Prerequisite
To be able to use VPN to access the GFZ network you have to activate VPN on the "Passwords & Services" site on the intranet.
Installing and Using Cisco AnyConnect
In case this is the first time you establish a VPN connection via ASA, you need to install the Cisco AnyConnect client. Therefore, go to https://asa.gfz-potsdam.de. As GROUP select 'GFZ-Mitarbeiter', Enter your username and password and click on 'Login'.

The client will install automatically. Click on 'Download' and follow the instructions on your display.

In case the automatic installation is not possible, click on the link below 'Install using the link below' and save the shell script on your hard disk.

Open a terminal and change into the directory where you saved the script. Execute the script as root:
chmod +x vpnsetup.shsudo ./vpnsetup.sh

Open the VPN client under Applications → Internet → Cisco AnyConnect Secure Mobility Client. Next to 'Connect to', enter 'asa.gfz-potsdam.de', choose 'GFZ-Mitarbeiter' as group and enter your username and password. Click on 'Connect'.

Installing and Using Openconnect
OpenConnect can be used as an alternative for the Cisco AnyConnect Client.
Open a terminal window and run the following command as root:
On Ubuntu machines:
apt-get install openconnect
On Suse machines:
zypper in openconnect
OpenConnect has to be run as root.
On Ubuntu machines:
openconnect --script=/usr/share/vpnc-scripts/vpnc-script --authgroup=GFZ asa.gfz-potsdam.de
On Suse machines:
openconnect --script=/etc/vpnc/vpnc-script --authgroup=GFZ asa.gfz-potsdam.de
Enter your username and password when prompted. The connection will now be established.
You can interrupt the connection by pressing CTRL+C.
To run the program in background add "-b" to the start command you can find above. To kill the process use the following command:
kill -HUP <pid>