< draft-ietf-v6ops-ipv6-ehs-packet-drops-05.txt   draft-ietf-v6ops-ipv6-ehs-packet-drops-06.txt >
IPv6 Operations Working Group (v6ops) F. Gont IPv6 Operations Working Group (v6ops) F. Gont
Internet-Draft SI6 Networks Internet-Draft SI6 Networks
Intended status: Informational N. Hilliard Intended status: Informational N. Hilliard
Expires: August 15, 2021 INEX Expires: October 10, 2021 INEX
G. Doering G. Doering
SpaceNet AG SpaceNet AG
W. Kumari W. Kumari
Google Google
G. Huston G. Huston
APNIC APNIC
W. Liu W. Liu
Huawei Technologies Huawei Technologies
February 11, 2021 April 8, 2021
Operational Implications of IPv6 Packets with Extension Headers Operational Implications of IPv6 Packets with Extension Headers
draft-ietf-v6ops-ipv6-ehs-packet-drops-05 draft-ietf-v6ops-ipv6-ehs-packet-drops-06
Abstract Abstract
This document summarizes the operational implications of IPv6 This document summarizes the operational implications of IPv6
extension headers specified in the IPv6 protocol specification extension headers specified in the IPv6 protocol specification
(RFC8200), and attempts to analyze reasons why packets with IPv6 (RFC8200), and attempts to analyze reasons why packets with IPv6
extension headers are often dropped in the public Internet. extension headers are often dropped in the public Internet.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 15, 2021. This Internet-Draft will expire on October 10, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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6.3. DDoS Management and Customer Requests for Filtering . . . 9 6.3. DDoS Management and Customer Requests for Filtering . . . 9
6.4. Network Intrusion Detection and Prevention . . . . . . . 10 6.4. Network Intrusion Detection and Prevention . . . . . . . 10
6.5. Firewalling . . . . . . . . . . . . . . . . . . . . . . . 10 6.5. Firewalling . . . . . . . . . . . . . . . . . . . . . . . 10
7. Operational Implications . . . . . . . . . . . . . . . . . . 11 7. Operational Implications . . . . . . . . . . . . . . . . . . 11
7.1. Inability to Find Layer-4 Information . . . . . . . . . . 11 7.1. Inability to Find Layer-4 Information . . . . . . . . . . 11
7.2. Route-Processor Protection . . . . . . . . . . . . . . . 11 7.2. Route-Processor Protection . . . . . . . . . . . . . . . 11
7.3. Inability to Perform Fine-grained Filtering . . . . . . . 12 7.3. Inability to Perform Fine-grained Filtering . . . . . . . 12
7.4. Security Concerns Associated with IPv6 Extension Headers 12 7.4. Security Concerns Associated with IPv6 Extension Headers 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9. Security Considerations . . . . . . . . . . . . . . . . . . . 13 9. Security Considerations . . . . . . . . . . . . . . . . . . . 13
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
11.1. Normative References . . . . . . . . . . . . . . . . . . 14 11.1. Normative References . . . . . . . . . . . . . . . . . . 14
11.2. Informative References . . . . . . . . . . . . . . . . . 15 11.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
IPv6 Extension Headers (EHs) allow for the extension of the IPv6 IPv6 Extension Headers (EHs) allow for the extension of the IPv6
protocol, and provide support for core functionality such as IPv6 protocol, and provide support for core functionality such as IPv6
fragmentation. However, common implementation limitations suggest fragmentation. However, common implementation limitations suggest
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contemporary routers and middle-boxes may need to access Layer-4 contemporary routers and middle-boxes may need to access Layer-4
information to make a forwarding decision. Finally, Section 7 information to make a forwarding decision. Finally, Section 7
discusses the operational implications of IPv6 EHs. discusses the operational implications of IPv6 EHs.
2. Disclaimer 2. Disclaimer
This document analyzes the operational challenges represented by This document analyzes the operational challenges represented by
packets that employ IPv6 Extension Headers, and documents some of the packets that employ IPv6 Extension Headers, and documents some of the
operational reasons why these packets are often dropped in the public operational reasons why these packets are often dropped in the public
Internet. This document is not a recommendation to drop such Internet. This document is not a recommendation to drop such
packets, but rather an analysis of why they are dropped. packets, but rather an analysis of why they are currently dropped.
