Accessing the cluster

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Accessing the clusters.png


  • A valid ETH account
  • Local computer with an SSH client
    • Linux and macOS contain SSH client in the operating system
    • Windows users need to install a third party SSH client, e.g., MobaXterm
  • An X11 server for graphical user interface (GUI) (optional)
    • Linux: Xorg is usually installed
    • macOS users need to install XQuartz
    • Windows: MobaXterm includes and enables an X11 server

How to access the cluster

  • Start your SSH client
  • Use ssh command to connect to the login node of Euler or Leonhard Open
  • Use your ETH credentials to log in

For new users and unverified accounts

  • Upon the first login, a verification code should be sent to your ETH email address (
  • Enter the verification code to the prompt
An access code has been sent to your ETH email address.
Enter the access code at the prompt below.
If you do not receive the access code within a few minutes,
then contact us by opening a ticket at

Access code (ending in ******Ls):

Login options

  • To use GUI on the cluster
    • For Windows users, X11 is already included and enabled in MobaXterm.
    • Linux and macOS users have to enable X11 forwarding when log in
   $ ssh -Y

Who can access the cluster

Euler Leonhard Open
Shareholders who invest in the cluster resources
Euler shareholders

Leonhard Open shareholders
External collaborators of shareholders
Guest users
All ETH members can access Euler as guest users with limited resources

External collaborators

Members of other institutions who have a collaboration with a research group at ETH may use the clusters for the purpose of said collaboration

  • Their counterpart (“sponsor”) at ETH can create an ETH guest account, e-mail address and VPN service for them
  • Then, they can access Euler like members of ETH


  • To connect from outside of the ETH network to the cluster, establish first a VPN connection. Then, connect to the cluster through SSH.
  • To connect from a compute node to an external service, use the ETH proxy service:
module load eth_proxy

Legal Compliance

The HPC clusters are subject to ETH’s acceptable use policy for IT resources (Benutzungsordnung für Telematik (BOT)), in particular:

  • Cluster accounts are strictly personal
  • DO NOT share your account (password, sshkeys) with anyone
  • DO NOT use someone else’s account, even if they say it’s OK
  • If you suspect that someone used your account, change your password and contact cluster support



  • In case of abuse, the offender’s account may be blocked temporarily or closed
  • System administrators are obliged by law to investigate abusive or illegal activities and report them to the relevant authorities

SSH Keys

  • SSH keys allows passwordless login which is useful for file transfers and automated tasks
  • When used properly, SSH keys are much safter than passwords
  • SSH keys always come in pairs:
    • A private key, stored on your local workstation (and nowhere else!)
    • A public key, stored on the computer(s) you want to connect to
    • You can generate as many pairs as you like, e.g., one for each computer you intend to connect to
  • Keys should be protected with a passphrase
  • SSH key management
    • ssh-agent unlocks keys for each terminal
    • keychain activates ssh-agent in every new terminal

Step 1: Create your keys

Ssh keys gen.png

Verify whether logging in with password works

  • Generate a key pair with the ed25519 algorithm for each computer you want to connect to
$ ssh-keygen -t ed25519 -f $HOME/.ssh/id_ed25519_euler
  • Enter a passphrase to protect your SSH keys

Step 2: Copy the public key to the cluster

Ssh keys copy.png

$ ssh-copy-id -i $HOME/.ssh/
$ ssh-copy-id -i $HOME/.ssh/

Step 3: Use keys with non-default names

Ssh keys connect.png

The login commands become:

$ ssh -i $HOME/.ssh/id_ed25519_euler
$ ssh -i $HOME/.ssh/id_ed25519_Leonhard

Alternatively, SSH clients can use this option automatically by adding the option IdentityFile in your $HOME/.ssh/config file, e.g.:

Host euler
User username
IdentityFile ~/.ssh/id_ed25519_euler

Next time you login, you can type

$ ssh euler

Further reading

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