Chapter 4 Authentication : Introduction to authentication : Types of authentication : VPN authentication : Authenticating SSL VPN users
  
Authenticating SSL VPN users
SSL VPN users can be
user accounts with passwords stored on the FortiGate unit
user accounts authenticated by an external RADIUS, LDAP or TACACS+ server
PKI users authenticated by certificate
You need to create a user group for your SSL VPN. Simply create a firewall user group, enable SSL VPN access for the group, and select the web portal the users will access.
SSL VPN access requires an SSL VPN security policy that permits access to members of your user group.