1. Getting set up


You MUST have PUMA, ARCHER2 and MOSRS accounts setup before starting this section.

1.1. Setup connection to PUMA & ARCHER2

To use the UM Introduction Tutorials you will first need to ensure you can connect from your local desktop to a both PUMA & ARCHER2. There a multiple ways in which you can do this depending on your desktop platform:

SSH key files

Before you try and connect to PUMA or ARCHER2, you need to make sure that you have the ssh-keys for both platforms available on your computer.

Connecting via a Terminal (GNU/Linux & macOS)

It is possible to connect via a terminal with an X11 connection (XQuartz is also required when using macOS)

Login to PUMA:

ssh -Y -i /path/to/id_rsa_puma <puma-username>@puma.nerc.ac.uk

Login to ARCHER2:

ssh -Y -i /path/to/id_rsa_archer <archer2-username>@login.archer2.ac.uk

It is also possible to define a ~/.ssh/config file entry for each with the necessary information, if desired. For example:

Host login.archer2.ac.uk
User <archer2_username>
IdentityFile ~/.ssh/id_rsa_archer
ForwardX11 no
ForwardX11Trusted no

so that you could then just connect using the command:

ssh -Y login.archer2.ac.uk

and similarly for PUMA.

Connecting via MobaXTerm

  • From Chrome, go to page: https://mobaxterm.mobatek.net/download.html

  • Under “Home Edition” select “Download now”

  • On next page select “MobaXterm Home Edition v21.4 (Portable edition)”.
    This should download the package.
  • Click the download icon in the bottom left hand corner.

  • Double-click on the MobaXterm_Personal_21.4 application file, and select “Extract all”.
    A new directory window will open up.
  • Double-click MobaXterm_Personal_21.4 to launch the application.

Next time, navigate to “Downloads” to open the application.

1.2. Set up your ARCHER2 environment

Login to ARCHER2 from your local desktop, copy the following profile to your home directory.

archer2$ cp /work/y07/shared/umshared/um-training/rose-profile ~/.profile

Change the permissions on your /home and /work directories to enable the NCAS-CMS team to help with any queries:

chmod -R g+rX /home/n02/n02/<your-username>
chmod -R g+rX /work/n02/n02/<your-username>

1.3. Set up your PUMA environment

Login to PUMA from your local desktop.

Configure ~/.profile

If this is the first time you have used your PUMA account, you will need to create a .profile. Copy our standard one:

puma$ cd
puma$ cp ~um/um-training/setup/.profile .

(If you already have a .profile, make sure it includes the lines from the standard file.)

Configure access to MOSRS

Run the mosrs-setup script which will take you through the set up process to access the Met Office Science Repository Service (Remember your MOSRS username is one word; usually firstnamelastname, all in lowercase):

puma$ ~um/um-training/mosrs-setup

Log out of PUMA and back in again (you will get a warning about not being able to find ~/.ssh/ssh-setup this can be ignored and will be resolved in the next step). You should be prompted for your Met Office Science Repository Service password. A new window should then pop up (it may be hidden behind other windows) for Rosie asking for Username for ‘u’ - ‘https://code.metoffice.gov.uk/rosie/u’ . Enter your MOSRS username again.


The cached password is configured to expire after 12 hours. Simply run the command mosrs-cache-password to re-cache it if this happens. Also if you know you won’t need access to the repositories during a login session then just press return when asked for your MOSRS password.

Configure connection to ARCHER2

Due to ARCHER2 security and the UM workflow it is necessary to generate a special ssh-key that allows submission of UM suite from PUMA.

i. Generate UM workflow ssh-key

Run the following command to generate your id_rsa_archerum ssh key:

puma$ ssh-keygen -t rsa -b 4096 -C "ARCHER2 UM Workflow" -f ~/.ssh/id_rsa_archerum

When prompted to Enter passphrase, this should be a fairly complicated and unguessable passphrase. You can use spaces in the passphrase if it helps you to remember it more readily. It is recommended that you don’t use your password in case it is hacked.

Your id_rsa_archerum key will be automatically detected and sent to ARCHER2 to be installed. This may take up to 48 hours, excluding weekends, to become activated and you will receive an email confirmation.


  • DO NOT use an empty passphrase. This presents a security issue.

  • DO NOT regenerate your id_rsa_archerum key once you have a working one in place, unless absolutely necessary.

ii. Update ssh config file

In your PUMA ~/.ssh/config file add the following section:

Host login.archer2.ac.uk
User <archer2_username>
IdentityFile ~/.ssh/id_rsa_archerum
ForwardX11 no
ForwardX11Trusted no

Where <archer2_username> should be replaced with your ARCHER2 username. If you don’t have a ~/.ssh/config file create one.

iii. Set up ssh-agent

Setting up an ssh-agent allows caching of your id_rsa_archerum key passphrase for a period of time.

puma$ cp ~um/um-training/setup/ssh-setup ~/.ssh

Log out of PUMA and back in again to start up the ssh-agent process.

Add your id_rsa_archerum key to your ssh-agent by running:

puma$ ssh-add ~/.ssh/id_rsa_archerum
Enter passphrase for /home/<puma-username>/.ssh/id_rsa:

Enter your passphrase when prompted. The ssh-agent will continue to run even when you log out of PUMA, however, it may stop from time to time, for example if PUMA is rebooted. For instructions on what to do in this situation see Restarting your ssh agent in the Appendix.

iv. Verify the setup is correct


Only proceed to this step once your id_rsa_archerum key has been installed on ARCHER2.

Log in to ARCHER2 with:

puma$ ssh login.archer2.ac.uk

You should not be prompted for your passphrase. The response from ARCHER2 should be:

puma$ ssh login.archer2.ac.uk
PTY allocation request failed on channel 0
Comand rejected by policy. Not in authorised list
Connection to login.archer2.ac.uk closed.


It is not possible to start an interactive login session on ARCHER2 from PUMA. For an interactive session you need to login from your local desktop or via your host institution.

You are now ready to try running a UM suite!