Requirements for Marking SIP Messages to be Logged
draft-ietf-insipid-logme-reqs-02

Internet Engineering Task Force                                 P. Dawes
Internet-Draft                                            Vodafone Group
Intended status: Informational                          January 21, 2015
Expires: July 25, 2015

           Requirements for Marking SIP Messages to be Logged
                    draft-ietf-insipid-logme-reqs-02

Abstract

   SIP networks use signalling monitoring tools to diagnose user
   reported problem and for regression testing if network or client
   software is upgraded.  As networks grow and become interconnected,
   including connection via transit networks, it becomes impractical to
   predict the path that SIP signalling will take between clients, and
   therefore impractical to monitor SIP signalling end-to-end.

   This draft describes requirements for adding an indicator to the SIP
   protocol which can be used to mark signalling as of interest to
   logging.  Such marking will typically be applied as part of network
   testing controlled by the network operator and not used in regular
   client signalling.  However, such marking can be carried end-to-end
   including the SIP terminals, even if a session originates and
   terminates in different networks.

Status of This Memo

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Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in this Document . . . . . . . . . . . . . .   2
   3.  Motivating Scenario . . . . . . . . . . . . . . . . . . . . .   3
   4.  Basic Diagnostic Procedure  . . . . . . . . . . . . . . . . .   4
   5.  Requirements for a "Log Me" Marker  . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
     6.1.  Trust Domain  . . . . . . . . . . . . . . . . . . . . . .   6
     6.2.  Security Threats  . . . . . . . . . . . . . . . . . . . .   6
       6.2.1.  "Log Me" Marking  . . . . . . . . . . . . . . . . . .   6
       6.2.2.  Sending Logged Information  . . . . . . . . . . . . .   7
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   If users experience problems with setting up sessions using SIP,
   their service provider needs to find out why by examining the SIP
   signalling.  Also, if network or client software or hardware is
   upgraded regression testing is needed.  Such diagnostics apply to a
   small proportion of network traffic and can apply end-to-end, even if
   signalling crosses several networks possibly belonging to several
   different network operators.  It may not be possible to predict the
   path through those networks in advance, therefore a mechanism is
   needed to mark a session as being of interest to enable SIP entities
   along the signalling path to provide diagnostic logging.  This draft
   describes the requirements for such a "log me" marker for SIP
   signalling.

2.  Conventions Used in this Document

   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].

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3.  Motivating Scenario

   Signalling for SIP session setup can cross several networks, and
   these networks may not have common ownership and also may be in
   differrent countries.  If a single operator wishes to perform
   regression testing or fault diagnosis end-to-end, the separate
   ownership of networks that carry the signalling and the explosion in
   the number of possible signalling paths through SIP entities from the
   originating to the terminating user make it impractical to pre-
   configure logging of an end-to-end SIP signalling of a session of
   interest.

   The figure below shows an example of a signalling path through
   multiple networks.

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      +------------------+          +------------------+
      | COUNTRY A        |          | COUNTRY B        |
      | Operator A       |          | Operator A       |
      |                  |          |                  |
      | SIP Phones       |          | SIP Phones       |
      |                  |        //|                  |
      +------------------+       // +------------------+
             |                  //
             |                 //
          ,'```',             //    +------------------+
      .`',.'        `..'``',<==//   | COUNTRY B        |
      ,'  Operator A         `',    | Operator A       |
      ;    Backbone Network    ..'--|                  |
      ',            ,.,    .'`      | PSTN phones      |
      '.,.`'.,,,.`   `''`           |                  |
             ||                     +------------------+
             ||
             \/
      +------------------+
      |                  |
      |  Transit Network |
      |                  |
      |                  |\\
      +------------------+ \\
              |             \\
              |              \\
      +------------------+    \\    +------------------+
      | COUNTRY D        |     \\   | COUNTRY C        |
      | Operator C       |      \\=>| Operator B       |
      |                  |          |                  |
      | SIP Phones       |          | SIP Phones       |
      |                  |          |                  |
      +------------------+          +------------------+

        Figure 1: Example signalling path through multiple networks

4.  Basic Diagnostic Procedure

   The skeleton diagnostic procedure is as follows:

   o  The user's terminal is placed in debug mode.  The terminal logs
      its own signalling and inserts a "log me" marker into SIP requests
      for session setup

   o  All SIP entities that the signalling traverses, from the first
      proxy the terminal connects to at the edge of the network to the
      destination client terminal, can detect that the "log me" marker

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      is present and can log SIP requests and responses that contain the
      marker if configured to do so.

   o  Subsequent responses and requests in the same dialog are logged.

   o  Logging stops, either because the dialog has ended or because a
      'stop event', typically expiry of a certain amount of time,
      occurred

   o  The user's terminal and any other SIP entity that has logged
      signalling sends logs to a server that is co-ordinating
      diagnostics.

