apt install strongswan-plugin-openssl sudo add-apt-repository ppa:nm-l2tp/network-manager-l2tp sudo apt-get update sudo apt-get install network-manager-l2tp sudo apt-get install network-manager-l2tp-gnome Source : http://parrabol.blogspot.com/2017/12/set-up-l2tp-over-ipsec-in-linux-mint-183.html