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Versions: 00 01 02 03 04 05 06 07 08 RFC 7065

BEHAVE                                                 M. Petit-Huguenin
Internet-Draft                                        Impedance Mismatch
Intended status: Standards Track                           S. Nandakumar
Expires: March 31, 2014                                     G. Salgueiro
                                                                P. Jones
                                                           Cisco Systems
                                                      September 27, 2013


 Traversal Using Relays around NAT (TURN) Uniform Resource Identifiers
                draft-petithuguenin-behave-turn-uris-08

Abstract

   This document specifies the syntax of Uniform Resource Identifier
   (URI) schemes for the Traversal Using Relays around NAT (TURN)
   protocol.  It defines two URI schemes to provision the TURN
   Resolution Mechanism [RFC5928].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 31, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Definitions of the TURN and TURNS URI . . . . . . . . . . . .   3
     3.1.  URI Scheme Syntax . . . . . . . . . . . . . . . . . . . .   3
     3.2.  URI Scheme Semantics  . . . . . . . . . . . . . . . . . .   4
   4.  Implementation Status . . . . . . . . . . . . . . . . . . . .   4
     4.1.  turnuri . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.2.  libjingle . . . . . . . . . . . . . . . . . . . . . . . .   5
     4.3.  Firefox . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  TURN URI Registration . . . . . . . . . . . . . . . . . .   6
     6.2.  TURNS URI Registration  . . . . . . . . . . . . . . . . .   7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .   9
   Appendix B.  Design Notes . . . . . . . . . . . . . . . . . . . .   9
   Appendix C.  Release notes  . . . . . . . . . . . . . . . . . . .  10
     C.1.  Modifications between petithuguenin-behave-turn-uris-08
           and petithuguenin-behave-turn-uris-07 . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   This document specifies the syntax and semantics of the Uniform
   Resource Identifier (URI) scheme for the Traversal Using Relays
   around NAT (TURN) protocol.

   The TURN protocol is a specification allowing hosts behind NAT to
   control the operation of a relay server.  The relay server allows
   hosts to exchange packets with its peers.  The peers themselves may
   also be behind NATs.  RFC 5766 [RFC5766] defines the specifics of the
   TURN protocol.

   The "turn" and "turns" URI schemes are used to designate a TURN
   server (also known as a relay) on Internet hosts accessible using the
   TURN protocol.  With the advent of standards such as [WEBRTC], we
   anticipate a plethora of endpoints and web applications to be able to
   identify and communicate with such a TURN server to carry out the
   TURN protocol.  This also implies those endpoints and/or applications
   to be provisioned with appropriate configuration required to identify



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   the TURN server.  Having an inconsistent syntax has its drawbacks and
   can result in non-interoperable solutions.  It can result in
   solutions that are ambiguous and have implementation limitations on
   the different aspects of the syntax and alike.  The "turn/turns" URI
   scheme helps alleviate most of these issues by providing a consistent
   way to describe, configure and exchange the information identifying a
   TURN server.  This would also prevent the shortcomings inherent with
   encoding similar information in non-uniform syntaxes such as the ones
   proposed in [WEBRTC], for example.

   [RFC5928] defines a resolution mechanism to convert a secure flag, a
   host name or IP address, a potentially empty port, and a potentially
   empty transport to a list of IP address, port, and TURN transport
   tuples.

   To simplify the provisioning of TURN clients, this document defines a
   TURN and a TURNS URI scheme that can carry the four components needed
   for the resolution mechanism.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "MAY", and "OPTIONAL"
   in this document are to be interpreted as described in [RFC2119] when
   they appear in ALL CAPS.  When these words are not in ALL CAPS (such
   as "should" or "Should"), they have their usual English meanings, and
   are not to be interpreted as RFC 2119 key words.

