Connecting to HPC (Off Campus)

To connect to our HPC facilities remotely you must sign up for another service, request an access token, as well as configure additional settings in your SSH client application. The steps needed are explained in this guide.

• Unix Timesharing Service - Registering for this additional service
• Just In Time Access - Requesting a remote access token
• Linux and Mac OS - Configure your SSH client application
• Windows - Configure your SSH client application

You are strongly encouraged to ensure that you have followed the Connecting to HPC (On Campus) guide first, and can connect successfully while physically present in Newcastle on either our WiFi or wired ethernet networks.

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Our HPC facilities are not directly connected to the internet and to access them you must first log in to the main NUIT Unix timesharing service. This is a public-facing Linux service which will allow you to then connect to the internal-only HPC facilities.

If you wish to connect to our HPC facilities remotely, you must first sign up for the timesharing service:

• https://services.ncl.ac.uk/itservice/technical-services/unix-time-sharing/

Once you have signed up for Unix timesharing, please ensure that you can connect to that service whilst on-campus first, before you attempt to use it remotely. The instructions for using the Unix timesharing service are available here:

• https://services.ncl.ac.uk/itservice/technical-services/unix-time-sharing/ssh/

After you have successfully connected to the Unix timesharing service whilst on-campus, you may move on to the next section; Just In Time Access.

Note: The Unix timesharing service is not operated by the RSE team. For any issues or queries with that service, please contact the IT Service help desk.

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From 2025 onwards, additional security measures mean that in order to access the NUIT Unix timeshare service whilst off-campus you must submit a Just In Time access request.

On a device connected to the internet, open a web browser and navigate to: https://ama.ncl.ac.uk

You will be requested to authenticate with your normal Newcastle University IT account details. After successfully authenticating you will be shown a simple page with a single form:

Click the Select a role drop-down and choose NUIT Unix Server (finan), and then press next:

You will be asked to enter a duration for the remote access; this currently defaults to 23 hours, press next once input:

You should see a success message indicating that your remote access request has been granted:

At this point you can then proceed to using an SSH client application to connect to the Unix timesharing service whilst off-campus, for the duration you requested above. Continue reading this document to understand how to use this access request to connect to the HPC facilities.

Note: the Just In Time access request system is not operated by RSE. For any issues with this system, please contact the IT Service help desk.

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To route your SSH client through the remotely-accessible Unix timesharing service, you can add the -oProxyJump option to the ssh command. See the examples below for Comet, though the same instructions will work for Rocket:

$ ssh -oProxyJump=n1234@unix.ncl.ac.uk n1234@comet.hpc.ncl.ac.uk

You will be prompted for your password twice; first for unix.ncl.ac.uk, and secondly for comet.hpc.ncl.ac.uk:

$ ssh -oProxyJump=n1234@unix.ncl.ac.uk n1234@comet.hpc.ncl.ac.uk
(n1234@unix.ncl.ac.uk) Password: 
n1234@comet.hpc.ncl.ac.uk's password: 
Last login: Mon Mar 10 14:04:02 2025 from 10.1.2.3
 
Your Lustre usage is:  1.91M
 
/nobackup is 94% full
[n1234@login01 ~]$

It is possible to automate these settings by editing your SSH config file on your local device. On Linux this is stored as $HOME/.ssh/config.

Open up the file (or create it, if it does not exist), and add the following entries:

Host unix
   HostName unix.ncl.ac.uk
   Port 22
   User n1234
   
Host rocket
   HostName rocket.hpc.ncl.ac.uk
   Port 22
   User n1234
   ProxyJump unix
   
Host comet
   HostName comet.hpc.ncl.ac.uk
   Port 22
   User n1234
   ProxyJump unix

Where the username n1234 is used, substitute your normal University IT account.

When saved, you should be able to log in to Comet and Rocket remotely, automatically tunneling through unix.ncl.ac.uk and needing no additional command line options by giving this simple command (example given for Comet):

$ ssh comet

If you would like to log in to unix.ncl.ac.uk and Comet or Rocket in a single step, without entering multiple passwords, please read our Password-less authentication using SSH keys guide.

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The Windows SSH client takes similar options to the Linux and Mac OS ssh tool, so you can use the same –oProxyJump option to use unix.ncl.ac.uk as the jumping off point. The example below shows the syntax for user n1234 (change to be your normal University IT account) for Comet:

ssh -oProxyJump=n1234@unix.ncl.ac.uk n1234@comet.hpc.ncl.ac.uk

As per the Connecting to HPC (On Campus) guide, this needs to be run from a Windows CMD prompt, as can be seen below with an example for Rocket:

When you run the command you will be prompted to enter your password twice; first for unix.ncl.ac.uk, and then again for the HPC facility you are connecting to.

Whilst PuTTY can be configured to use unix.ncl.ac.uk as a proxy jump host to point to the HPC facilities, configuring it is not especially clear. The help guide from the developer explains it in further detail:

• https://the.earth.li/~sgtatham/putty/0.83/htmldoc/Chapter4.html#config-proxy

It is non-trivial to configure PuTTY to automate this process without needing to enter multiple passwords. If you are interested in automating this login process then we recommend moving to Mobaxterm instead and then reading our Password-less authentication using SSH keys guide.

Mobaxterm has easy to use settings that enable the use of unix.ncl.ac.uk as a jumping off point to the HPC facilities. By following the steps below you can configure Mobaxterm to connect to Comet or Rocket whilst off-campus.

First create a new session by opening the Session menu from the top bar and selecting New Session:

As normal, choose the SSH session type and fill in the usual values:

• Remote host: comet.hpc.ncl.ac.uk (or the hostname of the HPC facility you are connecting to)
• Specify username: n1234 (replace with your normal University IT account)
• Port: 22

Then, under the Network Settings tab, add the following:

• Proxy type: SSH forwarding
• Host: unix.ncl.ac.uk
• Login: n1234 (replace with your normal University IT account)
• Port: 22

Upon opening the session you will be prompted to enter your password twice; first for unix.ncl.ac.uk, and then again for comet.hpc.ncl.ac.uk (assuming you are connecting to Comet).

If you would like to automate this process, without needing to enter multiple passwords, please read our Password-less authentication using SSH keys guide.

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