Overview
Server-to-server authentication is a new feature of Exchange Server 2013, Lync Server 2013, and SharePoint Server 2013. Server-to-server authentication allows one server to make a request on the behalf of a user for resources that are on another server. When two-way server-to-server authentication is configured between SharePoint Server 2013, Exchange Server 2012, and Lync Server 2013, each one of the servers trusts the requests coming from the others. With server-to-server authentication in place, you can build solutions that use features from all three. Server-to-server authentication uses the industry standard Open Authorization (OAuth) 2.0 protocol.