Connect with SSH

To access the Scientific Compute Cluster, you need

  1. an SSH client

Please note, that you can only connect to our frontends from inside the GÖNET, our campus network. If you are not inside GÖNET, you can either use a VPN or use to login.gwdg.de as a jump host.

This documentation shows how to generate SSH keys and connect with the ssh client on the command line in Linux, MacOS and Windows 10. If you want to use a graphical application, please refer to MobaXterm and PuTTY.

Since May 15th, 2020, authenticitation by password has been deactivated for security reasons. To log on to the frontends an SSH key is required.

Creating SSH Keys

On Linux, macOS and the latest Windows 10 Versions SSH is already built in. A key can be generated with the command ssh-keygen -t rsa -b 2048 -f <yourkey>. As soon as you enter the command you will be asked to secure the key with a passphrase. Please do not use keys without a passphrase to log in to our systems.

PS C:\Users\win10-virtual> ssh-keygen -t rsa -b 2048 -f .ssh/id-rsa
Generating public/private rsa key pair.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in .ssh/id-rsa.
Your public key has been saved in .ssh/id-rsa.pub.
The key fingerprint is:
SHA256:JIFSfI6/QBdnUaVsjKdHIfCqw1yjZyk96KDp07MlvbM win10-virtual@DESKTOP-N8DT68R
The key's randomart image is:
+---[RSA 2048]----+
|   o..o.ooo..    |
|  . o ooo= o     |
|   . +.++ B      |
|    o o+ =       |
|   . o+ S .      |
|   oo*.o .       |
|  o.O+*.         |
| + =o*o.         |
|+...+Eo          |
+----[SHA256]-----+

This creates both the private key file <yourkey> and a corresponding public key file <yourkey>.pub. Never give out your private key, but always upload only the public key!

Upload SSH Key

To upload a key, please log into your account on the GWDG Website, go to “My Account”. Then scroll down to “Other Settings” and click “edit”. You can now add a public key.
Note 1: If you copy your public key from a text editor or a terminal, please make sure that your editor or your terminal does not insert any linebreaks, because this will make the copy of your public key invalide.

Connecting to the System inside GÖNET

Just open a terminal and connect with ssh -i <yourkey> <userid>@login-mdc.hpc.gwdg.de or ssh login-mdc.hpc.gwdg.de -l <userid> -i <yourkey>
If you want to access one of our other frontends you can replace login-mdc with login-fas, For Example:

$ ssh login-fas.hpc.gwdg.de -l mboden -i .ssh/id-rsa
Last login: Mon Apr 20 13:54:52 2020 from i080.vpnclients.gwdg.de
gwdu102:22 14:51:56 ~ > 

Connecting to the System outside GÖNET

If you are outside the GÖNET, e.g. not on campus and are not able to connect to the VPN, you need to use login.gwdg.de as an SSH-gateway or jump host. For newer versions off SSH, this will work:

$ ssh login-fas.hpc.gwdg.de -l mboden -i .ssh/id-rsa -J login.gwdg.de
Last login: Mon Apr 20 13:54:52 2020 from i080.vpnclients.gwdg.de
gwdu103:22 14:51:56 ~ > 

If that does not work on your system, you may have an older version of SSH, which means you need to use:

$ ssh login-fas.hpc.gwdg.de -l mboden -i .ssh/id-rsa -o ProxyCommand="ssh -i .ssh/id-rsa -W %h:%p mboden@login.gwdg.de"
Last login: Mon Apr 20 13:54:52 2020 from i080.vpnclients.gwdg.de
gwdu103:22 14:51:56 ~ > 

Saving the SSH configuration

You can't be bothered to type all that everytime you want to connect to our frontends? Understandable. The good news is, you can use an SSH config to make your life easier.

The SSH config is a simple text file, which stores per-server-configuration or even global configurations for all SSH connections and is located at:

  • ${HOME}/.ssh/config on Linux and MacOS
  • %USERPROFILE%\.ssh\config on Windows 10
~/.ssh/config
host gwdg-login #can be any name you want
  hostname login.gwdg.de
  user mboden
  IdentityFile ~/.ssh/id-rsa
 
host hpc-gwdg 
  hostname gwdu101
  user mboden
  IdentityFile ~/.ssh/id-rsa
  ProxyJump gwdg-login
#  Older SSH Versions:
#  ProxyCommand ssh -W %h:%p gwdg-login
#  Windows 10
#  ProxyCommand C:\Windows\System32\OpenSSH\ssh.exe -W %h:%p gwdg-login
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