URI Scheme for Session Traversal Utilities for NAT (STUN) Protocol
draft-nandakumar-rtcweb-stun-uri-03
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 7064.
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|
|---|---|---|---|
| Authors | Suhas Nandakumar , Gonzalo Salgueiro , Paul Jones , Marc Petit-Huguenin | ||
| Last updated | 2013-01-23 | ||
| RFC stream | (None) | ||
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by Russ Housley
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| Stream | Stream state | (No stream defined) | |
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| IESG | IESG state | Became RFC 7064 (Proposed Standard) | |
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draft-nandakumar-rtcweb-stun-uri-03
RTCWEB S. Nandakumar
Internet-Draft G. Salgueiro
Intended status: Standards Track P. Jones
Expires: March 17, 2013 Cisco Systems
M. Petit-Huguenin
Impedance Mismatch
January 23, 2013
URI Scheme for Session Traversal Utilities for NAT (STUN) Protocol
draft-nandakumar-rtcweb-stun-uri-03
Abstract
This document is the specification of the syntax and semantics of the
Uniform Resource Identifier (URI) scheme for the Session Traversal
Utilities for NAT (STUN) protocol.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. This document may not be modified,
and derivative works of it may not be created, except to format it
for publication as an RFC or to translate it into languages other
than English.
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 17, 2013.
Copyright Notice
Copyright (c) 2012 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
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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
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Definition of the STUN or STUNS URI . . . . . . . . . . . . . . 3
3.1. URI Scheme Syntax . . . . . . . . . . . . . . . . . . . . . 3
3.2. URI Scheme Semantics . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
5.1. STUN URI Registration . . . . . . . . . . . . . . . . . . . 5
5.2. STUNS URI Registration . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . . 7
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . . 7
Appendix B. Design Notes . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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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
STUN server or any Internet host performing the operations of a STUN
server in the context of STUN usages (Section 14 RFC 5389 [RFC5389]).
With the advent of standards such as 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 endpoints and/or applications to be
provisioned with appropriate configuration required to identify the
STUN 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 'stun/stuns' URI
scheme helps alleviate most of these issues by providing a consistent
way to describe, 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].
3. Definition of the STUN or STUNS URI
3.1. URI Scheme Syntax
The "stun" URI takes the following form (the example below is non-
normative):
stun:<stun-host>:<stun-port>
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stuns:<stun-host>:<stun-port>
Note that the <port> part and the preceding ":" (colon) character, is
OPTIONAL.
A STUN/STUNS URI has the following formal ABNF syntax [RFC5234]:
stunURI = scheme ":" stun-host [ ":" stun-port ]
scheme = "stun" / "stuns"
stun-host = IP-literal / IPv4address / reg-name
stun-port = *DIGIT
IP-literal = "[" ( IPv6address / IPvFuture ) "]"
IPvFuture = "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )
IPv6address = 6( h16 ":" ) ls32
/ "::" 5( h16 ":" ) ls32
/ [ h16 ] "::" 4( h16 ":" ) ls32
/ [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
/ [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
/ [ *3( h16 ":" ) h16 ] "::" h16 ":" ls32
/ [ *4( h16 ":" ) h16 ] "::" ls32
/ [ *5( h16 ":" ) h16 ] "::" h16
/ [ *6( h16 ":" ) h16 ] "::"
h16 = 1*4HEXDIG
ls32 = ( h16 ":" h16 ) / IPv4address
IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
dec-octet = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255
reg-name = *( unreserved / pct-encoded / sub-delims )
<unreserved>, <sub-delims>, and <pct-encoded> are specified in
[RFC3986]. The core rules <DIGIT> and <HEXDIGIT> are used as
described in Appendix B of RFC 5234 [RFC5234].
3.2. URI Scheme Semantics
The STUN protocol supports sending messages over UDP, TCP or 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) and the "stun" scheme
MUST be used otherwise.
The required <stun-host> part of the "stun" URI denotes the STUN
server host.
For the optional DNS Discovery procedure mentioned in the Section 9
of RFC5389, "stun" URI scheme implies UDP as the transport protocol
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for SRV lookup and "stuns" URI scheme indicates TCP as the transport
protocol.
The <stun-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 RFC 5389 [RFC5389].
4. Security Considerations
The "stun" and "stuns" URI schemes do not introduce any specific
security issues beyond the security considerations discussed in
[RFC3986].
5. IANA Considerations
This section contains the registration information for the "stun" and
"stuns" URI Schemes (in accordance with [RFC4395]).
5.1. STUN URI Registration
URI scheme name: stun
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 "stun" URI scheme is intended to be used by applications that
might need access to a STUN server.
Interoperability considerations: N/A
Security considerations: See Section 4.
Contact: Suhas Nandakumar <snandaku@cisco.com>
Author/Change controller: The IESG
References: RFCXXXX
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[[NOTE TO RFC EDITOR: Please change XXXX to the number assigned to
this specification, and remove this paragraph on publication.]]
5.2. STUNS URI Registration
URI scheme name: stuns
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 "stuns" URI scheme is intended to be used by applications that
might need access to a STUN server over a secure connection.
Interoperability considerations: N/A
Security considerations: See Section 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. Acknowledgements
Many thanks to Cullen Jennings for his detailed review and thoughtful
comments on this document.
Thanks to Ted Hardie, Bjoern Hoehrmann for their comments,
suggestions and questions that helped to improve the this document.
This document was written with the xml2rfc tool described in
[RFC2629].
7. References
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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.
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.
[WEBRTC] W3C, "WebRTC 1.0: Real-time Communication Between
Browsers".
<http://dev.w3.org/2011/webrtc/editor/webrtc.html>.
Appendix A. Examples
Table 1 shows examples for 'stun/stuns'uri scheme. 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
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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 need of
";proto=" for the STUN URI cannot be sufficiently explained and
supporting it would render into an incomplete specification. This
would also result in loosing 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>
Authors' Addresses
Suhas Nandakumar
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
US
Email: snandaku@cisco.com
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
Marc Petit-Huguenin
Impedance Mismatch
Email: petithug@acm.org
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