3. Background Information 3. Background Information
It is useful to compare the basic structure of IPv6 packets against It is useful to compare the basic structure of IPv6 packets against
that of IPv4 packets, and analyze the implications of the two that of IPv4 packets, and analyze the implications of the two
different packet structures. different packet structures.
IPv4 packets have a variable-length header size, that allows for the IPv4 packets have a variable-length header size, that allows for the
use of IPv4 "options" -- optional information that may be of use by use of IPv4 "options" -- optional information that may be of use by
nodes processing IPv4 packets. The IPv4 header length is specified nodes processing IPv4 packets. The IPv4 header length is specified
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implications of IPv6 EHs, and the operational implications of implications of IPv6 EHs, and the operational implications of
dropping packets that employ IPv6 EHs and associated options. dropping packets that employ IPv6 EHs and associated options.
o [RFC7113] discusses how some popular RA-Guard implementations are o [RFC7113] discusses how some popular RA-Guard implementations are
subject to evasion by means of IPv6 extension headers. subject to evasion by means of IPv6 extension headers.
o [RFC8900] analyzes the fragility introduced by IP fragmentation. o [RFC8900] analyzes the fragility introduced by IP fragmentation.
A number of recent RFCs have discussed issues related to IPv6 A number of recent RFCs have discussed issues related to IPv6
extension headers, specifying updates to a previous revision of the extension headers, specifying updates to a previous revision of the
IPv6 standard ([RFC2460]), many of which have now been incorporated IPv6 standard [RFC2460], many of which have now been incorporated
into the current IPv6 core standard ([RFC8200]) or the IPv6 Node into the current IPv6 core standard [RFC8200] or the IPv6 Node
Requirements ([RFC8504]). Namely, Requirements [RFC8504]. Namely,
o [RFC5095] discusses the security implications of Routing Header o [RFC5095] discusses the security implications of Routing Header
Type 0 (RTH0), and deprecates it. Type 0 (RTH0), and deprecates it.
o [RFC5722] analyzes the security implications of overlapping o [RFC5722] analyzes the security implications of overlapping
fragments, and provides recommendations in this area. fragments, and provides recommendations in this area.
o [RFC7045] clarifies how intermediate nodes should deal with IPv6 o [RFC7045] clarifies how intermediate nodes should deal with IPv6
extension headers. extension headers.
o [RFC7112] discusses the issues arising in a specific fragmentation o [RFC7112] discusses the issues arising in a specific fragmentation
case where the IPv6 header chain is fragmented into two or more case where the IPv6 header chain is fragmented into two or more
fragments (and formally forbids such fragmentation case). fragments (and formally forbids such fragmentation).
o [RFC6946] discusses a flawed (but common) processing of the so- o [RFC6946] discusses a flawed (but common) processing of the so-
called IPv6 "atomic fragments", and specified improved processing called IPv6 "atomic fragments", and specified improved processing
of such packets. of such packets.
o [RFC8021] deprecates the generation of IPv6 atomic fragments. o [RFC8021] deprecates the generation of IPv6 atomic fragments.
o [RFC8504] clarifies processing rules for packets with extension o [RFC8504] clarifies processing rules for packets with extension
headers, and also allows hosts to enforce limits on the number of headers, and also allows hosts to enforce limits on the number of
options included in IPv6 EHs. options included in IPv6 EHs.
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containing IPv6 EHs are dropped in the public Internet. containing IPv6 EHs are dropped in the public Internet.
o [RFC7872] presents more comprehensive results and documents the o [RFC7872] presents more comprehensive results and documents the
methodology used to obtain these results. methodology used to obtain these results.
o [Huston-2017] and [Huston-2020] measured packet drops resulting o [Huston-2017] and [Huston-2020] measured packet drops resulting
from IPv6 fragmentation when communicating with DNS servers. from IPv6 fragmentation when communicating with DNS servers.
