draft-ietf-6man-deprecate-atomfrag-generation-04.txt   draft-ietf-6man-deprecate-atomfrag-generation-05.txt 
IPv6 maintenance Working Group (6man) F. Gont IPv6 maintenance Working Group (6man) F. Gont
Internet-Draft SI6 Networks / UTN-FRH Internet-Draft SI6 Networks / UTN-FRH
Intended status: Informational W. Liu Intended status: Informational W. Liu
Expires: May 29, 2016 Huawei Technologies Expires: July 23, 2016 Huawei Technologies
T. Anderson T. Anderson
Redpill Linpro Redpill Linpro
November 26, 2015 January 20, 2016
Deprecation of the Generation of IPv6 Atomic Fragments Generation of IPv6 Atomic Fragments Considered Harmful
draft-ietf-6man-deprecate-atomfrag-generation-04 draft-ietf-6man-deprecate-atomfrag-generation-05
Abstract Abstract
RFC2460 requires that when a host receives an ICMPv6 "Packet Too Big" RFC2460 requires that when a host receives an ICMPv6 "Packet Too Big"
message reporting an MTU smaller than 1280 bytes, the host includes a message reporting an MTU smaller than 1280 bytes, the host includes a
Fragment Header in all subsequent packets sent to that destination, Fragment Header in all subsequent packets sent to that destination,
without reducing the assumed Path-MTU. The simplicity with which without reducing the assumed Path-MTU. The simplicity with which
ICMPv6 "Packet Too Big" messages can be forged, coupled with the ICMPv6 "Packet Too Big" messages can be forged means that an attacker
widespread filtering of IPv6 fragments, results in an attack vector can leverage this functionality (the generation of IPv6 atomic
that can be leveraged for Denial of Service purposes. This document fragments) to trigger the use of fragmentation for any arbitrary IPv6
briefly discusses the aforementioned attack vector, and why the flow, and subsequently perform any fragmentation-based attack. This
aforementioned functionality is undesirable. document discusses the security implications of the generation of
IPv6 atomic fragments and a number of interoperability issues
associated with IPv6 atomic fragments, and concludes that the
aforementioned functionality is undesirable, thus documenting the
motivation for removing this functionality in the revision of the
core IPv6 protocol specification [I-D.ietf-6man-rfc2460bis].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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
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Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 May 29, 2016. This Internet-Draft will expire on July 23, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Denial of Service (DoS) attack vector . . . . . . . . . . . . 3 3. Security Implications of the Generation of IPv6 Atomic
4. Additional Considerations . . . . . . . . . . . . . . . . . . 4 Fragments . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 4. Additional Considerations . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7 8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Small Survey of OSes that Fail to Produce IPv6 Appendix A. Small Survey of OSes that Fail to Produce IPv6
Atomic Fragments . . . . . . . . . . . . . . . . . . 8 Atomic Fragments . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
[RFC2460] specifies the IPv6 fragmentation mechanism, which allows [RFC2460] specifies the IPv6 fragmentation mechanism, which allows
IPv6 packets to be fragmented into smaller pieces such that they fit IPv6 packets to be fragmented into smaller pieces such that they can
in the Path-MTU to the intended destination(s). fit in the Path-MTU to the intended destination(s).
Section 5 of [RFC2460] states that, when a host receives an ICMPv6 Section 5 of [RFC2460] states that, when a host receives an ICMPv6
"Packet Too Big" message [RFC4443] advertising an MTU smaller than "Packet Too Big" message [RFC4443] advertising an MTU smaller than
1280 bytes (the minimum IPv6 MTU), the host is not required to reduce 1280 bytes (the minimum IPv6 MTU), the host is not required to reduce
the assumed Path-MTU, but must simply include a Fragment Header in the assumed Path-MTU, but must simply include a Fragment Header in
all subsequent packets sent to that destination. The resulting all subsequent packets sent to that destination. The resulting
packets will thus *not* be actually fragmented into several pieces, packets will thus *not* be actually fragmented into several pieces,
but rather just include a Fragment Header with both the "Fragment but rather just include a Fragment Header with both the "Fragment
Offset" and the "M" flag set to 0 (we refer to these packets as Offset" and the "M" flag set to 0 (i.e., "atomic fragments"
"atomic fragments"). As required by [RFC6946], these atomic [RFC6946]). [RFC6946] requires that these atomic fragments be
fragments are essentially processed by the destination host as non- essentially processed by the destination host as non-fragmented
fragmented traffic (since there are not really any fragments to be traffic (since there are not really any fragments to be reassembled).
