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Versions: 00 01 02 03 04 05                                             
Network Working Group                                        C. Jennings
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                             N. Modadugu
Expires: December 4, 2007                            Stanford University
                                                            June 2, 2007


Session Initiation Protocol (SIP) over Datagram Transport Layer Security
                                 (DTLS)
                       draft-jennings-sip-dtls-04

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   This Internet-Draft will expire on December 4, 2007.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This specification defines how to use Datagram Transport Layer
   Security (DTLS) as a transport for Session Initiation Protocol (SIP).
   DTLS is a protocol for providing Transport Layer Security (TLS)
   security over a datagram protocol.  This specification also specifies
   the IANA registrations for using SIP with Datagram Congestion Control
   Protocol (DCCP).



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1.  Introduction

   Datagram Transport Layer Security (DTLS) [2] provides communication
   privacy similar to TLS [1] for datagram packets.  SIP can run over
   both stream and datagram transports, including UDP and TCP.  SIP [4]
   already defines how to use TLS with stream oriented transports.  This
   specification extends SIP to use DTLS with datagram oriented
   transports.


2.  Terminology

   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 [5].


3.  Transport Parameters

   Via header fields in SIP carry a transport protocol identifier.  This
   specification extends RFC 3261 to define the value "DTLS-UDP" for
   DTLS over UDP and "DTLS-DCCP" for DTLS over DCCP.  The update to the
   ABNF[3] in RFC 3261 for this parameter is the following:
   transport         =/ "DTLS-DCCP" / "DTLS-UDP"

   The following is an example Via header field:
   Via: SIP/2.0/DTLS-UDP atlanta.example.com:5060


4.  DTLS Usage

   The normal rules for sending a request over UDP in RFC 3261 apply to
   sending over DTLS.  Note that the congestion safety rules for UDP do
   not apply to DCCP.  In addition, the normal rules for validating a
   TLS connection in RFC 3261 apply to DTLS connections.  Requests with
   a SIPS URI can be sent over DTLS as well as TLS.


5.  Locating DTLS SIP Servers

   The normal rules from RFC 3263 [6] apply when locating a SIP server
   that supports DTLS.  The following new NAPTR[7] service values are
   defined: "SIPS+D2U" for UDP, and "SIPS+D2D" for DCCP[8].  In
   addition, the service value "SIP+D2D" should be used for SIP without
   DTLS over DCCP.

   The default port for DTLS over UDP or DCCP is 5061.




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6.  Security Considerations

   The security issues with SIP using DTLS are equivalent to the issues
   of using SIP with TLS.  All the security considerations in RFC 3261
   relevant to TLS apply to DTLS.


7.  IANA Considerations

   This document defines new NAPTR service field values for DTLS over
   DCCP and UDP as well as over DCCP with no DTLS.  IANA is requested to
   register these values under the "Registry for the SIP SRV Resource
   Record Services Field".  The resulting entries should be:

    Services Field        Protocol  Reference
    --------------------  --------  ---------
    SIPS+D2U              UDP       [RFCXXXX]
    SIPS+D2D              DCCP      [RFCXXXX]
    SIP+D2D               DCCP      [RFCXXXX]

   [Note to RFC Editor: Please replace XXXX with the RFC number of this
   specification.]


8.  Acknowledgments

   Much of text and outline for this specification came from RFC 4168
   authored by Jonathan Rosenberg, Henning Schulzrinne, and Gonzalo
   Camarillo.  Jakob Schlyter caught several typos.  Eric Rescorla
   provided helpful comments and text.


9.  Normative References

   [1]  Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
        RFC 2246, January 1999.

   [2]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
        Security", RFC 4347, April 2006.

   [3]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
        Specifications: ABNF", RFC 4234, October 2005.

   [4]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
        Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
        Session Initiation Protocol", RFC 3261, June 2002.

   [5]  Bradner, S., "Key words for use in RFCs to Indicate Requirement



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        Levels", BCP 14, RFC 2119, March 1997.

   [6]  Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol
        (SIP): Locating SIP Servers", RFC 3263, June 2002.

   [7]  Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
        Three: The Domain Name System (DNS) Database", RFC 3403,
        October 2002.

   [8]  Kohler, E., Handley, M., and S. Floyd, "Datagram Congestion
        Control Protocol (DCCP)", RFC 4340, March 2006.


Authors' Addresses

   Cullen Jennings
   Cisco Systems
   170 West Tasman Drive
   MS: SJC-21/2
   San Jose, CA  95134
   USA

   Phone: +1 408 902-3341
   Email: fluffy@cisco.com


   Nagendra Modadugu
   Stanford University
   353 Serra Mall
   Stanford, CA  94305
   USA

   Email: Nagendra@cs.stanford.edu


















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