Topic Last Modified: 2012-11-12

Server-to-server authentication typically involves three entities: the two servers that need to communicate with one another, and a third-party security token server. If two servers (for example, Server A and Server B) need to communicate, then both of those servers typically start by contacting a token server and obtain a mutually-trusted security token. Server A then present that security token to Server B (and vice-versa) as a way to guarantee both its authenticity and its trustworthiness.

However, that's a general rule. Lync Server 2013, Microsoft Exchange Server 2013, and Microsoft SharePoint Server 2013 do not need to use a third-party token server when communicating with one another; that's because these server products can create security tokens that can be accepted by one another without the need for a separate token server. (This capability is only available in Lync Server 2013, Exchange 2013, and SharePoint Server 2013. If you need to set up server-to-server authentication with other servers, including other Microsoft server products, then you will need to do so by using a third-party token server.)

In order to set up server-to-server authentication between Lync Server and Exchange you must do two things: 1) you must assign the appropriate certificates to each server; and, 2) you must configure each server to be a partner application of the other server: that means you must configure Lync Server 2013 to be a partner application for Exchange 2013, and you must configure Exchange 2013 to be a partner application for Lync Server 2013.

Configuring Lync Server 2013 to be a Partner Application for Exchange 2013

The easiest way to configure Lync Server 2013 to be a partner application with Exchange 2013 is to run the Configure-EnterprisePartnerApplication.ps1 script, a Windows PowerShell script that ships with Exchange 2013. To run this script, you must provide the URL for the Lync Server authentication metadata document; this will typically be the fully qualified domain name of the Lync Server 2013 pool followed by the suffix /metadata/json/1. For example:

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To configure Lync Server as a partner application, open the Exchange Management Shell and run a command similar to this (assuming that Exchange has been installed on drive C: and that it uses the default folder path):

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"C:\Program Files\Microsoft\Exchange Server\V15\Scripts\Configure-EnterprisePartnerApplication.ps1 -AuthMetaDataUrl '' -ApplicationType Lync"

After configuring the partner application it is recommended that you stop and restart Internet Information Services (IIS) on your Exchange mailbox and client access servers. You can restart IIS by using a command similar to this, which restarts the service on the computer atl-exchange-001:

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iisreset atl-exchange-001

This command can be run from within the Exchange Management Shell or from any other command window run under administrator privileges.

Configuring Exchange 2013 to be a Partner Application for Lync Server 2013

After you have configured Lync Server 2013 to be a partner application for Exchange 2013, you must then configure Exchange to be a partner application for Lync Server. This can be done by using the Lync Server Management Shell and specifying the authentication metadata document for Exchange; this will typically be the URI of the Exchange autodiscover service followed by the suffix /metadata/json/1. For example:

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In Lync Server, partner applications are configured by using the New-CsPartnerApplication cmdlet. In addition to specifying the metadata URI you should also set the application trust level to Full; this will allow Exchange to represent both itself and any authorized user in the realm. For example:

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New-CsPartnerApplication -Identity Exchange -ApplicationTrustLevel Full -MetadataUrl ""

Alternatively, you can create a partner application by copying and modifying the script code found in the Lync Server 2013 server-to-server authentication documentation. See the article Managing Server-to-Server Authentication (Oauth) and Partner Applications for more information.

If you have successfully configured partner applications for both Lync Server and Exchange that means that you have also successfully configured server-to-server authentication between the two products. Lync Server 2013 includes a Windows PowerShell cmdlet, Test-CsExStorageConnectivity, that enables you to verify that server-to-server authentication has been correctly configured and that the Lync Server Storage Service can connect to Exchange 2013. The cmdlet does this by connecting to the mailbox of an Exchange 2013 user, writing an item into the Conversation History folder for that user, and then, optionally, deleting that item.

To test the integration of Lync Server 2013 and Exchange 2013, run a command similar to this from within the Lync Server Management Shell:

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Test-CsExStorageConnectivity -SipUri ""

In the preceding command, the SipUri represents the SIP address of a user with an account on Exchange 2013; your command will fail in this is not a valid user account.

If the test succeeds and connectivity has been established, you can then proceed to configure optional features such as archiving integration and the unified contact store.