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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 RTCWEB S. Nandakumar 3 Internet-Draft G. Salgueiro 4 Intended status: Standards Track P. Jones 5 Expires: March 31, 2014 Cisco Systems 6 M. Petit-Huguenin 7 Impedance Mismatch 8 September 27, 2013 10 URI Scheme for Session Traversal Utilities for NAT (STUN) Protocol 11 draft-nandakumar-rtcweb-stun-uri-08 13 Abstract 15 This document is the specification of the syntax and semantics of the 16 Uniform Resource Identifier (URI) scheme for the Session Traversal 17 Utilities for NAT (STUN) protocol. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on March 31, 2014. 36 Copyright Notice 38 Copyright (c) 2013 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 3. Definition of the STUN or STUNS URI . . . . . . . . . . . . . 3 56 3.1. URI Scheme Syntax . . . . . . . . . . . . . . . . . . . . 3 57 3.2. URI Scheme Semantics . . . . . . . . . . . . . . . . . . 4 58 4. Implementation Status . . . . . . . . . . . . . . . . . . . . 4 59 4.1. libjingle . . . . . . . . . . . . . . . . . . . . . . . . 5 60 4.2. Firefox . . . . . . . . . . . . . . . . . . . . . . . . . 5 61 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 62 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 63 6.1. STUN URI Registration . . . . . . . . . . . . . . . . . . 6 64 6.2. STUNS URI Registration . . . . . . . . . . . . . . . . . 7 65 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 66 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 67 8.1. Normative References . . . . . . . . . . . . . . . . . . 8 68 8.2. Informative References . . . . . . . . . . . . . . . . . 8 69 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 9 70 Appendix B. Design Notes . . . . . . . . . . . . . . . . . . . . 9 71 Appendix C. Release notes . . . . . . . . . . . . . . . . . . . 9 72 C.1. Modifications between draft-nandakumar-rtcweb-stun-uri-08 73 and draft-nandakumar-rtcweb-stun-uri-07 . . . . . . . . . 10 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 76 1. Introduction 78 This document specifies the syntax and semantics of the Uniform 79 Resource Identifier (URI) scheme for the Session Traversal Utilities 80 for NAT (STUN) protocol. 82 STUN is a protocol that serves as a tool for other protocols in 83 dealing with Network Address Translator (NAT) traversal. It can be 84 used by an endpoint to determine the IP address and port allocated to 85 it by a NAT, to perform connectivity checks between two endpoints, 86 and used as a keepalive protocol to maintain NAT bindings. RFC 5389 87 [RFC5389] defines the specifics of the STUN protocol. 89 The "stun" and "stuns" URI schemes are used to designate a standalone 90 STUN server or any Internet host performing the operations of a STUN 91 server in the context of STUN usages (Section 14 RFC 5389 [RFC5389]). 92 With the advent of standards such as WEBRTC [WEBRTC], we anticipate a 93 plethora of endpoints and web applications to be able to identify and 94 communicate with such a STUN server to carry out the STUN protocol. 95 This also implies those endpoints and/or applications to be 96 provisioned with appropriate configuration required to identify the 97 STUN server. Having an inconsistent syntax has its drawbacks and can 98 result in non-interoperable solutions. It can result in solutions 99 that are ambiguous and have implementation limitations on the 100 different aspects of the syntax and alike. The 'stun/stuns' URI 101 scheme helps alleviate most of these issues by providing a consistent 102 way to describe, configure and exchange the information identifying a 103 STUN server. This would also prevent the shortcomings inherent with 104 encoding similar information in non-uniform syntaxes such as the ones 105 proposed in the WEBRTC Standards [WEBRTC], for example. 107 2. Terminology 109 The key words "MUST", "MUST NOT", "REQUIRED", "MAY", and "OPTIONAL" 110 in this document are to be interpreted as described in [RFC2119] when 111 they appear in ALL CAPS. When these words are not in ALL CAPS (such 112 as "should" or "Should"), they have their usual english meanings, and 113 are not to be interpreted as RFC 2119 key words. 