Ubuntu 18.04 L2TP/IPSec VPN

• Install network-manager-l2tp-gnome

  $ sudo apt install network-manager-l2tp-gnome

• Add the L2TP connection in Network Manager and set the Pre-shared key, Phase1 and Phase2 Algorithms:

  Phase1 Algorithms : 3des-sha1-modp1024

  Phase2 Algorithms : 3des-sha1

• Disable and stop the system xl2tpd:

  $ sudo systemctl disable xl2tpd

  $ sudo systemctl stop xl2tpd

• If you lost internet after disconnecting from VPN, use the following script to fix the permission:

  $ sudo vim /etc/NetworkManager/dispatcher.d/02-fixresolvconf.sh

  $ sudo chmod 755 02-fixresolvconf.sh

  #!/bin/sh -e
  # Fix the permission of systemd-resolved resolv.conf after disconnected from
  # VPN in Ubuntu 18.04
  if [ "$2" = "vpn-down" ]; then
    chmod 644 /run/systemd/resolve/stub-resolv.conf
    chown systemd-resolve:systemd-resolve /run/systemd/resolve/stub-resolv.conf
  fi