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 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 July 25, 2015. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. Dawes Expires July 25, 2015 [Page 1] Internet-Draft log me marker January 2015 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. 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]. Dawes Expires July 25, 2015 [Page 2] Internet-Draft log me marker January 2015 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. Dawes Expires July 25, 2015 [Page 3] Internet-Draft log me marker January 2015 +------------------+ +------------------+ | 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 Dawes Expires July 25, 2015 [Page 4] Internet-Draft log me marker January 2015 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. Dawes Expires July 25, 2015 [Page 5] Internet-Draft log me marker January 2015 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. Dawes Expires July 25, 2015 [Page 6] Internet-Draft log me marker January 2015 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. Dawes Expires July 25, 2015 [Page 7] Internet-Draft log me marker January 2015 [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 Dawes Expires July 25, 2015 [Page 8]