Duo Single Sign-On for Fortinet FortiGate VPN

Overview

As business applications move from on-premises to cloud hosted solutions, users experience password fatigue due to disparate logons for different applications. Single sign-on (SSO) technologies seek to unify identities across systems and reduce the number of different credentials a user has to remember or input to gain access to resources.

While SSO is convenient for users, it presents new security challenges. If a user's primary password is compromised, attackers may be able to gain access to multiple resources. In addition, as sensitive information makes its way to cloud-hosted services it is even more important to secure access by implementing two-factor authentication and zero-trust policies.

If you're looking to protect management access to your FortiGate device with Duo SSO, please see the Duo Single Sign-On for Fortinet FortiGate Administrators instructions.

About Duo Single Sign-On

Duo Single Sign-On is our cloud-hosted SSO product which layers Duo's strong authentication and flexible policy engine on top of Fortinet FortiGate logins. Duo Single Sign-On acts as an identity provider (IdP), authenticating your users using existing on-premises Active Directory (AD) or another SSO IdP. Duo SSO prompts users for two-factor authentication and performs endpoint assessment and verification before permitting access to Fortinet FortiGate.

Duo Single Sign-On is available in Duo Premier, Duo Advantage, and Duo Essentials plans, which also include the ability to define policies that enforce unique controls for each individual SSO application. For example, you can require that Salesforce users complete two-factor authentication at every login, but only once every seven days when accessing Fortinet FortiGate. Duo checks the user, device, and network against an application's policy before allowing access to the application.

Configure Single Sign-On

Before configuring Fortinet FortiGate with Duo SSO using Security Assertion Markup Language (SAML) 2.0 authentication you'll first need to enable Duo Single Sign-On for your Duo account and configure a working authentication source.

Once you have your SSO authentication source working, continue to the next step of creating the Fortinet FortiGate application in Duo.

Create the Fortinet FortiGate Application in Duo

1. Log on to the Duo Admin Panel and navigate to Applications → Protect an Application.

2. Locate the entry for Fortinet FortiGate with a protection type of "2FA with SSO hosted by Duo (Single Sign-On)" in the applications list. Click Protect to the far-right to start configuring Fortinet FortiGate. See Protecting Applications for more information about protecting applications in Duo and additional application options. You'll need the information on the Fortinet FortiGate page under Downloads later.

3. Fortinet FortiGate uses the Username attribute when authenticating. We've mapped the bridge attribute to Duo Single Sign-On supported authentication source attribute as follows:

   Bridge Attribute	Active Directory	SAML IdP
   <Username>	sAMAccountName	Username

   If you are using a non-standard username attribute for your authentication source, check the Custom attributes box and enter the name of the attribute you wish to use instead.

4. You can adjust additional settings for your new SAML application at this time — like changing the application's name from the default value, enabling self-service, or assigning a group policy.

5. Keep the Duo Admin Panel tab open. You will come back to it later

Duo Universal Prompt

The Duo Universal Prompt provides a simplified and accessible Duo login experience for web-based applications, offering a redesigned visual interface with security and usability enhancements.

Universal Prompt	Traditional Prompt

We've already updated the Duo Fortinet FortiGate application hosted in Duo's service to support the Universal Prompt, so there's no action required on your part to update the application itself. If you created your Fortinet FortiGate application before March 2024, you can activate the Universal Prompt experience for users from the Duo Admin Panel. Fortinet FortiGate applications created after March 2024 have the Universal Prompt activated by default.

If you created your Fortinet FortiGate application before March 2024, it's a good idea to read the Universal Prompt Update Guide for more information, about the update process and the new login experience for users, before you activate the Universal Prompt for your application.

Activate Universal Prompt

Activation of the Universal Prompt is a per-application change. Activating it for one application does not change the login experience for your other Duo applications.

The "Universal Prompt" area of the application details page shows that this application is "Ready to activate", with these activation control options:

• Show traditional prompt: Your users experience Duo's traditional prompt via redirect when logging in to this application.
• Show new Universal Prompt: (Default) Your users experience the Universal Prompt via redirect when logging in to this application.

The application's Universal Prompt status shows "Activation complete" here and on the Universal Prompt Update Progress report.

Should you ever want to roll back to the traditional prompt, you can return to this setting and change it back to Show traditional prompt. However, this will still deliver the Duo prompt via redirect, not in an iframe. Keep in mind that support for the traditional Duo prompt ended for the majority of applications in March 2024.

Universal Update Progress

Click the See Update Progress link to view the Universal Prompt Update Progress report. This report shows the update availability and migration progress for all your Duo applications. You can also activate the new prompt experience for multiple supported applications from the report page instead of visiting the individual details pages for each application.

Enable Fortinet FortiGate for SSO

1. Log into the Fortinet FortiGate GUI for your Fortinet FortiGate SP appliance.

2. In the left menu sidebar, navigate to System → Certificates.

3. At the top of the page, click Create/Import and then select Remote Certificate. The "Upload Remote Certificate" window opens.

4. Return to the Duo Admin Panel. Under "Downloads", click Download certificate.

5. Return to the Fortinet FortiGate "Upload Remote Certificate" window and click Upload. Open the certificate file you downloaded earlier and then click OK.

