[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-rosenberg-sipping-consent-reqs) 00 01 02 03 04 RFC 4453

SIPPING                                                     J. Rosenberg
Internet-Draft                                             Cisco Systems
Expires: January 19, 2006                              G. Camarillo, Ed.
                                                                Ericsson
                                                               D. Willis
                                                           Cisco Systems
                                                           July 18, 2005


Requirements for Consent-Based Communications in the Session Initiation
                             Protocol (SIP)
                 draft-ietf-sipping-consent-reqs-01.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on January 19, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   The Session Initiation Protocol (SIP) supports communications across
   many media types, including real-time audio, video, text, instant
   messaging, and presence.  In its current form, it allows session
   invitations, instant messages, and other requests to be delivered



Rosenberg, et al.       Expires January 19, 2006                [Page 1]

Internet-Draft            Consent Requirements                 July 2005


   from one party to another without requiring explicit consent of the
   recipient.  Without such consent, it is possible for SIP to be used
   for malicious purposes, including spam and denial-of-service attacks.
   This document identifies a set of requirements for extensions to SIP
   that add consent-based communications.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Problem Statement  . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  6
   5.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     5.1   Normative References . . . . . . . . . . . . . . . . . . .  7
     5.2   Informational References . . . . . . . . . . . . . . . . .  7
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . .  7
       Intellectual Property and Copyright Statements . . . . . . . .  9


































Rosenberg, et al.       Expires January 19, 2006                [Page 2]

Internet-Draft            Consent Requirements                 July 2005


1.  Introduction

   The Session Initiation Protocol (SIP) [1] supports communications
   across many media types, including real-time audio, video, text,
   instant messaging, and presence.  This communication is established
   by the transmission of various SIP requests (such as INVITE and
   MESSAGE [4]) from an initiator to the recipient, with whom
   communication is desired.  Although a recipient of such a SIP request
   can reject the request, and therefore decline the session, a SIP
   network will deliver a SIP request to the recipient without their
   explicit consent.

   Receipt of these requests without explicit consent can cause a number
   of problems in SIP networks.  These include spam and DoS (Denial of
   Service) attacks.  These problems have plagued email.  Fortunately,
   most SIP networks, at time of writing, were not interconnected with
   each other, and so the incidences of such problems have been lower.
   However, once such broad interconnection occurs, these problems will
   arise.  Therefore, it is important to address them proactively,
   before it is too late.

   This document elaborates on the problems posed by the current open
   model in which SIP was designed, and then goes on to define a set of
   requirements for adding a consent framework to SIP.

2.  Problem Statement

   In SIP networks designed according to the principles of RFC 3261 [1]
   and RFC 3263 [2], anyone on the Internet can create and send a SIP
   request to any other SIP user, by identifying that user with a SIP
   URI.  The SIP network will usually deliver this request to the user
   identified by that URI.  It is possible, of course, for network
   services, such as call screening, to block such messaging from
   occuring, but this is not widespread and certainly not a systematic
   solution to the problem under consideration here.

   Once the SIP request is received by the recipient, the user agent
   typically takes some kind of automated action to alert the user about
   receipt of the message.  For INVITE requests, this usually involves
   "ringing the phone", or creating a screen pop.  These indicators
   frequently convey the subject of the call and the identity of the
   caller.  Due to the real-time nature of the session, these alerts are
   typically disruptive in nature, so as to get the attention of the
   user.

   For MESSAGE requests, the content of the message is usually rendered
   to the user.




Rosenberg, et al.       Expires January 19, 2006                [Page 3]

Internet-Draft            Consent Requirements                 July 2005


   SUBSCRIBE [3] requests do not normally get delivered to the user
   agents residing on a user's devices.  Rather, they are normally
   processed by network-based state agents.  The watcher information
   event package allows a user to find out that such requests were
   generated for them, affording the user the opportunity to approve or
   deny the request.  As a result, SUBSCRIBE processing, and most
   notably presence, already has a consent-based operation.
   Nevertheless, this already-existing consent mechanism for SIP
   subscriptions does not protect network agents against DoS attacks.

   There are two principal problems that arise when MESSAGE and INVITE
   requests can be delivered to user agents directly, without their
   consent.  The first is spam.  For INVITE requests, this takes the
   form of typical "telemarketer" calls.  A user might receive a stream
   of never-ending requests for communications, each of them disrupting
   the user and demanding their attention.  For MESSAGE requests, the
   problem is even more severe.  The user might receive a never-ending
   stream of screen pops that deliver unwanted, malicious, or otherwise
   undesired content.

   The second problem is DoS attacks.  SIP proxies provide a convenient
   relay point for targeting a message to a particular user or IP
   address, and in particular, relaying to a recipient which is often
   not directly reachable without usage of the proxy.  Worse, some
   proxies or back to back user agents generate multiple outgoing
   requests upon receipt of an incoming request.  This occurs in forking
   proxies, and in URI-list services.  Examples of URI-list services are
   subscriptions to resource lists, dial out conference servers, and
   MESSAGE URI-list services.  These SIP elements can be used as an
   amplifier, allowing the transmission of a single SIP request to flood
   packets to a single recipient or network.  For example, a user can
   create a buddy list with 100 entries, each of which is a URI of the
   form "sip:identifier@target-IP", where target-IP is the IP address to
   which the attack is to be directed.  Sending a single SIP SUBSCRIBE
   request to such a list will cause the resource list server to
   generate 100 SUBSCRIBE requests, each to the IP address of the
   target, which does not even need to be a SIP node.

