Access Server: How to use phone calls and SMS with Duo MFA

Description

When using Access Server with the Duo post-authentication script, you can authenticate using the following methods:

• Passcode.
• Push notifications.
• Phone calls.
• SMS.

Authentication options in OpenVPN Connect v3

With default settings, when you attempt a VPN connection in the OpenVPN Connect v3 app, you'll see a Duo prompt with multiple challenge options:

Here's how to respond based on your preferred method:

1. Passcode:
   • Open the Duo app to find your passcode.
   • Enter the passcode into the Response field in the Duo prompt.
   • Once submitted, you're connected.
2. Push notifications:
   • Type "push" in the Response field.
   • You'll receive a push notification in your Duo app.
   • Accept the push notification to connect.
   • If you have multiple devices enrolled, use "push1," "push2," etc., to send the notification to a specific device.
3. Phone calls:
   • Type "phone" in the Response field.
   • If you have telephony credits, you'll receive a phone call.
   • Follow the voice instructions and confirm the login by pressing a key (based on your Duo settings).
   • If you have multiple devices enrolled, use "push1," "push2," etc., to receive the call on a specific device.
4. SMS:
   • Type "SMS" in the Response field.
   • You'll receive an SMS with a passcode if you have telephony credits.
   • The prompt will close, and the VPN connection will fail.
   • Retry the VPN connection, and in the new Duo prompt, enter the passcode you received via SMS.
   • Once submitted, you're connected.

Important notes

Telephony credits required:

• Phone calls and SMS require Duo telephony credits. Without those credits, these options won't work.
• To check your telephony credits, sign in to the Duo Admin Panel. Click Billing in the left sidebar, then select Telephony Credits.

Additional resources

• How to configure DUO MFA with Access Server
• Duo Telephony Credits

If you have additional questions, please submit a ticket.