rfc9565.original   rfc9565.txt 
OPSAWG M. Boucadair Internet Engineering Task Force (IETF) M. Boucadair
Internet-Draft Orange Request for Comments: 9565 Orange
Obsoletes: 7125 (if approved) 29 November 2023 Obsoletes: 7125 March 2024
Intended status: Standards Track Category: Standards Track
Expires: 1 June 2024 ISSN: 2070-1721
An Update to the tcpControlBits IP Flow Information Export (IPFIX) An Update to the tcpControlBits IP Flow Information Export (IPFIX)
Information Element Information Element
draft-ietf-opsawg-rfc7125-update-07
Abstract Abstract
RFC 7125 revised the tcpControlBits IP Flow Information Export RFC 7125 revised the tcpControlBits IP Flow Information Export
(IPFIX) Information Element that was originally defined in RFC 5102 (IPFIX) Information Element that was originally defined in RFC 5102
to reflect changes to the TCP header control bits since RFC 793. to reflect changes to the TCP header control bits since RFC 793.
However, that update is still problematic for interoperability However, that update is still problematic for interoperability
because some flag values have subsequently been deprecated. because some flag values have subsequently been deprecated.
This document removes stale information from the IPFIX registry and This document removes stale information from the IANA "IPFIX
avoids future conflicts with the authoritative TCP Header Flags Information Elements" registry and avoids future conflicts with the
registry. authoritative IANA "TCP Header Flags" registry.
This document obsoletes RFC 7125. This document obsoletes RFC 7125.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the Operations and
Management Area Working Group Working Group mailing list
(opsawg@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/opsawg/.
Source for this draft and an issue tracker can be found at
https://github.com/boucadair/-ipfix-rfc7125-update.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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-
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 1 June 2024. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9565.
Copyright Notice Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology
3. Revised tcpControlBits Information Element . . . . . . . . . 3 3. Revised tcpControlBits Information Element
4. An Example . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. An Example
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7. References
7.1. Normative References . . . . . . . . . . . . . . . . . . 5 7.1. Normative References
7.2. Informative References . . . . . . . . . . . . . . . . . 6 7.2. Informative References
Appendix A. Changes from RFC 7125 . . . . . . . . . . . . . . . 7 Appendix A. Changes from RFC 7125
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7 Acknowledgments
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Acknowledgments from RFC 7125
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8 Contributors
Author's Address
1. Introduction 1. Introduction
TCP defines a set of control bits (also known as "flags") for TCP defines a set of control bits (also known as "flags") for
managing connections (Section 3.1 of [RFC9293]). The "Transmission managing connections (Section 3.1 of [RFC9293]). The "TCP Header
Control Protocol (TCP) Header Flags" registry was initially set by Flags" registry was initially set by [RFC3168], but it was populated
[RFC3168], but it was populated with only TCP control bits that were with only TCP control bits that were defined in [RFC3168]. [RFC9293]
defined in [RFC3168]. [RFC9293] fixed that by moving that registry fixed that by moving that registry to be listed as a subregistry
to be listed as a subregistry under the "Transmission Control under the "Transmission Control Protocol (TCP) Parameters" registry
Protocol (TCP) Parameters" registry [TCP-FLAGS], adding bits that had [TCP-FLAGS], adding bits that had previously been specified in
previously been specified in [RFC0793], and removing the NS (Nonce [RFC0793], and removing the NS (Nonce Sum) bit per [RFC8311]. Also,
Sum) bit as per [RFC8311]. Also, Section 6 of [RFC9293] introduces Section 6 of [RFC9293] introduces "Bit Offset" to ease referencing
"Bit Offset" to ease referencing each header flag's offset within the each header flag's offset within the 16-bit aligned view of the TCP
16-bit aligned view of the TCP header (Figure 1 of [RFC9293]). header (Figure 1 of [RFC9293]). [TCP-FLAGS] is thus settled as the
[TCP-FLAGS] is thus settled as the authoritative reference for the authoritative reference for the assigned TCP control bits.
assigned TCP control bits.
Note: The bits in offsets 0 through 3 are not header flags, but Note: The bits in offsets 0 through 3 are not header flags, but
the TCP segment Data Offset field. the TCP segment Data Offset field.
[RFC7125] revised the tcpControlBits IP Flow Information Export [RFC7125] revised the tcpControlBits IP Flow Information Export
(IPFIX) Information Element (IE) that was originally defined in (IPFIX) Information Element that was originally defined in [RFC5102]
[RFC5102] to reflect changes to the TCP control bits since [RFC0793]. to reflect changes to the TCP control bits since [RFC0793]. However,
However, that update is still problematic for interoperability that update is still problematic for interoperability because a value
because a value was deprecated since then (Section 7 of [RFC8311]) was deprecated since then (Section 7 of [RFC8311]), and, therefore,
and, therefore, [RFC7125] risks deviating from the authoritative TCP [RFC7125] risks deviating from the authoritative "TCP Header Flags"
registry [TCP-FLAGS]. registry [TCP-FLAGS].
