Remote Access to Research Computing Resources

UCL's Research Computing services are accessible from inside the UCL firewall. If you wish to connect from outside, you need to either connect through a VPN or use SSH to log in to a machine accessible from outside and use that to "jump" through into the UCL network.

Connecting to the jump boxes

You can connect to the jump boxes by connecting with your SSH client to:

ssh0.theory.phys.ucl.ac.uk

Once connected you can then log on to the node you wish to use as normal.

You can configure your ssh client to automatically connect via these jump boxes so that you make the connection in one step.

Single-step logins using tunnelling

Linux / Unix / macOS

On the command line

# Log in to Butch, jumping via jump box
# Replace ccxxxxx with your own username.
ssh -o ProxyJump=ccxxxxx@ssh0.theory.phys.ucl.ac.uk ccxxxxx@angus.theory.phys.ucl.ac.uk

or

# Copy 'my_file', from the machine you are logged in to, into your Scratch on Kathleen
# Replace ccxxxxx with your own username.
scp -o ProxyJump=ccxxxxx@ssh0.theory.phys.ucl.ac.uk my_file ccxxxxx@angus.theory.phys.ucl.ac.uk:/Scratch/<username>

This tunnels through the jump box service in order to get you to your destination - you'll be asked for your password twice, once for each machine. You can use this to log in or to copy files.

You may also need to do this if you are trying to reach one cluster from another and there is a firewall in the way.

Using a config file

You can create a config which does this without you needing to type it every time.

Inside your ~/.ssh directory on your local machine, add the below to your config file (or create a file called config if you don't already have one).

Generically, it should be of this form where <name> can be anything you want to call this entry. You can use these as short-hand names when you run ssh.

Host <name>
   User <username>
   HostName <remote_hostname>
   proxyCommand ssh -W <remote_hostname>:22 <username>@ssh0.theory.phys.ucl.ac.uk

This proxyCommand option causes the commands you type in your client to be forwarded on over a secure channel to the specified remote host.

On newer versions of OpenSSH, you can use ProxyJump <username>@ssh0.theory.phys.ucl.ac.uk instead of this proxyCommand line.

Here are some examples - you can have as many of these as you need in your config file.

Host angus
   User ccxxxxx
   HostName angus.theory.phys.ucl.ac.uk
   proxyCommand ssh -W angus.theory.phys.ucl.ac.uk:22 <username>@ssh0.theory.phys.ucl.ac.uk

Host zed
   User ccxxxxx
   HostName zed.theory.phys.ucl.ac.uk
   proxyCommand ssh -W zed.theory.phys.ucl.ac.uk:22 <username>@ssh0.theory.phys.ucl.ac.uk

Host butch
   User ccxxxxx
   HostName butch.theory.phys.ucl.ac.uk
   proxyCommand ssh -W butch.theory.phys.ucl.ac.uk:22 <username>@ssh0.theory.phys.ucl.ac.uk

You can now just type ssh angus or scp file1 zed:~ and you will go through the jump box. You'll be asked for login details twice since you're logging in to two machines, the jump box and your endpoint.