Two factor authentication (2FA) enables increased security when authenticating user sessions. TekRADIUS supports many ways to support 2FA. You can implement 2FA with TekRADIUS built-in OTP Generator. Generated OTPs must be delivered to the users via either e-mail or SMS. You will need an SMTP / SMS account and delivery service/application.
Please see more details at https://www.kaplansoft.com/tekradius/Docs/2FA-with-Built-in-OTP-Generator.pdf