https://computingforgeeks.com/build-ipsec-vpn-server-with-ipsec-l2tp-and-cisco-ipsec-linux/



[µ§°O]¨Ï¥ÎUbuntu 16.04¬[³]L2TP Over IPSec VPN
https://eric0806.blogspot.com/2017/07/ubuntu-1604-l2tp-over-ipsec-vpn.html