5. Packet Forwarding Engine Constraints 5. Packet Forwarding Engine Constraints
Most contemporary routers use dedicated hardware (e.g., ASICs or Most contemporary carrier-grade routers use dedicated hardware (e.g.,
NPUs) to determine how to forward packets across their internal ASICs or NPUs) to determine how to forward packets across their
fabrics (see [IEPG94-Scudder] and [APNIC-Scudder] for details). One internal fabrics (see [IEPG94-Scudder] and [APNIC-Scudder] for
of the common methods of handling next-hop lookup is to send a small details). One of the common methods of handling next-hop lookup is
portion of the ingress packet to a lookup engine with specialised to send a small portion of the ingress packet to a lookup engine with
hardware (e.g., ternary CAM or RLDRAM) to determine the packet's specialised hardware (e.g., ternary CAM or Reduced Latency DRAM) to
next-hop. Technical constraints mean that there is a trade-off determine the packet's next-hop. Technical constraints mean that
between the amount of data sent to the lookup engine and the overall there is a trade-off between the amount of data sent to the lookup
performance of the lookup engine. If more data is sent, the lookup engine and the overall packet forwarding rate of the lookup engine.
engine can inspect further into the packet, but the overall If more data is sent, the lookup engine can inspect further into the
performance of the system will be reduced. If less data is sent, the packet, but the overall packet forwarding rate of the system will be
overall performance of the router will be increased but the packet reduced. If less data is sent, the overall packet forwarding rate of
lookup engine may not be able to inspect far enough into a packet to the router will be increased but the packet lookup engine may not be
determine how it should be handled. able to inspect far enough into a packet to determine how it should
be handled.
NOTE: NOTE:
For example, some contemporary high-end routers are known to For example, some contemporary high-end routers are known to
inspect up to 192 bytes, while others are known to parse up to 384 inspect up to 192 bytes, while others are known to parse up to 384
bytes of header. bytes of header.
If a hardware forwarding engine on a contemporary router cannot make If a hardware forwarding engine on a contemporary router cannot make
a forwarding decision about a packet because critical information is a forwarding decision about a packet because critical information is
not sent to the look-up engine, then the router will normally drop not sent to the look-up engine, then the router will normally drop
the packet. Section 6 discusses some of the reasons for which a the packet. Section 6 discusses some of the reasons for which a
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Systems Systems
The following subsections discuss some of the reasons for which The following subsections discuss some of the reasons for which
contemporary routers and middle-boxes may need to process Layer-3/ contemporary routers and middle-boxes may need to process Layer-3/
layer-4 information to make a forwarding decision. layer-4 information to make a forwarding decision.
6.1. ECMP and Hash-based Load-Sharing 6.1. ECMP and Hash-based Load-Sharing
In the case of ECMP (equal cost multi path) load sharing, the router In the case of ECMP (equal cost multi path) load sharing, the router
on the sending side of the link needs to make a decision regarding on the sending side of the link needs to make a decision regarding
which of the links to use for a given packet. Since round-robin which of the links to use to forward a given packet. Since round-
usage of the links is usually avoided to prevent packet reordering, robin usage of the links is usually avoided to prevent packet
forwarding engines need to use a mechanism that will consistently reordering, forwarding engines need to use a mechanism that will
forward the same data streams down the same forwarding paths. Most consistently forward the same data streams down the same forwarding
forwarding engines achieve this by calculating a simple hash using an paths. Most forwarding engines achieve this by calculating a simple
n-tuple gleaned from a combination of layer-2 through to layer-4 hash using an n-tuple gleaned from a combination of layer-2 through
packet header information. This n-tuple will typically use the src/ to layer-4 packet header information. This n-tuple will typically
dst MAC address, src/dst IP address, and if possible further layer-4 use the src/dst MAC address, src/dst IP address, and if possible
src/dst port information. further layer-4 src/dst port information.
In the IPv6 world, flows are expected to be identified by means of In the IPv6 world, flows are expected to be identified by means of
the IPv6 Flow Label [RFC6437]. Thus, ECMP and Hash-based Load- the IPv6 Flow Label [RFC6437]. Thus, ECMP and Hash-based Load-
Sharing should be possible without the need to process the entire Sharing should be possible without the need to process the entire
IPv6 header chain to obtain upper-layer information to identify IPv6 header chain to obtain upper-layer information to identify
flows. Historically, many IPv6 implementations failed to set the flows. [RFC7098] discusses how the IPv6 Flow Label can be used to
Flow Label, and ECMP / hash-based load-sharing devices also did not enhance layer 3/4 load distribution and balancing for large server
employ the Flow Label for performing their task. Clearly, widespread farms.
support of [RFC6437] would relieve middle-boxes from having to
process the entire IPv6 header chain, making Flow Label-based ECMP
and Hash-based Load-Sharing [RFC6438] feasible.