reassembled). The goal of these atomic fragments has been to convey The goal of these atomic fragments is simply to convey an appropriate
an appropriate Fragment Identification value to be employed by IPv6/ Identification value to be employed by IPv6/IPv4 translators for the
IPv4 translators for the resulting IPv4 fragments. resulting IPv4 fragments.
While atomic fragments might seem rather benign, there are scenarios While atomic fragments might seem rather benign, there are scenarios
in which the generation of IPv6 atomic fragments can introduce an in which the generation of IPv6 atomic fragments can be leveraged for
attack vector that can be exploited for denial of service purposes. performing a number of attacks against the corresponding IPv6 flows.
Since there are concrete security implications arising from the Since there are concrete security implications arising from the
generation of IPv6 atomic fragments, and there is no real gain in generation of IPv6 atomic fragments, and there is no real gain in
generating IPv6 atomic fragments (as opposed to e.g. having IPv6/IPv4 generating IPv6 atomic fragments (as opposed to e.g. having IPv6/IPv4
translators generate a Fragment Identification value themselves), we translators generate a Fragment Identification value themselves), we
conclude that this functionality is undesirable. conclude that this functionality is undesirable.
Section 3 describes some possible attack scenarios. Section 4 Section 3 briefly discusses the security implications of the
generation of IPv6 atomic fragments, and describes a specific Denial
of Service (DoS) attack vector that leverages the widespread
filtering of IPv6 fragments in the public Internet. Section 4
provides additional considerations regarding the usefulness of provides additional considerations regarding the usefulness of
generating IPv6 atomic fragments. generating IPv6 atomic fragments.
2. Terminology 2. Terminology
IPv6 atomic fragments IPv6 atomic fragments:
IPv6 packets that contain a Fragment Header with the Fragment IPv6 packets that contain a Fragment Header with the Fragment
Offset set to 0 and the M flag set to 0 (as defined by [RFC6946]). Offset set to 0 and the M flag set to 0 (as defined by [RFC6946]).
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
3. Denial of Service (DoS) attack vector 3. Security Implications of the Generation of IPv6 Atomic Fragments
Let us assume that Host A is communicating with Server B, and that, The security implications of IP fragmentation have been discussed at
as a result of the widespread filtering of IPv6 packets with length in [RFC6274] and [I-D.ietf-6man-predictable-fragment-id]. An
extension headers (including fragmentation) attacker can leverage the generation of IPv6 atomic fragments to
trigger the use of fragmentation in an arbitrary IPv6 flow and
subsequently perform any fragmentation-based attack against legacy
IPv6 nodes that do not implement [RFC6946].
