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Configure a federation trust

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Applies to: Exchange Server 2013

A federation trust establishes a trust relationship between a Microsoft Exchange 2013 organization and the Microsoft Entra authentication system. By configuring a federation trust, you can configure federated sharing with other federated Exchange organizations to share calendar free/busy information among recipients. Federated sharing can be configured between two federated Exchange 2013 organizations or between a federated Exchange 2013 organization and federated Exchange 2010 organizations. You can also set up sharing with a Microsoft 365 or Office 365 organization.

Note

Creating a federation trust is one of several steps in setting up federated sharing in your Exchange organization. To review all the steps, see Configure federated sharing.

For additional management tasks related to federation, see Federation procedures.

Important

This feature of Exchange Server 2013 isn't fully compatible with Office 365 operated by 21Vianet in China and some feature limitations may apply. For more information, see Office 365 operated by 21Vianet.

What do you need to know before you begin?

  • Estimated time to complete: 30 minutes.

  • You need to be assigned permissions before you can perform this procedure or procedures. To see what permissions you need, see the "Federation and certificates" permissions entry in the Exchange and Shell infrastructure permissions topic.

  • The domain used for establishing a federation trust should be resolvable from the Internet. This requires that the domain be registered with a domain registrar and the Domain Name System (DNS) zone for the domain to be hosted on a DNS server accessible from the Internet. If the organization receives Internet email for the domain, these requirements are already met.

  • You will need to add a TXT record to your public DNS. Review the requirements for adding a TXT record with the organization that hosts your public DNS records.

  • For information about keyboard shortcuts that may apply to the procedures in this topic, see Keyboard shortcuts in the Exchange admin center.

  • Both Exchange organizations in a federated sharing relationship must use the same Microsoft Entra authentication system for their federation trusts. This requirement applies when configuring federated sharing between two on-premises Exchange organizations or between an on-premises Exchange organization and an Exchange organization hosted by Microsoft 365 or Office 365.

  • When you create a federation trust with the Microsoft Entra authentication system for your Exchange 2013 organization, the federation trust will use the business instance of the Microsoft Entra authentication system. However, other federated Exchange organizations with previous versions of Exchange and existing federation trusts may be using either the business or consumer instance of the Microsoft Entra authentication system.

    The following Exchange organizations use the business instance of the Microsoft Entra authentication system by default:

    • Exchange 2013 organizations by using the Enable federation trust wizard and self-signed certificates for a federation trust.
    • Exchange 2010 SP1 or later organizations by using the New Federation Trust wizard and self-signed certificates for a federation trust.
    • Exchange organizations hosted by Microsoft 365 and Office 365.

    The following Exchange organizations use the consumer instance of the Microsoft Entra authentication system by default:

    • Release to manufacturing (RTM) version of Exchange 2010 organizations using certificates issued by third-party certification authorities.

    We recommend that all Exchange organizations use the business instance of the Microsoft Entra authentication system for federation trusts. Before configuring federated sharing between the two Exchange organizations, you need to verify which Microsoft Entra authentication system instance each Exchange organization is using for any existing federation trusts. To determine which Microsoft Entra authentication system instance an Exchange organization is using for an existing federation trust, run the following Shell command.

    Get-FederationInformation -DomainName <hosted Exchange domain namespace>

    The business instance returns a value of <uri:federation:MicrosoftOnline> for the TokenIssuerURIs parameter.

    The consumer instance returns a value of <uri:WindowsLiveID> for the TokenIssuerURIs parameter.

    To configure federated sharing with an Exchange organization that has an existing federation trust that's using the business instance of the Microsoft Entra authentication system, follow the steps in this topic. These steps are all you need to perform to create federation trusts that can be used to enable federated sharing between two Exchange 2013 organizations or between an Exchange 2013 organization and an Exchange 2010 organization that's already using the business instance of the Microsoft Entra authentication system.

    To configure federated sharing between your Exchange 2013 organization and an Exchange organization that has an existing federation trust that's using the consumer instance of the Microsoft Entra authentication system , the Exchange organization using the consumer instance should install Exchange 2010 SP2 or later, or upgrade to Exchange 2013. If you decide to install Exchange 2010 SP2 or later, use the New Federation Trust wizard to remove and re-create the existing federated domains and federation trusts. When the federation trusts are re-created, the business instance of the Microsoft Entra authentication system will be used.

Use the EAC to create and configure a federation trust

  1. On an Exchange 2013 server in your on-premises organization, navigate to Organization > Sharing.

  2. Click Enable to start the Enable federation trust wizard.

  3. After the wizard completes, click Close.

  4. In the Federation Trust section of the Sharing tab, click Modify.

  5. In Sharing-Enabled Domains, next to Step 1, click Browse.

  6. In Select Accepted Domains, select the primary shared domain from the list, and then click OK.

    Note

    The domain you select will be used to configure the OrgID for the federation trust. For more information about the OrgID, see Federation.

  7. Make a note of the federated domain proof that's generated for the primary shared domain. You'll use this string to create a TXT record on your public DNS server.

    Important

    The federated domain proof is a string of alphanumeric characters. To avoid input errors, we recommend that you copy the string from the EAC, and paste it into a text editor such as Notepad. You can then copy it from the text editor to the Clipboard, and then paste it into the Text field when creating the TXT record. If the TXT record is created by using an incorrect federated domain proof string, the Microsoft Entra authentication system won't be able to verify proof of domain ownership, and you won't be able to add it to the federated organization identifier.

