formerly known as Hummingbird Exceed). Exceed is an X server for Windows that will allow you to do X11 forwarding directly to your desktop. Please note that we do not officially support Exceed and cannot provide help in its configuration.

Cygwin X

You can download a copy of Cygwin 1.7 or later from their site. This includes an X11 client and server. As with Exceed, we do not officially support Cygwin and cannot provide help in its installation or configuration.

ITS Virtual Sites

Rather than installing and configuring software on your desktop, you can use Virtual Sites to connect to the Statistics and Computation service. This has the advantage of being officially supported, saves you any licensing costs, and doesn't require you to do any special configuration or commands.

X11 Forwarding on Windows

If you are using a local X11 installation, there are two popular methods to make X-based connections to the stats servers.

Be sure your X package is running before attempting forwarding.

Forwarding With Putty

Get and install a copy of putty as per these instructions. Once installed, you will need to take additional steps as follows to configure it for X11 forwarding.

Run putty and look for the field labelled "Host Name (or IP Address)". In it type scs.dsc.umich.edu. Then, in the menu on the left-hand side of the PuTTY window, select through the menus Connection ->SSH ->> X11. Select the box labelled Enable X11 forwarding. Then click on the open button at the bottom of the PuTTY window.

You will be prompted for your uniqname and password, and then logged into one of the SCS machines. Any graphical programs you run on the SCS will now appear on your screen.

Forwarding Using Xterms and ssh

Most X client installations include the xterm application. Open an xterm and you will see a terminal-like window. In that window, type the command ssh -X scs.dsc.umich.edu.

You will be prompted for your password, and then logged into one of the SCS machines. Any graphical programs you run on the SCS will now appear on your screen.

Mac (OSX)

To enable X11 forwarding on a Mac, you must have an X11 package installed and give the proper commands in a Mac terminal window.

X11 Packages For OSX/Macs

Which X11 package to install depends on which version of Mac OSX you are using.

OSX 10.8 and newer

Apple has dropped support for X11 and is instead using a freely available version of X11 called XQuartz. You will need to install that on your Mac to use X11.

You will not need to manually start XQuartz; the ssh command given below will do this for you automatically.

Macs with OSX 10.7 through 10.5

As of December 2015, XQuartz is available for OSX 10.6.3 and later, and OSX 10.7 and later. If you choose not to use it or have OSX 10.5, you must use Apples X11 package.

Apples X11 is an optional add-on. It may have already been installed on your Mac. If present, you will find it by opening Applications and look for X11 in the Utilities folder.

If it is not installed, you should be able to do so from your OS X installation DVD. If you do not have one, please contact your desktop support staff to have it installed.

As of OSX 10.11 (and possibly earlier?) you will not need to manually start X11; the ssh command given below will do this for you autmatically. If you have a version of OSX which does not do this, you will need to manually start your OSX versions' flavor of X11.

Macs with OSX 10.4 or earlier

If you are running OSX 10.4 or earlier, follow the instructions for 10.7 through 10.5 above to see if Apples X11 is installed. If it is not, follow the instructions in that section to install it.

Unlike 10.5 and later, you will have to manually start X11 before opening a connection to the stats servers. To start it, open Applications and then the Utilites folder, then double-click on the X application. It will usually open an xterm window for you automatically.

X11 Forwarding on the Mac

If you are running OSX 10.4 or earlier, be sure your X11 package is running. Later versions will start X11 automatically when you give the ssh command below.

You can make a forwarding connection to the SCS servers by opening a terminal window of any type (Mac Terminal, xterm, iTerm) and giving the command

    ssh -X uniqname@scs.dsc.umich.edu

If your Mac login ID is the same as your uniqname, you do not have to specify the uniqname.

You will be prompted for a password by the SCS server. Once logged in, any graphical program you run on the SCS server will open a window on your screen.

UNIX and Linux Desktops

Pretty much all UNIX and Linux desktops come with X11 installed and running. If you're running a graphical interface on your desktop, you're using X11. To connect to the SCS hosts for with forwarding, open a terminal window and type the command ssh -X scs.dsc.umich.edu.

You will be prompted for your password by the SCS server. Once logged in, any graphical programs you run on the SCS server will open a window on your screen.

SSH Keys and Login/SCS Access

Note that for technical reasons relating to the use of AFS, you cannot use ssh keys for password-less logins.