      Note that the target-IP does not need to be the same in all the
      URIs in order to attack a single machine.  For example, the
      target-IP addresses may all belong to the same subnetwork, in
      which case the target of the attack would be the access router of
      the subnetwork.

   Though the spam and DoS problems are not quite the same, both can be
   alleviated by adding a consent-based communications framework to SIP.
   Such a framework keeps servers from relaying messages to users
   without their consent.



Rosenberg, et al.       Expires January 19, 2006                [Page 4]

Internet-Draft            Consent Requirements                 July 2005


      The framework for SIP URI-list services [5] identifies these two
      problems (spam and DoS attacks) in the context of URI-list
      services.  That framework mandates the use of opt-in lists, which
      are a form of consent-based communications.  The reader can find
      an analysis on how a consent-based framework help alleviating
      spam-related problems in [6].

3.  Requirements

   The following identify requirements for a solution that provides
   consent-based communications in SIP.

   REQ 1: The solution must keep relays from delivering a SIP message to
      a recipient unless the recipient has explicitly granted permission
      for receipt of that type of message.

   REQ 2: The solution shall prevent SIP servers from generating more
      than one outbound request in response to an inbound request,
      unless permission to do so has been granted by the resource to
      whom the outbound request was to be targeted.

   REQ 3: The permissions shall be capable of specifying that messages
      from a specific user, identified by a SIP AoR, are permitted.

   REQ 4: It shall be possible for a user with a particular AoR to
      specify permissions separately for each resource that wishes to
      relay requests to that AOR.

   REQ 5: The permissions shall be capable of specifying that only
      certain types of messages, such as INVITE or MESSAGE request, are
      permitted from a user.

   REQ 6: It shall be possible for a user to revoke permissions at any
      time.

   REQ 7: It shall be possible for the users to specify that permissions
      are time limited, and must be refreshed after expiration.

   REQ 8: It shall not be required for a user or user agent to store
      information in order to be able to revoke permissions that were
      previously granted for a relay resource.

   REQ 9: The solution shall work in an inter-domain context, without
      requiring pre-established relationships between domains.







Rosenberg, et al.       Expires January 19, 2006                [Page 5]

Internet-Draft            Consent Requirements                 July 2005



   REQ 10: The solution shall work for all current and future SIP
      methods.

   REQ 11: The solution shall be applicable to forking proxies.

   REQ 12: The solution shall be applicable to URI-list services, such
      as resource list servers, MESSAGE URI-list services, and
      conference servers performing dial-out functions.

   REQ 13: The solution shall be applicable to both stored and request-
      contained URI-list services.

   REQ 14: The solution shall allow anonymous communications, as long as
      the recipient is willing to accept anonymous communications.

   REQ 15: If the recipient of requests wishes to be anonymous, it shall
      be possible for them to grant permissions without a sender knowing
      their identity.

   REQ 16: The solution shall prevent against attacks that seek to
      undermine the underlying goal of consent.  That is, it should not
      be possible to "fool" the system into delivering a request for
      which permission was not, in fact, granted.

   REQ 17: The solution shall not require the recipient of the
      communications to be connected to the network at the time
      communications is attempted.

   REQ 18: The solution shall note require the sender of a
      communications to be connected at the time that a recipient
      provides permission.

   REQ 19: The solution should not, in and of itself, create substantial
      additional messaging.  Doing so defeats some of the purpose of the
      solution.

   REQ 20: The solution should scale to Internet-wide deployment.

4.  Security Considerations

   Security has been discussed throughout this specification.

5.  References







Rosenberg, et al.       Expires January 19, 2006                [Page 6]

Internet-Draft            Consent Requirements                 July 2005


5.1  Normative References

   [1]  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.

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

5.2  Informational References

   [3]  Roach, A., "Session Initiation Protocol (SIP)-Specific Event
        Notification", RFC 3265, June 2002.

   [4]  Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C., and
        D. Gurle, "Session Initiation Protocol (SIP) Extension for
        Instant Messaging", RFC 3428, December 2002.

   [5]  Camarillo, G. and A. Roach, "Requirements and Framework for
        Session Initiation Protocol (SIP)Uniform  Resource Identifier
        (URI)-List Services", draft-ietf-sipping-uri-services-03 (work
        in progress), April 2005.

   [6]  Rosenberg, J. and C. Jennings, "The Session Initiation Protocol
        (SIP) and Spam", draft-rosenberg-sipping-spam-01 (work in
        progress), October 2004.


Authors' Addresses

   Jonathan Rosenberg
   Cisco Systems
   600 Lanidex Plaza
   Parsippany, NJ  07054
   US

   Phone: +1 973 952-5000
   Email: jdrosen@cisco.com
   URI:   http://www.jdrosen.net












Rosenberg, et al.       Expires January 19, 2006                [Page 7]

Internet-Draft            Consent Requirements                 July 2005


   Gonzalo Camarillo (editor)
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: Gonzalo.Camarillo@ericsson.com


   Dean Willis
   Cisco Systems
   2200 E. Pres. George Bush Turnpike
   Richardson, TX  75082
   USA

   Email: dean.willis@softarmor.com



































Rosenberg, et al.       Expires January 19, 2006                [Page 8]

Internet-Draft            Consent Requirements                 July 2005


Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.


Disclaimer of Validity

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Copyright Statement

   Copyright (C) The Internet Society (2005).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.


Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.




Rosenberg, et al.       Expires January 19, 2006                [Page 9]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/