ssh_login.md

Connecting with SSH

For security reasons, ZIH systems are only accessible for hosts within the domains of TU Dresden.

Virtual Private Network (VPN)

To access HPC systems from outside the campus networks it's recommended to set up a VPN connection to enter the campus network. While active it allows the user to connect directly to the HPC login nodes.

For more information on our VPN and how to set it up, please visit the corresponding ZIH service catalogue page.

Connecting from Linux

Please use an up-to-date SSH client. The login nodes accept the following encryption algorithms:

• aes128-ctr
• aes192-ctr
• aes256-ctr
• aes128-gcm@openssh.com
• aes256-gcm@openssh.com
• chacha20-poly1305@openssh.com
• chacha20-poly1305@openssh.com

SSH Session

If your workstation is within the campus network, you can connect to the HPC login nodes directly.

marie@local$ ssh <zih-login>@taurus.hrsk.tu-dresden.de

If you connect for the fist time, the client will ask you to verify the host by its fingerprint:

marie@local$: ssh <zih-login>@taurus.hrsk.tu-dresden.de
The authenticity of host 'taurus.hrsk.tu-dresden.de (141.30.73.104)' can't be established.
RSA key fingerprint is SHA256:HjpVeymTpk0rqoc8Yvyc8d9KXQ/p2K0R8TJ27aFnIL8.
Are you sure you want to continue connecting (yes/no)?

Compare the shown fingerprint with the documented fingerprints. Make sure they match. Than you can accept by typing y or yes.

X11-Forwarding

If you plan to use an application with graphical user interface (GUI), you need to enable X11-forwarding for the connection. Add the option -X or -XC to your SSH command. The -C enables compression which usually improves usability in this case).

marie@local$ ssh -XC <zih-login>@taurus.hrsk.tu-dresden.de

!!! info

Also consider to use a [DCV session](desktop_cloud_visualization.md) for remote desktop
visualization at ZIH systems.

Password-less SSH

Of course, password-less SSH connecting is supported at ZIH. All public SSH keys for ZIH systems have to be generated following these rules:

• The ED25519 algorithm has to be used, e.g., ssh-keygen -t ed25519
• A non-empty passphrase for the private key must be set.

The generated public key is usually saved at ~/.ssh/id_ed25519 at your local system. To allow for password-less SSH connection to ZIH systems, it has to be added to the file .ssh/authorized_keys within your home directory /home/<zih-login>/ at ZIH systems.

marie@local$ ssh -i id-ed25519 <zih-login>@taurus.hrsk.tu-dresden.de
Enter passphrase for key 'id-ed25519':

Connecting from Windows

We recommend one of the following applications:

• MobaXTerm: homepage | ZIH Tutorial
• PuTTY: homepage | ZIH Tutorial
• OpenSSH Server: docs

The page key fingerprints holds the up-to-date fingerprints for the login nodes. Make sure they match.