RFC 8123
Requirements for Marking SIP Messages to be Logged
RFC 8123 🎀 Requirements for Marking SIP Messages to be Logged
Okay bestie, here's the header info first 💅
- Series: Internet Engineering Task Force (IETF) 🌸
- Number and title: RFC 8123, Requirements for Marking SIP Messages to be Logged ✨
- Authors: P. Dawes (Vodafone Group) and C. Arunachalam (Cisco Systems) 🧚
- Category: Informational 💖
- ISSN: 2070-1721
- Date: March 2017 🍓
- Obsoletes and updates: this header has no Obsoletes or Updates line, so this doc doesn't list any ✨
Abstract 🦋
Okay so SIP networks use signaling monitoring tools to debug customer-reported problems, and to run regression testing whenever network or client software gets upgraded 🛠️. As networks grow and get interconnected, including through transit networks, it becomes impractical to predict the path SIP signaling takes between clients. That means it's also impractical to monitor SIP signaling end-to-end 😭.
This document describes the requirements for adding an indicator to the SIP Protocol Data Unit (PDU) or a SIP message that marks the PDU as a candidate for logging ✨. The marking will typically be applied during network testing that the network operator controls, and it isn't used in regular client signaling. Still, the marking can be carried end-to-end, including to the SIP terminals, even if a session starts and ends in different networks 💜.
Status of This Memo 📝
This document is not an Internet Standards Track specification. It's published for informational purposes 🌈.
It's a product of the Internet Engineering Task Force (IETF), and it represents the consensus of the IETF community. It got public review and was approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are candidates for any level of Internet Standard, so see Section 2 of RFC 7841 🎀.
Info about the current status of this document, any errata, and how to give feedback can be found at http://www.rfc-editor.org/info/rfc8123 🔥.
Copyright Notice ⭐
Copyright (c) 2017 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, because 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 they are provided without warranty as described in the Simplified BSD License 🫶.
Table of Contents 🗺️
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Network Boundary . . . . . . . . . . . . . . . . . . . . 3
3.2. Trust Domain . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Intermediary . . . . . . . . . . . . . . . . . . . . . . 4
4. Motivating Scenario . . . . . . . . . . . . . . . . . . . . . 4
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Example Network Arrangement . . . . . . . . . . . . . . . 5
4.3. Example Debugging Procedure . . . . . . . . . . . . . . . 6
5. "Log Me" Marking Requirements . . . . . . . . . . . . . . . . 6
5.1. Message Logs . . . . . . . . . . . . . . . . . . . . . . 6
5.2. "Log Me" Marking . . . . . . . . . . . . . . . . . . . . 7
5.3. Processing the "Log Me" Marker . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6.1. Trust Domain . . . . . . . . . . . . . . . . . . . . . . 8
6.2. Security Threats . . . . . . . . . . . . . . . . . . . . 9
6.2.1. "Log Me" Marking . . . . . . . . . . . . . . . . . . 9
6.2.2. Logged Information . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 111. Introduction ✨
Okay so service providers, enterprises, and others who run networks that use SIP (see [RFC3261]) need to be able to debug problems their end users report 🐛. They also need to run regression tests when SIP client software or hardware gets upgraded 💅. That debugging and testing might stay inside one service provider's network, or it might happen between the administrative domains of different network operators. That includes domains in different countries that are connected through networks owned by one or more third parties 🌍.
A mechanism is needed to mark particular SIP sessions (the ones related to debugging or regression testing) as candidates for logging 🎯. This marking must be carried inside the candidate SIP messages as they get routed across networks and geographies. That way logging can happen at each SIP entity without anyone having to know ahead of time which SIP entities the signaling will go through 🦋. The marking also has to account for SIP messages possibly crossing different network operators, different countries, regions with different privacy requirements, and different trust domains 🔐. This document describes the requirements for such a "log me" marker for SIP signaling 💜.
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 [RFC2119]. The one twist is that instead of describing interoperability requirements, they're used to describe requirements that the "log me" marker solution has to satisfy 🎀.
3. Terminology 🧚
3.1. Network Boundary 🌸
A network boundary is the part of a signaling path where messages pass between entities under different administrative control. Figure 2 in [RFC5853] shows a network boundary between the originating gateway GW-A1 in operator A's network and the Session Border Controller (SBC) in operator B's network. The boundary matters in this document because manipulating signaling at the boundary could prevent end-to-end testing or troubleshooting 😭.
Topology hiding and protocol repair (see [RFC5853]) are two common functions that manipulate signaling at the network boundary. These functions are performed by SIP device types (see [RFC7092]), such as a Session Border Controller and an Interconnection Border Control Function (IBCF) 🫣.
3.2. Trust Domain 🔐
In this document, a trust domain is the set of entities that have been identified, by prior agreement, as the participating elements in logging. That's typically for debugging or regression testing 💖. A trust domain contains all SIP entities under the configuration control of the network operator performing regression testing, plus all SIP entities under the configuration control of peer network operators who have agreed to take part in that testing. The whole point of trust domain requirements is to stop network operators from accidentally triggering logging in networks that aren't part of any testing or troubleshooting 🙅♀️.