  8. In Step 2, click Add Add Icon. to add additional domains to the federated trust for email addresses that will be used by users in your organization that require federated sharing features. For example, if you have users that use a subdomain in their email address such as sales.contoso.com, you would add the sales.contoso.com domain to the federation trust.

    Note

    A federated domain proof string will be created for each additional domain selected. You must create separate TXT records on your public DNS for each additional domain.

  9. Using the federated domain proof strings created for each domain, create TXT records for each of these domains on your public DNS server. Depending on the update schedule of your public DNS host, replication of DNS changes may take 15 minutes or longer.

  10. After the TXT records are created and replicated, click Update.

Use the Shell to create and configure a federation trust

  1. Run this command to create a unique subject key identifier for the federation trust certificate:

    $ski = [System.Guid]::NewGuid().ToString("N")

  2. Use this syntax to create a self-signed certificate for the federation trust:

    New-ExchangeCertificate -FriendlyName "<Descriptive Name>" -DomainName <domain> -Services Federation -KeySize 2048 -PrivateKeyExportable $true -SubjectKeyIdentifier $ski

    This example creates a self-signed certificate for the federation trust with the Microsoft Entra authentication system. The certificate uses the friendly name value Exchange Federated Sharing, and the domain value is retrieved from the USERDNSDOMAIN environment variable.

    New-ExchangeCertificate -FriendlyName "Exchange Federated Sharing" -DomainName $env:USERDNSDOMAIN -Services Federation -KeySize 2048 -PrivateKeyExportable $true -SubjectKeyIdentifier $ski

  3. To create the federation trust and automatically deploy the self-signed certificate that you created in the previous step to the Exchange servers in your organization, use this syntax:

    Get-ExchangeCertificate | ?{$_.FriendlyName -eq "<FriendlyName>"} | New-FederationTrust -Name "<Descriptive Name>"

    This example creates the federation trust named Microsoft Entra authentication and deploys the self-signed certificate named Exchange Federated Sharing.

    Get-ExchangeCertificate | ?{$_.FriendlyName -eq "Exchange Federated Sharing"} | New-FederationTrust -Name "Azure AD Authentication"

  4. Use this syntax to return the proof of domain ownership TXT record that's required for any domain that you'll configure for the federation trust.

    Get-FederatedDomainProof -DomainName <domain>

    This example returns the proof of domain ownership TXT record that's required for the primary shared domain contoso.com.

    Get-FederatedDomainProof -DomainName contoso.com

    Notes:

    • Each domain or subdomain that's configured for the federation trust requires a proof of domain ownership TXT record, so you might need to run this command multiple times using different DomainName values.

    • We recommend that you copy the domain proof string by right-clicking in the Shell, selecting Mark, selecting the Proof value, and then pressing Enter so you can use it when you create the TXT record. If you create the TXT record with an incorrect federated domain proof string, the Microsoft Entra authentication system can't verify your ownership of the domain, and you won't be able to add it to the federated organization identifier.

  5. Using the information from the previous step, create TXT records on your public DNS server in every domain that will be included in the federation trust. Depending on the update schedule of your public DNS host, replication of DNS changes may take 15 minutes or longer. Continue after you've verified that the new TXT records are available.

    Important

    The TXT record should be created for every domain that is being federated/shared. If this is a hybrid environment then all accepted domains that are validated in Exchange Online should have TXT records created.

  6. Run this command to retrieve the metadata and certificate from Microsoft Entra ID:

    Set-FederationTrust -RefreshMetadata -Identity "Azure AD authentication"

  7. Use this syntax to configure the primary shared domain for the federation trust that you created in Step 3. The domain that you specify will be used to configure the organization identifier (OrgID) for the federation trust. For more information about the OrgID, see Federated organization identifier.

    Set-FederatedOrganizationIdentifier -DelegationFederationTrust "<Federation Trust Name>" -AccountNamespace <Accepted Domain> -Enabled $true

    This example configures the accepted domain contoso.com as the primary shared domain for the federation trust named Microsoft Entra authentication.

    Set-FederatedOrganizationIdentifier -DelegationFederationTrust "Azure AD authentication" -AccountNamespace contoso.com -Enabled $true

  8. To add other domains to the federation trust, use this syntax:

    Add-FederatedDomain -DomainName <AdditionalDomain>

    This examples adds the subdomain sales.contoso.com to the federated trust, because users with email addresses in the sales.contoso.com domain require federated sharing features.

    Add-FederatedDomain -DomainName sales.contoso.com

    Remember, any domain or subdomain that you add to the federation trust requires a proof of domain ownership TXT record,

For detailed syntax and parameter information, see New-ExchangeCertificate, New-FederationTrust, Get-FederatedDomainProof, Set-FederationTrust, Set-FederatedOrganizationIdentifier, and Add-FederatedDomain.

How do you know this worked?

The successful completion of the Enable federation trust and Sharing-Enabled Domains wizards will be your first indication that the federation trust was configured as expected.

To further verify that you have successfully created and configured the federation trust, do the following:

  1. Run the following Shell command to verify the federation trust information.

    Get-FederationTrust | Format-List

  2. Replace <PrimarySharedDomain> with your primary shared domain, and run the following Shell command to verify that federation information can be retrieved from your organization.

    Get-FederationInformation -DomainName <PrimarySharedDomain>

For detailed syntax and parameter information, see Get-FederationTrust and Get-FederationInformation.

Tip

Having problems? Ask for help in the Exchange forums. Visit the forums at Exchange Server.