Internet Engineering Task Force (IETF) R. Mahy
Request for Comments: 5766 Unaffiliated
Category: Standards Track P. Matthews
ISSN: 2070-1721 Alcatel-Lucent
J. Rosenberg
jdrosen.net
April 2010
Traversal Using Relays around NAT (TURN):
Relay Extensions to Session Traversal Utilities for NAT (STUN)
Abstract
If a host is located behind a NAT, then in certain situations it can
be impossible for that host to communicate directly with other hosts
(peers). 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 TURN (Traversal
Using Relays around NAT), that allows the host to control the
operation of the relay and to exchange packets with its peers using
the relay. TURN differs from some 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 ICE
(Interactive Connectivity Establishment) approach to NAT traversal,
though it also can be used without ICE.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc5766.
Mahy, et al. Standards Track [Page 1]RFC 5766 TURN April 2010Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Overview of Operation . . . . . . . . . . . . . . . . . . . . 5
2.1. Transports . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2. Allocations . . . . . . . . . . . . . . . . . . . . . . . 9
2.3. Permissions . . . . . . . . . . . . . . . . . . . . . . . 11
2.4. Send Mechanism . . . . . . . . . . . . . . . . . . . . . . 12
2.5. Channels . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6. Unprivileged TURN Servers . . . . . . . . . . . . . . . . 15
2.7. Avoiding IP Fragmentation . . . . . . . . . . . . . . . . 16
2.8. RTP Support . . . . . . . . . . . . . . . . . . . . . . . 17
2.9. Anycast Discovery of Servers . . . . . . . . . . . . . . . 17
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 18
4. General Behavior . . . . . . . . . . . . . . . . . . . . . . . 19
5. Allocations . . . . . . . . . . . . . . . . . . . . . . . . . 22
6. Creating an Allocation . . . . . . . . . . . . . . . . . . . . 23
6.1. Sending an Allocate Request . . . . . . . . . . . . . . . 23
6.2. Receiving an Allocate Request . . . . . . . . . . . . . . 24
6.3. Receiving an Allocate Success Response . . . . . . . . . . 28
6.4. Receiving an Allocate Error Response . . . . . . . . . . . 29
7. Refreshing an Allocation . . . . . . . . . . . . . . . . . . . 31
7.1. Sending a Refresh Request . . . . . . . . . . . . . . . . 31
7.2. Receiving a Refresh Request . . . . . . . . . . . . . . . 31
7.3. Receiving a Refresh Response . . . . . . . . . . . . . . . 32
8. Permissions . . . . . . . . . . . . . . . . . . . . . . . . . 32
9. CreatePermission . . . . . . . . . . . . . . . . . . . . . . . 34
9.1. Forming a CreatePermission Request . . . . . . . . . . . . 34
9.2. Receiving a CreatePermission Request . . . . . . . . . . . 34
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