6. In the left menu sidebar, navigate to VPN → SSL-VPN Settings. The "SSL-VPN Settings" page opens.

7. Make note of your port number in the Listen on Port field, under "Connection Settings". You will need it later.

8. In the left menu sidebar, navigate to User & Authentication → Single Sign-On.

9. At the top of the page, click Create New.

10. Enter a unique name for your SSO integration into the Name field.

11. Under "Service Provider Configuration", your IP address is pre-populated in the Address field. Add the port number you noted earlier to the end of the IP address.

    Example: 192.168.11.123:8443

12. Click Next.

13. Return to the Duo Admin Panel. Under "Metadata", copy the Entity ID and paste it into the Fortinet FortiGate Entity ID field, under "Identity Provider Details".

14. Return to the Duo Admin Panel. Copy the Assertion consumer service URL and paste it into the Fortinet FortiGate Assertion consumer service URL field.

15. Return to the Duo Admin Panel. Copy the Single logout service URL and paste it into the Fortinet FortiGate Single logout service URL field.

    

16. In Fortinet FortiGate, click the Certificate drop-down menu and select the certificate you uploaded from Duo earlier.

17. Under "Additional SAML Attributes", type Username into the Attribute used to identity users field. This is case-sensitive.

18. Type groups into the Attribute used to identity groups field. This is case-sensitive.

19. Click Submit.

20. In the top right corner of the page, click the CLI Console icon.

21. In the CLI Console, type show user saml on the command line and press Enter. This command lists your current configurations.

22. Type config user saml and press Enter.

23. Copy the entire line that contains your SSO integration name and paste it on the command line, and then press Enter.

    Example: edit "yourSSO"

24. Copy the entire set single-sign-on-url line and paste it on the command line. Do not press Enter yet.

    Example: set single-sign-on-url "https://192.168.11.123:8443/remote/saml/?acs"

25. At the end of the command, replace ?acs with login and then press Enter.

    Example: set single-sign-on-url "https://192.168.11.123:8443/remote/saml/login"

26. Type next and press Enter.

27. Type end and press Enter. Close the CLI Console.

28. In the "Name" column, double-click your SSO integration. The "Edit Single Sign-On" page opens.

29. Under "Service Provider Configuration", copy the Entity ID and paste it into the Duo Admin Panel Entity ID field, under "Service Provider".

30. Return to Fortinet FortiGate. Under "Service Provider Configuration", copy the Assertion consumer service URL and paste it into the Duo Admin Panel Assertion consumer service URL field, under "Service Provider".

    

Group Mapping

Group mapping is required. To map Duo groups to different groups in Fortinet FortiGate, do the following:

1. In the left menu sidebar, navigate to User & Authentication → User Groups.

2. In the "Group Name" column, double-click the group you want to map. The "Edit User Group" page opens.

3. Under "Remote Groups", click Add. The "Add Group Match" window opens.

4. Click the Remote Server drop-down menu and select your SSO integration.

5. At the bottom of the "Add Group Match" window, click OK.

6. In the "Edit User Group" page, click OK.

7. In the "Group Name" column, copy your mapped group and paste it into the Duo Admin Panel Fortinet Group Name field, under "Service Provider".

8. In the Duo Admin Panel, select the applicable Duo group from the Duo groups drop-down menu.

   

9. Scroll to the bottom of the page and click Save.

Learn more about Fortinet FortiGate SSO at the Fortinet Document Library.

Using SSO

You can log on to your Fortinet FortiGate by navigating to your Fortinet FortiGate SSO page using your virtual server IP address or host name with the port, i.e. https://192.168.11.123:8443.

Active Directory Login

With Active Directory as the Duo SSO authentication source, enter the primary username (email address) on the Duo SSO login page and click or tap Next.

Enter the AD primary password and click or tap Log in to continue.

Enable Duo Passwordless to log in to Duo SSO backed by Active Directory authentication without entering a password in the future.

SAML Login

With another SAML identity provider as the Duo SSO authentication source, Duo SSO immediately redirects the login attempt to that SAML IdP for primary authentication. Users do not see the Duo SSO primary login screen.

Duo Authentication

Successful verification of your primary credentials by Active Directory or a SAML IdP redirects back to Duo. Complete Duo two-factor authentication when prompted and then you'll return to Fortinet FortiGate to complete the login process.

* Universal Prompt experience shown.

You can also log into Fortinet FortiGate using Duo Central, our cloud-hosted portal which allows users to access all of their applications in one spot. Link to Fortinet FortiGate in Duo Central by adding it as an application tile. Once the tile has been added, log into Duo Central and click the tile for IdP-initiated authentication to Fortinet FortiGate.

Congratulations! Your Fortinet FortiGate users now authenticate using Duo Single Sign-On.

See the full user login experience, including expired password reset (available for Active Directory authentication sources) in the Duo End User Guide for SSO.

Enable Remembered Devices

To minimize additional Duo two-factor prompts when switching between Fortinet FortiGate and your other Duo Single Sign-On SAML applications, be sure to apply a shared "Remembered Devices" policy to your SAML applications.

Troubleshooting

Need some help? Try searching our Knowledge Base articles or Community discussions. For further assistance, contact Support.