Unfortunately, even nodes that already implement [RFC6946] can be
subject to DoS attacks as a result of the generation of IPv6 atomic
fragments. Let us assume that Host A is communicating with Server B,
and that, as a result of the widespread dropping of IPv6 packets that
contain extension headers (including fragmentation)
[I-D.ietf-v6ops-ipv6-ehs-in-real-world], some intermediate node [I-D.ietf-v6ops-ipv6-ehs-in-real-world], some intermediate node
filters fragments between Host A and Server B. If an attacker sends filters fragments between Host A and Server B. If an attacker sends
a forged ICMPv6 "Packet Too Big" (PTB) error message to server B, a forged ICMPv6 "Packet Too Big" (PTB) error message to server B,
reporting an MTU smaller than 1280, this will trigger the generation reporting an MTU smaller than 1280, this will trigger the generation
of IPv6 atomic fragments from that moment on (as required by of IPv6 atomic fragments from that moment on (as required by
[RFC2460]). When server B starts sending IPv6 atomic fragments (in [RFC2460]). When server B starts sending IPv6 atomic fragments (in
response to the received ICMPv6 PTB), these packets will be dropped, response to the received ICMPv6 PTB), these packets will be dropped,
since we previously noted that packets with IPv6 EHs were being since we previously noted that IPv6 packets with extension headers
dropped between Host A and Server B. Thus, this situation will were being dropped between Host A and Server B. Thus, this situation
result in a Denial of Service (DoS) scenario. will result in a Denial of Service (DoS) scenario.
Another possible scenario is that in which two BGP peers are Another possible scenario is that in which two BGP peers are
employing IPv6 transport, and they implement Access Control Lists employing IPv6 transport, and they implement Access Control Lists
(ACLs) to drop IPv6 fragments (to avoid control-plane attacks). If (ACLs) to drop IPv6 fragments (to avoid control-plane attacks). If
the aforementioned BGP peers drop IPv6 fragments but still honor the aforementioned BGP peers drop IPv6 fragments but still honor
received ICMPv6 Packet Too Big error messages, an attacker could received ICMPv6 Packet Too Big error messages, an attacker could
easily attack the peering session by simply sending an ICMPv6 PTB easily attack the peering session by simply sending an ICMPv6 PTB
message with a reported MTU smaller than 1280 bytes. Once the attack message with a reported MTU smaller than 1280 bytes. Once the attack
packet has been sent, it will be the aforementioned routers packet has been sent, it will be the aforementioned routers
themselves the ones dropping their own traffic. themselves the ones dropping their own traffic.
skipping to change at page 4, line 22 skipping to change at page 4, line 42
use of extension headers (by the attacker) could make this use of extension headers (by the attacker) could make this
difficult, if at all possible. difficult, if at all possible.
o Many implementations fail to perform validation checks on the o Many implementations fail to perform validation checks on the
received ICMPv6 error messages, as recommended in Section 5.2 of received ICMPv6 error messages, as recommended in Section 5.2 of
[RFC4443] and documented in [RFC5927]. It should be noted that in [RFC4443] and documented in [RFC5927]. It should be noted that in
some cases, such as when an ICMPv6 error message has (supposedly) some cases, such as when an ICMPv6 error message has (supposedly)
been elicited by a connection-less transport protocol (or some been elicited by a connection-less transport protocol (or some
other connection-less protocol being encapsulated in IPv6), it may other connection-less protocol being encapsulated in IPv6), it may
be virtually impossible to perform validation checks on the be virtually impossible to perform validation checks on the
received ICMPv6 error messages. And, because of IPv6 extension received ICMPv6 error message. And, because of IPv6 extension
headers, the ICMPv6 payload might not even contain any useful headers, the ICMPv6 payload might not even contain any useful
information on which to perform validation checks. information on which to perform validation checks.
o Upon receipt of one of the aforementioned ICMPv6 "Packet Too Big" o Upon receipt of one of the aforementioned ICMPv6 "Packet Too Big"
error messages, the Destination Cache [RFC4861] is usually updated error messages, the Destination Cache [RFC4861] is usually updated
to reflect that any subsequent packets to such destination should to reflect that any subsequent packets to such destination should
include a Fragment Header. This means that a single ICMPv6 include a Fragment Header. This means that a single ICMPv6
"Packet Too Big" error message might affect multiple communication "Packet Too Big" error message might affect multiple communication
instances (e.g., TCP connections) with such destination. instances (e.g., TCP connections) with such destination.
