This topic describes the Active Directory Federation Services (AD FS) 2.0 topology when partner employees access applications published by Forefront Unified Access Gateway (UAG) using non-federated authentication. In this topology, partner employees authenticate to the Forefront UAG trunk using federated authentication and to the published application using non-federated authentication, for example, Kerberos constrained delegation (KCD). This topology enables you to provide a single sign-on (SSO) experience for partner employees. It also allows you to define authorization rules for published applications in Forefront UAG that are based on the incoming claims.

Topology Description

The following diagram shows the main components in the system.


In this topology:

  • Forefront UAG is configured as a relying party of the corporate AD FS 2.0 server (Resource Federation server in the diagram).

  • A separate Active Directory Domain Services (AD DS) server is used within the corporation; however, you can configure AD FS 2.0 to run on your AD DS server.

  • The corporate AD FS 2.0 server is configured to trust the partner federation server (Account Federation server). This trust is a federated trust, not a domain trust.

  • A web application has been published through Forefront UAG. You can publish the application using either host address translation (HAT) or alternate publishing name (APN). See Forefront UAG with AD FS 2.0 topologies.

flow

When users from the partner organization attempt to access the published application, the following simplified flow occurs:

  • The partner users attempt to access the published application using claims-based authentication by accessing the Forefront UAG portal and then clicking the published application.

  • Forefront UAG redirects the web browser request to the Resource Federation server to authenticate the user.

  • The Resource Federation server shows the home realm discovery page to users on which they must choose the organization to which they belong; in this case, the partner organization.

  • The Resource Federation server redirects the web browser to the Account Federation server where users authenticate using their own credentials, after which they receive a security token. Some authentication schemes prompt for credentials.

  • Users are silently redirected several times and automatically authenticated using the security token created by the Account Federation server to the Resource Federation server and then to Forefront UAG.

    If the published application supports the Kerberos version 5 protocol, Forefront UAG can perform SSO to the application using Kerberos constrained delegation – the user is not required to enter credentials.

    If the published application uses NTLM, on first using the application, users must enter credentials for the AD DS server in the resource organization. When accessing a second application through the Forefront UAG portal that uses NTLM and the same AD DS server, Forefront UAG can perform SSO.

    Javascript must be enabled on the client browser.
  • After the first successful connection to the Forefront UAG portal, the Resource Federation server stores a cookie on the user’s computer. The cookie is stored by default for 30 days; the duration is configurable in the web.config file on the Resource Federation server. During this time, users are not required to answer identification questions on the home realm discovery page; that is, choosing the organization to which they belong.

Deployment tasks