A reboot is enough to get the L2TP/Ipsec VPN Applet in the Ubuntu notification area. This GUI provides a system tray icon from which a privileged user can establish and bring down L2TP over IPsec VPN connections.
One note: I did have to stop the system xl2tpd service with sudo service xl2tpd stop before I could connect to my VPN -- otherwise xl2tpd would ignore the IPsec tunnel and try connecting directly over L2TP. L2TP Setup: Ubuntu Command Line – StrongVPN 13. Restart ipsec and xl2tpd: (starting ipsec and xl2tpd ) Type /usr/sbin/ipsec start and tap Enter key. 14. Type /etc/init.d/xl2tpd start and tap on the Enter key. 15. You are now ready to start using VPN. Startup sequence: (starting VPN connection ) ipsec up L2TP-PSK L2TP over IPsec VPN from Ubuntu to Vigor Router | DrayTek Sep 25, 2018
One note: I did have to stop the system xl2tpd service with sudo service xl2tpd stop before I could connect to my VPN -- otherwise xl2tpd would ignore the IPsec tunnel and try connecting directly over L2TP.
RUT950 L2TP over IPsec (Windows 10) - Wiki Knowledge Base
L2TP/IPSec is an advanced protocol formally standardized in IETF RFC 3193 and now the recommended replacement for PPTP where secure data encryption is required. The L2TP payload is encrypted using the standardized IPSec protocol. Regarding speed, L2TP/IPSEC encapsulates data twice making it less efficient and slightly slower than PPTP and OpenVPN.
Nov 05, 2018 Authenticate L2TP over IPsec with Freeradius | Linux