5.  Requirements for a "Log Me" Marker

   o  REQ1: It MUST be possible to mark a SIP request or response as of
      interest for logging by inserting a "log me" marker.  This is
      known as "log me" marking.

   o  REQ2: It MUST be possible for a "log me" marker to cross network
      boundaries.

   o  REQ3: A "log me" marker is most effective if it passes end-to-end.
      However, source networks should behave responsibly and not leave
      it to a downstream network to detect and remove a marker that it
      will not use.  A "log me" marker SHOULD be removed at trust domain
      boundaries.

   o  REQ4: SIP entities SHOULD log SIP requests or responses with a
      "log me" marker.

   o  REQ5: If a UA receives a request with a "log me" marker, it MUST
      echo that "log me" marker in responses to that request.

   o  REQ6: A SIP proxy MAY perform "log me" marking of requests and
      responses.  Typical cases where a proxy needs to perform "log me"
      marking are when a UA has not marked a request and when responses
      received on a dialog of interest for logging do not contain a "log
      me" marker.  In these cases, the entity that performs "log me"
      marking is stateful inasmuch as it must remember when a dialog is
      of interest for logging.

   o  REQ7: For SIP proxies, logging of SIP requests that contain a "log
      me" marker MAY be stateless.  For example, it is OPTIONAL for a
      SIP entity to maintain state of which SIP requests contained a
      "log me" marker in order to log responses to those requests.
      Echoing a "log me" marker in responses is the responsibility of
      the UA that receives a request.

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   o  REQ8: A "log me" marker MAY include an identifier that indicates
      the test case that caused it to be inserted, known as a test case
      identifier.  The test case identifier does not have any impact on
      session setup, it is used by the diagnostic server to collate all
      logged SIP requests and responses to the initial SIP request in a
      dialog or standalone transaction.  The Session-ID described in RFC
      7206 [RFC7206] and I-D.ietf-insipid-session-id-12
      [I-D.ietf-insipid-session-id] could be used as the test case
      identifier but it would be useful for the UA to log a human
      readable name together with this Session-ID when it performs "log
      me" marking of an initial SIP request.

6.  Security Considerations

   Potential security impacts of a "log me" marker are whether the
   marker itself contains any sensitive information, whether detecting
   its presence or absence reveals sensitive information, and whether
   maliciously adding a "log me" can be used to attack a network.  This
   section analyses these potential impacts.

6.1.  Trust Domain

   Since a "log me" marker may cause a SIP entity to log the SIP header
   and body of a request or response, the "log me" marker should be
   removed at a trust domain boundary.  If a prior agreement to log
   sessions exists with the net hop network then the "log me" marker
   might not be removed.

6.2.  Security Threats

6.2.1.  "Log Me" Marking

   The "log me" marker is not sensitive information, although it will
   sometimes be inserted because a particular device is experiencing
   problems.

   The presence of a "log me" marker will cause some SIP entities to log
   signalling.  Therefore, this marker must be removed at the earliest
   opportunity if it has been incorrectly inserted.

   Activating a debug mode affects the operation of a terminal,
   therefore it must be supplied by an authorized server to an
   authorized terminal, it must not be altered in transit, and it must
   not be readable by an unauthorized third party.

   Logged signalling is privacy-sensitive data, therefore it must be
   passed to an authorized server, it must not be altered in transit,
   and it must not be readable by an unauthorized third party.

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6.2.2.  Sending Logged Information

   A SIP entity that has logged information should encrypt it, such that
   it can be decrypted only by the debug server, before sending it to a
   debug server in order to protect the content of logs from a third
   party.

7.  Acknowledgments

   The author wishes to thank Paul Kyzivat, Christer Holmberg, James
   Polk, Hadriel Kaplan, Keith Drage, and Gonzalo Salgueiro for their
   constructive comments and guidance while developing this document.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

8.2.  Informative References

   [I-D.ietf-insipid-session-id]
              Jones, P., Polk, J., Salgueiro, G., and C. Pearce, "End-
              to-End Session Identification in IP-Based Multimedia
              Communication Networks", draft-ietf-insipid-session-id-12
              (work in progress), January 2015.

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              June 1999.

   [RFC3261]  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.

   [RFC3311]  Rosenberg, J., "The Session Initiation Protocol (SIP)
              UPDATE Method", RFC 3311, October 2002.

   [RFC3428]  Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C.,
              and D. Gurle, "Session Initiation Protocol (SIP) Extension
              for Instant Messaging", RFC 3428, December 2002.

   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552, July
              2003.

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   [RFC3903]  Niemi, A., "Session Initiation Protocol (SIP) Extension
              for Event State Publication", RFC 3903, October 2004.

   [RFC6086]  Holmberg, C., Burger, E., and H. Kaplan, "Session
              Initiation Protocol (SIP) INFO Method and Package
              Framework", RFC 6086, January 2011.

   [RFC7206]  Jones, P., Salgueiro, G., Polk, J., Liess, L., and H.
              Kaplan, "Requirements for an End-to-End Session
              Identification in IP-Based Multimedia Communication
              Networks", RFC 7206, May 2014.

Author's Address

   Peter Dawes
   Vodafone Group
   The Connection
   Newbury, Berkshire  RG14 2FN
   UK

   Email: peter.dawes@vodafone.com

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