Network Working Group H. Alvestrand Internet-Draft Google Intended status: Standards Track August 18, 2013 Expires: February 19, 2014 Transports for RTCWEB draft-ietf-rtcweb-transports-00 Abstract This document describes the data transport protocols used by RTCWEB, including the protocols used for interaction with intermediate boxes such as firewalls, relays and NAT boxes. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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 February 19, 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 publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect Alvestrand Expires February 19, 2014 [Page 1] Internet-Draft WebRTC Transports August 2013 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. Transport and Middlebox specification . . . . . . . . . . . . . 3 2.1. System-provided interfaces . . . . . . . . . . . . . . . . 3 2.2. Middle box related functions . . . . . . . . . . . . . . . 3 2.3. Transport protocols implemented . . . . . . . . . . . . . . 4 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . . 5 6.2. Informative References . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Alvestrand Expires February 19, 2014 [Page 2] Internet-Draft WebRTC Transports August 2013 1. Introduction The IETF RTCWEB effort, part of the WebRTC effort carried out in cooperation between the IETF and the W3C, is aimed at specifying a protocol suite that is useful for real time multimedia exchange between browsers. The overall effort is described in the RTCWEB overview document, [I-D.ietf-rtcweb-overview]. This document focuses on the data transport protocos that are used by conforming implementations. This protocol suite is designed for WebRTC, and intends to satisfy the security considerations described in the WebRTC security documents, [I-D.ietf-rtcweb-security] and [I-D.ietf-rtcweb-security-arch]. 2. Transport and Middlebox specification 2.1. System-provided interfaces The protocol specifications used here assume that the following protocols are available to the implementations of the RTCWEB protocols: o UDP. This is the protocol assumed by most protocol elements described. o TCP. This is used for HTTP/WebSockets, as well as for TURN/SSL and ICE-TCP. For both protocols, this specification assumes the ability to set the DSCP code point of the sockets opened. It does not assume that the DSCP codepoints will be honored, and does assume that they may be zeroed or changed, since this is a local configuration issue. This specification does not assume that the implementation will have access to ICMP or raw IP. 2.2. Middle box related functions The primary mechanism to deal with middle boxes is ICE, which is an appropriate way to deal with NAT boxes and firewalls that accept traffic from the inside, but only from the outside if it's in response to inside traffic (simple stateful firewalls). In order to deal with symmetric NATs, TURN MUST be supported. Alvestrand Expires February 19, 2014 [Page 3] Internet-Draft WebRTC Transports August 2013 In order to deal with firewalls that block all UDP traffic, TURN over TCP MUST be supported. (QUESTION: What about ICE-TCP?) The following specifications MUST be supported: o ICE [RFC5245] o TURN, including TURN over TCP [[QUESTION: and TURN over TLS]], [RFC5766]. For referring to STUN and TURN servers, this specification depends on the STUN URI, [I-D.nandakumar-rtcweb-stun-uri]. 2.3. Transport protocols implemented For data transport over the RTCWEB data channel [I-D.ietf-rtcweb-data-channel], RTCWEB implementations support SCTP over DTLS over ICE. This is specified in [I-D.ietf-tsvwg-sctp-dtls-encaps]. Negotiation of this transport in SCTP is defined in [I-D.ietf-mmusic-sctp-sdp]. The setup protocol for RTCWEB data channels is described in [I-D.jesup-rtcweb-data-protocol]. For transport of media, secure RTP is used. The details of the profile of RTP used are described in "RTP Usage" [I-D.ietf-rtcweb-rtp-usage]. RTCWEB implementations MUST support multiplexing of SCTP/DTLS and RTP over the same port pair, as described in the DTLS_SRTP specification [RFC5764], section 5.1.2. 3. IANA Considerations This document makes no request of IANA. Note to RFC Editor: this section may be removed on publication as an RFC. 4. Security Considerations Security considerations are enumerated in [I-D.ietf-rtcweb-security]. Alvestrand Expires February 19, 2014 [Page 4] Internet-Draft WebRTC Transports August 2013 5. Acknowledgements This document is based on earlier versions embedded in [I-D.ietf-rtcweb-overview], which were the results of contributions from many RTCWEB WG members. 6. References 6.1. Normative References [I-D.ietf-mmusic-sctp-sdp] Loreto, S. and G. Camarillo, "Stream Control Transmission Protocol (SCTP)-Based Media Transport in the Session Description Protocol (SDP)", draft-ietf-mmusic-sctp-sdp-04 (work in progress), June 2013. [I-D.ietf-rtcweb-data-channel] Jesup, R., Loreto, S., and M. Tuexen, "RTCWeb Data Channels", draft-ietf-rtcweb-data-channel-05 (work in progress), July 2013. [I-D.ietf-rtcweb-rtp-usage] Perkins, C., Westerlund, M., and J. Ott, "Web Real-Time Communication (WebRTC): Media Transport and Use of RTP", draft-ietf-rtcweb-rtp-usage-07 (work in progress), July 2013. [I-D.ietf-rtcweb-security] Rescorla, E., "Security Considerations for WebRTC", draft-ietf-rtcweb-security-05 (work in progress), July 2013. [I-D.ietf-rtcweb-security-arch] Rescorla, E., "WebRTC Security Architecture", draft-ietf-rtcweb-security-arch-07 (work in progress), July 2013. [I-D.ietf-tsvwg-sctp-dtls-encaps] Jesup, R., Loreto, S., Stewart, R., and M. Tuexen, "DTLS Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp-dtls-encaps-01 (work in progress), July 2013. [I-D.nandakumar-rtcweb-stun-uri] Nandakumar, S., Salgueiro, G., Jones, P., and M. Petit- Huguenin, "URI Scheme for Session Traversal Utilities for NAT (STUN) Protocol", draft-nandakumar-rtcweb-stun-uri-05 Alvestrand Expires February 19, 2014 [Page 5] Internet-Draft WebRTC Transports August 2013 (work in progress), July 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols", RFC 5245, April 2010. [RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the Secure Real-time Transport Protocol (SRTP)", RFC 5764, May 2010. [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. 6.2. Informative References [I-D.ietf-rtcweb-overview] Alvestrand, H., "Overview: Real Time Protocols for Brower- based Applications", draft-ietf-rtcweb-overview-06 (work in progress), February 2013. [I-D.jesup-rtcweb-data-protocol] Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channel Protocol", draft-jesup-rtcweb-data-protocol-04 (work in progress), February 2013. Author's Address Harald Alvestrand Google Email: harald@alvestrand.no Alvestrand Expires February 19, 2014 [Page 6]