This documentation is for people comfortable with command line interface.
Install the openvpn package for your distribution, or compile from source. You need OpenVPN 2.3.4 or newer.
For Debian/Ubuntu based systems, the command is:
sudo apt-get install openvpn
Generate and download a configuration file (My account > Services: VPN > "Generate OpenVPN configuration file" > "Generate"), and save it in your home directory (or any place you want on your computer).
When using this connection method, OpenVPN will not automatically configure your computer to use the DNS servers provided by the VPN.
You need to:
cdto that directory.
sudo openvpn --config arethusa.ovpn
Once connected, check your IP addresses.
Press Control-C when you want to stop the VPN.
The OpenVPN log is directly shown on your terminal.