The instruction from Studnet Bonn is really easy to follow.
Firstly, you connect your computer with the network socket in your room by cable.
Secondly, open your browser and go to this page
Thirdly, direct to this page, using your Personenkennzahl and Wohnplatznummer (both can be found in your rental contract) to register and set up your password first.
Then, set up internet login by going to this page which is for linux system. After this you will get a link through your email to activate internet access and your username
After that, I used Automatic configuration using a VPN start script
Open your terminal, type this:
$ sudo apt-get install pptp-linux
Download the shell script which create all necessary steps to build up a vpn connection in that link
$ mv ~/Downloads/vpn--bonn.sh .
Edit the script, using your username provided in you email and your password in the previous step, by typing this into your terminal
$ emacs vpn--bonn.sh &
Make the script executable:
$ sudo chmod 755 vpn--bonn.sh $ sudo ./vpn--bonn.sh start
Voilà! Now it runs automatically.