FortiOS supports two different types of authentication based on your situation and needs.

Security policy authentication is easily applied to all users logging on to a network, or network service. For example if a group of users on your network such as the accounting department who have access to sensitive data need to access the Internet, it is a good idea to make sure the user is a valid user and not someone trying to send company secrets to the Internet. Security policy authentication can be applied to as many or as few users as needed, and it supports a number of authentication protocols to easily fit with your existing network.

Virtual Private Network (VPN) authentication enables secure communication with hosts located outside the company network, making them part of the company network while the VPN tunnel is operating. Authentication applies to the devices at both ends of the VPN and optionally VPN users can be authenticated as well.