Chapter 3 Authentication for FortiOS 5.0 : Introduction to authentication : Types of authentication : VPN authentication : Authenticating PPTP and L2TP VPN users
  
Authenticating PPTP and L2TP VPN users
PPTP and L2TP are older VPN tunneling protocols that do not provide authentication themselves. FortiGate units restrict PPTP and L2TP access to users who belong to one specified user group. Users authenticate themselves to the FortiGate unit by username/password. You can configure PPTP and L2TP VPNs only in the CLI. Before you configure the VPN, create a firewall user group and add to it the users who are permitted to use the VPN. Users are authenticated when they attempt to connect to the VPN. For more information about configuring PPTP or L2TP VPNs, see the FortiGate CLI Reference.