115 3. Definition of the STUN or STUNS URI 117 3.1. URI Scheme Syntax 119 A STUN/STUNS URI has the following formal ABNF syntax [RFC5234]: 121 stunURI = scheme ":" host [ ":" port ] 122 scheme = "stun" / "stuns" 124 , and are specified in [RFC3986]. While these two ABNF 125 productions are defined in [RFC3986] as components of the generic 126 hierarchical URI, this does not imply that the stun and stuns URI 127 schemes are hierarchical URIs. Developers MUST NOT use a generic 128 hierarchical URI parser to parse a stun or stuns URI. 130 3.2. URI Scheme Semantics 132 The "stun" and "stuns" URI schemes are used to designate a standalone 133 STUN server or any Internet host performing the operations of a STUN 134 server in the context of STUN usages (Section 14 RFC 5389 [RFC5389]). 135 The STUN protocol supports sending messages over UDP, TCP or TLS- 136 over-TCP. The "stuns" URI scheme MUST be used when STUN is run over 137 TLS-over-TCP (or in the future DTLS-over-UDP) and the "stun" scheme 138 MUST be used otherwise. 140 The required part of the "stun" URI denotes the STUN server 141 host. 143 For the optional DNS Discovery procedure mentioned in the Section 9 144 of RFC5389, "stun" URI scheme implies UDP as the transport protocol 145 for SRV lookup and "stuns" URI scheme indicates TCP as the transport 146 protocol. 148 As specified in [RFC5389], the part, if present, denotes the 149 port on which the STUN server is awaiting connection requests. If it 150 is absent, the default port is 3478 for both UDP and TCP. The 151 default port for STUN over TLS is 5349 as per Section 9 of [RFC5389]. 153 4. Implementation Status 155 Note to RFC Editor: Please remove this section and the reference to 156 [RFC6982] before publication. 158 This section records the status of known implementations of the 159 protocol defined by this specification at the time of posting of this 160 Internet-Draft, and is based on a proposal described in [RFC6982]. 161 The description of implementations in this section is intended to 162 assist the IETF in its decision processes in progressing drafts to 163 RFCs. Please note that the listing of any individual implementation 164 here does not imply endorsement by the IETF. Furthermore, no effort 165 has been spent to verify the information presented here that was 166 supplied by IETF contributors. This is not intended as, and must not 167 be construed to be, a catalog of available implementations or their 168 features. Readers are advised to note that other implementations may 169 exist. 171 According to [RFC6982], "this will allow reviewers and working groups 172 to assign due consideration to documents that have the benefit of 173 running code, which may serve as evidence of valuable experimentation 174 and feedback that have made the implemented protocols more mature. 175 It is up to the individual working groups to use this information as 176 they see fit". 178 4.1. libjingle 180 Organization: Google Inc. 182 Name: libjingle revision 4831 https://code.google.com/p/chromium/ 183 codesearch#chromium/src/third_party/libjingle/source/talk/app/ 184 webrtc/peerconnection.cc 186 Description: Libjingle is a set of components provided by Google to 187 implement Jingle protocols XEP-166 (http://xmpp.org/extensions/ 188 xep-0166.html) and XEP-167 (http://xmpp.org/extensions/ 189 xep-0167.html). 191 Level of maturity: Beta. 193 Coverage: Implements draft-nandakumar-rtcweb-stun-uri-07 without 194 IPv6. The stun and stuns schemes are parsed, and TLS is used when 195 the secure bit is set. 197 Licensing: BSD 3-clauses license. 199 Contact: https://code.google.com/p/chromium/ 201 URL: https://code.google.com/p/chromium/codesearch#chromium/src/ 202 third_party/libjingle/source/talk/app/webrtc/peerconnection.cc 204 4.2. Firefox 206 Organization: Mozilla 208 Name: Firefox Aurora 21 http://hg.mozilla.org/mozilla-central/rev/ 209 6b5016ab9ebb 211 Description: Mozilla Firefox is a free and open source web browser. 