wdiff rfc7064.original rfc7064.txt

RTCWEB
Internet Engineering Task Force (IETF) S. Nandakumar
Internet-Draft
Request for Comments: 7064 G. Salgueiro
Intended status:
Category: Standards Track P. Jones
Expires: March 31, 2014
ISSN: 2070-1721 Cisco Systems
M. Petit-Huguenin
Impedance Mismatch
September 27,
November 2013

URI Scheme for the Session Traversal Utilities for NAT (STUN) Protocol
draft-nandakumar-rtcweb-stun-uri-08

Abstract

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

Status of This Memo

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provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on March 31, 2014.
http://www.rfc-editor.org/info/rfc7064.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Definition of the STUN "stun" or STUNS "stuns" URI . . . . . . . . . . . . . 3
3.1. URI Scheme Syntax . . . . . . . . . . . . . . . . . . . . 3
3.2. URI Scheme Semantics . . . . . . . . . . . . . . . . . . 4
4. Implementation Status . . . . . . . . . . . . . . . . . . . . 4
4.1. libjingle . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Firefox . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. STUN 5
5.1. "stun" URI Registration . . . . . . . . . . . . . . . . . . 6
6.2. STUNS 5
5.2. "stuns" URI Registration . . . . . . . . . . . . . . . . . 7
7. 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8 7
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 9 8
Appendix B. Design Notes . . . . . . . . . . . . . . . . . . . . 9
Appendix C. Release notes . . . . . . . . . . . . . . . . . . . 9
C.1. Modifications between draft-nandakumar-rtcweb-stun-uri-08
and draft-nandakumar-rtcweb-stun-uri-07 . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 8

1. Introduction

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

STUN is a protocol that serves as a tool for other protocols in
dealing with Network Address Translator (NAT) traversal. It can be
used by an endpoint to determine the IP address and port allocated to
it by a NAT, to perform connectivity checks between two endpoints,
and used as a keepalive protocol to maintain NAT bindings. RFC 5389
[RFC5389] defines the specifics of the STUN protocol.

The "stun" and "stuns" URI schemes are used to designate a standalone stand-
alone STUN server or any Internet host performing the operations of a
STUN server in the context of STUN usages (Section 14 of RFC 5389
[RFC5389]). With the advent of standards such as WEBRTC WebRTC [WEBRTC], we
anticipate a plethora of endpoints and web applications to be able to
identify and communicate with such a STUN server to carry out the
STUN protocol. This also implies those that endpoints and/or applications to must
be provisioned with the appropriate configuration required to identify the
STUN server. Having an inconsistent syntax has its drawbacks adds ambiguity 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. limitations.
The 'stun/stuns' "stun" and "stuns" URI
scheme helps schemes help alleviate most of these
issues by providing a consistent way to describe, configure configure, and
exchange the information identifying a STUN server. This would also prevent the shortcomings inherent with
encoding similar information in non-uniform syntaxes such as the ones
proposed in the WEBRTC Standards [WEBRTC], for example.

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, English meanings and
are not to be interpreted as RFC 2119 key words.

3. Definition of the STUN "stun" or STUNS "stuns" URI

3.1. URI Scheme Syntax

A STUN/STUNS URI has

"stun" and "stuns" URIs have the following formal ABNF syntax
[RFC5234]:

stunURI = scheme ":" host [ ":" port ]
scheme = "stun" / "stuns"

<host>,

<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 the stun "stun" and stuns "stuns" URI
schemes are hierarchical URIs. Developers MUST NOT use a generic
hierarchical URI parser to parse a stun "stun" or stuns "stuns" URI.

3.2. URI Scheme Semantics

The "stun" and "stuns" URI schemes are used to designate a standalone stand-
alone STUN server or any Internet host performing the operations of a
STUN server in the context of STUN usages (Section 14 of RFC 5389
[RFC5389]). The STUN protocol supports sending messages over UDP, TCP
TCP, or TLS-
over-TCP. TLS-over-TCP. The "stuns" URI scheme MUST be used when STUN
is run over TLS-over-TCP (or in the future DTLS-over-UDP) DTLS-over-UDP), and the
"stun" scheme MUST be used otherwise.

The required <host> part of the "stun" URI denotes the STUN server
host.

For the optional DNS Discovery discovery procedure mentioned in the Section 9 of RFC5389,
RFC 5389, the "stun" URI scheme implies UDP as the transport protocol
for SRV lookup and "stuns" URI scheme indicates TCP as the transport
protocol.

As specified in [RFC5389], the <port> part, if present, denotes the
port on which the STUN server is awaiting connection requests. If it
is absent, the default port is 3478 for both UDP and TCP. The
default port for STUN over TLS is 5349 as per Section 9 of [RFC5389].

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 lookup, and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve "stuns" URI scheme indicates TCP as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to
transport protocol.

As specified in [RFC5389], the individual working groups to use this information as
they see fit".

4.1. 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 <port> part, if present, denotes the
port on which the STUN server 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-nandakumar-rtcweb-stun-uri-07 without
IPv6. The stun and stuns schemes are parsed, and TLS awaiting connection requests. If it
is used when absent, the secure bit is set.