While support of [RFC6437] is currently widespread for current Historically, many IPv6 implementations failed to set the Flow Label,
versions of all popular host implementations, there is still only and hash-based ECMP/load-sharing devices also did not employ the Flow
marginal usage of the IPv6 Flow Label for ECMP and load balancing Label for performing their task. While support of [RFC6437] is
[Cunha-2020]. A contributing factor could be the issues that have currently widespread for current versions of all popular host
been found in host implementations and middle-boxes [Jaeggli-2018]. implementations, there is still only marginal usage of the IPv6 Flow
Label for ECMP and load balancing [Cunha-2020]. A contributing
factor could be the issues that have been found in host
implementations and middle-boxes [Jaeggli-2018].
Clearly, widespread support of [RFC6437] would relieve middle-boxes
from having to process the entire IPv6 header chain, making Flow
Label-based ECMP and Load-Sharing [RFC6438] feasible.
6.2. Enforcing infrastructure ACLs 6.2. Enforcing infrastructure ACLs
Infrastructure ACLs (iACLs) drop unwanted packets destined to a Infrastructure ACLs (iACLs) drop unwanted packets destined to a
network's infrastructure IP addresses. Typically, iACLs are deployed network's infrastructure IP addresses. Typically, iACLs are deployed
because external direct access to a network's infrastructure because external direct access to a network's infrastructure
addresses is operationally unnecessary, and can be used for attacks addresses is operationally unnecessary, and can be used for attacks
of different sorts against router control planes. To this end, of different sorts against router control planes. To this end,
traffic usually needs to be differentiated on the basis of layer-3 or traffic usually needs to be differentiated on the basis of layer-3 or
layer-4 criteria to achieve a useful balance of protection and layer-4 criteria to achieve a useful balance of protection and
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NIDS's, but they can also prevent intrusions by reacting to detected NIDS's, but they can also prevent intrusions by reacting to detected
attack attempts by e.g., triggering packet filtering policies at attack attempts by e.g., triggering packet filtering policies at
firewalls and other devices. firewalls and other devices.
Use of extension headers can be problematic for NIDS/IPS, since: Use of extension headers can be problematic for NIDS/IPS, since:
o Extension headers increase the complexity of resulting traffic, o Extension headers increase the complexity of resulting traffic,
and the associated work and system requirements to process it. and the associated work and system requirements to process it.
o Use of unknown extension headers can prevent an NIDS/IPS from o Use of unknown extension headers can prevent an NIDS/IPS from
processing layer-4 information processing layer-4 information.
o Use of IPv6 fragmentation requires a stateful fragment-reassembly o Use of IPv6 fragmentation requires a stateful fragment-reassembly
operation, even for decoy traffic employing forged source operation, even for decoy traffic employing forged source
addresses (see e.g., [nmap]). addresses (see e.g., [nmap]).
As a result, in order to increase the efficiency or effectiveness of As a result, in order to increase the efficiency or effectiveness of
these systems, packets employing IPv6 extension headers are often these systems, packets employing IPv6 extension headers are often
dropped at the network ingress point(s) of networks that deploy these dropped at the network ingress point(s) of networks that deploy these
systems. systems.
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unconditionally, forward the packet unconditionally, or process the unconditionally, forward the packet unconditionally, or process the
packet outside the normal forwarding path. Forwarding packets packet outside the normal forwarding path. Forwarding packets
unconditionally will usually allow for the circumvention of security unconditionally will usually allow for the circumvention of security
controls (see e.g., Section 6.5), while processing packets outside of controls (see e.g., Section 6.5), while processing packets outside of
the normal forwarding path will usually open the door to DoS attacks the normal forwarding path will usually open the door to DoS attacks
(see e.g., Section 5). Thus, in these scenarios, devices often (see e.g., Section 5). Thus, in these scenarios, devices often
simply resort to dropping such packets unconditionally. simply resort to dropping such packets unconditionally.
7.2. Route-Processor Protection 7.2. Route-Processor Protection
Most contemporary routers have a fast hardware-assisted forwarding Most contemporary carrier-grade routers have a fast hardware-assisted
plane and a loosely coupled control plane, connected together with a forwarding plane and a loosely coupled control plane, connected
link that has much less capacity than the forwarding plane could together with a link that has much less capacity than the forwarding
handle. Traffic differentiation cannot be performed by the control plane could handle. Traffic differentiation cannot be performed by
plane, because this would overload the internal link connecting the the control plane, because this would overload the internal link
forwarding plane to the control plane. connecting the forwarding plane to the control plane.