o As noted in Section 4, SIIT [RFC6145] (including derivative o As noted in Section 4, SIIT [RFC6145] (including derivative
protocols such as Stateful NAT64 [RFC6146]) is the only technology protocols such as Stateful NAT64 [RFC6146]) is the only technology
which currently makes use of atomic fragments. Unfortunately, an which currently makes use of atomic fragments. Unfortunately, an
IPv6 node cannot easily limit its exposure to the aforementioned IPv6 node cannot easily limit its exposure to the aforementioned
attack vector by only generating IPv6 atomic fragments towards attack vector by only generating IPv6 atomic fragments towards
IPv4 destinations behind a stateless translator. This is due to IPv4 destinations behind a stateless translator. This is due to
the fact that Section 3.3 of RFC6052 [RFC6052] encourages the fact that Section 3.3 of [RFC6052] encourages operators to use
operators to use a Network-Specific Prefix (NSP) that maps the a Network-Specific Prefix (NSP) that maps the IPv4 address space
IPv4 address space into IPv6. When an NSP is being used, IPv6 into IPv6. When an NSP is being used, IPv6 addresses representing
addresses representing IPv4 nodes (reached through a stateless IPv4 nodes (reached through a stateless translator) are
translator) are indistinguishable from native IPv6 addresses. indistinguishable from native IPv6 addresses.
4. Additional Considerations 4. Additional Considerations
Besides the security assessment provided in Section 3, it is Besides the security assessment provided in Section 3, it is
interesting to evaluate the pros and cons of having an IPv6-to-IPv4 interesting to evaluate the pros and cons of having an IPv6-to-IPv4
translating router rely on the generation of IPv6 atomic fragments. translating router rely on the generation of IPv6 atomic fragments.
Relying on the generation of IPv6 atomic fragments implies a reliance Relying on the generation of IPv6 atomic fragments implies a reliance
on: on:
1. ICMPv6 packets arriving from the translator to the IPv6 node 1. ICMPv6 packets arriving from the translator to the IPv6 node
2. The ability of the nodes receiving ICMPv6 PTB messages reporting 2. The ability of the nodes receiving ICMPv6 PTB messages reporting
an MTU smaller than 1280 bytes to actually produce atomic an MTU smaller than 1280 bytes to actually produce atomic
fragments fragments
3. Support for IPv6 fragmentation on the IPv6 side of the translator 3. Support for IPv6 fragmentation on the IPv6 side of the translator
4. The ability of the translator implementation to access the
information conveyed by the IPv6 Fragment Header
Unfortunately, Unfortunately,
o There exists a fair share of evidence of ICMPv6 Packet Too Big 1. There exists a fair share of evidence of ICMPv6 Packet Too Big
messages being dropped on the public Internet (for instance, that messages being dropped on the public Internet (for instance, that
is one of the reasons for which PLPMTUD [RFC4821] was produced). is one of the reasons for which PLPMTUD [RFC4821] was produced).
Therefore, relying on such messages being successfully delivered Therefore, relying on such messages being successfully delivered
will affect the robustness of the protocol that relies on them. will affect the robustness of the protocol that relies on them.
o A number of IPv6 implementations have been known to fail to 2. A number of IPv6 implementations have been known to fail to
generate IPv6 atomic fragments in response to ICMPv6 PTB messages generate IPv6 atomic fragments in response to ICMPv6 PTB messages
reporting an MTU smaller than 1280 bytes (see Appendix A for a reporting an MTU smaller than 1280 bytes (see Appendix A for a
small survey). Additionally, the results included in Section 6 of small survey). Additionally, the results included in Section 6
[RFC6145] note that 57% of the tested web servers failed to of [RFC6145] note that 57% of the tested web servers failed to
produce IPv6 atomic fragments in response to ICMPv6 PTB messages produce IPv6 atomic fragments in response to ICMPv6 PTB messages
reporting an MTU smaller than 1280 bytes. Thus, any protocol reporting an MTU smaller than 1280 bytes. Thus, any protocol
relying on IPv6 atomic fragment generation for proper functioning relying on IPv6 atomic fragment generation for proper functioning
will have interoperability problems with the aforementioned IPv6 will have interoperability problems with the aforementioned IPv6
stacks. stacks.