3.3. Intermediary 🦋
The term "intermediary" is defined in Section 2 of [RFC7989]. It refers to any entity along the call signaling path ✨.
4. Motivating Scenario 🎬
4.1. Introduction 🌈
Signaling for SIP session setup can cross several networks. Those networks may not have common ownership, and they may be in different countries 🌍. If a single operator wants to run regression testing or fault debugging end-to-end, two things make that hard. One is the separate ownership of the networks carrying the signaling. The other is the explosion in the number of possible signaling paths through SIP entities from the originating user to the terminating user. Together they make it impractical to preconfigure logging of an end-to-end SIP signaling session of interest 🤯.
4.2. Example Network Arrangement 🗺️
The figure below shows an example of a signaling path through multiple networks 🧩.
+------------------+ +------------------+
| COUNTRY W | | COUNTRY X |
| Operator A | | Operator A |
| | | |
| SIP Phones | | SIP Phones |
| | //| |
+------------------+ // +------------------+
| //
| //
,'```', // +------------------+
.`',.' `..'``',<==// | COUNTRY X |
,' Operator A `', | Operator A |
; Backbone Network ..'--| |
', ,., .'` | PSTN phones |
'.,.`'.,,,.` `''` | |
|| +------------------+
||
\/
+------------------+
| |
| Transit Network |
| |
| |\\
+------------------+ \\
| \\
| \\
+------------------+ \\ +------------------+
| COUNTRY Z | \\ | COUNTRY Y |
| Operator C | \\=>| Operator B |
| | | |
| SIP Phones | | SIP Phones |
| | | |
+------------------+ +------------------+
Figure 1: Example Signaling Path through Multiple Networks4.3. Example Debugging Procedure 🔍
Here's one possible set of steps to show how the debugging procedure might go 🎀.
- The user's terminal is placed in debug mode. The terminal logs its own signaling and inserts a "log me" marker into SIP requests for session setup 📱.
- All SIP entities that the signaling traverses, from the first proxy the terminal connects to at the edge of the network to the destination client terminal, detect that the "log me" marker is present. Then they log SIP requests and responses that contain the marker, if configured to do so 👀.
- Subsequent responses and requests in the same dialog are also marked with a "log me" marker. For some scenarios, such as call transfer, related dialogs may also be marked with a "log me" marker 🔁.
- Logging stops, either because the dialog has ended or because a "stop event" occurred. A stop event is typically the expiry of a certain amount of time ⏳.
- Logs are retrieved, for example, by logging on to the SIP entity or entities that contain the logs 💾.
5. "Log Me" Marking Requirements 💌
Part 2 is next, so don't go anywhere 🧚💖
5.1. Message Logs 📝✨
REQ1 okay bestie, so if a SIP message gets logged, the entire thing (SIP headers AND the message body) MUST be logged using a standard logging format such as the SIP Common Log Format (CLF) defined in [RFC6873]. no skipping the juicy bits 🙅♀️💅
REQ2 header fields SHOULD be logged in the exact form they showed up in the message 🎀. They SHOULD NOT be converted between long and compact forms as described in [RFC3261], Section 7.3.3. main character header energy, keep it as-is 💜
When and how signaling logs get pulled back out is out of scope for this doc 🙈. Logs might be retrieved by logging on to the SIP entity that holds them, by sending them to a central server that's coordinating the debugging, by storing them on removable media for a later manual collection, or by some other method 🌸. All log retrieval mechanisms MUST adhere to the authorization and privacy protection policies set forth by the network administrator. no exceptions, periodt 🔐
5.2. "Log Me" Marking 🏷️
REQ3 it MUST be possible to mark a SIP request or response to be considered for logging by inserting a "log me" marker. this is called "log me" marking 🦋.
REQ4 it MUST be possible for a "log me" marker to cross network boundaries 🌈.
REQ5 a "log me" marker MAY include an identifier that shows which test case caused it to be inserted, known as a "test case identifier" 🧚. The test case identifier doesn't affect session setup at all 🙌. It's used to collate all logged SIP requests and responses to the initial SIP request in a dialog or standalone transaction. The local Universally Unique Identifier (UUID) portion of the Session-ID described in [RFC7206] and [RFC7989] could be used as a random test case identifier ✨.
5.3. Processing the "Log Me" Marker 🔍
REQ6 a "log me" marker is most effective if all networks on the signaling path agree to pass it 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 is not expecting 😬.
REQ7 the presence of a "log me" marker indicates that a request or response is part of debugging or regression testing 🐛.
REQ8 it MUST be possible to insert a "log me" marker in SIP responses that correspond to SIP requests with a "log me" marker, so the complete SIP transaction gets logged 💖. This requirement applies to endpoints, SIP/Public Switched Telephone Network (PSTN) gateways, and back-to-back user agents (B2BUAs).
