Login Nodes

Introduction

The login nodes are the place where you can interact with the cluster (batch system, storage, software, ...). Please be aware that you share the login nodes with other users, so avoid doing heavy computations on them.

We use a load balancer to dispatch the users on different login nodes. You can access them with ssh at the following address: euler.ethz.ch.

Accessing the cluster

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Prerequisites 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, PuTTY, Git BASH or Windows Subsystem Linux (WSL) 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

From a terminal (Linux, MacOS, Git BASH, WSL) Start a terminal Use ssh command to connect to the login node of Euler $ ssh username@euler.ethz.ch Use your ETH credentials to log in

For Windows users How to access the cluster with MobaXterm: MobaXterm is a convenient tool for accessing the cluster as it includes an SSH client, a local shell and data transfer functions. How to access the cluster with PuTTY: PuTTY is an SSH client and does not provide a local shell. WinSCP can import a saved PuTTY session to create a connection for data transfer. To run Jupyter Notebook or VSCode on Euler

For new users and unverified accounts Upon the first login, a verification code should be sent to your ETH email address (username@ethz.ch) 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 http://smartdesk.ethz.ch Access code (ending in ******Ls): Accept the cluster’s usage rules upon the first access

Login options To use GUI on the cluster In MobaXterm, X11 forwarding is already included and enabled In PuTTY, go to Connection > SSH > X11, check the box Enable X11 forwarding From a terminal (Linux, MacOS, Git BASH, WSL), users have to enable X11 forwarding when log in $ ssh -Y username@euler.ethz.ch After a successful login with password, generate SSH keys for passwordless login

Who can access the cluster

Euler CPU Euler GPU Shareholders who invest in the cluster resources ✓ Euler CPU shareholders ✓ Euler GPU 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

Security

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

Consequences:

• 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, automated tasks and running interactive tools on the cluster
• When used properly, SSH keys are much safer 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
• You can unlock keys with SSH key management tools such as ssh-agent and keychain

Step 1: Create your keys
	First, 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-copy-id -i $HOME/.ssh/id_ed25519_euler.pub username@euler.ethz.ch
Step 3: Use keys with non-default names
	The login commands become: $ ssh -i $HOME/.ssh/id_ed25519_euler username@euler.ethz.ch Alternatively, SSH clients can use this option automatically by adding the option IdentityFile in your $HOME/.ssh/config file, e.g.: Host euler HostName euler.ethz.ch User username IdentityFile ~/.ssh/id_ed25519_euler Next time you login, you can type $ ssh euler

SSH key management with SSH Agent

As we have to enter the passphrase to unlock the keys, it takes away the convenience of passwordless login. We can use an SSH agent (ssh-agent) to unlock the SSH keys.

$ eval `ssh-agent`
Agent pid 17906

$ ssh-add $HOME/.ssh/id_ed25519_euler
Enter passphrase for id_ed25519_euler:
Identity added: id_ed15519_euler (username@local-computer-name)

Further reading

• New account request process for HPC clusters
• User guide: Accessing the clusters
• Troubleshooting

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