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 <userid>
  IdentityFile ~/.ssh/id-rsa
  ProxyJump gwdg-login
#  Older SSH Versions:
#  ProxyCommand ssh -i .ssh/id-rsa -W %h:%p gwdg-login
#  Windows 10
#  ProxyCommand ssh.exe -i .ssh/id-rsa -W %h:%p gwdg-login