This document defines the Tunnel Extensible Authentication Protocol (TEAP) version 1. TEAP is a tunnel-based EAP method that enables secure communication between a peer and a server by using the Transport Layer Security (TLS) protocol to establish a mutually authenticated tunnel. Within the tunnel, TLV objects are used to convey authentication-related data between the EAP peer and the EAP server. This document obsoletes RFC 7170 and updates RFC 9427 by moving all TEAP specifications from those documents to this one.