This document fixes that problem by removing stale information from This document fixes that problem by removing stale information from
the IPFIX registry [IPFIX] and avoiding future conflicts with the the "IPFIX Information Elements" registry [IPFIX] and avoiding future
authoritative TCP registry [TCP-FLAGS]. The update in this document conflicts with the authoritative "TCP Header Flags" registry
is also useful to enhance observability. For example, network [TCP-FLAGS]. The update in this document also enhances
operators can identify when packets are being observed with observability. For example, network operators can identify packets
unassigned TCP flags set and, therefore, identify which applications that are observed with unassigned TCP flags set and, therefore,
in the network should be upgraded to reflect the changes to TCP flags identify which applications in the network should be upgraded to
that were introduced, e.g., in [RFC8311]. reflect the changes to TCP flags that were introduced, e.g., in
[RFC8311].
The main changes to [RFC7125] are listed in Appendix A. The main changes from [RFC7125] are listed in Appendix A.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This document uses the terms defined in Section 2 of [RFC7011]. This document uses the terms defined in Section 2 of [RFC7011].
3. Revised tcpControlBits Information Element 3. Revised tcpControlBits Information Element
ElementId: 6 ElementID: 6
Data Type: unsigned16 Name: tcpControlBits
Abstract Data Type: unsigned16
Data Type Semantics: flags Data Type Semantics: flags
Description: TCP control bits observed for the packets of this Flow. Status: current
Description: TCP control bits observed for the packets of this Flow.
This information is encoded as a bit field; each TCP control bit This information is encoded as a bit field; each TCP control bit
has a corresponding bit in that field. A bit is set to 1 if any has a corresponding bit in that field. A bit is set to 1 if any
observed packet of this Flow has the corresponding TCP control bit observed packet of this Flow has the corresponding TCP control bit
set to 1. The bit is cleared to 0 otherwise. set to 1. The bit is cleared to 0 otherwise.
As per [RFC9293], the assignment of the TCP control bits is Per [RFC9293], the assignment of TCP control bits is managed by
managed by IANA from the "TCP Header Flags" registry [TCP-FLAGS]. IANA via the "TCP Header Flags" registry [TCP-FLAGS].
That registry is authoritative to retrieve the most recent TCP Implementers can retrieve the current TCP control bits from that
control bits. registry, which is authoritative for them.
As the most significant 4 bits of octets 12 and 13 (counting from As the most significant 4 bits of octets 12 and 13 (counting from
zero) of the TCP header [RFC9293] are used to encode the TCP data zero) of the TCP header [RFC9293] are used to encode the TCP data
offset (header length), the corresponding bits in this Information offset (header length), the corresponding bits in this Information
Element MUST be reported by the Exporter with a value of zero and Element MUST be reported by the Exporter with a value of zero and
MUST be ignored by the Collector. Use the tcpHeaderLength MUST be ignored by the Collector. Use the tcpHeaderLength
Information Element to encode this value. Information Element to encode this value.
All TCP control bits (including those unassigned) MUST be exported All TCP control bits (including those unassigned) MUST be exported
as observed in the TCP headers of the packets of this Flow. as observed in the TCP headers of the packets of this Flow.
skipping to change at page 4, line 46 skipping to change at line 173
Information Element. Information Element.
Note that previous revisions of this Information Element's Note that previous revisions of this Information Element's
definition specified that flags with bit offset positions 8 and 9 definition specified that flags with bit offset positions 8 and 9
must be exported as zero, even if observed. Collectors should must be exported as zero, even if observed. Collectors should
therefore not assume that a value of zero for these bits in this therefore not assume that a value of zero for these bits in this
Information Element indicates the bits were never set in the Information Element indicates the bits were never set in the
observed traffic, especially if these bits are zero in every Flow observed traffic, especially if these bits are zero in every Flow
Record sent by a given Exporter. Record sent by a given Exporter.
Note also that [TCP-FLAGS] indexes the bit offset from the most- Note also that the "TCP Header Flags" registry [TCP-FLAGS] indexes
significant bit of octet 12 to the least-significant bit of octet the bit offset from the most significant bit of octet 12 to the
13 in the TCP header, but the tcpControlBits is encoded as a least significant bit of octet 13 in the TCP header, but the
regular unsigned 16 bit integer. tcpControlBits is encoded as a regular unsigned 16-bit integer.
Units: Units:
Range: Range:
References: [RFC9293][This-Document] Additional Information: See the assigned TCP control bits in the
"TCP Header Flags" registry [TCP-FLAGS].
Additional Information: See the assigned TCP control bits in Reference: [RFC9293], RFC 9565
[TCP-FLAGS].