o IPv6 atomic fragment generation represents a case in which 3. IPv6 atomic fragment generation represents a case in which
fragmented traffic is produced where otherwise it would not be fragmented traffic is produced where otherwise it would not be
needed. Since there is widespread filtering of IPv6 fragments in needed. Since there is widespread filtering of IPv6 fragments in
the public Internet [I-D.ietf-v6ops-ipv6-ehs-in-real-world], this the public Internet [I-D.ietf-v6ops-ipv6-ehs-in-real-world], this
would mean that the (unnecessary) use of IPv6 fragmentation might would mean that the (unnecessary) use of IPv6 fragmentation might
result, unnecessarily, in a Denial of Service situation even in result, unnecessarily, in a Denial of Service situation even in
legitimate cases. legitimate cases.
Finally, we note that SIIT essentially employs the Fragment Header of 4. The packet-handling API at the node where the translator is
IPv6 atomic fragments to signal the translator how to set the DF bit running may obscure fragmentation-related information. In such
of IPv4 datagrams (the DF bit is cleared when the IPv6 packet scenarios, the information conveyed by the Fragment Header may be
contains a Fragment Header, and is otherwise set to 1 when the IPv6 unavailable to the translator. [JOOL] discusses a sample
packet does not contain an IPv6 Fragment Header). Additionally, the framework (Linux Netfilter) that hinders access to the
translator will employ the low-order 16-bits of the IPv6 Fragment information conveyed in IPv6 atomic fragments.
Identification for setting the IPv4 Fragment Identification. At
least in theory, this is expected to reduce the Fragment ID collision We note that SIIT essentially employs the Fragment Header of IPv6
rate in the following specific scenario: atomic fragments to signal the translator how to set the DF bit of
IPv4 datagrams (the DF bit is cleared when the IPv6 packet contains a
Fragment Header, and is otherwise set to 1 when the IPv6 packet does
not contain an IPv6 Fragment Header). Additionally, the translator
will employ the low-order 16-bits of the IPv6 Fragment Identification
for setting the IPv4 Fragment Identification. At least in theory,
this is expected to reduce the IPv4 Identification collision rate in
the following specific scenario:
1. An IPv6 node communicates with an IPv4 node (through SIIT) 1. An IPv6 node communicates with an IPv4 node (through SIIT)
2. The IPv4 node is located behind an IPv4 link with an MTU < 1260 2. The IPv4 node is located behind an IPv4 link with an MTU smaller
than 1260 bytes
3. ECMP routing [RFC2992] with more than one translator is employed 3. ECMP routing [RFC2992] with more than one translator is employed
for e.g., redundancy purposes for e.g., redundancy purposes
In such a scenario, if each translator were to select the IPv4 In such a scenario, if each translator were to select the IPv4
Fragment Identification on its own (rather than selecting the IPv4 Identification on its own (rather than selecting the IPv4
Fragment ID from the low-order 16-bits of the Fragment Identification Identification from the low-order 16-bits of the Fragment
of atomic fragments), this could possibly lead to IPv4 Fragment ID Identification of IPv6 atomic fragments), this could possibly lead to
collisions. However, since a number of implementations set IPv6 IPv4 Identification collisions. However, since a number of
Fragment ID according to the output of a Pseudo-Random Number implementations set the IPv6 Fragment Identification according to the
Generator (PRNG) (see Appendix B of output of a Pseudo-Random Number Generator (PRNG) (see Appendix B of
[I-D.ietf-6man-predictable-fragment-id]) and the translator only [I-D.ietf-6man-predictable-fragment-id]) and the translator only
employs the low-order 16-bits of such value, it is very unlikely that employs the low-order 16-bits of such value, it is very unlikely that
relying on the Fragment ID of the IPv6 atomic fragment will result in relying on the Fragment Identification of the IPv6 atomic fragment
a reduced Fragment ID collision rate (when compared to the case where will result in a reduced IPv4 Identification collision rate (when
the translator selects each IPv4 Fragment ID on its own). compared to the case where the translator selects each IPv4
Identification on its own).