213 Level of maturity: Beta. 215 Coverage: Implements draft-nandakumar-rtcweb-stun-uri-03. The 216 mozilla code parses the turn and turns schemes but does not seems 217 to use TLS. 219 Licensing: Mozilla Public License, v. 2.0. 221 Contact: http://www.mozilla.org/en-US/firefox/channel/ 223 URL: http://hg.mozilla.org/mozilla-central/file/4ff1e574e509/media/ 224 webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp 226 5. Security Considerations 228 The "stun" and "stuns" URI schemes do not introduce any specific 229 security issues beyond the security considerations discussed in 230 [RFC3986]. These URI schemes are intended for use in specific 231 environments that involve NAT traversal. Users of the scheme need to 232 carefully consider the security properties of the context in which 233 they are using them. 235 While the stun and stuns URIs do not themselves include the username 236 or password that will be used to authenticate the STUN client, in 237 certain environments, such as WebRTC, the username and password will 238 almost certainly be provisioned remotely by an external agent at the 239 same time as a stuns URI is sent to that client. Thus, in such 240 situations, if the username and password were received in clear there 241 would be little or no benefit to using a stuns URI. For this reason 242 a STUN client MUST ensure that the username, password, and stuns URI 243 and any other security-relevant parameters are received with 244 equivalent security before using the stuns URI. Receiving those 245 parameters over another TLS session can provide the appropriate level 246 of security, if both TLS sessions are similarly parameterised, e.g. 247 with commensurate strength ciphersuites. 249 6. IANA Considerations 251 This section contains the registration information for the "stun" and 252 "stuns" URI Schemes (in accordance with [RFC4395]). Note that these 253 URI schemes are intended for use in very specific NAT traversal 254 environments, and should not be used otherwise on the open Web or 255 Internet. 257 6.1. STUN URI Registration 259 URI scheme name: stun 261 Status: permanent 263 URI scheme syntax: See Section 3.1. 265 URI scheme semantics: See Section 3.2. 267 Encoding considerations: There are no encoding considerations beyond 268 those in [RFC3986]. 270 Applications/protocols that use this URI scheme name: 272 The "stun" URI scheme is intended to be used by applications with 273 a need to identify a STUN server to be used for NAT traversal. 275 Interoperability considerations: N/A 277 Security considerations: See Section 5. 279 Contact: Suhas Nandakumar 281 Author/Change controller: The IESG 283 References: RFCXXXX 285 [[NOTE TO RFC EDITOR: Please change XXXX to the number assigned to 286 this specification, and remove this paragraph on publication.]] 288 6.2. STUNS URI Registration 290 URI scheme name: stuns 292 Status: permanent 294 URI scheme syntax: See Section 3.1. 296 URI scheme semantics: See Section 3.2. 298 Encoding considerations: There are no encoding considerations beyond 299 those in [RFC3986]. 301 Applications/protocols that use this URI scheme name: 303 The "stun" URI scheme is intended to be used by applications with 304 a need to identify a STUN server to be used for NAT traversal over 305 a secure connection. 307 Interoperability considerations: N/A 309 Security considerations: See Section 5. 311 Contact: Suhas Nandakumar 313 Author/Change controller: The IESG 315 References: RFCXXXX; 317 [[NOTE TO RFC EDITOR: Please change XXXX to the number assigned to 318 this specification, and remove this paragraph on publication.]] 320 7. Acknowledgements 321 The authors would like to extend a very special thanks to Cullen 322 Jennings for bringing to our attention the WebRTC need for this 323 document, as well as his detailed review and thoughtful comments on 324 this document. 