https://github.com/hwdsl2/setup-ipsec-vpn
wget https://git.io/vpnsetup -O vpnsetup.sh && sudo sh vpnsetup.sh
OR,
wget https://git.io/vpnsetup -O vpnsetup.sh
nano -w vpnsetup.sh
[Replace with your own values: YOUR_IPSEC_PSK, YOUR_USERNAME and YOUR_PASSWORD]
sudo sh vpnsetup.sh