1 Introduction

The Active Directory Federation Services (AD FS) Proxy Protocol is used by a security token service (STS) proxy to obtain configuration data about an STS in order to assist users in selecting an acceptable security realm from which to obtain a security token. The protocol is also used by an STS to relay Microsoft Web Browser Federated Sign-On Protocol [MS-MWBF] requests back to an STS.

Sections 1.5, 1.8, 1.9, 2, and 3 of this specification are normative. All other sections and examples in this specification are informative.