To be able to work freely you have to build up a VPN connection to this university.
Proceed as follows:

• unlock universe sources:
  • open System Settings
    
  • System
  • Software & Updates
    
  • Ubuntu Software
  • select Community-maintained free and open-source software (universe)
  • Close
  • Finaly answer "Reload" on the question if you want to update the cache
    
• install the following pakages:
  • Ubuntu/Debian:
    • network-manager-openconnect
    • network-manager-openconnect-gnome
    
    for example in the terminal with sudo apt-get install network-manager-openconnect network-manager-openconnect-gnome
  • openSUSE 13.2:
    • NetworkManager-openconnect-0.9.10.0-2.1.4.x86_64
    • openconnect-6.00-3.1.3.x86_64
  • Arch Linux
    • networkmanager-openconnect
    for example in the terminal with pacman -S networkmanager-openconnect
    
    
  • open the Network-Manager
    • Add and choose a Connection Type ⇒ Multiprotocol-VPN-Client (openconnect), not Cisco-Compatible VPN-Client (vpnc)
      
    • Connection name: TUHH-VPN (arbitrary)
    • General:
      • Gateway: any1.rz.tuhh.de
      • CA-Certificate: /etc/ssl/certs/T-TeleSec_GlobalRoot_Class_2.pem ( ⇒ Download )
    
    • Connect to TUHH-VPN
      
    • enter RZ username and password
      
    
  • for the console: sudo openconnect any1.rz.tuhh.de
    
  There is an alternative or secondary gateway: vpn.rz.tu-harburg.de
  You can repeat the steps above to create an option against the failure of the main server.

Questions/Support