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 Being connected to an ETH network (either through wifi or using VPN) 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)

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	✓ Upon invitation of their ETH collaborator	✓ If the ETH collaborator's share contains GPUs
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

How to access the cluster ?

From a terminal (Linux, MacOS, Git BASH, WSL)

• Make sure that you are connected to the ETH network, either by using the on-side wifi/Ethernet or by using a VPN
• 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 (not the wi-fi password, that is usually different)

For Windows users

You have several options and tools available to you :

• 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 all operating systems

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

After a successful login with password, generate SSH keys for passwordless login.

To use a 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

A word about security and legal compliance

For security reasons, the cluster is accessible only within the ETH network. Therefore, to connect from outside of the ETH network to the cluster, establish first a VPN connection. Then, connect to the cluster through SSH. For security reasons, the access to external services (e.g. git, wget, pip install,...) on Euler's compute nodes is NOT enables by default. 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, but we recommend to have a single one per device that you are using. Keep in mind that :

• 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 If you don't have an SSH key pair already, then generate a key pair with the ed25519 algorithm $ ssh-keygen -t ed25519 Enter a passphrase to protect your SSH keys

The output should give you the location of where the ssh keys has been stored, if you didn't specify any yourself. Please store this path and make sure that the paths provided in the next commands of this tutorial are matching it.

Step 2: Copy the public key to the cluster

$ ssh-copy-id -i $HOME/.ssh/id_ed25519.pub username@euler.ethz.ch

Next time you login, you can type

$ ssh euler.ethz.ch

Step 3: SSH key management with SSH Agent

The final step is to add the key to the ssh agent. This step has to be done each time that you turn off and then turn on your personal workstation. The advantage is that you would need to do it only once per session, all of the subsequent logins should be password-less. Here are the steps :

$ eval `ssh-agent`
Agent pid 17906

$ ssh-add $HOME/.ssh/id_ed25519
Enter passphrase for id_ed25519:
Identity added: id_ed15519 (username@local-computer-name)

• all of the next connections to Euler should not require any password or passphrase until you turn your computer off.

Further reading

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

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