3.  Definitions of the TURN and TURNS URI

3.1.  URI Scheme Syntax

   A TURN/TURNS URI has the following formal ABNF syntax [RFC5234]:

   turnURI       = scheme ":" host [ ":" port ]
                   [ "?transport=" transport ]
   scheme        = "turn" / "turns"
   transport     = "udp" / "tcp" / transport-ext
   transport-ext = 1*unreserved


   <host>, and <port> are specified in [RFC3986].  While these two ABNF
   productions are defined in [RFC3986] as components of the generic
   hierarchical URI, this does not imply that that the turn and turns
   schemes are hierarchical URIs.  Developers MUST NOT use a generic
   hierarchical URI parser to parse a turn or turns URI.

   The <host>, <port> and <transport> components are passed without
   modification to the [RFC5928] algorithm.  <secure> is set to false if



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   <scheme> is equal to "turn" and set to true if <scheme> is equal to
   "turns" and passed to the [RFC5928] algorithm with the other
   components.

3.2.  URI Scheme Semantics

   The "turn" and "turns" URI schemes are used to designate a TURN
   server (also known as a relay) on Internet hosts accessible using the
   TURN protocol.  The TURN protocol supports sending messages over UDP,
   TCP or TLS-over-TCP.  The "turns" URI scheme MUST be used when TURN
   is run over TLS-over-TCP (or in the future DTLS-over-UDP) and the
   "turn" scheme MUST be used otherwise.

   The required <host> part of the "turn" URI denotes the TURN server
   host.

   As specified in [RFC5766] and [RFC5928], the <port> part, if present,
   denotes the port on which the TURN server is awaiting connection
   requests.  If it is absent, the default port is 3478 for both UDP and
   TCP.  The default port for TURN over TLS is 5349.

4.  Implementation Status

   Note to RFC Editor: Please remove this section and the reference to
   [RFC6982] before publication.

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in [RFC6982].
   The description of implementations in this section is intended to
   assist the IETF in its decision processes in progressing drafts to
   RFCs.  Please note that the listing of any individual implementation
   here does not imply endorsement by the IETF.  Furthermore, no effort
   has been spent to verify the information presented here that was
   supplied by IETF contributors.  This is not intended as, and must not
   be construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may
   exist.

   According to [RFC6982], "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

4.1.  turnuri




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   Organization:   Impedance Mismatch

   Name:   turnuri 0.3.4 http://debian.implementers.org/stable/source/
      turnuri.tar.gz

   Description:   A reference implementation of this document and of RFC
      5928 [RFC5928].

   Level of maturity:   Beta.

   Coverage:   Fully implements this specification and RFC 5928.

   Licensing:   AGPL3

   Contact:   Marc Petit-Huguenin <marc@petit-huguenin.org>.

4.2.  libjingle

   Organization:   Google Inc.

   Name:   libjingle revision 4831 https://code.google.com/p/chromium/
      codesearch#chromium/src/third_party/libjingle/source/talk/app/
      webrtc/peerconnection.cc

   Description:   Libjingle is a set of components provided by Google to
      implement Jingle protocols XEP-166 (http://xmpp.org/extensions/
      xep-0166.html) and XEP-167 (http://xmpp.org/extensions/
      xep-0167.html).

   Level of maturity:   Beta.

   Coverage:   Implements draft-petithuguenin-behave-turn-uris-07
      without IPv6.  The turn and turns schemes are parsed, and TLS is
      used when the secure bit is set.  The libjingle library does not
      use the SRV and NAPTR RR from the RFC 5928 resolution mechanism.

   Licensing:   BSD 3-clauses license.

   Contact:   https://code.google.com/p/chromium/

4.3.  Firefox

   Organization:   Mozilla

   Name:   Firefox Aurora 21 http://hg.mozilla.org/mozilla-central/rev/
      6b5016ab9ebb

   Description:   Mozilla Firefox is a free and open source web browser.



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   Level of maturity:   Beta.

