Internet Engineering Task Force P. Dawes
Internet-Draft Vodafone Group
Intended status: Informational C. Arunachalam
Expires: April 6, 2017 Cisco Systems
October 3, 2016
Requirements for Marking SIP Messages to be Logged
draft-ietf-insipid-logme-reqs-08
Abstract
SIP networks use signaling 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 signaling will take between clients, and
therefore impractical to monitor SIP signaling 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 signaling. 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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 6, 2017.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
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 . . . . . . . . . . . . . . . 4
4.3. Example Debugging Procedure . . . . . . . . . . . . . . . 5
5. Logme Marking Requirements . . . . . . . . . . . . . . . . . 6
5.1. Message Logs . . . . . . . . . . . . . . . . . . . . . . 6
5.2. "Log Me" Marking . . . . . . . . . . . . . . . . . . . . 6
5.3. Processing the "Log Me" Marker . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6.1. Trust Domain . . . . . . . . . . . . . . . . . . . . . . 8
6.2. Security Threats . . . . . . . . . . . . . . . . . . . . 8
6.2.1. "Log Me" Marking . . . . . . . . . . . . . . . . . . 8
6.2.2. Logged Information . . . . . . . . . . . . . . . . . 9
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Service providers, enterprises, and others who operate networks that
use SIP (see [RFC3261]) need the ability to debug end user reported
problems and also to run regression tests if SIP client software/
hardware is upgraded. Such debugging and tests might be confined to
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a single service provider or network, or may occur between the
administrative domains of different network operators, including
domains 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
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 network operators, different countries, regions with
different privacy requirements, and different trust domains. This
draft 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].
3. Terminology
3.1. Network Boundary
A network boundary is the part of a signaling path where messages
pass between entities that are under different administrative
control. [RFC5853] Figure 2 shows a network boundary between GW-A1
in operator A's network and the SBC in operator B's network. A
network boundary is significant in this document because manipulation
of signaling at the boundary could prevent end-to-end testing or
troubleshooting.
[RFC5853] gives examples of manipulating signaling to prevent the
sending network passing on sensitive information, for example
topology hiding, or the receiving network protecting itself from
signaling that is not under its control, for example protocol repair.
Example SIP device types (see [RFC7092]) that might manipulate
signaling at a network boundary are a Session Border Controller
performing protocol repair or Interconnection Border Control Function
(IBCF) performing topology hiding.
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3.2. Trust Domain
In this document a trust domain is the set of entities that have been
identified, by prior agreement, as participating elements in logging,
typically for the purpose of debugging or regression testing. A
trust domain contains all SIP entities under configuration control of
the network operator that is performing regression testing plus all
SIP entities that are under configuration control of peer network
operators who have agreed to participate in that regression testing.
The purpose of trust domain requirements is to prevent network
operators inadvertently triggering logging in networks that are not
part of any testing or troubleshooting.
3.3. Intermediary
The term "intermediary" is defined in [I-D.ietf-insipid-session-id]
section 2 and refers to any entity along the call signaling path.
4. Motivating Scenario
4.1. Introduction
Signaling 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 signaling and the explosion in the number of possible
signaling paths through SIP entities from the originating to the
terminating user make it impractical to pre-configure logging of an
end-to-end SIP signaling of a session of interest.
4.2. Example Network Arrangement
The figure below gives an example of a signaling 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 signaling path through multiple networks
4.3. Example Debugging Procedure
One possible set of steps is outlined below to illustrate the
debugging procedure.
o 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.
o All SIP entities that the signaling traverses, from the first
proxy the terminal connects to at the edge of the network to the
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destination client terminal, detect that the "log me" marker is
present and log SIP requests and responses that contain the marker
if configured to do so.
o Subsequent responses and requests in the same dialog are also
marked with a "log me" marker.
o Logging stops, either because the dialog has ended or because a
'stop event', typically expiry of a certain amount of time,
occurred.
o Logs are retrieved, for example by logging on to the SIP entity
that contains the logs.
5. Logme Marking Requirements
5.1. Message Logs
o REQ1: The entire SIP message (SIP headers and message body) MUST
be logged using the SIP CLF format defined in [RFC6873], with
Vendor-ID = 00000000 and Tag = 02 in the <OptionalFields> portion
of the SIP CLF record (see [RFC6873] clause 4.4).
o REQ2: Header fields SHOULD be logged in the form in which they
appear in the message, they SHOULD NOT be converted between long
and compact forms described in [RFC3261] clause 7.3.3.
When and how signaling 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.
5.2. "Log Me" Marking
o REQ3: 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 REQ4: It MUST be possible for a "log me" marker to cross network
boundaries.
o REQ5: 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 local UUID portion of
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Session-ID described in [RFC7206] and
[I-D.ietf-insipid-session-id] could be used as a random test case
identifier.
5.3. Processing the "Log Me" Marker
o REQ6: 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 REQ7: 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.
o REQ8: 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. This requirement applies to cases
where the UA is the endpoint of communication, where the UA is one
side of a gateway such as a SIP/PSTN gateway, and where the UA is
one side of a B2BUA.
o REQ9: A SIP intermediary 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 "log me" 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.
Another use case is when the session origination UA that inserted
log me marker is no longer participating in the session (e.g.,
call transfer scenarios) and the intermediary adds "log me" marker
in related sessions to enable end-to-end signaling analysis. 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 REQ10: SIP intermediaries 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.
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Echoing a "log me" marker in responses is the responsibility of
the UA that receives a request.
o REQ11: "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 SHOULD be applied to in-dialog
requests and responses in either direction. "log me" marking MUST
NOT be stopped and re-started on a given dialog.
The definition of types of events that cause logging to stop and
configuring 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 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
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 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.
Activating a debug mode affects the operation of a terminal,
therefore debugging configuration MUST be supplied by an authorized
party to an authorized terminal, debugging configuration MUST NOT be
altered in transit, and MUST NOT be readable by an unauthorized third
party.
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Logged signaling is privacy-sensitive data, therefore signaling logs
MUST NOT be readable by an unauthorized third party.
6.2.2. Logged Information
A SIP entity that has logged information should prevent unauthorized
access to that logged information.
7. Acknowledgments
The authors wish to thank Jorgen Axell, Keith Drage, Vijay Gurbani,
Christer Holmberg, Hadriel Kaplan, Paul Kyzivat, James Polk, Gonzalo
Salgueiro, Alberto Llamas, Brett Tate and Paul Giralt 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,
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., Salgueiro, G., Pearce, C., and P. Giralt, "End-
to-End Session Identification in IP-Based Multimedia
Communication Networks", draft-ietf-insipid-session-id-27
(work in progress), August 2016.
[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>.
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[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>.
Authors' Addresses
Peter Dawes
Vodafone Group
The Connection
Newbury, Berkshire RG14 2FN
UK
Email: peter.dawes@vodafone.com
Chidambaram Arunachalam
Cisco Systems
7200-12 Kit Creek Road
Research Triangle Park, NC, NC 27709
US
Email: carunach@cisco.com
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