Accessing RC Systems

Accessing RC Systems

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Contact & Support
For support for any of our services or for general advice and consultancy, email:

After you have applied for and been granted access to our services, you can log in using a terminal application that supports the ssh access protocol.

Aristotle is a teaching machine accessible to everyone with a UCL user ID and does not need to be applied for.

Logging in from Linux or Mac OS X

Use the terminal and run the below command to ssh into the correct machine. Replace <your_UCL_user_id> with your central UCL username.


ssh <your_UCL_user_id>


ssh <your_UCL_user_id>


ssh <your_UCL_user_id>

You will then be asked to enter your UCL password. This user ID and password are those provided to you by Information Services Division.

If you will want to run graphical applications, read on to "Running graphical applications using X-forwarding".

Logging in from Windows

On Windows you need something that will give you a suitable terminal and ssh - usually PuTTY, although you could also use Cygwin if you wanted a full Linux-like environment.

Using PuTTY

PuTTY is a common SSH client on Windows and is available on Desktop@UCL. You can find it under Start > All Programs > Applications O-P > PuTTY

You will need to create an entry for the host you are connecting to with the settings below. If you want to save your settings, give them an easily-identifiable name in the "Saved Sessions" box and press "Save". Then you can select it and "Load" next time you use PuTTY.

Putty GUI

You will then have a screen come up that asks you for your username and password. Only enter your username, not "". The password field will remain entirely blank when you enter it - it does not show placeholders to indicate you have typed something.

Login problems

If you experience difficulties with your login, please make sure that you are typing your UCL user ID and your password correctly.

If you get a host key error message, have a look at Summary of Legion changes - you will need to delete old host keys.

If you still cannot get access but can access other UCL services like Socrates, please contact us on

If you cannot access anything, please see UCL MyAccount - you may need to request a password reset from the Service Desk.

Accessing services from outside UCL

If you wish to access any of our machines from outside UCL, you cannot do so directly as they are behind UCL's firewall. To do so you will have to either ssh in to UCL's gateway first:

ssh <your_UCL_user_id>

and from there ssh in to the correct host as described above, or login first to your departmental gateway (if you have one) and then login from there.

IS VPN Service

Alternatively, you can use the IS VPN service to connect to UCL using a virtual private network. That way, once the connection has been established, you can establish an ssh connection to the host machine directly, for example:

ssh <your_UCL_user_id>

Running graphical applications using X-forwarding

X-forwarding allows users to run a graphical program on a remote computer and display the user interface on their own computer.

X-forwarding on Linux

If you wish to have X-windows functionality enabled you have to make sure that you add either the -X or -Y flags (see man ssh for details) on all ssh commands you have to run to establish a connection to Legion.

For example, connecting from outside of UCL:

ssh -X <your_UCL_user_id>

and then

ssh -X <your_UCL_user_id>

X-forwarding on Mac OS X

You will need to install XQuartz to provide an X-Window System for Mac OS X. (Previously known as

You can then follow the Linux instructions using

X-forwarding on Windows

You will need:

  • An SSH client; e.g., PuTTY
  • An X server program; e.g., Exceed, Xming

Exceed is available on Desktop@UCL machines and downloadable from the UCL software database. Xming is open source (and mentioned here without testing).

Exceed on Desktop@UCL

  1. Load Exceed. You can find it under Start > All Programs > Applications O-P > Open Text Exceed 14 > Exceed
  2. Open PuTTY (Applications O-P > PuTTY)
  3. In PuTTY, set up the connection with the host machine as usual:
    1. Host name: (for example)
    2. Port: 22
    3. Connection type: SSH
  4. Then, from the Category menu, select Connection > SSH > X11 for 'Options controlling SSH X11 forwarding'
    1. Make sure the box marked 'Enable X11 forwarding' is checked.
  5. Return to the session menu and save these settings with a new identifiable name for reuse in future.
  6. Click 'Open' and login to the host as usual
  7. To test that X-forwarding is working try one of these test applications:
    1. nedit: a text editor
    2. xeyes: to bring up a set of eyes that track the mouse position on the screen
    3. glxgears: to bring up an animated set of gears
    4. xclock: a clock

If these work, you have successfully enabled X forwarding for graphical applications. (Note they may not be available on all systems).

Installing Xming on your own computer

Xming is a popular open source X server for Windows. These are instructions for using it alongside PuTTY. Other SSH clients and X servers are available. We cannot verify how well it may be working.

  1. Install both PuTTY and Xming if you have not done so already. During Xming installation, choose not to install an SSH client.
  2. Open Xming - the Xming icon should appear on the task bar.
  3. Open PuTTY
  4. Set up PuTTY as shown in the Exceed section.

Transferring files

Read on to Managing data on RC systems.