   Coverage:   Implements draft-petithuguenin-behave-turn-uri-03 without
      RFC 5928.  The mozilla code parses the turn and turns schemes but
      does not seems to use TLS.

   Licensing:   Mozilla Public License, v2.0.

   Contact:   http://www.mozilla.org/en-US/firefox/channel/

5.  Security Considerations

   Security considerations for the resolution mechanism are discussed in
   Section 5 of [RFC5928].  Note that this section contains normative
   text defining authentication procedures to be followed by turn
   clients when TLS is used.

   The "turn" and "turns" URI schemes do not introduce any specific
   security issues beyond the security considerations discussed in
   [RFC3986].

   While the turn and turns URIs do not themselves include the username
   or password that will be used to authenticate the TURN client, in
   certain environments, such as WebRTC, the username and password will
   almost certainly be provisioned remotely by an external agent at the
   same time as a turns URI is sent to that client.  Thus, in such
   situations, if the username and password were received in clear there
   would be little or no benefit to using a turns URI.  For this reason
   a TURN client MUST ensure that the username, password, and turns URI
   and any other security-relevant parameters are received with
   equivalent security before using the turns URI.  Receiving those
   parameters over another TLS session can provide the appropriate level
   of security, if both TLS sessions are similarly parameterised, e.g.
   with commensurate strength ciphersuites.

6.  IANA Considerations

   This section contains the registration information for the "turn" and
   "turns" URI Schemes (in accordance with [RFC4395]).

6.1.  TURN URI Registration

   URI scheme name: turn

   Status: permanent

   URI scheme syntax: See Section 3.1.




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   URI scheme semantics: See Section 3.2.

   Encoding considerations: There are no encoding considerations beyond
   those in [RFC3986].

   Applications/protocols that use this URI scheme name:

      The "turn" URI scheme is intended to be used by applications with
      a need to identify a TURN server to be used for NAT traversal.

   Interoperability considerations: N/A

   Security considerations: See Section 5.

   Contact: Marc Petit-Huguenin <petithug@acm.org>

   Author/Change controller: The IESG

   References: RFCXXXX

   [[NOTE TO RFC EDITOR: Please change XXXX to the number assigned to
   this specification, and remove this paragraph on publication.]]

6.2.  TURNS URI Registration

   URI scheme name: turns

   Status: permanent

   URI scheme syntax: See Section 3.1.

   URI scheme semantics: See Section 3.2.

   Encoding considerations: There are no encoding considerations beyond
   those in [RFC3986].

   Applications/protocols that use this URI scheme name:

      The "turns" URI scheme is intended to be used by applications with
      a need to identify a TURN server to be used for NAT traversal over
      a secure connection.

   Interoperability considerations: N/A

   Security considerations: See Section 5.

   Contact: Marc Petit-Huguenin <petithug@acm.org>




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   Author/Change controller: The IESG

   References: RFCXXXX

   [[NOTE TO RFC EDITOR: Please change XXXX to the number assigned to
   this specification, and remove this paragraph on publication.]]

7.  Acknowledgements

   Thanks to Margaret Wasserman, Magnus Westerlund, Juergen
   Schoenwaelder, Sean Turner, Ted Hardie, Dave Thaler, Alfred E.
   Heggestad, Eilon Yardeni, Dan Wing, Alfred Hoenes, and Jim Kleck for
   the comments, suggestions and questions that helped improve the
   draft-petithuguenin-behave-turn-uri-bis document.

   Many thanks to Cullen Jennings for his detailed review and thoughtful
   comments on the draft-nandakumar-rtcweb-turn-uri document.

   Thanks to Bjoern Hoehrmann, Dan Wing, Russ Housley, S. Moonesamy,
   Graham Klyne, Harald Alvestrand, Hadriel Kaplan, Tina Tsou, Spencer
   Dawkins, Ted Lemon, Barry Leiba, Pete Resnick, and Stephen Farrell
   for the comments, suggestions and questions that helped improve this
   document.

