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Duo Single Sign-On for G Suite

Last Updated: April 13th, 2020

Duo offers a variety of methods for adding two-factor authentication and flexible security policies to G Suite SSO logins, complete with inline self-service enrollment and Duo Prompt.

These same instructions provide SAML SSO to Google Cloud Platform (GCP) as well, as G Suite and GCP share the underlying domain's authentication configuration. Learn more about SSO and GCP.

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.

Duo Single Sign-On

Duo Single Sign-On, now in public beta, is our cloud-hosted SSO product which layers Duo's strong authentication and flexible policy engine on top of G Suite logins using the Security Assertion Markup Language (SAML) 2.0 authentication standard. Duo Single Sign-On acts as an identity provider (IdP), authenticating your users using existing on-premises Active Directory (AD) or any SAML 2.0 IdP and prompting for two-factor authentication before permitting access to G Suite.

Duo Single Sign-On's public beta is available in Duo Beyond, Duo Access, and Duo MFA 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 G Suite. Duo checks the user, device, and network against an application's policy before allowing access to the application.

Configure Single Sign-On

Before configuring G Suite you'll first need to configure Duo Single Sign-On with a working an authentication source.

Create the G Suite Application in Duo

  1. Log on to the Duo Admin Panel and navigate to Applications.

  2. Click Protect an Application and locate the "Single Sign-On (hosted by Duo)" entry for G Suite in the applications list. Click Protect to the far-right to start configuring G Suite. See Protecting Applications for more information about protecting applications in Duo and additional application options. You'll need the information on the G Suite page under Metadata later.

Enable G Suite SSO

Add Duo Single Sign-On as a new single sign-on provider for G Suite.

  1. Log on to the Google Admin console and navigate to Security > Set up single sign-on (SSO) with a third party IdP.

  2. Check the Setup SSO with third party identity provider box.

  3. Copy the Sign-in page URL from the Duo Admin Panel Metadata section and paste it into the G Suite Sign-in page URL field.

    Example: https://sso-abc1def2.sso.duosecurity.com/saml2/sp/DIABC123678901234567/sso

  4. Copy the Sign-out page URL from the Duo Admin Panel Metadata section and paste it into the G Suite Sign-out page URL field.

    Example: https://sso-abc1def2.sso.duosecurity.com/saml2/sp/DIABC123678901234567/slo

  5. Click Download certificate next to "Verification certificate" on the Duo Admin Panel under Downloads to download the Duo Single Sign-On signing certificate. Upload the certiciate to G Suite in the Verification certificate section.

  6. Check the Use a domain-specific issuer box.

  7. If your organization has a web service for Active Directory password changes enter that URL into the "Change password URL" field. Otherwise, leave this field blank.

  8. After you've entered all the required information click SAVE.

    G Suite Single Sign-On Setting Edit

Learn more about G Suite SSO at the G Suite Help site.

Update the G Suite Application in Duo

  1. Return to the Duo Admin Panel with the G Suite application open. Find the Service Provider section.

  2. Enter your G Suite domain name in the Domain name field.

  3. G Suite uses the Mail attribute when authenticating. We've mapped the <Email Address> bridge attribute to Duo Single Sign-On supported authentication source attributes as follows:

    Bridge Attribute Active Directory SAML IdP
    <Email Address> mail Email

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

    Duo G Suite Application Settings

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

G Suite Session Duration

G Suite Business, Education, and Enterprise editions have the ability to customize how long a session remains valid after logging in with a third-party SAML IdP (like Duo Single Sign-On). Set this in the Google Admin console under SecurityGoogle session Control. Learn more about this G Suite option at the Google support site.

Verify SSO

You can log on to G Suite using your organization's domain login page e.g. https://mail.google.com/a/example.com for Gmail. This redirects to the Duo Single Sign-On login page. Enter your primary directory logon information, approve Duo two-factor authentication, and get redirected back to the G Suite site after authenticating.

Duo Single Sign-On Login and Authentication Prompt

Users can also enter the email address on the main G Suite login page https://accounts.google.com) or any and click the Sign In button (with a blank password) to be forwarded to the Duo Single Sign-On logon page.

Congratulations! Your G Suite users now authenticate using Duo Single Sign-On.

Enable Remembered Devices

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

Microsoft AD FS

Microsoft's Active Directory Federation Services (AD FS) is a popular choice for SSO because it easily integrates with the AD identity store many organizations already have deployed. Duo's support for cloud applications and SSO drops in to an existing AD FS installation to provide secondary authentication after a user passes primary authentication (successful Active Directory logon).

If you don't already have AD federation running the first step is to install and configure Microsoft AD FS in your organization. Deployment Guides for AD FS versions 2.1, and 3.0/4.0 are available from Microsoft.

Once your AD FS services are up and running, the second step is to configure the SSO partnership between your AD FS service and the external cloud resource, in this case G Suite. Learn more about configuring G Suite SSO with AD FS at the G Suite Help site.

After you have successfully configured and tested AD FS SSO login to G Suite using your AD domain credentials, you can then install the Duo AD FS integration. AD FS protection is included with Duo's paid plans.

With the Duo integration for AD FS installed, users pass primary authentication to the AD FS service as usual. Once primary authentication succeeds, users are forwarded to the Duo service for secondary authentication. After approving logon using one of Duo's authentication methods, the user is fully logged in to G Suite.

Other Identity Partners

Using a third-party SSO provider for cloud application access? Duo partners with leading cloud SSO providers like Okta and OneLogin to secure access with our strong and flexible authentication platform.

You can also use Duo two-factor authentication with CAS and Shibboleth on-premises IdPs.

Troubleshooting

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