Licensing: BSD 3-clauses license.

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

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

4.2. Firefox

Organization: Mozilla

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

Description: Mozilla Firefox default port is a free 3478 for both UDP and open source web browser.

Level of maturity: Beta.

Coverage: Implements draft-nandakumar-rtcweb-stun-uri-03. TCP. The
mozilla code parses the turn and turns schemes but does not seems
to use TLS.

Licensing: Mozilla Public License, v. 2.0.

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

URL: http://hg.mozilla.org/mozilla-central/file/4ff1e574e509/media/
webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp

5.
default port for STUN over TLS is 5349 as per Section 9 of [RFC5389].

4. Security Considerations

The "stun" and "stuns" URI schemes do not introduce any specific
security issues beyond the security considerations discussed in
[RFC3986]. These URI schemes are intended for use in specific
environments that involve NAT traversal. Users of the scheme need to
carefully consider the security properties of the context in which
they are using them.

While the stun and stuns URIs do

Although a "stun" or "stuns" URI does not themselves itself include the username
or password that will be used to authenticate the STUN 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 stuns "stuns" URI is sent to that client. Thus, in such
situations, if the username and password were received in clear the clear,
there would be little or no benefit to using a stuns "stuns" URI. For this reason
reason, a STUN client MUST ensure that the username, password, and stuns URI
"stuns" URI, and any other security-relevant parameters are received
with equivalent security before using the stuns "stuns" URI. Receiving
those parameters over another TLS session can provide the appropriate
level of security, security if both TLS sessions are similarly parameterised, e.g. parameterized,
e.g., with commensurate strength ciphersuites.

5. IANA Considerations

This section contains the registration information for the "stun" and
"stuns" URI Schemes schemes (in accordance with [RFC4395]). Note that these
URI schemes are intended for use in very specific NAT traversal
environments,
environments and should not be used otherwise on the open Web or
Internet.

6.1. STUN

5.1. "stun" URI Registration

URI scheme name: stun

Status: permanent

URI scheme syntax: See Section 3.1. 3.1

URI scheme semantics: See Section 3.2. 3.2

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

Applications/protocols that use this URI scheme name:

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

Interoperability considerations: N/A

Security considerations: See Section 5. 4

Contact: Suhas Nandakumar <snandaku@cisco.com>

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. STUNS 7064

5.2. "stuns" URI Registration

URI scheme name: stuns

Status: permanent

URI scheme syntax: See Section 3.1. 3.1

URI scheme semantics: See Section 3.2. 3.2

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

Applications/protocols that use this URI scheme name:

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

Interoperability considerations: N/A

Security considerations: See Section 5. 4

Contact: Suhas Nandakumar <snandaku@cisco.com>

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. 7064

6. Acknowledgements

The authors would like to extend a very special thanks to Cullen
Jennings for bringing to our attention the WebRTC to WebRTC's need for this
document, as well as his detailed review and thoughtful comments on
this document.

This document has benefited from extensive discussion and review of
many of the members of the RTCWEB and BEHAVE working groups. The
authors would also like to acknowledge Ted Hardie, Bjoern Hoehrmann,
Russ Housley, Subramanian Moonesamy, Hadriel Kaplan, Graham Klyne,
Peter Saint-Andre, Ted Lemon, Barry Leiba, Pete Resnick, Spencer
Dawkins, Stephen Farrell Farrell, and Harald Alvestrand for their invaluable
input, reviews, feedback comments, and suggestions that helped to
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 Area Director, for sponsoring this document as well as
his careful reviews.

This document was written with the xml2rfc tool described in
[RFC2629].

7. References

8.1.

7.1. 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.

8.2.

7.2. Informative References

[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.

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

[RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
"Session Traversal Utilities for NAT (STUN)", RFC 5389,
October 2008.

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

[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>.

Appendix A. Examples

Table 1 shows examples for 'stun/stuns'uri scheme. the "stun" and "stuns" URI schemes. For
all these examples, the <host> component is populated with
"example.org".

+-----------------------+
| URI |
+-----------------------+
| stun:example.org |
| stuns:example.org |
| stun:example.org:8000 |
+-----------------------+

Table 1

Appendix B. Design Notes

o One recurring comment was to stop using the suffix "s" on the URI
scheme,
scheme and to move the secure option to a parameter (e.g.,
";proto=tls"). We decided against this idea because the need for
";proto=" for the STUN URI cannot be sufficiently explained explained, and
supporting it would render an incomplete specification. This
would also result in lost 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>

o Following the advice of Section 2.2 of [RFC4395], and because the
STUN URI does not describe a hierarchical structure, the STUN URIs
are opaque.

Appendix C. Release notes
NOTE TO RFC EDITOR: This section must be removed before publication
as an RFC.

C.1. Modifications between draft-nandakumar-rtcweb-stun-uri-08 and
draft-nandakumar-rtcweb-stun-uri-07

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

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

Email:
USA

EMail: snandaku@cisco.com

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

Email:
USA

EMail: gsalguei@cisco.com

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

Email:
USA

EMail: paulej@packetizer.com

Marc Petit-Huguenin
Impedance Mismatch

Email:

EMail: petithug@acm.org