Internet Engineering Task Force P. Dawes
Internet-Draft Vodafone Group
Intended status: Informational C. Arunachalam
Expires: July 14, 2016 Cisco Systems
January 11, 2016
Requirements for Marking SIP Messages to be Logged
draft-ietf-insipid-logme-reqs-05
Abstract
SIP networks use signalling monitoring tools to debug customer
reported problems 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 data unit (PDU, or a SIP message) that marks the PDU as a
candidate for 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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This Internet-Draft will expire on July 14, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in this Document . . . . . . . . . . . . . . 3
3. Motivating Scenario . . . . . . . . . . . . . . . . . . . . . 3
4. Basic Debugging Procedure . . . . . . . . . . . . . . . . . . 4
5. Requirements for a "Log Me" Marker . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6.1. Trust Domain . . . . . . . . . . . . . . . . . . . . . . 7
6.2. Security Threats . . . . . . . . . . . . . . . . . . . . 7
6.2.1. "Log Me" Marking . . . . . . . . . . . . . . . . . . 7
6.2.2. Sending Logged Information . . . . . . . . . . . . . 7
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Service providers who use SIP (see RFC 3261 [RFC3261]) in their
networks need the ability to debug customer reported problems and
also need to run regression tests if SIP client software/hardware is
upgraded. Such debugging and tests might be confined to a single
service provider or network may occur between the administrative
domains of service providers, including providers in different
countries that are interconnected through networks belonging to one
or more third parties.
A mechanism is needed to mark particular SIP sessions, i.e. those
related to debugging or regression testing, as candidates for logging
and this marking must be carried within the candidate SIP messages as
they are routed across networks (and geographies) to enable logging
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at each SIP entity without having to know in advance the list of SIP
entities through which the SIP signaling messages will traverse.
Such marking must take into account that SIP messages might traverse
different service providers, different countries, regions with
different privacy requirements, and different trust domains. 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].
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
different countries. If a single operator wishes to perform
regression testing or fault debugging 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 gives an example of a signalling path through
multiple networks.
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+------------------+ +------------------+
| 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 signalling path through multiple networks
4. Basic Debugging Procedure
The debugging procedure steps are outlined below. The entire SIP
message (SIP headers and message body) MUST be logged using the SIP
CLF format defined in RFC 6873 [RFC6873], with Vendor-ID = 00000000
and Tag = 02 in the <OptionalFields> portion of the SIP CLF record
(see RFC 6873 [RFC6873] clause 4.4). Header fields MUST be logged in
their long form and not the compact form described in RFC 3261
[RFC3261] clause 7.3.3.
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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
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. The definition of stop event types and the
configuration of stop events in the SIP entity is outside the
scope of this document.
o When and how signalling logs are retrieved is out of scope of this
document. Logs might be retrieved by logging on to the SIP entity
that contains the logs, by sending logs to a central server that
is co-ordinating debugging, by storing them on removable media for
later manual collection, or by some other method.
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: The presence of a "log me" marker indicates that a request
or response is part of debugging or regression testing. SIP
entities that support "log me" marking SHOULD log SIP requests or
responses that contain a "log me" marker." The SIP entity checks
for the presence of a "log me" marker and writes any request or
response that contains a "log me" marker to a log file.
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o REQ5: If a UA that supports "log me" marking 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 insert a "log me" marker into requests and
responses. The typical case for which a proxy needs to insert a
"log me" marker is for compatibility with UAs that have not
implemented "logme" marking, i.e. when a UA has not marked a
request or when responses received on a dialog of interest for
logging do not contain an echoed "log me" marker. In these cases,
the entity that inserts a "log me" marker is stateful inasmuch as
it must remember when a dialog is of interest for logging. An
entity that inserts a "log me" marker SHOULD also log the SIP
request or response as per REQ4.
o REQ7: SIP proxies MAY be stateless in terms of logging of SIP
requests that contain a "log me" marker, i.e. they MAY base the
decision to log a SIP request or response solely on the presence
of the "log me" marker. 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.
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 debugging 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.
o REQ9: "log me" marking of requests and responses MUST be applied
on a per-dialog granularity. If applied, "log me" marking MUST
begin with the dialog-creating request and SHOULD continue to the
dialog end. "log me" marking MUST NOT be stopped and re-started on
a given dialog.
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
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adversely affect a network. This section analyses how to meet these
requirements.
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 next 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 MUST not convey any sensitive information,
although the "log me" marker 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 debugging configuration must be supplied by an authorized
server to an authorized terminal, debugging configuration must not be
altered in transit, and must not be readable by an unauthorized third
party.
Logged signalling is privacy-sensitive data, therefore signalling
logs must be passed to an authorized server, must not be altered in
transit, and must not be readable by an unauthorized third party.
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 authors wish to thank Jorgen Axell, Keith Drage, Vijay Gurbani,
Christer Holmberg, Hadriel Kaplan, Paul Kyzivat, James Polk, and
Gonzalo Salgueiro for their constructive comments and guidance while
developing this document.
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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
[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.
[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>.
[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>.
Authors' Addresses
Peter Dawes
Vodafone Group
The Connection
Newbury, Berkshire RG14 2FN
UK
Email: peter.dawes@vodafone.com
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Chidambaram Arunachalam
Cisco Systems
7200-12 Kit Creek Road
Research Triangle Park, NC, NC 27709
US
Email: carunach@cisco.com
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