Revision: 2 Revision: 2
4. An Example 4. An Example
Figure 1 shows an example of a tcpControlBits Information Element set Figure 1 shows an example of a tcpControlBits Information Element set
to 146. This Information Element is used to report TCP control bits to 0x92, where MSB indicates the most significant bit and LSB
for a Flow that has CWR (Congestion Window Reduced), ACK, and SYN indicates the least significant bit. This Information Element is
flag bits set (that is, bit offset positions 8, 11, and 14). used to report TCP control bits for a Flow that has CWR (Congestion
Window Reduced), ACK, and SYN flag bits set (that is, bit offset
positions 8, 11, and 14).
MSB LSB MSB LSB
1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0|0|0|0|1|0|0|1|0|0|1|0| |0|0|0|0|0|0|0|0|1|0|0|1|0|0|1|0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: An Example of tcpControlBits Information Element Figure 1: An Example of the tcpControlBits Information Element
5. IANA Considerations 5. IANA Considerations
IANA is requested to update the "tcpControlBits" entry of the [IPFIX] IANA has updated the "tcpControlBits" entry of the "IPFIX Information
to echo the details provided in Section 3. Elements" registry [IPFIX] to echo the details provided in Section 3.
6. Security Considerations 6. Security Considerations
Because the setting of TCP control bits may be misused in some flows Because the setting of TCP control bits may be misused in some Flows
(e.g., Distributed Denial-of-Service (DDoS) attacks), an Exporter has (e.g., Distributed Denial-of-Service (DDoS) attacks), an Exporter has
to report all observed control bits even if no meaning is associated to report all observed control bits even if no meaning is associated
with a given TCP flag. This document uses a stronger requirements with a given TCP flag. This document uses a stronger requirements
language compared to [RFC7125]. language compared to [RFC7125].
This document does not add new security considerations to those This document does not add new security considerations to those
already discussed for IPFIX in [RFC7011]. already discussed for IPFIX in [RFC7011].
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken, [RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
"Specification of the IP Flow Information Export (IPFIX) "Specification of the IP Flow Information Export (IPFIX)
Protocol for the Exchange of Flow Information", STD 77, Protocol for the Exchange of Flow Information", STD 77,
RFC 7011, DOI 10.17487/RFC7011, September 2013, RFC 7011, DOI 10.17487/RFC7011, September 2013,
<https://www.rfc-editor.org/rfc/rfc7011>. <https://www.rfc-editor.org/info/rfc7011>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9293] Eddy, W., Ed., "Transmission Control Protocol (TCP)", [RFC9293] Eddy, W., Ed., "Transmission Control Protocol (TCP)",
STD 7, RFC 9293, DOI 10.17487/RFC9293, August 2022, STD 7, RFC 9293, DOI 10.17487/RFC9293, August 2022,
<https://www.rfc-editor.org/rfc/rfc9293>. <https://www.rfc-editor.org/info/rfc9293>.
[TCP-FLAGS] [TCP-FLAGS]
IANA, "TCP Header Flags", n.d., IANA, "TCP Header Flags",
<https://www.iana.org/assignments/tcp-parameters/tcp- <https://www.iana.org/assignments/tcp-parameters/>.
parameters.xhtml#tcp-header-flags>.
7.2. Informative References 7.2. Informative References
[IPFIX] IANA, "IP Flow Information Export (IPFIX) Entities", n.d., [IPFIX] IANA, "IPFIX Information Elements",
<https://www.iana.org/assignments/ipfix/ipfix.xhtml>. <https://www.iana.org/assignments/ipfix/>.
[RFC0793] Postel, J., "Transmission Control Protocol", RFC 793, [RFC0793] Postel, J., "Transmission Control Protocol", RFC 793,
DOI 10.17487/RFC0793, September 1981, DOI 10.17487/RFC0793, September 1981,
<https://www.rfc-editor.org/rfc/rfc793>. <https://www.rfc-editor.org/info/rfc793>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP", of Explicit Congestion Notification (ECN) to IP",
RFC 3168, DOI 10.17487/RFC3168, September 2001, RFC 3168, DOI 10.17487/RFC3168, September 2001,
<https://www.rfc-editor.org/rfc/rfc3168>. <https://www.rfc-editor.org/info/rfc3168>.
[RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J. [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J.
Meyer, "Information Model for IP Flow Information Export", Meyer, "Information Model for IP Flow Information Export",
RFC 5102, DOI 10.17487/RFC5102, January 2008, RFC 5102, DOI 10.17487/RFC5102, January 2008,
<https://www.rfc-editor.org/rfc/rfc5102>. <https://www.rfc-editor.org/info/rfc5102>.
