STUN

RFC 7983 defines a scheme for a Real-time Transport Protocol (RTP) receiver to demultiplex Datagram Transport Layer Security (DTLS), Session Traversal Utilities for NAT (STUN), Secure Real-time Transport Protocol (SRTP) / Secure Real-time Transport Control Protocol (SRTCP), ZRTP, and Traversal Using Relays around NAT (TURN) channel packets arriving on a single port. This document updates RFC 7983 and RFC 5764 to also allow QUIC packets to be multiplexed on a single receiving socket.

Session Traversal Utilities for NAT (STUN) is a protocol that serves as a tool for other protocols in dealing with NAT traversal. It can be used by an endpoint to determine the IP address and port allocated to it by a NAT. It can also be used to check connectivity between two endpoints and as a keep-alive protocol to maintain NAT bindings. STUN works with many existing NATs and does not require any special behavior from them.

STUN is not a NAT traversal solution by itself. Rather, it is a tool to be used in the context of a NAT traversal solution.

This document obsoletes RFC 5389.

If a host is located behind a NAT, it can be impossible for that host to communicate directly with other hosts (peers) in certain situations. In these situations, it is necessary for the host to use the services of an intermediate node that acts as a communication relay. This specification defines a protocol, called "Traversal Using Relays around NAT" (TURN), that allows the host to control the operation of the relay and to exchange packets with its peers using the relay. TURN differs from other relay control protocols in that it allows a client to communicate with multiple peers using a single relay address.

The TURN protocol was designed to be used as part of the Interactive Connectivity Establishment (ICE) approach to NAT traversal, though it can also be used without ICE.

This document obsoletes RFCs 5766 and 6156.

Current Traversal Using Relays around NAT (TURN) server discovery mechanisms are relatively static and limited to explicit configuration. These are usually under the administrative control of the application or TURN service provider, and not the enterprise, ISP, or the network in which the client is located. Enterprises and ISPs wishing to provide their own TURN servers need auto-discovery mechanisms that a TURN client could use with minimal or no configuration. This document describes three such mechanisms for TURN server discovery.

This document updates RFC 5766 to relax the requirement for mutual authentication in certain cases.

It is desirable to minimize traffic disruption caused by changing IP address during a mobility event. One mechanism to minimize disruption is to expose a shorter network path to the mobility event so that only the local network elements are aware of the changed IP address and the remote peer is unaware of the changed IP address.

This document provides such an IP address mobility solution using Traversal Using Relays around NAT (TURN). This is achieved by allowing a client to retain an allocation on the TURN server when the IP address of the client changes.

This document defines how Datagram Transport Layer Security (DTLS), Real-time Transport Protocol (RTP), RTP Control Protocol (RTCP), Session Traversal Utilities for NAT (STUN), Traversal Using Relays around NAT (TURN), and ZRTP packets are multiplexed on a single receiving socket. It overrides the guidance from RFC 5764 ("SRTP Extension for DTLS"), which suffered from four issues described and fixed in this document.

This document updates RFC 5764.

A host with multiple interfaces needs to choose the best interface for communication. Oftentimes, this decision is based on a static configuration and does not consider the path characteristics, which may affect the user experience.

This document describes a mechanism for an endpoint to measure the path characteristics fractional loss and RTT using Session Traversal Utilities for NAT (STUN) messages.

To prevent WebRTC applications, such as browsers, from launching attacks by sending traffic to unwilling victims, periodic consent to send needs to be obtained from remote endpoints.

This document describes a consent mechanism using a new Session Traversal Utilities for NAT (STUN) usage.

This document proposes the use of OAuth 2.0 to obtain and validate ephemeral tokens that can be used for Session Traversal Utilities for NAT (STUN) authentication. The usage of ephemeral tokens ensures that access to a STUN server can be controlled even if the tokens are compromised.

Session Initiation Protocol (SIP) Back-to-Back User Agents (B2BUAs) are often designed to be on the media path rather than just intercepting signaling. This means that B2BUAs often act on the media path leading to separate media legs that the B2BUA correlates and bridges together. When acting on the media path, B2BUAs are likely to receive Session Traversal Utilities for NAT (STUN) packets as part of Interactive Connectivity Establishment (ICE) processing.

This document defines behavior for a B2BUA performing ICE processing. The goal of this document is to ensure that B2BUAs properly handle SIP messages that carry ICE semantics in Session Description Protocol (SDP) and STUN messages received as part of the ICE procedures for NAT and Firewall traversal of multimedia sessions.

Application-Layer Protocol Negotiation (ALPN) labels for Session Traversal Utilities for NAT (STUN) usages, such as Traversal Using Relays around NAT (TURN) and NAT discovery, are defined in this document to allow an application layer to negotiate STUN usages within the Transport Layer Security (TLS) connection. ALPN protocol identifiers defined in this document apply to both TLS and Datagram Transport Layer Security (DTLS).

This document discusses some of the security problems and practical problems with the current Session Traversal Utilities for NAT (STUN) authentication for Traversal Using Relays around NAT (TURN) messages.

This document specifies the usage of Datagram Transport Layer Security (DTLS) as a transport protocol for Session Traversal Utilities for NAT (STUN). It provides guidance on when and how to use DTLS with the currently standardized STUN usages. It also specifies modifications to the STUN and Traversal Using Relay NAT (TURN) URIs and to the TURN resolution mechanism to facilitate the resolution of STUN and TURN URIs into the IP address and port of STUN and TURN servers supporting DTLS as a transport protocol. This document updates RFCs 5389 and 5928.

This document specifies the syntax and semantics of the Uniform Resource Identifier (URI) scheme for the Session Traversal Utilities for NAT (STUN) protocol.

This specification defines a new Session Initiation Protocol (SIP) Via header field parameter, "keep", which allows adjacent SIP entities to explicitly negotiate usage of the Network Address Translation (NAT) keep-alive mechanisms defined in SIP Outbound, in cases where SIP Outbound is not supported, cannot be applied, or where usage of keep-alives is not implicitly negotiated as part of the SIP Outbound negotiation. [STANDARDS-TRACK]

This specification defines an extension of Traversal Using Relays around NAT (TURN), a relay protocol for Network Address Translator (NAT) traversal. This extension allows a TURN client to request TCP allocations, and defines new requests and indications for the TURN server to open and accept TCP connections with the client\'s peers. TURN and this extension both purposefully restrict the ways in which the relayed address can be used. In particular, it prevents users from running general-purpose servers from ports obtained from the TURN server. [STANDARDS-TRACK]

This specification defines an experimental usage of the Session Traversal Utilities for NAT (STUN) Protocol that discovers the presence and current behavior of NATs and firewalls between the STUN client and the STUN server. This document defines an Experimental Protocol for the Internet community.

The Session Traversal Utilities for NAT (STUN) protocol defines several STUN attributes. The content of some of these -- FINGERPRINT, MESSAGE-INTEGRITY, and XOR-MAPPED-ADDRESS -- involve binary-logical operations (hashing, xor). This document provides test vectors for those attributes. This document is not an Internet Standards Track specification; it is published for informational purposes.