Finally, we note that [RFC6145] is currently the only "consumer" of Finally, we note that [RFC6145] is currently the only "consumer" of
IPv6 atomic fragments, and it correctly and diligently notes (in IPv6 atomic fragments, and it correctly and diligently notes (in
Section 6) the possible interoperability problems of relying on IPv6 Section 6) the possible interoperability problems of relying on IPv6
atomic fragments, proposing as a workaround that leads to more robust atomic fragments, proposing as a workaround that leads to more robust
behavior and simplified code. behavior and simplified code.
5. IANA Considerations 5. IANA Considerations
There are no IANA registries within this document. The RFC-Editor There are no IANA registries within this document. The RFC-Editor
can remove this section before publication of this document as an can remove this section before publication of this document as an
RFC. RFC.
6. Security Considerations 6. Security Considerations
This document describes a Denial of Service (DoS) attack vector that This document briefly discusses the security implications of the
leverages the widespread filtering of IPv6 fragments in the public generation of IPv6 atomic fragments, and describes a specific Denial
Internet by means of ICMPv6 PTB error messages. It concludes that of Service (DoS) attack vector that leverages the widespread
the generation of IPv6 atomic fragments is an undesirable feature. filtering of IPv6 fragments in the public Internet. It concludes
that the generation of IPv6 atomic fragments is an undesirable
feature, and documents the motivation for removing this functionality
from [I-D.ietf-6man-rfc2460bis].
7. Acknowledgements 7. Acknowledgements
The authors would like to thank (in alphabetical order) Alberto The authors would like to thank (in alphabetical order) Congxiao Bao,
Leiva, Bob Briscoe, Brian Carpenter, Tatuya Jinmei, Jeroen Massar, Bob Briscoe, Brian Carpenter, Tatuya Jinmei, Bob Hinden, Alberto
Erik Nordmark, and Ole Troan, for providing valuable comments on Leiva, Xing Li, Jeroen Massar, Erik Nordmark, Qiong Sun, Ole Troan,
earlier versions of this document. and Tina Tsou, for providing valuable comments on earlier versions of
this document.
Fernando Gont would like to thank Fernando Gont would like to thank Fernando Gont would like to thank Jan Zorz / Go6 Lab
Jan Zorz / Go6 Lab <http://go6lab.si/>, and Jared Mauch / NTT <http://go6lab.si/>, and Jared Mauch / NTT America, for providing
America, for providing access to systems and networks that were access to systems and networks that were employed to produce some of
employed to produce some of tests that resulted in the publication of tests that resulted in the publication of this document.
this document. Additionally, he would like to thank SixXS Additionally, he would like to thank SixXS <https://www.sixxs.net>
<https://www.sixxs.net> for providing IPv6 connectivity. for providing IPv6 connectivity.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>. December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
skipping to change at page 8, line 15 skipping to change at page 9, line 5
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010, DOI 10.17487/RFC6052, October 2010,
<http://www.rfc-editor.org/info/rfc6052>. <http://www.rfc-editor.org/info/rfc6052>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6 NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <http://www.rfc-editor.org/info/rfc6146>. April 2011, <http://www.rfc-editor.org/info/rfc6146>.
[RFC6274] Gont, F., "Security Assessment of the Internet Protocol
Version 4", RFC 6274, DOI 10.17487/RFC6274, July 2011,
<http://www.rfc-editor.org/info/rfc6274>.
[RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments", [RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments",
RFC 6946, DOI 10.17487/RFC6946, May 2013, RFC 6946, DOI 10.17487/RFC6946, May 2013,
<http://www.rfc-editor.org/info/rfc6946>. <http://www.rfc-editor.org/info/rfc6946>.
