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Connecting to KLC

Connect to KLC with a Secure Shell (ssh)

A common way to connect to Linux servers such as KLC is to use a secure shell or "ssh" client. These are programs that allow you to connect to a remote server and provide you with a command line interface during your session. Most ssh clients give you the option of connecting with a full graphical interface ("X11 forwarding") or through a plain text interface.

You can make a connection to a specific KLC server (klc02.ci.northwestern.edu), or you can connect to a "load balancer" (klc.northwestern.edu) which will take you to the server that currently experiences the lowest traffic. 

Connecting from Windows

Kellogg's Windows machines do not come with any ssh clients pre-installed. So you will have to choose one and install it. Your choice is mostly a question of personal taste, but Research Support staff like MobaXterm, which has a very good free version. Because neither Research Support nor KIS can provide support for your installation, you should consider purchasing their pro version, which provides access to their technical support. Alternative ssh clients include PuTTY, SecureCRT, and Cygwin.

Similarly, you need a secure FTP (sftp) client in order to transfer files between KLC and your computer. Windows laptops do not come with a standard pre-installed. Your options here include:
  • Using MobaXterm, SecureCRT, or another ssh client that comes with a built-in file transfer feature.
  • Using the free Cyberduck program, recommended by NUIT.
  • Paying for a program like MountainDuck, which lets you mount a KLC directory as a Windows drive letter.
Connecting from a Mac

Mac laptops do come with Terminal installed as a standard program. To create a "plain" (non X11) connection to the least busy KLC, you simply open Terminal and type:

ssh your-netid@klc.northwestern.edu

If you prefer a graphical (X11) session, type:

ssh -Y your-netid@klc.northwestern.edu

Note: Depending on the vintage of your Mac, you might need to install the free XQuartz application for X11 to work.

For file transfers, in addition to using programs such as CyberDuck or MountainDuck, you can also issue "scp" or similar commands from Terminal.

Connect to KLC with the FastX Client

The FastX Client is an application for Microsoft Windows, Mac OS X, and Linux personal computers that makes a network connection to KLC using SSH. It connects you to the Kellogg Linux servers with full graphics support via the Linux X Windows system, also called X11. FastX is made available to members of the Northwestern community under a campus site license. FastX is accessible through your web browser, as well as an installed desktop client.

Prepare to Use FastX (VPN required for off-campus users)

To download, configure, or connect using FastX from an off-campus location, you must first establishVPN connection. This gives you an authenticated and secure connection to the Northwestern Network that is trusted by the FastX server and by KLC.

FastX Web Browser Client

You can access to the KLC via your web browser using the FastX Browser Client. You will use your NetID as your user name and your NetID password.

If you are not seeking a specific KLC node, you can use the following URL to connect through the KLC load balancer:

The individual KLC nodes can be accessed at the following URLs:

FastX Desktop Client

You will only need to follow the configuration steps the first time you connect to KLC with the Desktop Client. After FastX is configured you can use it whenever you want to connect to KLC.

Install and Configure FastX

Connect with FastX

Install and Configure FastX

You only need to do the steps in this section once on each computer you want to use to connect to KLC.

Step 1: Download and Install FastX (VPN Connection required)


  1. Download the FastX Installer to your PC.
  2. Run the installer.

Mac OS X:

  1. Download the FastX disk image to your Mac.
  2. Open the disk image named FastX.dmg.
  3. Drag FastX into your Applications folder.


  1. Download the FastX client for Linux.
  2. Extract the tarball and copy the folder to your preferred location, such /usr/local or /opt.

Step 2: Run FastX for the First Time


Use the Start Menu (Click Start Menu > All Programs > FastX) or use the Start Screen to find the FastX application and Run it. When p;rompted, allow FastX to communicate through the firewall.

Mac OS X:

  1. In the Finder, open the Applications folder and locate FastX.
  2. Press the Control-key and click the FastX icon.
  3. Choose Open from the pop-up menu.
  4. Click Open.

Note: FastX will be stored as an exception to your security settings and you will subsequently be able to run it by double-clicking the FastX icon. You will have to do this each time you upgrade FastX.

Step 3: Create a KLC Connection

FastX uses SSH to connect to a KLC node.

1. Click the PLUS icon in the upper right corner of the window.

2. Select SSH from the drop-down list. A New Connection window will open.

3. There are five different machines and you can create a connection for each of the machines, one at a time:

  1. Name: KLC01, KLC02, KLC03, KLC04, or KLC05
  2. Host: klc01.ci.northwestern.edu, klc02.ci.northwestern.edu, klc03.ci.northwestern.edu, klc04.ci.northwestern.edu, or klc05.ci.northwestern.edu
  3. Port: 22
  4. UserEnter your own NetID in lower-case letters.

4. Click Save.

5. Click "Continue" when asked about the unrecognized host key.

Connect with FastX

This section shows you how to create a connection to KLC each time you want to connect and how to manage your connections.

Step 1: Open a Connection to a KLC Node

1. With FastX open, double-click one of your KLC connections in the Connections window.

2. A window will pop up. Enter your NetID password. Then click Continue.

FastX will open an SSH connection to KLC and open a Session Management window for KLC. You will have no sessions to begin with, so the window will appear to be empty.

Step 2: Start a Session

1. Click the PLUS icon in the upper right corner of the Session Management window to create a new Session. 

2. A new window will appear. Click the Bookmarks pull down menu and select an application from the drop-down list.

3. The Command box will change to start the application you chose. Your Session Management window will change to show that you have a single session,

and your application will also open:

(Optional) Step 3: Disconnecting and Reconnecting Sessions

It is possible to leave your FastX session running on the server while your client machine is disconnected. This can be useful for running long calculations.  Running sessions are listed in the FastX Session Management window. Sessions continue to run on the KLC node until you terminate them

You can disconnect from a running session without terminating it by selecting the session from the list and then clicking the Pause Button that will appear when a session is selected. You might want to disconnect in your office, go home, and then reconnect. 

You can reconnect to a paused session by double-clicking on the session, or by selecting a session and then clicking the Reconnect Button which looks like “play” button.

If a connection is lost, as in the case of a network failure, the session will disconnect. To re-establish a session after a connection loss, first open a connection to KLC. Your session still will be listed again in the Sessions window.

Step 4: Terminating Sessions

When finished, sessions should be terminated by quitting the application or typing "exit” in the terminal. Sessions can also be terminated from the FastX program by clicking the Blue X Button that appears on the right when a session is selected.

IMPORTANT NOTE: Each of the five KLC nodes has its own list of sessions, so you will have to reconnect to the same node to resume a paused session.