Duo Single Sign-On for AWS Client 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.

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 AWS Client VPN 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 AWS Client VPN.

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 AWS Client VPN. Duo checks the user, device, and network against an application's policy before allowing access to the application.

Configure Single Sign-On

Before configuring AWS Client VPN 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 AWS Client VPN application in Duo.

Create the AWS Client VPN Application in Duo

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

2. Locate the entry for AWS Client VPN 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 AWS Client VPN. See Protecting Applications for more information about protecting applications in Duo and additional application options. You'll need the information on the AWS Client VPN page under Downloads later.

3. AWS Client VPN uses the Mail attribute, First name attribute, and Last name attribute when authenticating. We've mapped the bridge attributes to Duo Single Sign-On supported authentication source attributes as follows:

   Bridge Attribute	Active Directory	SAML IdP
   <Email Address>	mail	Email
   <First Name>	givenName	FirstName
   <Last Name>	sn	LastName

   If you are using non-standard attributes for your authentication source, check the Custom attributes box and enter the name of the attributes 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 AWS Client VPN 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 AWS Client VPN application before March 2024, you can activate the Universal Prompt experience for users from the Duo Admin Panel. AWS Client VPN applications created after March 2024 have the Universal Prompt activated by default.

If you created your AWS Client VPN 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.

Add an Identity Provider

1. In your AWS console, type IAM into the Search bar at the top of the page.

2. In the search results, click IAM. The "IAM Dashboard" opens.

3. In the left menu sidebar, navigate to Access management → Identity providers. The "Identity providers" page opens.

4. Click Add provider. The "Add an Identity provider" page opens.

5. In the "Configure provider" section, click the SAML radio button.

6. Enter a unique name for your provider into the Provider name field.

7. Return to the Duo Admin Panel. Under "Downloads", click Download XML.

8. Return to the AWS Client VPN "Add an Identity provider" page. In the "Configure provider" section, click Choose file. Open the XML file you downloaded from Duo earlier.

9. Scroll down to the bottom of the page and click Add provider.

Create a Client VPN Endpoint

1. In your AWS console, type VPC into the Search bar at the top of the page.

2. In the search results, click VPC. The "VPC dashboard" opens.

3. In the left menu sidebar, navigate to Virtual private network (VPN) → Client VPN endpoints. The "Client VPN endpoints" page opens.

4. Click Create client VPN endpoint. The "Create client VPN endpoint" page opens.

5. In the "Details" section, enter a unique name for your client VPN endpoint into the Name tag field.

6. Enter a brief description for your client VPN endpoint into the Description field.

7. Enter 10.0.0.0/22 into the Client IPv4 CIDR field. This is the IP range that will be allocated to your remote users.

8. In the "Authentication information" section, click the Server certificate ARN drop-down menu and select your server certificate.

9. Click the Use user-based authentication checkbox.

10. Click the Federated authentication radio button.

11. Click the SAML provider ARN drop-down menu and select the provider you created earlier.

12. Click the Self-service SAML provider ARN drop-down menu and select the provider you created earlier.

13. In the "Other parameters" section, click the Enable split-tunnel toggle switch.

14. Click the VPC ID drop-down menu and select your VPC ID. To verify your VPC ID, go to your EC2 Dashboard and look in the "Account attributes" box.

15. Click the Security group IDs drop-down menu and select the default VPC security group.

16. Scroll down to the bottom of the page and click Create client VPN endpoint. The "Client VPN endpoints" page opens.

Associate a Target Network

1. On the "Client VPN endpoints" page, click the radio button next to your endpoint.

2. Click the Target network associations tab.

3. At the bottom of the page, click Associate target network. The "Associate target network" page opens.

4. In the "Details" section, click the VPC drop-down menu and select your VPC ID. To verify your VPC ID, go to your EC2 Dashboard and look in the "Account attributes" box.

5. Click the Choose a subnet to associate drop-down menu and select your subnet. To verify your subnet, go to your EC2 Dashboard and navigate to Instances → Instances in the left menu sidebar. On the "Instances" page, make sure the zone in the Availability Zone column matches the zone for the subnet.

6. Click Associate target network. The "Client VPN endpoints" page opens.

Add an Authorization Rule

1. On the "Client VPN endpoints" page, click the radio button next to your endpoint.

2. Click the Authorization rules tab.

3. At the bottom of the page, click Add authorization rule. The "Add authorization rule" page opens.

4. Open your AWS console in another tab. Type VPC into the Search bar at the top of the page.

5. In the search results, click VPC. The "VPC dashboard" opens.

6. In the left menu sidebar, navigate to Virtual private cloud → Your VPCs.

7. On your VPC row, copy the IP address in the IPv4 CIDR column.

8. Return to the "Add authorization rule" page. In the "Details" section, paste the IP address into the Destination network to enable access field.

9. Click the Allow access to users in a specific access group radio button.

10. Enter a unique group name into the Access group ID field.

11. Enter a brief description for your group ID into the Description field.

12. Click Add authorization rule.

13. Return to the Duo Admin Panel. Enter the group name you created in AWS Client VPN earlier into the AWS Client VPN Group, under "Service Provider".

14. Select the applicable Duo group from the Duo groups drop-down menu.

    

15. In the Duo Admin Panel, scroll down to the bottom of the page and click Save.

Configure the AWS VPN Client

1. On the "Client VPN endpoints" page, click the radio button next to your endpoint.

2. At the top of the page, click Download client configuration.

3. Open your AWS VPN Client. With the AWS VPN Client window selected, navigate to File → Manage Profiles. The "Manage Profiles" window opens.

4. Click Add Profile. The "Add Profile" window opens.

5. Enter a unique name for your profile into the Display Name field.

6. Click the VPN Configuration File and open the client configuration file you downloaded earlier.

7. Click Add Profile.

8. In the "Manage Profiles" window, click Done.

Learn more about AWS Client VPN SSO at AWS Documentation.

Using SSO

You can log on to your AWS VPN Client by opening the client and selecting your profile. Click Connect to be redirected to Duo Single Sign-On to begin authentication.

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 AWS Client VPN to complete the login process.

* Universal Prompt experience shown.

AWS Client VPN supports SP-initiated authentication only, meaning that you must start your SSO login from that application's sign-in page. You won't be able to add AWS Client VPN as an application tile in Duo Central for IdP-initiated logins.

Congratulations! Your AWS Client VPN 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 AWS Client VPN 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.