REQ9 the "log me" marker mechanism SHOULD allow a SIP intermediary to request logging of SIP requests and responses on behalf of the originating endpoint 👑. The typical use case is compatibility with User Agents (UAs) that haven't implemented "log me" marking, i.e., when a UA hasn't marked a request, or when responses received on a dialog of interest for logging don't contain an echoed "log me" marker. Another use case is when the session origination UA that inserted the "log me" marker is no longer participating in the session (for example, call transfer scenarios), and the intermediary adds a "log me" marker in related sessions to enable end-to-end signaling analysis 🧩.
REQ10 the mechanism MUST allow stateless processing of SIP requests that contain a "log me" marker by SIP intermediaries 🫧. This requirement lets SIP intermediaries base the decision to log a SIP request or response solely on the presence of the "log me" marker.
REQ11 the scope of a SIP message logging request includes all requests and responses within a given dialog 📞. The scope can be extended to related dialogs that correspond to an end-to-end session for scenarios discussed in REQ9. The "log me" request MUST be indicated at the beginning of the dialog of interest and SHOULD continue to the dialog end without any stop and restart during the duration of the dialog 🍓.
REQ12 the presence of a "log me" marker might cause some SIP entities to log signaling. Therefore, this marker MUST be removed at the earliest opportunity if it has been incorrectly inserted (for example, mid-dialog or outside the configured start and stop of "log me" marking) 🧹.
The definition of types of events that cause logging to stop, and the configuration of SIP entities to detect such "stop events", is outside the scope of this document 🛑.
6. Security Considerations 🔐💀
In order to prevent any security implications of a "log me" marker, the marker itself MUST NOT contain any sensitive information, detecting its presence or absence MUST NOT reveal sensitive information, and maliciously adding a "log me" marker MUST NOT adversely affect a network. This section analyzes how to meet these requirements. this part is very serious, so read it twice 🫶
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 MUST be removed at a trust domain boundary. If a prior agreement to log sessions exists with the next hop network, then the "log me" marker SHOULD NOT be removed. 🙌
6.2. Security Threats ⚠️
6.2.1. "Log Me" Marking
The "log me" marker MUST NOT convey any sensitive information, although the "log me" marker will sometimes be inserted because a particular device is experiencing problems. The "log me" marker MUST NOT reveal any information related to any SIP user or device. 🕵️♀️
The insertion of the "log me" marker at the endpoint MUST be approved by the end user or by the network administrator. Similarly, network administrator authorization is required for a SIP intermediary to insert a "log me" marker on behalf of a UA that does not support "log me" marking. 👑
Activating a debug mode affects the operation of a terminal; therefore, the debugging configuration MUST be supplied by an authorized party to an authorized terminal through a secure communication channel. no leaks, no vibes-only security 🔒
6.2.2. Logged Information
Logged signaling is privacy-sensitive data; therefore, signaling logs MUST NOT be readable by an unauthorized third party. 🙈🔐
7. IANA Considerations 🎀
This document does not require any IANA actions. 💅
8. References 📚
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6873] Salgueiro, G., Gurbani, V., and A. Roach, "Format for the
Session Initiation Protocol (SIP) Common Log Format
(CLF)", RFC 6873, DOI 10.17487/RFC6873, February 2013,
<http://www.rfc-editor.org/info/rfc6873>.8.2. Informative References
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002,
<http://www.rfc-editor.org/info/rfc3261>.
[RFC5853] Hautakorpi, J., Ed., Camarillo, G., Penfield, R.,
Hawrylyshen, A., and M. Bhatia, "Requirements from Session
Initiation Protocol (SIP) Session Border Control (SBC)
Deployments", RFC 5853, DOI 10.17487/RFC5853, April 2010,
<http://www.rfc-editor.org/info/rfc5853>.
[RFC7092] Kaplan, H. and V. Pascual, "A Taxonomy of Session
Initiation Protocol (SIP) Back-to-Back User Agents",
RFC 7092, DOI 10.17487/RFC7092, December 2013,
<http://www.rfc-editor.org/info/rfc7092>.
[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, DOI 10.17487/RFC7206, May 2014,
<http://www.rfc-editor.org/info/rfc7206>.
[RFC7989] Jones, P., Salgueiro, G., Pearce, C., and P. Giralt, "End-
to-End Session Identification in IP-Based Multimedia
Communication Networks", RFC 7989, DOI 10.17487/RFC7989,
October 2016, <http://www.rfc-editor.org/info/rfc7989>.Acknowledgments 🫶🌸
The authors wish to thank Jorgen Axell, Ben Campbell, Keith Drage, Vijay Gurbani, Christer Holmberg, Hadriel Kaplan, Paul Kyzivat, James Polk, Gonzalo Salgueiro, Alberto Llamas, Brett Tate, Paul Giralt, Stewart Bryant, Sean Turner, and Dan Romascanu for their constructive comments and guidance while developing this document. the whole squad 👑💜
Authors' Addresses 💌
Peter Dawes
Vodafone Group
The Connection
Newbury, Berkshire RG14 2FN
United Kingdom
Email: peter.dawes@vodafone.com
Chidambaram Arunachalam
Cisco Systems
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
United States of America
Email: carunach@cisco.comthe end, bestie 🌈✨🦋
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