Internet DRAFT - draft-petithuguenin-behave-turn-uris
draft-petithuguenin-behave-turn-uris
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
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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
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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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