The Hop-by-Hop Options header has been particularly challenging since The Hop-by-Hop Options header has been particularly challenging since
in most circumstances, the corresponding packet is punted to the in most circumstances, the corresponding packet is punted to the
control plane for processing. As a result, operators usually drop control plane for processing. As a result, many operators currently
IPv6 packets containing this extension header. [RFC6192] provides drop IPv6 packets containing this extension header. [RFC6192]
advice regarding protection of a router's control plane. provides advice regarding protection of a router's control plane.
7.3. Inability to Perform Fine-grained Filtering 7.3. Inability to Perform Fine-grained Filtering
Some router implementations do not have support for fine-grained Some router implementations do not have support for fine-grained
filtering of IPv6 extension headers. For example, an operator that filtering of IPv6 extension headers. For example, an operator that
wishes to drop packets containing Routing Header Type 0 (RHT0), may wishes to drop packets containing Routing Header Type 0 (RHT0), may
only be able to filter on the extension header type (Routing Header). only be able to filter on the extension header type (Routing Header).
This could result in an operator enforcing a more coarse filtering This could result in an operator enforcing a more coarse filtering
policy (e.g., "drop all packets containing a Routing Header" vs. policy (e.g., "drop all packets containing a Routing Header" vs.
"only drop packets that contain a Routing Header Type 0"). "only drop packets that contain a Routing Header Type 0").
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IPv6 Fragment Headers are employed to allow fragmentation of IPv6 IPv6 Fragment Headers are employed to allow fragmentation of IPv6
packets. While many of the security implications of the packets. While many of the security implications of the
fragmentation / reassembly mechanism are known from the IPv4 world, fragmentation / reassembly mechanism are known from the IPv4 world,
several related issues have crept into IPv6 implementations. These several related issues have crept into IPv6 implementations. These
range from denial of service attacks to information leakage, as range from denial of service attacks to information leakage, as
discussed in [RFC7739], [Bonica-NANOG58] and [Atlasis2012]). discussed in [RFC7739], [Bonica-NANOG58] and [Atlasis2012]).
8. IANA Considerations 8. IANA Considerations
There are no IANA registries within this document. The RFC-Editor This document has no IANA actions.
can remove this section before publication of this document as an
RFC.
9. Security Considerations 9. Security Considerations
The security implications of IPv6 extension headers are discussed in The security implications of IPv6 extension headers are discussed in
Section 7.4. This document does not introduce any new security Section 7.4. This document does not introduce any new security
issues. issues.
10. Acknowledgements 10. Acknowledgements
The authors would like to thank (in alphabetical order) Mikael The authors would like to thank (in alphabetical order) Mikael
Abrahamsson, Fred Baker, Dale W. Carder, Brian Carpenter, Tim Chown, Abrahamsson, Fred Baker, Dale W. Carder, Brian Carpenter, Tim Chown,
Owen DeLong, Gorry Fairhurst, Tom Herbert, Lee Howard, Tom Petch, Owen DeLong, Gorry Fairhurst, Guillermo Gont, Tom Herbert, Lee
Sander Steffann, Eduard Vasilenko, Eric Vyncke, Rob Wilton, Jingrong Howard, Tom Petch, Sander Steffann, Eduard Vasilenko, Eric Vyncke,
Xie, and Andrew Yourtchenko, for providing valuable comments on Rob Wilton, Jingrong Xie, and Andrew Yourtchenko, for providing
earlier versions of this document. valuable comments on earlier versions of this document.
Fernando Gont would like to thank Jan Zorz / Go6 Lab Fernando Gont would like to thank Jan Zorz / Go6 Lab
<https://go6lab.si/>, Jared Mauch, and Sander Steffann <https://go6lab.si/>, Jared Mauch, and Sander Steffann
<https://steffann.nl/>, for providing access to systems and networks <https://steffann.nl/>, for providing access to systems and networks
that were employed to perform experiments and measurements involving that were employed to perform experiments and measurements involving
packets with IPv6 Extension Headers. packets with IPv6 Extension Headers.
