For the shell Gnome in Debian 9 use instruction for Ubuntu 16.04.
If there is no PPTP interface, start in the console:
apt install pptp-linux
and restart the network-manager service
1. Create a VPN server with the OpenVPN connection type
Open the program installation manual
2. Save the configuration file .ovpn
Import the .ovpn configuration manually if your OS supports it
3. To connect via the terminal, install the package openvpn
Official instruction
For the package manager apt
apt-get install openvpn
4. Enter the command in the terminal
sudo openvpn ./myvpn-vpn-xxxxxx.ovpn
Specify the path to the saved file