   The authors would also like to express their gratitude to Dan Wing
   for his assistance in shepherding this document.  We also want to
   thank Gonzalo Camarillo, the Real-time Applications and
   Infrastructure Director, for sponsoring this document as well his
   careful reviews.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66, RFC
              3986, January 2005.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC5766]  Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using
              Relays around NAT (TURN): Relay Extensions to Session
              Traversal Utilities for NAT (STUN)", RFC 5766, April 2010.




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   [RFC5928]  Petit-Huguenin, M., "Traversal Using Relays around NAT
              (TURN) Resolution Mechanism", RFC 5928, August 2010.

8.2.  Informative References

   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", BCP 35, RFC
              4395, February 2006.

   [WEBRTC]   Bergkvist, A., Burnett, D., Jennings, C., and A.
              Narayanan, "WebRTC 1.0: Real-time Communication Between
              Browsers", World Wide Web Consortium WD WD-
              webrtc-20120821, August 2012,
              <http://www.w3.org/TR/2012/WD-webrtc-20120821>.

   [RFC6982]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", RFC 6982, July
              2013.

Appendix A.  Examples

   Table 1 shows how the <secure>, <port> and <transport> components are
   populated from various URIs.  For all these examples, the <host>
   component is populated with "example.org".

   +---------------------------------+----------+--------+-------------+
   | URI                             | <secure> | <port> | <transport> |
   +---------------------------------+----------+--------+-------------+
   | turn:example.org                | false    |        |             |
   | turns:example.org               | true     |        |             |
   | turn:example.org:8000           | false    | 8000   |             |
   | turn:example.org?transport=udp  | false    |        | UDP         |
   | turn:example.org?transport=tcp  | false    |        | TCP         |
   | turns:example.org?transport=tcp | true     |        | TLS         |
   +---------------------------------+----------+--------+-------------+

                                  Table 1

Appendix B.  Design Notes

   o  One recurring comment was to stop using the suffix "s" on URI
      scheme, and to move the secure option to a parameter (e.g.
      ";proto=tls").  We decided against this idea because the STUN URI
      does not have a ";proto=" parameter and we would have lost the
      symmetry between the TURN and STUN URIs.  A more detailed account
      of the reasoning behind this is available at <http://blog.marc
      .petit-huguenin.org/2012/09/on-design-of-stun-and-turn-uri-
      formats.html>



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   o  Following the advice of RFC 4395 section 2.2., and because the
      TURN URI does not describe a hierarchical structure, the TURN URIs
      are opaque URIs.

   o  <password> is not used in the URIs because it is deprecated
      [RFC3986].  <username> and <auth> are not used in the URIs because
      they do not guide the resolution mechanism.

   o  As discussed at IETF 72 in Dublin, there is no generic parameters
      in the URI to prevent compatibility issues.

Appendix C.  Release notes

   This section must be removed before publication as an RFC.

C.1.  Modifications between petithuguenin-behave-turn-uris-08 and
      petithuguenin-behave-turn-uris-07

   o  s/eventually/potentially/

   o  Changed the ABNF to use references from RFC 3986 instead of
      copying them.

   o  Converted the design note about hierarchical parsers into a MUST
      NOT statement.

   o  Updated the RFC 6982 forms for Chrome and Firefox.

   o  Added text in security section about verifying that username,
      password and uris are received over a secure connection.

Authors' Addresses

   Marc Petit-Huguenin
   Impedance Mismatch

   Email: petithug@acm.org


   Suhas Nandakumar
   Cisco Systems
   170 West Tasman Drive
   San Jose, CA  95134
   US

   Email: snandaku@cisco.com





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   Gonzalo Salgueiro
   Cisco Systems
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709
   US

   Email: gsalguei@cisco.com


   Paul E. Jones
   Cisco Systems
   7025 Kit Creek Road
   Research Triangle Park, NC  27709
   US

   Email: paulej@packetizer.com



































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