[I-D.ietf-6man-predictable-fragment-id] [I-D.ietf-6man-predictable-fragment-id]
Gont, F., "Security Implications of Predictable Fragment Gont, F., "Security Implications of Predictable Fragment
Identification Values", draft-ietf-6man-predictable- Identification Values", draft-ietf-6man-predictable-
fragment-id-10 (work in progress), October 2015. fragment-id-10 (work in progress), October 2015.
[I-D.ietf-v6ops-ipv6-ehs-in-real-world] [I-D.ietf-v6ops-ipv6-ehs-in-real-world]
Gont, F., Linkova, J., Chown, T., and S. LIU, Gont, F., Linkova, J., Chown, T., and S. LIU,
"Observations on the Dropping of Packets with IPv6 "Observations on the Dropping of Packets with IPv6
Extension Headers in the Real World", draft-ietf-v6ops- Extension Headers in the Real World", draft-ietf-v6ops-
ipv6-ehs-in-real-world-01 (work in progress), October ipv6-ehs-in-real-world-02 (work in progress), December
2015. 2015.
[I-D.ietf-6man-rfc2460bis]
Deering, S. and B. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", draft-ietf-6man-rfc2460bis-02 (work
in progress), December 2015.
[Morbitzer] [Morbitzer]
Morbitzer, M., "TCP Idle Scans in IPv6", Master's Thesis. Morbitzer, M., "TCP Idle Scans in IPv6", Master's Thesis.
Thesis number: 670. Department of Computing Science, Thesis number: 670. Department of Computing Science,
Radboud University Nijmegen. August 2013, Radboud University Nijmegen. August 2013,
<https://www.ru.nl/publish/pages/578936/ <http://www.ru.nl/publish/pages/769526/
m_morbitzer_masterthesis.pdf>. m_morbitzer_masterthesis.pdf>.
[JOOL] Leiva Popper, A., "nf_defrag_ipv4 and nf_defrag_ipv6",
April 2015, <https://github.com/NICMx/Jool/wiki/
nf_defrag_ipv4-and-nf_defrag_ipv6#implementation-gotchas>.
Appendix A. Small Survey of OSes that Fail to Produce IPv6 Atomic Appendix A. Small Survey of OSes that Fail to Produce IPv6 Atomic
Fragments Fragments
[This section will probably be removed from this document before it [This section will probably be removed from this document before it
is published as an RFC]. is published as an RFC].
This section includes a non-exhaustive list of operating systems that This section includes a non-exhaustive list of operating systems that
*fail* to produce IPv6 atomic fragments. It is based on the results *fail* to produce IPv6 atomic fragments. It is based on the results
published in [RFC6946] and [Morbitzer]. published in [RFC6946] and [Morbitzer]. It is simply meant as a
datapoint regarding the extent to which IPv6 implementations can be
relied upon to generate IPv6 atomic fragments.
The following Operating Systems fail to generate IPv6 atomic The following Operating Systems fail to generate IPv6 atomic
fragments in response to ICMPv6 PTB messages that report an MTU fragments in response to ICMPv6 PTB messages that report an MTU
smaller than 1280 bytes: smaller than 1280 bytes:
o FreeBSD 8.0 o FreeBSD 8.0
o Linux kernel 2.6.32 o Linux kernel 2.6.32
o Linux kernel 3.2 o Linux kernel 3.2
o Linux kernel current
o Mac OS X 10.6.7 o Mac OS X 10.6.7
o NetBSD 5.1 o NetBSD 5.1
Authors' Addresses Authors' Addresses
Fernando Gont Fernando Gont
SI6 Networks / UTN-FRH SI6 Networks / UTN-FRH
Evaristo Carriego 2644 Evaristo Carriego 2644
Haedo, Provincia de Buenos Aires 1706 Haedo, Provincia de Buenos Aires 1706
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