[RFC7125] Trammell, B. and P. Aitken, "Revision of the [RFC7125] Trammell, B. and P. Aitken, "Revision of the
tcpControlBits IP Flow Information Export (IPFIX) tcpControlBits IP Flow Information Export (IPFIX)
Information Element", RFC 7125, DOI 10.17487/RFC7125, Information Element", RFC 7125, DOI 10.17487/RFC7125,
February 2014, <https://www.rfc-editor.org/rfc/rfc7125>. February 2014, <https://www.rfc-editor.org/info/rfc7125>.
[RFC8311] Black, D., "Relaxing Restrictions on Explicit Congestion [RFC8311] Black, D., "Relaxing Restrictions on Explicit Congestion
Notification (ECN) Experimentation", RFC 8311, Notification (ECN) Experimentation", RFC 8311,
DOI 10.17487/RFC8311, January 2018, DOI 10.17487/RFC8311, January 2018,
<https://www.rfc-editor.org/rfc/rfc8311>. <https://www.rfc-editor.org/info/rfc8311>.
[RFC9487] Graf, T., Claise, B., and P. Francois, "Export of Segment [RFC9487] Graf, T., Claise, B., and P. Francois, "Export of Segment
Routing over IPv6 Information in IP Flow Information Routing over IPv6 Information in IP Flow Information
Export (IPFIX)", RFC 9487, DOI 10.17487/RFC9487, November Export (IPFIX)", RFC 9487, DOI 10.17487/RFC9487, November
2023, <https://www.rfc-editor.org/rfc/rfc9487>. 2023, <https://www.rfc-editor.org/info/rfc9487>.
Appendix A. Changes from RFC 7125 Appendix A. Changes from RFC 7125
* Clean-up the description by removing mentions of stale flag bits, * Cleaned up the description of the tcpControlBits Information
referring to the flag bits by their bit offset position, and Element by removing mentions of stale flag bits, referring to the
relying upon the IANA TCP registry. flag bits by their bit offset position, and relying upon the IANA
"TCP Header Flags" registry.
* Remove the table of TCP flag bits from the description of the * Removed the table of TCP flag bits from the description of the
tcpControlBits Information Element. tcpControlBits Information Element.
* Add [TCP-FLAGS] to the Additional Information field of the * Added the reference [TCP-FLAGS] to the Additional Information
tcpControlBits Information Element. field of the tcpControlBits Information Element.
* Use strong normative language for exporting observed flags. * Used strong normative language for exporting observed flags.
* Update the references of the tcpControlBits Information Element. * Updated the references of the tcpControlBits Information Element.
* Bump the revision of the tcpControlBits Information Element. * Bumped the revision of the tcpControlBits Information Element.
* Replace obsolete RFCs (e.g., [RFC0793]). * Replaced obsolete RFCs (e.g., [RFC0793]).
* Add an Example Section * Added an example section (Section 4).
Acknowledgments Acknowledgments
This document was triggered by a discussion of the author in opsawg This document was triggered by a discussion in the opsawg working
with the authors of [RFC9487]. group between the author and the authors of [RFC9487].
Thanks to Christian Jacquenet, Thomas Graf, and Benoît Claise for the Thanks to Christian Jacquenet, Thomas Graf, and Benoît Claise for the
review and comments. review and comments.
Thanks to Michael Scharf for the tsvart review, Ketan Talaulikar for Thanks to Michael Scharf for the tsvart review, Ketan Talaulikar for
the rtgdir review, and Elwyn Davies for the genart review. the rtgdir review, and Elwyn Davies for the genart review.
Thanks to Rob Wilton for the AD review. Thanks to Rob Wilton for the AD review.
Thanks for Tim Bray for the artart review and Shawn Emery for the Thanks to Tim Bray for the artart review and Shawn Emery for the
secdir review. secdir review.
Thanks to Éric Vyncke and Paul Wouters for the comments in the IESG Thanks to Éric Vyncke and Paul Wouters for the comments in the IESG
review. review.
Acknowledgments from [RFC7125]: Thanks to Andrew Feren, Lothar Acknowledgments from RFC 7125
Braun, Michael Scharf, and Simon Josefsson for comments on the
revised definition. This work is partially supported by the Thanks to Andrew Feren, Lothar Braun, Michael Scharf, and Simon
European Commission under grant agreement FP7-ICT-318627 mPlane; Josefsson for comments on the revised definition. This work is
this does not imply endorsement by the Commission. partially supported by the European Commission under grant agreement
FP7-ICT-318627 mPlane; this does not imply endorsement by the
Commission.
Contributors Contributors
The authors of [RFC7125] are as follows: The authors of [RFC7125] are as follows:
* Brian Trammell Brian Trammell
* Paul Aitken Paul Aitken
Author's Address Author's Address
Mohamed Boucadair Mohamed Boucadair
Orange Orange
35000 Rennes 35000 Rennes
France France
Email: mohamed.boucadair@orange.com Email: mohamed.boucadair@orange.com
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