How-to: Configure SMS Two Factor Authentication on a FortiGate

A while ago I wrote a 'How-to' guide on the steps required to configure SMS Two Factor Authentication using a FortiAuthenticator and a FortiGate. This involved configuring the a SMS gateway on the FortiAuthenticator using HTTP and then getting the FortiGate to send authentication requests to it.

A little known fact is that the FortiGate can actually do two factor SMS authentication out of the box, all for free and with no licenses required! There's two ways of configuring the SMS authentication. Firstly with the prepaid FortiGuard SMS servers (preconfigured) and then with your own custom SMS server.

Ttoday I decided to test out this feature with my custom SMS server and initially struggled as there's no proper documentation on how it actually works, what it sends etc. Below are the steps I took and the bits of information that I gleamed during the configuration.

How-to: Configure SMS Two Factor Authentication with FortiAuthenticator and FortiGate SSL VPN

Recently I've been doing some tests with the FortiAuthenticator using FortiMobile tokens. I decided to test out the SMS Gateway feature for sending two-factor one time passwords (OTP) straight to mobiles via SMS (something I generally don't recommend but thought it would be cool to test).

Below is the config I used to setup the FortiAuthenticator to send an OTP via SMS to my moblie for SSL VPN logins.