326 This document has benefited from extensive discussion and review of 327 many of the members of the RTCWEB and BEHAVE working groups. The 328 authors would also like to acknowledge Ted Hardie, Bjoern Hoehrmann, 329 Russ Housley, Subramanian Moonesamy, Hadriel Kaplan, Graham Klyne, 330 Peter Saint-Andre, Ted Lemon, Barry Leiba, Pete Resnick, Spencer 331 Dawkins, Stephen Farrell and Harald Alvestrand for their invaluable 332 input, reviews, feedback comments, and suggestions that helped to 333 improve this document. 335 The authors would also like to express their gratitude to Dan Wing 336 for his assistance in shepherding this document. We also want to 337 thank Gonzalo Camarillo, the Real-time Applications and 338 Infrastructure Director, for sponsoring this document as well his 339 careful reviews. 341 This document was written with the xml2rfc tool described in 342 [RFC2629]. 344 8. References 346 8.1. Normative References 348 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 349 Requirement Levels", BCP 14, RFC 2119, March 1997. 351 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 352 Resource Identifier (URI): Generic Syntax", STD 66, RFC 353 3986, January 2005. 355 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 356 Specifications: ABNF", STD 68, RFC 5234, January 2008. 358 8.2. Informative References 360 [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, 361 June 1999. 363 [RFC4395] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and 364 Registration Procedures for New URI Schemes", BCP 35, RFC 365 4395, February 2006. 367 [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, 368 "Session Traversal Utilities for NAT (STUN)", RFC 5389, 369 October 2008. 371 [RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 372 Code: The Implementation Status Section", RFC 6982, July 373 2013. 375 [WEBRTC] Bergkvist, A., Burnett, D., Jennings, C., and A. 376 Narayanan, "WebRTC 1.0: Real-time Communication Between 377 Browsers", World Wide Web Consortium WD WD- 378 webrtc-20120821, August 2012, 379 . 381 Appendix A. Examples 383 Table 1 shows examples for 'stun/stuns'uri scheme. For all these 384 examples, the component is populated with "example.org". 386 +-----------------------+ 387 | URI | 388 +-----------------------+ 389 | stun:example.org | 390 | stuns:example.org | 391 | stun:example.org:8000 | 392 +-----------------------+ 394 Table 1 396 Appendix B. Design Notes 398 o One recurring comment was to stop using the suffix "s" on URI 399 scheme, and to move the secure option to a parameter (e.g., 400 ";proto=tls"). We decided against this idea because the need for 401 ";proto=" for the STUN URI cannot be sufficiently explained and 402 supporting it would render an incomplete specification. This 403 would also result in lost symmetry between the TURN and STUN URIs. 404 A more detailed account of the reasoning behind this is available 405 at 408 o Following the advice of Section 2.2 of [RFC4395], and because the 409 STUN URI does not describe a hierarchical structure, the STUN URIs 410 are opaque. 412 Appendix C. Release notes 413 NOTE TO RFC EDITOR: This section must be removed before publication 414 as an RFC. 416 C.1. Modifications between draft-nandakumar-rtcweb-stun-uri-08 and 417 draft-nandakumar-rtcweb-stun-uri-07 419 o Changed the ABNF to use references from RFC 3986 instead of 420 copying them. 422 o Converted the design note about hierarchical parsers into a MUST 423 NOT statement. 425 o Updated the RFC 6982 forms for Chrome and Firefox. 427 o Added text in security section about verifying that username, 428 password and uris are received over a secure connection. 430 Authors' Addresses 432 Suhas Nandakumar 433 Cisco Systems 434 170 West Tasman Drive 435 San Jose, CA 95134 436 US 438 Email: snandaku@cisco.com 440 Gonzalo Salgueiro 441 Cisco Systems 442 7200-12 Kit Creek Road 443 Research Triangle Park, NC 27709 444 US 446 Email: gsalguei@cisco.com 448 Paul E. Jones 449 Cisco Systems 450 7025 Kit Creek Road 451 Research Triangle Park, NC 27709 452 US 454 Email: paulej@packetizer.com 455 Marc Petit-Huguenin 456 Impedance Mismatch 458 Email: petithug@acm.org