11. References 11. References
11.1. Normative References 11.1. Normative References
skipping to change at page 17, line 18 skipping to change at page 17, line 24
Chains", draft-wkumari-long-headers-03 (work in progress), Chains", draft-wkumari-long-headers-03 (work in progress),
June 2015. June 2015.
[IEPG94-Scudder] [IEPG94-Scudder]
Petersen, B. and J. Scudder, "Modern Router Architecture Petersen, B. and J. Scudder, "Modern Router Architecture
for Protocol Designers", IEPG 94. Yokohama, Japan. for Protocol Designers", IEPG 94. Yokohama, Japan.
November 1, 2015, <http://www.iepg.org/2015-11-01-ietf94/ November 1, 2015, <http://www.iepg.org/2015-11-01-ietf94/
IEPG-RouterArchitecture-jgs.pdf>. IEPG-RouterArchitecture-jgs.pdf>.
[Jaeggli-2018] [Jaeggli-2018]
Jaeggli, G., "Dealing with IPv6 fragmentation in the Jaeggli, J., "IPv6 flow label: misuse in hashing", APNIC
DNS", APNIC Blog, 2018, Blog, 2018, <https://blog.apnic.net/2018/01/11/ipv6-flow-
<https://blog.apnic.net/2018/01/11/ipv6-flow-label-misuse- label-misuse-hashing/>.
hashing/>.
[Linkova-Gont-IEPG90] [Linkova-Gont-IEPG90]
Linkova, J. and F. Gont, "IPv6 Extension Headers in the Linkova, J. and F. Gont, "IPv6 Extension Headers in the
Real World v2.0", IEPG 90. Toronto, ON, Canada. July 20, Real World v2.0", IEPG 90. Toronto, ON, Canada. July 20,
2014, <http://www.iepg.org/2014-07-20-ietf90/iepg- 2014, <http://www.iepg.org/2014-07-20-ietf90/iepg-
ietf90-ipv6-ehs-in-the-real-world-v2.0.pdf>. ietf90-ipv6-ehs-in-the-real-world-v2.0.pdf>.
[Microsoft-SA] [Microsoft-SA]
Microsoft, "Windows TCP/IP Remote Code Execution Microsoft, "Windows TCP/IP Remote Code Execution
Vulnerability (CVE-2021-24094)", February 2021, Vulnerability (CVE-2021-24094)", February 2021,
skipping to change at page 18, line 29 skipping to change at page 18, line 34
[RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label [RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label
for Equal Cost Multipath Routing and Link Aggregation in for Equal Cost Multipath Routing and Link Aggregation in
Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011, Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011,
<https://www.rfc-editor.org/info/rfc6438>. <https://www.rfc-editor.org/info/rfc6438>.
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing
of IPv6 Extension Headers", RFC 7045, of IPv6 Extension Headers", RFC 7045,
DOI 10.17487/RFC7045, December 2013, DOI 10.17487/RFC7045, December 2013,
<https://www.rfc-editor.org/info/rfc7045>. <https://www.rfc-editor.org/info/rfc7045>.
[RFC7098] Carpenter, B., Jiang, S., and W. Tarreau, "Using the IPv6
Flow Label for Load Balancing in Server Farms", RFC 7098,
DOI 10.17487/RFC7098, January 2014,
<https://www.rfc-editor.org/info/rfc7098>.
[RFC7113] Gont, F., "Implementation Advice for IPv6 Router [RFC7113] Gont, F., "Implementation Advice for IPv6 Router
Advertisement Guard (RA-Guard)", RFC 7113, Advertisement Guard (RA-Guard)", RFC 7113,
DOI 10.17487/RFC7113, February 2014, DOI 10.17487/RFC7113, February 2014,
<https://www.rfc-editor.org/info/rfc7113>. <https://www.rfc-editor.org/info/rfc7113>.
[RFC7739] Gont, F., "Security Implications of Predictable Fragment [RFC7739] Gont, F., "Security Implications of Predictable Fragment
Identification Values", RFC 7739, DOI 10.17487/RFC7739, Identification Values", RFC 7739, DOI 10.17487/RFC7739,
February 2016, <https://www.rfc-editor.org/info/rfc7739>. February 2016, <https://www.rfc-editor.org/info/rfc7739>.
[RFC7872] Gont, F., Linkova, J., Chown, T., and W. Liu, [RFC7872] Gont, F., Linkova, J., Chown, T., and W. Liu,
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