TRAMInternet Engineering Task Force (IETF) P. PatilInternet-DraftRequest for Comments: 7443 T. ReddyIntended status:Category: Informational G. SalgueiroExpires: May 29, 2015ISSN: 2070-1721 Cisco M. Petit-Huguenin Impedance MismatchNovember 25, 2014 Application LayerJanuary 2015 Application-Layer Protocol Negotiation (ALPN) Labels for Session Traversal Utilities for NAT (STUN) Usagesdraft-ietf-tram-alpn-08AbstractApplication LayerApplication-Layer Protocol Negotiation (ALPN) labels for Session Traversal Utilities for NAT (STUN) usages, such as Traversal Using Relays around NAT (TURN) and NAT discovery, are defined in this document to allow an application layer to negotiate STUN usages within the Transport Layer Security (TLS) connection. ALPN protocol identifiers defined in this document apply to both TLS and Datagram Transport Layer Security (DTLS). Status of This Memo ThisInternet-Draftdocument issubmitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documentsnot an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force (IETF).Note that other groups may also distribute working documents as Internet-Drafts. The listIt represents the consensus ofcurrent Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents validthe IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are amaximumcandidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status ofsix monthsthis document, any errata, and how to provide feedback on it may beupdated, replaced, or obsoleted by other documentsobtained atany 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 May 29, 2015.http://www.rfc-editor.org/info/rfc7443. Copyright Notice Copyright (c)20142015 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 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. IANA Considerations . . . . . . . . . . . . . . . . . . . . .32 3. Security Considerations . . . . . . . . . . . . . . . . . . . 3 4.Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3 5.References . . . . . . . . . . . . . . . . . . . . . . . . .4 5.1.3 4.1. Normative References . . . . . . . . . . . . . . . . . .4 5.2.3 4.2. Informative References . . . . . . . . . . . . . . . . . 4Authors' Addresses . . . . .Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . .45 1. Introduction STUN can be securely transported using TLS-over-TCP (referred to as TLS [RFC5246]), as specified in [RFC5389], or TLS-over-UDP (referred to as DTLS [RFC6347]), as specified in [RFC7350]. ALPN [RFC7301] enables an endpoint to positively identify an application protocol in TLS/DTLS and distinguish it from other TLS/ DTLS protocols. With ALPN, the client sends the list of supported application protocols as part of the TLS/DTLS ClientHello message. The server chooses a protocol and sends the selected protocol as part of the TLS/DTLS ServerHello message. Application protocol negotiation can thus be accomplished within the TLS/DTLS handshake, without adding network round-trips. STUN protocol usages, such as TURN [RFC5766], can be used to identify the purpose of a flow without initiating a session. This document proposes the following ALPN labels to identify STUN protocol [RFC5389] usages. 'stun.turn': Label to identify the specific use of STUN over (D)TLS for TURN (Section 4.6 of [RFC7350]). 'stun.nat-discovery': Label to identify the specific use of STUN over (D)TLS for NAT discovery (Section 4.1 of [RFC7350]). 2. IANA Considerations The following entriesare to behave been added to the"Application Layer"Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry established by [RFC7301]. The "stun.turn" label identifies the use of TURN usage (D)TLS: Protocol: Traversal Using Relays around NAT (TURN) Identification Sequence: 0x73 0x74 0x75 0x6E 0x2E 0x74 0x75 0x72 0x6E ("stun.turn") Specification: This document(RFCXXXX)(RFC 7443) The "stun.nat-discovery" label identifies the use of STUN for the purposes of NAT discovery over (D)TLS: Protocol: NAT discovery using Session Traversal Utilities for NAT (STUN) Identification Sequence: 0x73 0x74 0x75 0x6E 0x2E 0x6e 0x61 0x74 0x2d 0x64 0x69 0x73 0x63 0x6f 0x76 0x65 0x72 0x79("stun.nat- discovery")("stun.nat-discovery") Specification: This document(RFCXXXX)(RFC 7443) 3. Security Considerations The ALPN STUN protocol identifier does not introduce any specific security considerations beyond those detailed in the TLS ALPN Extension specification [RFC7301]. It also does not impact the security of TLS/DTLS session establishmentnoror application data exchange.5.4. References5.1.4.1. Normative References [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August2008.2008, <http://www.rfc-editor.org/info/rfc5246>. [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, "Session Traversal Utilities for NAT (STUN)", RFC 5389, October2008.2008, <http://www.rfc-editor.org/info/rfc5389>. [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security Version 1.2", RFC 6347, January2012.2012, <http://www.rfc-editor.org/info/rfc6347>. [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, "Transport Layer Security (TLS) Application-Layer Protocol Negotiation Extension", RFC 7301, July2014.2014, <http://www.rfc-editor.org/info/rfc7301>. [RFC7350] Petit-Huguenin, M. and G. Salgueiro, "Datagram Transport Layer Security (DTLS) as Transport for Session Traversal Utilities for NAT (STUN)", RFC 7350, August2014. 5.2.2014, <http://www.rfc-editor.org/info/rfc7350>. 4.2. Informative References [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, April2010. 4.2010, <http://www.rfc-editor.org/info/rfc5766>. Appendix A. Acknowledgements This work benefited from the discussions and invaluable input by the various members of the TRAM working group. These include Simon Perrault, Paul Kyzivat, BrandonWilliamsWilliams, and Andrew Hutton. Special thanks to Martin Thomson and Oleg Moskalenko for their constructive comments, suggestions, and early reviews that were critical to the formulation and refinement of this document. Barry Leiba, Stephen Farrell, AdrianFarrelFarrel, and Richard Barnes provided useful feedback during IESG review. Thanks to Russ Housley for his Gen-ART review and Adam Langley for his IETF LC review comments as TLS expert. The authors would also like to express their gratitude to the TRAM WG chairs Gonzalo Camarillo and especially Simon Perrault, who also acted as document shepherd. Lastly, we also want to thank the Transport Area Director Spencer Dawkins for his support and careful reviews. Authors' Addresses Prashanth Patil Cisco Systems, Inc. Bangalore IndiaEmail:EMail: praspati@cisco.com Tirumaleswar Reddy Cisco Systems, Inc. Cessna Business Park, Varthur Hobli Sarjapur Marathalli Outer Ring Road Bangalore, Karnataka 560103 IndiaEmail:EMail: tireddy@cisco.com Gonzalo Salgueiro Cisco Systems, Inc. 7200-12 Kit Creek Road Research Triangle Park, NC 27709US Email:United States EMail: gsalguei@cisco.com Marc Petit-Huguenin Impedance MismatchUSA Email:United States EMail: marc@petit-huguenin.org