Cluster Access


If you need remote access to the CLC linux cluster, this is the place to find directions. Your first step is to get an SSH client. If you have linux on your machine, then you probably already have Openssh installed; but if not, and you have a recent version of linux, you can probably use up2date, yum, apt-get, yast, or any other updating software that comes with your distribution. If you have Windows on your computer, you can download SSH clients from and navigate to the 'File Transfer' section to download the appropriate client. For Mac OS X, SSH is part of the operating system and can be accessed from the program.

If you do not need to display any graphical applications, you can simply use any SSH client for your platform. Please follow the directions immediately below for instructions on this method. If you do need to run a graphical application, please skip to the next section. (When we talk about graphical applications we are referring to applications that open a window, whether it be to interface with the application, or to display data, if a window opens when using the application, we call that a graphical application.) 

Non-graphical SSH


If you are connecting to the cluster from Linux/Unix and are using a command line ssh client, just type "ssh <PSUid>" where <PSUid> is your Penn State User Id. If you have not ssh'ed to the cluster from that machine before you will get a message stating that the authenticity of the host cannot be established, it will give you an RSA key, and ask if you want to continue. Type 'yes' to continue, and then enter your password when it prompts you for it.


There are several ssh clients for Windows such as PuTTY (a Google seach will lead to this download), SSH Secure Shell, (from under File Transfer), and Cygwin  which is not only an ssh client, but a bash shell environment and X server. See for download instructions.  If you are using Secure Shell for Windows, start the application, and click the 'Quick Connect' button. Then enter the cluster name "" and your username. Leave the port set to 22, hit Enter, and when it prompts you for your password, enter your Penn State password.

Mac OS X

If you are using Mac OS X, start the application by going to the Finder -> Applications -> Utilities -> Terminal. Once the terminal window comes up, type "ssh <PSUid>" where <PSUid> is your Penn State User ID. If you have not ssh'ed to the cluster from that machine before you will get a message stating that the authenticity of the host cannot be established, it will give you an RSA key, and ask if you want to continue. Type 'yes' to continue, and then enter your password when it prompts you for it.

Graphical SSH


If you are using a fairly recent version of a more popular distribution of linux (Red Hat, Fedora, Suse, Debian, etc.) then you shouldn't need any special software. Since you are using linux, you most llikely already have X windows running. If you don't have a graphical login then you'll need to start the X Windows system, but this is not the normal setup for a desktop linux machine. The only change you might have to make, is when connecting to the cluster, use the command "ssh -Y <PSUid>". The -Y option enables trusted X11 forwarding. This means that X11 will be forwarded to your screen and not subjected to the X11 security extention controls. For more information type "man ssh" on your linux console.


In order to display graphical applications from the cluster on a windows PC, you need to have an X windows environment. This is different from Microsoft's "Windows" Operating system. The most common way to do this is to download and install X/cygwin. During the installation, follow all of the default prompts until you are prompted to install a selection of packages. The default is fine, but you will need two additional applications to follow along with this tutorial. In the 'Net' category, select the 'openssh' package. Selecting this will automatically select any dependencies it requires. You will also need to click on the 'X11' category and choose 'xterm'. Again, selecting this will automatically select its dependencies. Continue with the installation, choosing the default prompts. Once you have installed everything, click on the cygwin icon on your desktop, and a window will appear.

This black window is your bash environment. You can use this as though you were on a linux machine. You can run asn ssh client from this window, or view the files on your windows machine, but with typical bash commands, or use bash commands to run a script. Additional applications such as vi are installable through cygwin's installer program. If you've deleted it, you can just download the setup.exe file from cygwin's site and run it again.

The next step is to start the windowing environment. In the bash command line window, type "startx" and hit "Enter" as shown below.

After you hit "Enter" text will scroll up and off the screen of your bash shell window. Don't worry, because after a second or two another window should appear, only this time it's white. This is your "xterm" window. See the example below:

Inside the xterm window is where you will connect to the cluster. Type "ssh -Y <PSUid>" where <PSUid> is your PSU ID. See below.

Once you've logged in, you should be able to access any application on the cluster, and even be able to use the graphical interface. In the following images, we started Maple, and you can see that it starts and works just like if it were on your own machine.


Mac OS X

Macintosh computers running Mac OS X already have a built in X11 windows system, and it's conveniently called X11. It is located under Applications -> Utilities -> X11. Start it up and it will open an xterm window for you.

Once you have the xterm window up, ssh to the cluster by typeing "ssh -Y <PSUid>" where <PSUid> is your PSU ID. See the following image for an example: