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RE: draft-ietf-v6ops-nap-05

The 05 update to v6ops-nap- was sent to the ID editor earlier today.
Attached is the diff between it and the existing -04. I believe it addresses
all the outstanding comments.

Tony

> -----Original Message-----
> From: Ralph Droms [mailto:rdroms@cisco.com]
> Sent: Saturday, December 02, 2006 12:29 AM
> To: Tony Hain; 'Brian E Carpenter'
> Cc: 'Gunter Van de Velde (gvandeve)'; 'Eric Klein'; 'Fred Baker (fred)';
> 'Cullen Jennings'; 'Margaret Wasserman'
> Subject: Re: draft-ietf-v6ops-nap-04
> 
> This revision looks to me to be OK for publication...
> 
> - Ralph
> 
> 
> On 11/29/06 4:53 PM, "Tony Hain" <alh-ietf@tndh.net> wrote:
> 
> > Brian E Carpenter wrote:
> >> ...
> >> There is a classification of NAT types in RFC 2663 and another one
> >> in RFC 3489. But I'm not sure that would help us. I don't think the
> >> differences are significant in this context. They mainly affect the
> >> gymnastics needed by upper layers, and NAP6 avoids all that.
> >
> > I agree, the differences really don't make a difference here.
> >
> >>
> >>> and the one about an HA adding latency, which I
> >>> believe is bogus in context since the HA is sitting on path as the nat
> >>> replacement.
> >>
> >> Might be worth saying exactly that: Any overhead introduced by the
> >> HA may be considered roughly equivalent to that introduced by a NAT,
> >> but without the additional overhead of an ALG.
> >
> > Added text:
> > Note that in this usage context the HA is replacing the NAT function at
> the
> > edge of the network, so concerns about additional latency for routing
> > through a tunnel to the HA do not apply because it is effectively on the
> > same path that the NAT traffic would have taken.
> >
> >>
> >> I agree with all the changes.
> >>
> >> Only one nit that the Editor isn't guaranteed to find struck me:
> >>
> >>> 4.4 Privacy and Topology Hiding using IPv6
> >>>
> >>> Partial host privacy is achieved in IPv6 using RFC 041 pseudo-random
> >>
> >> s/041/3041/
> >
> > Fixed.
> >
> >>
> >> Thanks for all the work.
> >>
> >>     Brian
> >
> > If all the authors agree with this version I will send it as -05.txt
> >
> > Tony
> >
> >
Title: Diff: draft-ietf-v6ops-nap-04.txt - draft-ietf-v6ops-nap-05-draft2.txt
 draft-ietf-v6ops-nap-04.txt   draft-ietf-v6ops-nap-05-draft2.txt 
Network Working Group G. Van de Velde Network Working Group G. Van de Velde
Internet-Draft T. Hain Internet-Draft T. Hain
Intended status: Informational R. Droms Intended status: Informational R. Droms
Expires: April 16, 2007 Cisco Systems Expires: June 2, 2007 Cisco Systems
B. Carpenter B. Carpenter
IBM IBM
E. Klein E. Klein
Tel Aviv University Tel Aviv University
October 13, 2006 November 29, 2006
Network Architecture Protection for IPv6 Network Architecture Protection for IPv6
<draft-ietf-v6ops-nap-04.txt> <draft-ietf-v6ops-nap-05.txt>
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 39 skipping to change at page 1, line 39
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 16, 2007. This Internet-Draft will expire on June 2, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
Although there are many perceived benefits to Network Address Although there are many perceived benefits to Network Address
Translation (NAT), its primary benefit of "amplifying" available Translation (NAT), its primary benefit of "amplifying" available
address space is not needed in IPv6. In addition to NAT's many address space is not needed in IPv6. In addition to NAT's many
serious disadvantages, there is a perception that other benefits serious disadvantages, there is a perception that other benefits
exist, such as a variety of management and security attributes that exist, such as a variety of management and security attributes that
could be useful for an Internet Protocol site. IPv6 does not support could be useful for an Internet Protocol site. IPv6 was designed
NAT by design and this document shows how Network Architecture with the intention of making NAT unnecessary, and this document shows
Protection (NAP6) using IPv6 can provide the same or more benefits how Network Architecture Protection (NAP6) using IPv6 can provide the
without the need for address translation. same or more benefits without the need for address translation.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Perceived Benefits of NAT and its Impact on IPv4 . . . . . . . 7 2 Perceived Benefits of NAT and its Impact on IPv4 . . . . . . . 7
2.1. Simple Gateway between Internet and Private Network . . . 7 2.1 Simple Gateway between Internet and Private Network . . . . 7
2.2. Simple Security due to Stateful Filter Implementation . . 7 2.2 Simple Security due to Stateful Filter Implementation . . . 7
2.3. User/Application tracking . . . . . . . . . . . . . . . . 8 2.3 User/Application tracking . . . . . . . . . . . . . . . . . 8
2.4. Privacy and Topology Hiding . . . . . . . . . . . . . . . 9 2.4 Privacy and Topology Hiding . . . . . . . . . . . . . . . . 9
2.5. Independent Control of Addressing in a Private Network . . 10 2.5 Independent Control of Addressing in a Private Network . . 10
2.6. Global Address Pool Conservation . . . . . . . . . . . . . 10 2.6 Global Address Pool Conservation . . . . . . . . . . . . . 10
2.7. Multihoming and Renumbering with NAT . . . . . . . . . . . 11 2.7 Multihoming and Renumbering with NAT . . . . . . . . . . . 11
3. Description of the IPv6 Tools . . . . . . . . . . . . . . . . 12 3 Description of the IPv6 Tools . . . . . . . . . . . . . . . . 12
3.1. Privacy Addresses (RFC 3041) . . . . . . . . . . . . . . . 12 3.1 Privacy Addresses (RFC 3041) . . . . . . . . . . . . . . . 12
3.2. Unique Local Addresses . . . . . . . . . . . . . . . . . . 13 3.2 Unique Local Addresses . . . . . . . . . . . . . . . . . . 13
3.3. DHCPv6 Prefix Delegation . . . . . . . . . . . . . . . . . 14 3.3 DHCPv6 Prefix Delegation . . . . . . . . . . . . . . . . . 14
3.4. Untraceable IPv6 Addresses . . . . . . . . . . . . . . . . 14 3.4 Untraceable IPv6 Addresses . . . . . . . . . . . . . . . . 14
4. Using IPv6 Technology to Provide the Market Perceived 4 Using IPv6 Technology to Provide the Market Perceived
Benefits of NAT . . . . . . . . . . . . . . . . . . . . . . . 14 Benefits of NAT . . . . . . . . . . . . . . . . . . . . . . . 15
4.1. Simple Gateway between Internet and Internal Network . . . 15 4.1 Simple Gateway between Internet and Internal Network . . . 15
4.2. IPv6 and Simple Security . . . . . . . . . . . . . . . . . 15 4.2 IPv6 and Simple Security . . . . . . . . . . . . . . . . . 16
4.3. User/Application Tracking . . . . . . . . . . . . . . . . 18 4.3 User/Application Tracking . . . . . . . . . . . . . . . . . 18
4.4. Privacy and Topology Hiding using IPv6 . . . . . . . . . . 18 4.4 Privacy and Topology Hiding using IPv6 . . . . . . . . . . 18
4.5. Independent Control of Addressing in a Private Network . . 21 4.5 Independent Control of Addressing in a Private Network . . 21
4.6. Global Address Pool Conservation . . . . . . . . . . . . . 21 4.6 Global Address Pool Conservation . . . . . . . . . . . . . 22
4.7. Multihoming and Renumbering . . . . . . . . . . . . . . . 22 4.7 Multihoming and Renumbering . . . . . . . . . . . . . . . . 22
5. Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . 22 5 Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.1. Medium/large private networks . . . . . . . . . . . . . . 23 5.1 Medium/large private networks . . . . . . . . . . . . . . . 23
5.2. Small Private Networks . . . . . . . . . . . . . . . . . . 24 5.2 Small Private Networks . . . . . . . . . . . . . . . . . . 25
5.3. Single User Connection . . . . . . . . . . . . . . . . . . 26 5.3 Single User Connection . . . . . . . . . . . . . . . . . . 27
5.4. ISP/Carrier Customer Networks . . . . . . . . . . . . . . 27 5.4 ISP/Carrier Customer Networks . . . . . . . . . . . . . . . 27
6. IPv6 Gap Analysis . . . . . . . . . . . . . . . . . . . . . . 28 6 IPv6 Gap Analysis . . . . . . . . . . . . . . . . . . . . . . 28
6.1. Simple Security . . . . . . . . . . . . . . . . . . . . . 28 6.1 Simple Security . . . . . . . . . . . . . . . . . . . . . . 28
6.2. Subnet Topology Masking . . . . . . . . . . . . . . . . . 28 6.2 Subnet Topology Masking . . . . . . . . . . . . . . . . . . 29
6.3. Minimal Traceability of Privacy Addresses . . . . . . . . 28 6.3 Minimal Traceability of Privacy Addresses . . . . . . . . . 29
6.4. Site Multihoming . . . . . . . . . . . . . . . . . . . . . 29 6.4 Site Multihoming . . . . . . . . . . . . . . . . . . . . . 29
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 7 IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
8. Security Considerations . . . . . . . . . . . . . . . . . . . 29 8 Security Considerations . . . . . . . . . . . . . . . . . . . 30
9. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 30 9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 30 10 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 31
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
11.1. Normative References . . . . . . . . . . . . . . . . . . . 30 11.1 Normative References . . . . . . . . . . . . . . . . . . . 31
11.2. Informative References . . . . . . . . . . . . . . . . . . 31 11.2 Informative References . . . . . . . . . . . . . . . . . . 31
Appendix A. Additional Benefits due to Native IPv6 and Appendix A Additional Benefits due to Native IPv6 and
Universal Unique Addressing . . . . . . . . . . . . . 32 Universal Unique Addressing . . . . . . . . . . . . . 33
A.1. Universal Any-to-Any Connectivity . . . . . . . . . . . . 32 A.1 Universal Any-to-Any Connectivity . . . . . . . . . . . . . 33
A.2. Auto-configuration . . . . . . . . . . . . . . . . . . . . 33 A.2 Auto-configuration . . . . . . . . . . . . . . . . . . . . 34
A.3. Native Multicast Services . . . . . . . . . . . . . . . . 33 A.3 Native Multicast Services . . . . . . . . . . . . . . . . . 34
A.4. Increased Security Protection . . . . . . . . . . . . . . 33 A.4 Increased Security Protection . . . . . . . . . . . . . . . 34
A.5. Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 34 A.5 Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 35
A.6. Merging Networks . . . . . . . . . . . . . . . . . . . . . 34 A.6 Merging Networks . . . . . . . . . . . . . . . . . . . . . 35
Appendix B. Revision history . . . . . . . . . . . . . . . . . . 35 Appendix B Revision history . . . . . . . . . . . . . . . . . . . 36
B.1. Changes from *-vandevelde-v6ops-nap-00 to B.1 Changes from *-vandevelde-v6ops-nap-00 to
*-vandevelde-v6ops-nap-01 . . . . . . . . . . . . . . . . 35 *-vandevelde-v6ops-nap-01 . . . . . . . . . . . . . . . . . 36
B.2. Changes from *-vandevelde-v6ops-nap-01 to B.2 Changes from *-vandevelde-v6ops-nap-01 to
*-ietf-v6ops-nap-00 . . . . . . . . . . . . . . . . . . . 35 *-ietf-v6ops-nap-00 . . . . . . . . . . . . . . . . . . . . 36
B.3. Changes from *-ietf-v6ops-nap-00 to *-ietf-v6ops-nap-01 . 35 B.3 Changes from *-ietf-v6ops-nap-00 to *-ietf-v6ops-nap-01 . . 36
B.4. Changes from *-ietf-v6ops-nap-01 to *-ietf-v6ops-nap-02 . 35 B.4 Changes from *-ietf-v6ops-nap-01 to *-ietf-v6ops-nap-02 . . 36
B.5. Changes from *-ietf-v6ops-nap-02 to *-ietf-v6ops-nap-03 . 39 B.5 Changes from *-ietf-v6ops-nap-02 to *-ietf-v6ops-nap-03 . . 40
B.6. Changes from *-ietf-v6ops-nap-03 to *-ietf-v6ops-nap-04 . 41 B.6 Changes from *-ietf-v6ops-nap-03 to *-ietf-v6ops-nap-04 . . 42
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 42 B.7 Changes from *-ietf-v6ops-nap-04 to *-ietf-v6ops-nap-05 . . 43
Intellectual Property and Copyright Statements . . . . . . . . . . 44 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 44
Intellectual Property and Copyright Statements . . . . . . . . . . 46
1. Introduction 1 Introduction
There have been periodic claims that IPv6 will require a Network There have been periodic claims that IPv6 will require a Network
Address Translation (NAT), because with IPv4 people use NAT to Address Translation (NAT), because network administrators use NAT to
accomplish that person's preferred task. This document will explain meet a variety of needs when using IPv4 and those needs will also
why those pronouncements are false by showing how to accomplish the have to be met when using IPv6. Although there are many perceived
task goal without address translation. Although there are many benefits to NAT, its primary benefit of "amplifying" available
perceived benefits to NAT, its primary benefit of "amplifying" address space is not needed in IPv6. The serious disadvantages and
available address space is not needed in IPv6. The serious impact on applications by ambiguous address space and Network Address
disadvantages and impact on applications by ambiguous address space Translation [3] [7]have been well documented [6] [8]so there will not
and Network Address Translation [1] [5]have been well documented [4] be much additional discussion here. However, given its wide
[6]so there will not be much additional discussion here. However, deployment NAT undoubtedly has some perceived benefits, though the
given its wide deployment NAT undoubtedly has some perceived bulk of those using it have not evaluated the technical trade-offs.
benefits, though the bulk of those using it have not evaluated the Indeed, it is often claimed that some connectivity and security
technical trade-offs. Indeed, it is often claimed that some concerns can only be solved by using a NAT device, without any
connectivity and security concerns can only be solved by using a NAT mention of the negative impacts on applications. This is amplified
device, without any mention of the negative impacts on applications. through the widespread sharing of vendor best practice documents and
This is amplified through the widespread sharing of vendor best sample configurations that do not differentiate the translation
practice documents and sample configurations that do not function of address expansion from the state function of limiting
differentiate the translation function of address expansion from the connectivity.
state function of limiting connectivity.
This document describes the goals for utilizing a NAT device in an This document describes the uses of a NAT device in an IPv4
IPv4 environment that are regularly cited as solutions for perceived environment that are regularly cited as 'solutions' for perceived
problems. It then shows how these needs can be met without using the problems. It then shows how the goals of the network manager can be
header modification feature of NAT in an IPv6 network. It should be met in an IPv6 network without using the header modification feature
noted that this document is 'informational', as it discusses of NAT. It should be noted that this document is 'informational', as
approaches that will work to accomplish the goals. It is it discusses approaches that will work to accomplish the goals of the
specifically not a BCP that is recommending any one approach. network manager. It is specifically not a BCP that is recommending
any one approach, or a manual on how to configure a network.
As far as security and privacy are concerned, this document considers As far as security and privacy are concerned, this document considers
how to mitigate a number of threats. Some are obviously external, how to mitigate a number of threats. Some are obviously external,
such as having a hacker or a worm infected machine outside trying to such as having a hacker or a worm infected machine outside trying to
penetrate and attack the local network. Some are local such as a penetrate and attack the local network. Some are local such as a
disgruntled employee disrupting business operations, or the disgruntled employee disrupting business operations, or the
unintentional negligence of a user downloading some malware which unintentional negligence of a user downloading some malware which
then proceeds to attack from within. Some may be inherent in the then proceeds to attack from within. Some may be inherent in the
device hardware ("embedded") such as having some firmware in a device hardware ("embedded") such as having some firmware in a
domestic appliance "call home" to its manufacturer without the user's domestic appliance "call home" to its manufacturer without the user's
consent. consent.
Another consideration discussed is the view that NAT can be used to Another consideration discussed is the view that NAT can be used to
fulfill the goals of a security policy. At a technical level the fulfill the goals of a security policy. On the one hand, NAT does
translation process fundamentally can not produce security because satisfy some policy goals, such as topology hiding; at the same time
mangling the address in the header does not fulfill any useful it defeats others, such as the ability to produce an end-to-end audit
security functions; in fact it breaks the ability to produce an audit trail at network level. That said, there are artifacts of NAT
trail which is a fundamental security tool. That said, the artifacts devices that do provide some value.
of NAT devices do provide some value.
1. The need to establish state before anything gets through from 1. The need to establish state before anything gets through from
outside to inside solves one set of problems. outside to inside solves one set of problems.
2. The need to stop receiving any packets when finished with a flow 2. The expiration of state to stop receiving any packets when
solves a set of problems finished with a flow solves a set of problems
3. the need to appear to be attached at the edge of the network 3. The ability for nodes to appear to be attached at the edge of the
solves a set of problems network solves a set of problems
4. and the ability to have addresses that are not publicly routed 4. The ability to have addresses that are not publicly routed solves
solves yet another set (mostly changes where the state is and yet another set (mostly changes where the state is and scale
scale requirements for the first one). requirements for the first one).
This document describes several techniques that may be combined in an This document describes several techniques that may be combined in an
IPv6 deployment to protect the integrity of its network architecture. IPv6 deployment to protect the integrity of its network architecture.
It will focus on the 'how to accomplish a goal' perspective, leaving It will focus on the 'how to accomplish a goal' perspective, leaving
most of the 'why that goal' perspective for other documents. These most of the 'why that goal is useful' perspective for other
techniques, known collectively as Network Architecture Protection documents. These techniques, known collectively as Network
(NAP6), retain the concept of a well defined boundary between Architecture Protection (NAP6), retain the concept of a well defined
"inside" and "outside" the private network, and allow firewalling, boundary between "inside" and "outside" the private network, while
topology hiding, and privacy. NAP6 will achieve these security goals allowing firewalling, topology hiding, and privacy. NAP6 will
without address translation whilst regaining the ability for achieve these security goals without address translation whilst
arbitrary any-to-any connectivity. regaining the ability for arbitrary any-to-any connectivity.
IPv6 Network Architecture Protection can be summarized in the IPv6 Network Architecture Protection can be summarized in the
following table. It presents the marketed "benefits" of IPv4+NAT following table. It presents the marketed benefits of IPv4+NAT with
with a cross-reference of how those are delivered in both the IPv4 a cross-reference of how those are delivered in both the IPv4 and
and IPv6 environments. IPv6 environments.
Goal IPv4 IPv6 Goal IPv4 IPv6
+------------------+-----------------------+-----------------------+ +------------------+-----------------------+-----------------------+
| Simple Gateway | DHCP - single | DHCP-PD - arbitrary | | Simple Gateway | DHCP - single | DHCP-PD - arbitrary |
| as default router| address upstream | length customer | | as default router| address upstream | length customer |
| and address pool | DHCP - limited | prefix upstream | | and address pool | DHCP - limited | prefix upstream |
| manager | number of individual | SLAAC via RA | | manager | number of individual | SLAAC via RA |
| | devices downstream | downstream | | | devices downstream | downstream |
| | see section 2.1 | see section 4.1 | | | see section 2.1 | see section 4.1 |
+------------------|-----------------------|-----------------------+ +------------------|-----------------------|-----------------------+
skipping to change at page 7, line 4 skipping to change at page 7, line 5
+------------------|-----------------------|-----------------------+ +------------------|-----------------------|-----------------------+
| Renumbering and | Address translation | Preferred lifetime | | Renumbering and | Address translation | Preferred lifetime |
| Multi-homing | at border | per prefix & Multiple| | Multi-homing | at border | per prefix & Multiple|
| | | addresses per | | | | addresses per |
| | | interface | | | | interface |
| | see section 2.7 | see section 4.7 | | | see section 2.7 | see section 4.7 |
+------------------+-----------------------+-----------------------+ +------------------+-----------------------+-----------------------+
This document first identifies the perceived benefits of NAT in more This document first identifies the perceived benefits of NAT in more
detail, and then shows how IPv6 NAP6 can provide each of them. It detail, and then shows how IPv6 NAP6 can provide each of them. It
concludes with a IPv6 NAP6 case study and a gap analysis of work that concludes with a IPv6 NAP6 case study and a gap analysis of standards
remains to be done for a complete NAP6 solution. work that remains to be done for an optimal NAP6 solution.
2. Perceived Benefits of NAT and its Impact on IPv4 2 Perceived Benefits of NAT and its Impact on IPv4
This section provides insight into the generally perceived benefits This section provides insight into the generally perceived benefits
of the use of IPv4 NAT. The goal of this description is not to of the use of IPv4 NAT. The goal of this description is not to
analyze these benefits or the accuracy of the perception (detailed analyze these benefits or the accuracy of the perception (detailed
discussions in [4]), but to describe the deployment requirements and discussions in [6]), but to describe the deployment requirements and
set a context for the later descriptions of the IPv6 approaches for set a context for the later descriptions of the IPv6 approaches for
dealing with those requirements. dealing with those requirements.
2.1. Simple Gateway between Internet and Private Network 2.1 Simple Gateway between Internet and Private Network
A NAT device can connect a private network with addresses allocated A NAT device can connect a private network with addresses allocated
from any part of the space (ambiguous [1] or global registered & from any part of the space (ambiguous [3]or global registered &
unregistered address) towards the Internet, though extra effort is unregistered address) towards the Internet, though extra effort is
needed when the same range exists on both sides of the NAT. The needed when the same range exists on both sides of the NAT. The
address space of the private network can be built from globally address space of the private network can be built from globally
unique addresses, from ambiguous address space or from both unique addresses, from ambiguous address space or from both
simultaneously. In the simple case of private use addresses, without simultaneously. In the simple case of private use addresses, without
needing specific configuration the NAT device enables access between needing specific configuration the NAT device enables access between
the client side of a distributed client-server application in the the client side of a distributed client-server application in the
private network and the server side located in the public Internet. private network and the server side located in the public Internet.
Wide-scale deployments have shown that using NAT to act as a simple Wide-scale deployments have shown that using NAT to act as a simple
gateway attaching a private IPv4 network to the Internet is simple gateway attaching a private IPv4 network to the Internet is simple
and practical for the non-technical end user. Frequently a simple and practical for the non-technical end user. Frequently a simple
user interface, or even a default configuration is sufficient for user interface, or even a default configuration is sufficient for
configuring both device and application access rights. configuring both device and application access rights.
This simplicity comes at a price as the resulting topology puts This simplicity comes at a price, as the resulting topology puts
restrictions on applications. The NAT simplicity works well when the restrictions on applications. The NAT simplicity works well when the
applications are limited to a client/server model with the server applications are limited to a client/server model with the server
deployed on the public side of the NAT. For peer-to-peer, multi- deployed on the public side of the NAT. For peer-to-peer, multi-
party, or servers deployed on the private side of the NAT, helper party, or servers deployed on the private side of the NAT, helper
technologies must be available. These helper technologies are technologies must also be deployed. These helper technologies are
frequently complex to develop and manage, creating a hidden cost to frequently complex to develop and manage, creating a hidden cost to
this 'simple gateway'. this 'simple gateway'.
2.2. Simple Security due to Stateful Filter Implementation 2.2 Simple Security due to Stateful Filter Implementation
It is frequently believed that through its session-oriented It is frequently believed that through its session-oriented
operation, NAT puts in an extra barrier to keep the private network operation, NAT puts in an extra barrier to keep the private network
protected from outside influences. Since a NAT device typically protected from outside influences. Since a NAT device typically
keeps state only for individual sessions, attackers, worms, etc. keeps state only for individual sessions, attackers, worms, etc.
cannot exploit this state to attack a specific host on any other cannot exploit this state to attack a specific host on any other
port, though in the port overload case of NAPT attacking all active port, though in the port overload case of NAPT attacking all active
ports will impact a potentially wide number of hosts. This benefit ports will impact a potentially wide number of hosts. This benefit
may be partially real, however, experienced hackers are well aware of may be partially real, however, experienced hackers are well aware of
NAT devices and are very familiar with private address space, and NAT devices and are very familiar with private address space, and
have devised methods of attack (such as trojan horses) that readily have devised methods of attack (such as trojan horses) that readily
penetrate NAT boundaries. For these reasons the sense of security penetrate NAT boundaries. While the stateful filtering offered by
provided by NAT is actually an illusion. NAT offers a measure of protection against a variety of
straightforward network attacks, it does not protect against all
attacks despite being presented as a one-size-fits-all answer.
The act of address translation does not provide security in itself; The act of translating address bits within the header does not
for example, consider a configuration with static NAT translation and provide security in itself. For example consider a configuration
all inbound ports translating to a single machine. In such a with static NAT translation and all inbound ports translating to a
scenario the security risk for that machine is identical to the case single machine. In such a scenario the security risk for that
with no NAT device in the communication path. As result there is no machine is identical to the case with no NAT device in the
specific security value in the address translation function. The communication path, as any connection to the pubic address will be
perceived security of NAT comes from the lack of pre- established or delivered to the mapped target.
permanent mapping state. Dynamically establishing state in response
to internal requests reduces the threat of unexpected external The perceived security of NAT comes from the lack of pre- established
connections to internal devices. This role, often marketed as a or permanent mapping state. This is often used as a 'better than
firewall, is really an arbitrary artifact while a real firewall has nothing' level of protection because it doesn't require complex
explicit management controls. management to filter out unwanted traffic. Dynamically establishing
state in response to internal requests reduces the threat of
unexpected external connections to internal devices, and this level
of protection would also be available from a basic firewall. (A
basic firewall, supporting clients accessing public side servers,
would improve on that level of protection by avoiding the problem of
state persisting as different clients use the same private side
address over time.) This role, often marketed as a firewall, is
really an arbitrary artifact while a real firewall has often offers
explicit and more comprehensive management controls.
In some cases, NAT operators (including domestic users) may be In some cases, NAT operators (including domestic users) may be
obliged to configure quite complex port mapping rules to allow obliged to configure quite complex port mapping rules to allow
external access to local applications such as a multi-player game or external access to local applications such as a multi-player game or
web servers. In this case the NAT actually adds management web servers. In this case the NAT actually adds management
complexity compared to a simple router. In situations where two or complexity compared to the simple router discussed in 2.1. In
more devices need to host the same application or otherwise use the situations where two or more devices need to host the same
same public port this complexity shifts from difficult to impossible. application or otherwise use the same public port, this complexity
shifts from difficult to impossible.
2.3. User/Application tracking 2.3 User/Application tracking
One usage of NAT is for the local network administrator to track user One usage of NAT is for the local network administrator to track user
and application traffic. Although NATs create temporary state for and application traffic. Although NATs create temporary state for
active sessions, in general they provide limited capabilities for the active sessions, in general they provide limited capabilities for the
administrator of the NAT to gather information about who in the administrator of the NAT to gather information about who in the
private network is requesting access to which Internet location. private network is requesting access to which Internet location.
This is done by periodically logging the network address translation This is done by periodically logging the network address translation
details of the private and the public addresses from the NAT device's details of the private and the public addresses from the NAT device's
state database. state database.
The subsequent checking of this database is not always a simple task, The subsequent checking of this database is not always a simple task,
especially if Port Address Translation is used. It also has an especially if Port Address Translation is used. It also has an
unstated assumption that the administrative instance has a mapping unstated assumption that the administrative instance has a mapping
between a private IPv4-address and a network element or user at all between a private IPv4-address and a network element or user at all
times, or the administrator has a time-correlated list of the times, or the administrator has a time-correlated list of the
address/port mappings. address/port mappings.
2.4. Privacy and Topology Hiding 2.4 Privacy and Topology Hiding
One goal of 'topology hiding' is to prevent external entities from One goal of 'topology hiding' is to prevent external entities from
making a correlation between the topological location of devices on making a correlation between the topological location of devices on
the local network. The ability of NAT to provide Internet access to the local network. The ability of NAT to provide Internet access to
a large community of users by the use of a single (or a few) global a large community of users by the use of a single (or a few) global
IPv4 routable addresses offers a simple mechanism to hide the IPv4 routable address(es) offers a simple mechanism to hide the
internal topology of a network. In this scenario the large community internal topology of a network. In this scenario the large community
will be represented in the Internet by a single (or a few) IPv4 will be represented in the Internet by a single (or a few) IPv4
address(es). address(es).
The use of NAT then results in a user behind a NAT gateway actually By using NAT a system appears to the Internet as if it originated
appearing from the Internet as a user inside the NAT box itself; inside the NAT box itself; i.e., the IPv4 address that appears on the
i.e., the IPv4 address that appears on the Internet is only Internet is only sufficient to identify the NAT so all internal nodes
sufficient to identify the NAT so all internal nodes appear to exist appear to exist at the demarcation edge. When concealed behind a NAT
at the demarcation edge. When concealed behind a NAT it is it is impossible to tell from the outside which member of a family,
impossible to tell from the outside which member of a family, which which customer of an Internet cafe, or which employee of a company
customer of an Internet cafe, or which employee of a company
generated or received a particular packet. Thus, although NATs do generated or received a particular packet. Thus, although NATs do
nothing to provide application level privacy, they do prevent the nothing to provide application level privacy, they do prevent the
external tracking and profiling of individual systems by means of external tracking and profiling of individual systems by means of
their IP addresses, usually known as 'device profiling'. their IP addresses, usually known as 'device profiling'.
At the same time a NAT creates a smaller pool of addresses for a much At the same time a NAT creates a smaller pool of addresses for a much
more focused point of attack, where the adversary does not need to more focused point of attack, where the adversary does not need to
scan the entire local network but can instead concentrate on the scan the entire local network but can instead concentrate on the
active ports associated with the NAT adress. By periodically active ports associated with the public NAT adress. By periodically
scanning the limited 16 bit port range on the public side of the NAT, scanning the limited 16 bit port range on the public side of the NAT,
the attack will routinely find all ports that are open to active the attack will routinely find all ports that are open to active
nodes. internal nodes.
There is a similarity with privacy based on application level There is a similarity with privacy based on application level
proxies. When using an application level gateway for browsing the proxies. When using an application level gateway for browsing the
web for example, the 'privacy' of a web user can be provided by web for example, the 'privacy' of a web user can be provided by
masking the true identity of the original web user towards the masking the true identity of the original web user towards the
outside world (although the details of what is - or is not - logged outside world (although the details of what is - or is not - logged
at the NAT/proxy will be different). at the NAT/proxy will be different).
Some network managers prefer to hide as much as possible of their Some network managers prefer to hide as much as possible of their
internal network topology from outsiders as a useful precaution to internal network topology from outsiders as a useful precaution to
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ports. Once a list of available devices has been mapped, a port-scan ports. Once a list of available devices has been mapped, a port-scan
on these IP addresses can be performed. Scanning works by tracking on these IP addresses can be performed. Scanning works by tracking
which ports do not receive unreachable errors from either the which ports do not receive unreachable errors from either the
firewall or host. With the list of open ports an attacker can firewall or host. With the list of open ports an attacker can
optimize the time needed for a successful attack by correlating it optimize the time needed for a successful attack by correlating it
with known vulnerabilities to reduce the number of attempts. For with known vulnerabilities to reduce the number of attempts. For
example, FTP usually runs on port 21, and HTTP usually runs on port example, FTP usually runs on port 21, and HTTP usually runs on port
80. Any vulnerable open ports could be used for access to an end 80. Any vulnerable open ports could be used for access to an end
system to command it to start initiating attacks on others. system to command it to start initiating attacks on others.
2.5. Independent Control of Addressing in a Private Network 2.5 Independent Control of Addressing in a Private Network
Many private IPv4 networks take benefit from using the address space Many private IPv4 networks make use of the address space defined in
defined in RFC 1918 to enlarge the available addressing space for RFC 1918 to enlarge the available addressing space for their private
their private network, and at the same time reduce their need for network, and at the same time reduce their need for globally routable
globally routable addresses. This type of local control of address addresses. This type of local control of address resources allows a
resources allows a sufficiently large pool for a clean and sufficiently large pool for a clean and hierarchical addressing
hierarchical addressing structure in the local network. structure in the local network.
Another benefit is due to the usage of independent addresses on Another benefit is the ability to change providers with minimal
majority of the network infrastructure there is an increased ability operational difficulty due to the usage of independent addresses on
to change provider with less operational difficulties. majority of the network infrastructure. Changing the addresses on
the public side of the NAT avoids the administrative challenge of
changing every device in the network.
Section 2.7 describes some disadvantages that appear if independent Section 2.7 describes some disadvantages that appear if independent
networks using ambiguous addresses [1]have to be merged. networks using ambiguous addresses [3]have to be merged.
2.6. Global Address Pool Conservation 2.6 Global Address Pool Conservation
While the widespread use of IPv4+NAT has reduced the potential While the widespread use of IPv4+NAT has reduced the potential
consumption rate, the ongoing depletion of the IPv4 address range has consumption rate, the ongoing depletion of the IPv4 address range has
already taken the remaining pool of unallocated IPv4 addresses below already taken the remaining pool of unallocated IPv4 addresses well
25%. While mathematical models based on historical IPv4 prefix below 25%. While mathematical models based on historical IPv4 prefix
consumption periodically attempt to predict the future exhaustion consumption periodically attempt to predict the future exhaustion
date of the IPv4 address pool, a direct result of this continuous date of the IPv4 address pool, a direct result of this continuous
resource consumption is that the administrative overhead for resource consumption is that the administrative overhead for
acquiring globally unique IPv4 addresses will continue increasing in acquiring globally unique IPv4 addresses will continue increasing in
direct response to tightening allocation policies. direct response to tightening allocation policies.
In response to the increasing administrative overhead many Internet In response to the increasing administrative overhead many Internet
Service Providers (ISPs) have already resorted to the ambiguous Service Providers (ISPs) have already resorted to the ambiguous
addresses defined in RFC 1918 behind a NAT for the various services addresses defined in RFC 1918 behind a NAT for the various services
they provide as well as connections for their end customers. This they provide as well as connections for their end customers. This
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The limit of this approach is something substantially less than 2^48 The limit of this approach is something substantially less than 2^48
possible active **application** endpoints (approximately [2^32 minus possible active **application** endpoints (approximately [2^32 minus
2^29] * [2* 2^16 minus well known port space]), as distinct from 2^29] * [2* 2^16 minus well known port space]), as distinct from
addressable devices each with their own application endpoint range. addressable devices each with their own application endpoint range.
Those who advocate layering of NAT frequently forget to mention that Those who advocate layering of NAT frequently forget to mention that
there are topology restrictions placed on the applications. Forced there are topology restrictions placed on the applications. Forced
into this limiting situation such customers can rightly claim that into this limiting situation such customers can rightly claim that
despite the optimistic predictions of mathematical models, the global despite the optimistic predictions of mathematical models, the global
pool of IPv4 addresses is effectively already exhausted. pool of IPv4 addresses is effectively already exhausted.
2.7. Multihoming and Renumbering with NAT 2.7 Multihoming and Renumbering with NAT
Allowing a network to be multihomed and renumbering a network are Allowing a network to be multihomed and renumbering a network are
quite different functions. However these are argued together as quite different functions. However these are argued together as
reasons for using NAT, because making a network multihomed is often a reasons for using NAT, because making a network multihomed is often a
transitional state required as part of network renumbering, and NAT transitional state required as part of network renumbering, and NAT
interacts with both in the same way. interacts with both in the same way.
For enterprise networks, it is highly desirable to provide resiliency For enterprise networks, it is highly desirable to provide resiliency
and load-balancing to be connected to more than one Internet Service and load-balancing to be connected to more than one Internet Service
Provider (ISP) and to be able to change ISPs at will. This means Provider (ISP) and to be able to change ISPs at will. This means
that a site must be able to operate under more than one CIDR prefix that a site must be able to operate under more than one CIDR prefix
[16]and/or readily change its CIDR prefix. Unfortunately, IPv4 was [2]and/or readily change its CIDR prefix. Unfortunately, IPv4 was
not designed to facilitate either of these maneuvers. However, if a not designed to facilitate either of these maneuvers. However, if a
site is connected to its ISPs via NAT boxes, only those boxes need to site is connected to its ISPs via NAT boxes, only those boxes need to
deal with multihoming and renumbering issues. deal with multihoming and renumbering issues.
Similarly, if two enterprise IPv4 networks need to be merged and Similarly, if two enterprise IPv4 networks need to be merged and
RFC1918 addresses are used, there is a high probability of address RFC1918 addresses are used, there is a high probability of address
overlaps. In those situations it may well be that installing a NAT overlaps. In those situations it may well be that installing a NAT
box between them will avoid the need to renumber one or both. For box between them will avoid the need to renumber one or both. For
any enterprise, this can be a short term financial saving, and allow any enterprise, this can be a short term financial saving, and allow
more time to renumber the network components. The long term solution more time to renumber the network components. The long term solution
is a single network without usage of NAT to avoid the ongoing is a single network without usage of NAT to avoid the ongoing
operational complexity of overlapping addresses. operational complexity of overlapping addresses.
The addition of an extra NAT as a solution may be sufficient for some The addition of an extra NAT as a solution may be sufficient for some
networks; however when the merging networks were already using networks; however when the merging networks were already using
address translation it will create major problems due to address translation it will create major problems due to
administrative difficulties of overlapping address spaces in the administrative difficulties of overlapping address spaces in the
merged networks. merged networks.
3. Description of the IPv6 Tools 3 Description of the IPv6 Tools
This section describes several features that can be used as part of This section describes several features that can be used as part of
the NAP6 solution to replace the protection features associated with the NAP6 solution to replace the protection features associated with
IPv4 NAT. IPv4 NAT.
The reader must clearly distinguish between features of IPv6 that The reader must clearly distinguish between features of IPv6 that
were fully defined when this document was drafted and those that were were fully defined when this document was drafted and those that were
potential features that still required more work to define them. The potential features that still required more work to define them. The
latter are summarized later in the 'Gap Analysis' section of this latter are summarized later in the 'Gap Analysis' section of this
document. However, we do not distinguish in this document between document. However, we do not distinguish in this document between
fully defined features of IPv6 and those that were already widely fully defined features of IPv6 and those that were already widely
implemented at the time of writing. implemented at the time of writing.
3.1. Privacy Addresses (RFC 3041) 3.1 Privacy Addresses (RFC 3041)
There are situations where it is desirable to prevent device There are situations where it is desirable to prevent device
profiling, for example by web sites that are accessed from the device profiling, for example by web sites that are accessed from the device
as it moves around the Internet. IPv6 privacy addresses were defined as it moves around the Internet. IPv6 privacy addresses were defined
to provide that capability. IPv6 addresses consist of a routing to provide that capability. IPv6 addresses consist of a routing
prefix, subnet-id part (SID) and an interface identifier part (IID). prefix, subnet-id part (SID) and an interface identifier part (IID).
As originally defined, IPv6 stateless address auto-configuration As originally defined, IPv6 stateless address auto-configuration
(SLAAC) will typically embed the IEEE Link Identifier of the (SLAAC) will typically embed the IEEE Link Identifier of the
interface as the IID part, though this practice facilitates tracking interface as the IID part, though this practice facilitates tracking
and profiling of a device through the consistent IID. RFC 3041 [7] and profiling of a device through the consistent IID. RFC 3041
describes an extension to SLAAC to enhance device privacy. Use of [9]describes an extension to SLAAC to enhance device privacy. Use of
the privacy address extension causes nodes to generate global-scope the privacy address extension causes nodes to generate global-scope
addresses from interface identifiers that change over time, addresses from interface identifiers that change over time,
consistent with system administrator policy. Changing the interface consistent with system administrator policy. Changing the interface
identifier (thus the global-scope addresses generated from it) over identifier (thus the global-scope addresses generated from it) over
time makes it more difficult for eavesdroppers and other information time makes it more difficult for eavesdroppers and other information
collectors to identify when addresses used in different transactions collectors to identify when addresses used in different transactions
actually correspond to the same node. A relatively short valid actually correspond to the same node. A relatively short valid
lifetime for the privacy address also has the side effect of reducing lifetime for the privacy address also has the effect of reducing the
the attack profile of a device, as it is not directly attackable once attack profile of a device, as it is not directly attackable once it
it stops answering at the temporary use address. stops answering at the temporary use address.
While the primary implementation and source of randomized RFC 3041 While the primary implementation and source of randomized RFC 3041
addresses is expected to be from end-systems running stateless auto- addresses is expected to be from end-systems running stateless auto-
configuration, there is nothing that prevents a DHCP server from configuration, there is nothing that prevents a DHCP server from
running the RFC 3041 algorithm for any new IEEE identifier it hears running the RFC 3041 algorithm for any new IEEE identifier it hears
in a request, then remembering that for future queries. This would in a request, then remembering that for future queries. This would
allow using them in DNS for registered services since the assumption allow using them in DNS for registered services since the assumption
of a DHCP server based deployment would be a persistent value that of a DHCP server based deployment would be a persistent value that
minimizes DNS churn. A DHCP based deployment would also allow for minimizes DNS churn. A DHCP based deployment would also allow for
local policy to periodically change the entire collection of end local policy to periodically change the entire collection of end
device addresses while maintaining some degree of central knowledge device addresses while maintaining some degree of central knowledge
and control over which addresses should be in use at any point in and control over which addresses should be in use at any point in
time. time.
Randomizing the IID, as defined in RFC 3041, is effectively a sparse Randomizing the IID, as defined in RFC 3041, is effectively a sparse
allocation technique which only precludes tracking of the lower 64 allocation technique which only precludes tracking of the lower 64
bits of the IPv6 address. Masking of the subnet ID will require bits of the IPv6 address. Masking of the subnet ID will require
additional approaches as discussed below in 3.4. Additional additional approaches as discussed below in 3.4. Additional
considerations are discussed in [19]. considerations are discussed in [20].
3.2. Unique Local Addresses 3.2 Unique Local Addresses
Achieving the goal of autonomy, that many perceive as a value of NAT, Achieving the goal of autonomy, that many perceive as a value of NAT,
is required for local network and application services stability is required for local network and application services stability
during periods of intermittent connectivity or moving between one or during periods of intermittent connectivity or moving between one or
more providers. Such autonomy in a single routing prefix environment more providers. Such autonomy in a single routing prefix environment
would lead to massive expansion of the global routing tables (as seen would lead to massive expansion of the global routing tables (as seen
in IPv4), so IPv6 provides for simultaneous use of multiple prefixes. in IPv4), so IPv6 provides for simultaneous use of multiple prefixes.
The Unique Local Address prefix (ULA) [15]has been set aside for use The Unique Local Address prefix (ULA) [19]has been set aside for use
in local communications. The ULA address prefix for any network is in local communications. The ULA address prefix for any network is
routable over a locally defined collection of routers. These routable over a locally defined collection of routers. These
prefixes are not intended to be routed on the public global Internet prefixes are not intended to be routed on the public global Internet
as large scale inter-domain distribution of routes for ULA prefixes as large scale inter-domain distribution of routes for ULA prefixes
would have a negative impact on global route aggregation. would have a negative impact on global route aggregation.
ULAs have the following characteristics: ULAs have the following characteristics:
o For all practical purposes a globally unique prefix o For all practical purposes a globally unique prefix
* Allows networks to be combined or privately interconnected * Allows networks to be combined or privately interconnected
without creating address conflicts or requiring renumbering of without creating address conflicts or requiring renumbering of
interfaces using these prefixes interfaces using these prefixes
* If accidentally leaked outside of a network via routing or DNS, * If accidentally leaked outside of a network via routing or DNS,
it is highly unlikely that there will be a conflict with any it is highly unlikely that there will be a conflict with any
other addresses other addresses
o ISP independent and can be used for communications inside of a o ISP independent and can be used for communications inside of a
network without having any permanent or only intermittent Internet network without having any permanent or only intermittent Internet
connectivity connectivity
o Well-known prefix to allow for easy filtering at network o Well-known prefix to allow for easy filtering at network
boundaries preventing leakage of local routes and packets. boundaries preventing leakage of routes and packets that should
remain local.
o In practice, applications may treat these addresses like global o In practice, applications may treat these addresses like global
scoped addresses but address selection algorithms may need to scoped addresses but address selection algorithms may need to
distinguish between ULAs and ordinary global scope unicast distinguish between ULAs and ordinary global scope unicast
addresses to assure stability. The policy table defined in [10] addresses to assure stability. The policy table defined in [13]is
is one way to bias this selection, by giving higher preference to one way to bias this selection, by giving higher preference to
FC00::/7 over 2001::/3. Mixing the two kinds of addresses may FC00::/7 over 2001::/3. Mixing the two kinds of addresses may
lead to undeliverable packets during times of instability, but lead to undeliverable packets during times of instability, but
that mixing is not likely to happen when the rules of RFC 3484 are that mixing is not likely to happen when the rules of RFC 3484 are
followed. followed.
o ULAs have no intrinsic security properties. However, they have o ULAs have no intrinsic security properties. However, they have
the useful property that their routing scope is limited by default the useful property that their routing scope is limited by default
within an administrative boundary. Their usage is suggested at within an administrative boundary. Their usage is suggested at
several points in this document, as a matter of administrative several points in this document, as a matter of administrative
convenience. convenience.
3.3. DHCPv6 Prefix Delegation 3.3 DHCPv6 Prefix Delegation
One of the functions of a simple gateway is managing the local use One of the functions of a simple gateway is managing the local use
address range. The Prefix Delegation (DHCP-PD) options [11] provide address range. The Prefix Delegation (DHCP-PD) options [14]provide a
a mechanism for automated delegation of IPv6 prefixes using the mechanism for automated delegation of IPv6 prefixes using the Dynamic
Dynamic Host Configuration Protocol (DHCP) [9]. This mechanism Host Configuration Protocol (DHCP) [12]. This mechanism (DHCP-PD) is
(DHCP-PD) is intended for delegating a long-lived prefix from a intended for delegating a long-lived prefix from a delegating router
delegating router (possibly incorporating a DHCPv6 server) to a (possibly incorporating a DHCPv6 server) to a requesting router,
requesting router, possibly across an administrative boundary, where possibly across an administrative boundary, where the delegating
the delegating router does not require knowledge about the topology router does not require knowledge about the topology of the links in
of the links in the network to which the prefixes will be assigned. the network to which the prefixes will be assigned.
3.4. Untraceable IPv6 Addresses 3.4 Untraceable IPv6 Addresses
The main goal of untraceable IPv6 addresses is to create an The main goal of untraceable IPv6 addresses is to create an
apparently amorphous network infrastructure as seen from external apparently amorphous network infrastructure, as seen from external
networks to protect the local infrastructure from malicious outside networks, to protect the local infrastructure from malicious outside
influences and from mapping of any correlation between the network influences and from mapping of any correlation between the network
activities of multiple devices from external networks. When using activities of multiple devices from external networks. When using
untraceable IPv6 addresses, it could be that two apparently untraceable IPv6 addresses, it could be that two apparently
sequential addresses are allocated to devices on very different parts sequential addresses are allocated to devices on very different parts
of the local network instead of belonging to devices adjacent to each of the local network instead of belonging to devices adjacent to each
other on the same subnet. other on the same subnet.
Since IPv6 addresses will not be in short supply even within a single Since IPv6 addresses will not be in short supply even within a single
/64 (or shorter) prefix, it is possible to generate them effectively /64 (or shorter) prefix, it is possible to generate them effectively
at random when untraceability is required. They will be globally at random when untraceability is required. They will be globally
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assignment is intended to mislead the outside world about the assignment is intended to mislead the outside world about the
structure of the local network. In particular the subnet structure structure of the local network. In particular the subnet structure
may be invisible in the address. Thus a flat routing mechanism will may be invisible in the address. Thus a flat routing mechanism will
be needed within the site. The local routers need to maintain a be needed within the site. The local routers need to maintain a
correlation between the topological location of the device and the correlation between the topological location of the device and the
untraceable IPv6 address. For smaller deployments this correlation untraceable IPv6 address. For smaller deployments this correlation
could be done by generating IPv6 host route entries, or for larger could be done by generating IPv6 host route entries, or for larger
ones by utilizing an indirection device such as a Mobile IPv6 Home ones by utilizing an indirection device such as a Mobile IPv6 Home
Agent. Additional details are in section 4.7. Agent. Additional details are in section 4.7.
4. Using IPv6 Technology to Provide the Market Perceived Benefits of 4 Using IPv6 Technology to Provide the Market Perceived Benefits of NAT
NAT
The facilities in IPv6 described in Section 3 can be used to provide The facilities in IPv6 described in Section 3 can be used to provide
the protection perceived to be associated with IPv4 NAT. This the protection perceived to be associated with IPv4 NAT. This
section gives some examples of how IPv6 can be used securely. section gives some examples of how IPv6 can be used securely.
4.1. Simple Gateway between Internet and Internal Network 4.1 Simple Gateway between Internet and Internal Network
As a simple gateway, the device manages both packet routing and local As a simple gateway, the device manages both packet routing and local
address management. A basic IPv6 router should have a default address management. A basic IPv6 router should have a default
configuration to advertise inside the site a locally generated random configuration to advertise inside the site a locally generated random
ULA prefix, independently from the state of any external ULA prefix, independently from the state of any external
connectivity. This would allow local nodes in a topology more connectivity. This would allow local nodes in a topology more
complex than a single link to communicate amongst themselves complex than a single link to communicate amongst themselves
independent of the state of a global connection. If the network independent of the state of a global connection. If the network
happened to concatenate with another local network, the randomness in happened to concatenate with another local network, the randomness in
ULA creation is highly unlikely to result in address collisions. ULA creation is highly unlikely to result in address collisions.
With external connectivity the simple gateway should use DHCP-PD to With external connectivity the simple gateway should use DHCP-PD to
acquire a routing prefix from the service provider for use when acquire a routing prefix from the service provider for use when
connecting to the global Internet. End-system connections involving connecting to the global Internet. End-system connections involving
other nodes on the global Internet will always use the global IPv6 other nodes on the global Internet that follow the policy table in
addresses derived from this prefix delegation. It should be noted RFC 3484 will always use the global IPv6 addresses derived from this
that the address selection policy table in end-systems defined in RFC prefix delegation. It should be noted that the address selection
3484 should be configured to prefer the ULA prefix range over the policy table should be configured to prefer the ULA prefix range over
DHCP-PD prefix range when the goal is to keep local communications the DHCP-PD prefix range when the goal is to keep local
stable during periods of transient external connectivity. communications stable during periods of transient external
connectivity.
In the very simple case there is no explicit routing protocol on In the very simple case there is no explicit routing protocol on
either side of the gateway, and a single default route is used either side of the gateway, and a single default route is used
internally pointing out to the global Internet. A slightly more internally pointing out to the global Internet. A slightly more
complex case might involve local internal routing protocols, but with complex case might involve local internal routing protocols, but with
the entire local network sharing a common global prefix there would the entire local network sharing a common global prefix there would
still not be a need for an external routing protocol as the service still not be a need for an external routing protocol as the service
provider could install a route for the prefix delegated via DHCP-PD provider could install a route for the prefix delegated via DHCP-PD
pointing toward the connecting link. pointing toward the connecting link.
4.2. IPv6 and Simple Security 4.2 IPv6 and Simple Security
The vulnerability of an IPv6 host is similar to that of an IPv4 host The vulnerability of an IPv6 host directly connected towards the
directly connected towards the Internet. The use of firewall and Internet is similar to that of an IPv4 host. The use of firewall and
Intrusion Detection Systems (IDS) is recommended for those that want Intrusion Detection Systems (IDS) is recommended for those that want
boundary protection in addition to host defenses. A proxy may be boundary protection in addition to host defenses. A proxy may be
used for certain applications, but with the caveat that the end to used for certain applications, but with the caveat that the end to
end transparency is broken. However, with IPv6, the following end transparency is broken. However, with IPv6, the following
protections are available without the use of NAT while maintaining protections are available without the use of NAT while maintaining
end-to-end reachability: end-to-end reachability:
1. Short lifetimes on privacy extension suffixes reduce the attack 1. Short lifetimes on privacy extension suffixes reduce the attack
profile since the node will not respond to the address once its profile since the node will not respond to the address once its
lifetime becomes invalid. lifetime becomes invalid.
2. IPsec is often cited as the reason for improved security because
2. IPsec is a mandatory service for IPv6 implementations. IPsec it is a mandatory service for IPv6 implementations. Broader
functions to authenticate the correspondent, prevent session availability does not by itself improve security because its use
hijacking, prevent content tampering, and optionally masks the is still regulated by the availability of a key infrastructure.
packet contents. While IPsec is commonly available in some IPv4 IPsec functions to authenticate the correspondent, prevent
implementations and can support NATs, NAT support has limitations session hijacking, prevent content tampering, and optionally
and does not work in all situations. In addition, the use of masks the packet contents. While IPsec is commonly available in
IPsec with NATs consumes extra bandwidth for UDP encapsulation some IPv4 implementations and with extensions can support NAT
and keepalive overhead [12]. In the IPv4/NAT environment, the traversals, NAT support has limitations and does not work in all
usage of IPSec has been largely limited to edge-to-edge VPN situations. The use of IPsec with NATs requires an additional
deployments, its potential for end-to-end deployment is UDP encapsulation and keepalive overhead [15]. In the IPv4/NAT
significantly enhanced in an IPv6 network. It should be noted environment, the usage of IPSec has been largely limited to edge-
that encrypted IPsec traffic will bypass content-aware firewalls, to-edge VPN deployments. The potential for end-to-end IPsec use
which is presumed to be acceptable for parties with whom the site is significantly enhanced when NAT is removed from the network,
has established a security association. as connections can be initiated from either end. It should be
noted that encrypted IPsec traffic will bypass content-aware
firewalls, which is presumed to be acceptable for parties with
whom the site has established a security association.
3. The size of the address space of a typical subnet (64 bits of 3. The size of the address space of a typical subnet (64 bits of
IID) will make a complete subnet ping sweep virtually impossible IID) will make a complete subnet ping sweep virtually impossible
due to the potential number of combinations available. Reducing due to the potential number of combinations available [21].
the security threat of port scans on identified nodes requires Reducing the security threat of port scans on identified nodes
sparse distribution within the subnet to minimize the probability requires sparse distribution within the subnet to minimize the
of scans finding adjacent nodes. This scanning protection will probability of scans finding adjacent nodes. This scanning
be nullified if IIDs are configured in any structured groupings protection will be nullified if IIDs are configured in any
within the IID space. Provided that IIDs are essentially structured groupings within the IID space. Provided that IIDs
randomly distributed across the available space, address scanning are essentially randomly distributed across the available space,
based attacks will effectively fail. This protection exists if address scanning based attacks will effectively fail. This
the attacker has no direct access to the specific subnet and protection exists if the attacker has no direct access to the
therefore is trying to scan it remotely. If an attacker has specific subnet and therefore is trying to scan it remotely. If
local access then he could use ND [3]and ping6 to the link-scope an attacker has local access then he could use ND [5]and ping6 to
multicast ff02::1 to detect the IEEE based address of local the link-scope multicast ff02::1 to detect the IEEE based address
neighbors, then apply the global prefix to those to simplify its of local neighbors, then apply the global prefix to those to
search (of course, a locally connected attacker has many scanning simplify its search (of course, a locally connected attacker has
options with IPv4 as well). many scanning options with IPv4 as well).
Assuming the network administrator is aware of [20]the increased size Assuming the network administrator is aware of [21]the increased size
of the IPv6 address will make topology probing much harder, and of the IPv6 address will make topology probing much harder, and
almost impossible for IPv6 devices. The intention of topology almost impossible for IPv6 devices. The intention of topology
probing is to identify a selection of the available hosts inside an probing is to identify a selection of the available hosts inside an
enterprise. This mostly starts with a ping-sweep. Since the IPv6 enterprise. This mostly starts with a ping-sweep. Since the IPv6
subnets are 64 bits worth of address space, this means that an subnets are 64 bits worth of address space, this means that an
attacker has to send out a simply unrealistic number of pings to map attacker has to send out a simply unrealistic number of pings to map
the network, and virus/worm propagation will be thwarted in the the network, and virus/worm propagation will be thwarted in the
process. At full-rate full-duplex 40Gbps (400 times the typical process. At full-rate full-duplex 40Gbps (400 times the typical
100Mbps LAN, and 13,000 times the typical DSL/Cable access link) it 100Mbps LAN, and 13,000 times the typical DSL/Cable access link) it
takes over 5000 years to scan the entirety of a single 64 bit subnet. takes over 5000 years to scan the entirety of a single 64 bit subnet.
skipping to change at page 17, line 15 skipping to change at page 17, line 32
address the same threats if correctly configured firewalls and IDS address the same threats if correctly configured firewalls and IDS
systems are used at the perimeter. systems are used at the perimeter.
It must be noted that even a firewall doesn't fully secure It must be noted that even a firewall doesn't fully secure
a network. Many attacks come from inside or are at a layer a network. Many attacks come from inside or are at a layer
higher than the firewall can protect against. In the final higher than the firewall can protect against. In the final
analysis, every system has to be responsible for its own analysis, every system has to be responsible for its own
security, and every process running on a system has to be security, and every process running on a system has to be
robust in the face of challenges like stack overflows etc. robust in the face of challenges like stack overflows etc.
What a firewall does is prevent a network administration What a firewall does is prevent a network administration
from having to pay for bandwidth to carry unauthorized from having to carry unauthorized
traffic, and in so doing reduce the probability of certain traffic, and in so doing reduce the probability of certain
kinds of attacks across the protected boundary. kinds of attacks across the protected boundary.
To implement simple security for IPv6 in, for example, a DSL To implement simple security for IPv6 in, for example a DSL or Cable
connected home network, the DSL broadband gateway/router should be Modem connected home network, the broadband gateway/router should be
equipped with stateful firewall capabilities. These should provide a equipped with stateful firewall capabilities. These should provide a
default configuration where incoming traffic is limited to return default configuration where incoming traffic is limited to return
traffic resulting from outgoing packets (sometimes known as traffic resulting from outgoing packets (sometimes known as
reflective session state). There should also be an easy interface reflective session state). There should also be an easy interface
which allows users to create inbound 'pinholes' for specific purposes which allows users to create inbound 'pinholes' for specific purposes
such as online-gaming. Another consideration would be the capability such as online-gaming.
for service provider mediated pinhole management where things like
voice call signaling could dynamically establish pinholes based on
predefined authentication rules.
Administrators and the designers of configuration interfaces for Administrators and the designers of configuration interfaces for
simple IPv6 firewalls need to provide a means of documenting the simple IPv6 firewalls need to provide a means of documenting the
security caveats that arise from a given set configuration rules so security caveats that arise from a given set configuration rules so
that users (who are normally oblivious to such things) can be made that users (who are normally oblivious to such things) can be made
aware of the risks. As rules are improved iteratively, the goal will aware of the risks. As rules are improved iteratively, the goal will
be to make use of the IPv6 Internet more secure without increasing be to make use of the IPv6 Internet more secure without increasing
the perceived complexity for users who just want to accomplish a the perceived complexity for users who just want to accomplish a
task. task.
4.3. User/Application Tracking 4.3 User/Application Tracking
IPv6 enables the collection of information about data flows. Due to IPv6 enables the collection of information about data flows. Due to
the fact that all addresses used for Internet and intra-/inter- site the fact that all addresses used for Internet and intra-/inter- site
communication are unique, it is possible for an enterprise or ISP to communication are unique, it is possible for an enterprise or ISP to
get very detailed information on any communication exchange between get very detailed information on any communication exchange between
two or more devices. Unless privacy addresses [7] are in use, this two or more devices. Unless privacy addresses [9]are in use, this
enhances the capability of data- flow tracking for security audits enhances the capability of data- flow tracking for security audits
compared with IPv4 NAT, because in IPv6 a flow between a sender and compared with IPv4 NAT, because in IPv6 a flow between a sender and
receiver will always be uniquely identified due to the unique IPv6 receiver will always be uniquely identified due to the unique IPv6
source and destination addresses. source and destination addresses.
At the same time, this tracking is per address. In environments At the same time, this tracking is per address. In environments
where the goal is tracking back to the user, additional external where the goal is tracking back to the user, additional external
information will be necessary correlating a user with an address. In information will be necessary correlating a user with an address. In
the case of short lifetime privacy address usage, this external the case of short lifetime privacy address usage, this external
information will need to be based on more stable information such as information will need to be based on more stable information such as
the layer 2 media address. the layer 2 media address.
4.4. Privacy and Topology Hiding using IPv6 4.4 Privacy and Topology Hiding using IPv6
Partial host privacy is achieved in IPv6 using pseudo-random privacy Partial host privacy is achieved in IPv6 using RFC 3041 pseudo-random
addresses RFC 3041 which are generated as required, so that a session privacy addresses [9]which are generated as required, so that a
can use an address that is valid only for a limited time. This only session can use an address that is valid only for a limited time.
allows such a session to be traced back to the subnet that originates This only allows such a session to be traced back to the subnet that
it, but not immediately to the actual host, where IPv4 NAT is only originates it, but not immediately to the actual host, where IPv4 NAT
traceable to the most public NAT interface. is only traceable to the most public NAT interface.
Due to the large IPv6 address space available there is plenty of Due to the large IPv6 address space available there is plenty of
freedom to randomize subnet allocations. By doing this, it is freedom to randomize subnet allocations. By doing this, it is
possible to reduce the correlation between a subnet and its location. possible to reduce the correlation between a subnet and its location.
When doing both subnet and IID randomization [7]a casual snooper When doing both subnet and IID randomization a casual snooper won't
won't be able to deduce much about the networks topology. The be able to deduce much about the networks topology. The obtaining of
obtaining of a single address will tell the snooper very little about a single address will tell the snooper very little about other
other addresses. This is different from IPv4 where address space addresses. This is different from IPv4 where address space
limitations cause this to be not true. In most usage cases this limitations cause this to be not true. In most usage cases this
concept should be sufficient for address privacy and topology hiding, concept should be sufficient for address privacy and topology hiding,
with the cost being a more complex internal routing configuration. with the cost being a more complex internal routing configuration.
As discussed in Section 3.1, there are multiple parts to the IPv6 As discussed in Section 3.1, there are multiple parts to the IPv6
address, and different techniques to manage privacy for each which address, and different techniques to manage privacy for each which
may be combined to protect the entire address. In the case where a may be combined to protect the entire address. In the case where a
network administrator wishes to fully isolate the internal IPv6 network administrator wishes to fully isolate the internal IPv6
topology, and the majority of its internal use addresses, one option topology, and the majority of its internal use addresses, one option
is to run all internal traffic using Unique Local Addresses (ULA). is to run all internal traffic using Unique Local Addresses (ULA).
By definition this prefix block is not to be advertised into the By definition this prefix block is not to be advertised into the
public routing system, so without a routing path external traffic public routing system, so without a routing path external traffic
will never reach the site. For the set of hosts that do in fact need will never reach the site. For the set of hosts that do in fact need
to interact externally, by using multiple IPv6 prefixes (ULAs and one to interact externally, by using multiple IPv6 prefixes (ULAs and one
or more global addresses) all of the internal nodes that do not need or more global addresses) all of the internal nodes that do not need
external connectivity, and the internally used addresses of those external connectivity, and the internally used addresses of those
that do will be masked from the outside. The policy table defined in that do will be masked from the outside. The policy table defined in
[10]provides a mechanism to bias the selection process when multiple [13]provides a mechanism to bias the selection process when multiple
prefixes are in use such that the ULA would be preferred when the prefixes are in use such that the ULA would be preferred when the
correspondent is also local. correspondent is also local.
There are other scenarios for the extreme situation when a network There are other scenarios for the extreme situation when a network
manager also wishes to fully conceal the internal IPv6 topology. In manager also wishes to fully conceal the internal IPv6 topology. In
these cases the goal in replacing the IPv4 NAT approach is to make these cases the goal in replacing the IPv4 NAT approach is to make
all of the topology hidden nodes appear from the outside to logically all of the topology hidden nodes appear from the outside to logically
exist at the edge of the network, just as they would when behind a exist at the edge of the network, just as they would when behind a
NAT. NAT. This figure shows the relationship between the logical subnets
and the topology masking router discussed in the bullet points that
o One approach uses explicit host routes in the IGP to remove the follow.
external correlation between physical topology attachment point
and end-to-end IPv6 address. In the figure below the hosts would
be allocated prefixes from one or more logical subnets, and would
inject host routes to internally identify their real attachment
point. This solution does however show severe scalability issues
and requires hosts to securely participate in the IGP, as well as
having the firewall block all external to internal traceroute for
the logical subnet. The specific limitations are dependent on the
IGP protocol, the physical topology, and the stability of the
system. In any case the approach should be limited to uses with
substantially fewer than the maximum number of routes that the IGP
can support (generally between 5,000 and 50,000 total entries
including subnet routes). Hosts should also listen to the IGP for
duplicate use before finalizing an interface address assignment as
the duplicate address detection will only check for use on the
attached segment, not the logical subnet.
o Another technical approach to fully hide the internal topology is
use of a tunneling mechanism. Mobile IPv6 without route
optimization is one approach for using an automated tunnel, as it
always starts in tunnel mode via the Home Agent (HA). In this
deployment model the application perceived addresses of the nodes
are routed via the edge HA. This indirection method truly masks
the internal topology, as from outside the local network all nodes
with global access appear to share the prefix of one or more
logical subnets attached to the HA rather than their real
attachment point. Duplicate address detection is handled as a
normal process of the HA binding update. While turning off all
binding updates with the coorespondent node would appear to be
necessary to prevent leakage of topology information, that
approach would also force all internal traffic using the home
address to route via the HA tunnel, which may be undesirable. A
more efficient method would be to allow internal route
optimizations while dropping outbound binding update messages at
the firewall. Another approach for the internal traffic would be
to use the policy table of RFC 3484 to bias a ULA prefix as
preferred internally, leaving the logical subnet Home Address
external for use. The downsides with a Mobile IPv6 based solution
is that it requires a home agent in the network, the configuration
of a security association with the HA for each hidden node, and
consumes some amount of bandwidth for tunnel overhead.
o Another method (where the layer 2 topology allows) uses a virtual
lan approach to logically attach the devices to one or more
subnets on the edge router. This approach leads the end nodes to
believe they actually share a common segment. The downsides of
this approach is that all internal traffic would be directed over
sub-optimal paths via the edge router, as well as the complexity
of managing a distributed logical lan.
Internet Internet
| |
\ \
| |
+------------------+ +------------------+
| topology |-+-+-+-+-+-+-+-+-- | topology |-+-+-+-+-+-+-+-+--
| masking | Logical subnets | masking | Logical subnets
| router |-+-+-+-+-+-+-+-+-- | router |-+-+-+-+-+-+-+-+--
+------------------+ for topology +------------------+ for topology
| hidden nodes | hidden nodes
| |
Real internal -------------+- Real internal -------------+-
topology | | topology | |
| -+---------- | -+----------
-----------+--------+ -----------+--------+
| |
| |
| |
o One approach uses explicit host routes in the IGP to remove the
external correlation between physical topology attachment point
and end-to-end IPv6 address. In the figure above the hosts would
be allocated prefixes from one or more logical subnets, and would
inject host routes into the IGP to internally identify their real
attachment point. This solution does however show severe
scalability issues and requires hosts to securely participate in
the IGP, as well as having the firewall block all external to
internal traceroute for the logical subnet. The specific
limitations are dependent on the IGP protocol, the physical
topology, and the stability of the system. In any case the
approach should be limited to uses with substantially fewer than
the maximum number of routes that the IGP can support (generally
between 5,000 and 50,000 total entries including subnet routes).
Hosts should also listen to the IGP for duplicate use before
finalizing an interface address assignment as the duplicate
address detection will only check for use on the attached segment,
not the logical subnet.
o Another technical approach to fully hide the internal topology is
use of a tunneling mechanism. Mobile IPv6 without route
optimization is one approach for using an automated tunnel, as it
always starts in tunnel mode via the Home Agent (HA). In this
deployment model the application perceived addresses of the nodes
are routed via the edge HA acting as the topology masking router
(above). This indirection method truly masks the internal
topology, as from outside the local network all nodes with global
access appear to share the prefix of one or more logical subnets
attached to the HA rather than their real attachment point. Note
that in this usage context the HA is replacing the NAT function at
the edge of the network, so concerns about additional latency for
routing through a tunnel to the HA do not apply because it is
effectively on the same path that the NAT traffic would have
taken. Duplicate address detection is handled as a normal process
of the HA binding update. While turning off all binding updates
with the coorespondent node would appear to be necessary to
prevent leakage of topology information, that approach would also
force all internal traffic using the home address to route via the
HA tunnel, which may be undesirable. A more efficient method
would be to allow internal route optimizations while dropping
outbound binding update messages at the firewall. Another
approach for the internal traffic would be to use the policy table
of RFC 3484 to bias a ULA prefix as preferred internally, leaving
the logical subnet Home Address external for use. The downsides
with a Mobile IPv6 based solution is that it requires a home agent
in the network, the configuration of a security association with
the HA for each hidden node, and consumes some amount of bandwidth
for tunnel overhead.
o Another method (where the layer 2 topology allows) uses a virtual
lan approach to logically attach the devices to one or more
subnets on the edge router. This approach leads the end nodes to
believe they actually share a common segment. The downsides of
this approach is that all internal traffic would be directed over
sub-optimal paths via the edge router, as well as the complexity
of managing a distributed logical lan.
One issue to be aware of is that subnet scope multicast will not work One issue to be aware of is that subnet scope multicast will not work
for the logical hidden subnets, except in the vlan case. While a for the logical hidden subnets, except in the vlan case. While a
limited scope multicast to a collection of nodes that are arbitrarily limited scope multicast to a collection of nodes that are arbitrarily
scattered makes no technical sense, care should be exercised to avoid scattered makes no technical sense, care should be exercised to avoid
deploying applications that expect limited scope multicast in deploying applications that expect limited scope multicast in
conjunction with topology hiding. conjunction with topology hiding.
Another issue that this document will not define is the mechanism for Another issue that this document will not define is the mechanism for
a topology hidden node to learn its logical subnet. While manual a topology hidden node to learn its logical subnet. While manual
configuration would clearly be sufficient, DHCP could be used for configuration would clearly be sufficient, DHCP could be used for
address assignment, with the recipient node discovering it is in a address assignment, with the recipient node discovering it is in a
hidden mode when the attached subnet prefix doesn't match the one hidden mode when the attached subnet prefix doesn't match the one
assigned. assigned.
4.5. Independent Control of Addressing in a Private Network 4.5 Independent Control of Addressing in a Private Network
IPv6 provides for autonomy in local use addresses through ULAs. At IPv6 provides for autonomy in local use addresses through ULAs. At
the same time IPv6 simplifies simultaneous use of multiple addresses the same time IPv6 simplifies simultaneous use of multiple addresses
per interface so that an IPv6 NAT is not required between the ULA and per interface so that an IPv6 NAT is not required between the ULA and
the public Internet because nodes that need access to the public the public Internet because nodes that need access to the public
Internet will have a global use address as well. When using IPv6, Internet will have a global use address as well. When using IPv6,
the need to ask for more address space will become far less likely the need to ask for more address space will become far less likely
due to the increased size of the subnets, along with an allocation due to the increased size of the subnets, along with an allocation
policy that recognizes table fragmentation is also an important policy that recognizes table fragmentation is also an important
consideration. While global IPv6 allocation policy is managed consideration. While global IPv6 allocation policy is managed
through the Regional Internet Registries, it is expected that they through the Regional Internet Registries, it is expected that they
will continue with derivatives of [8] for the foreseeable future so will continue with derivatives of [10]for the foreseeable future so
the number of subnet prefixes available to an organization should not the number of subnet prefixes available to an organization should not
be a limitation which would create an artificial demand for NAT. be a limitation which would create an artificial demand for NAT.
Ongoing subnet address maintenance may become simpler when IPv6 Ongoing subnet address maintenance may become simpler when IPv6
technology is utilized. Under IPv4 address space policy restrictions technology is utilized. Under IPv4 address space policy restrictions
each subnet must be optimized, so one has to look periodically into each subnet must be optimized, so one has to look periodically into
the number of hosts on a segment and the subnet size allocated to the the number of hosts on a segment and the subnet size allocated to the
segment and rebalance. For example an enterprise today may have a segment and rebalance. For example an enterprise today may have a
mix of IPv4 /28 - /23 size subnets, and may shrink/grow these as mix of IPv4 /28 - /23 size subnets, and may shrink/grow these as
their network user base changes. For IPv6 all subnets have /64 their network user base changes. For IPv6 all subnets have /64
prefixes which will reduce the operational and configuration prefixes which will reduce the operational and configuration
overhead. overhead.
4.6. Global Address Pool Conservation 4.6 Global Address Pool Conservation
IPv6 provides sufficient space to completely avoid the need for IPv6 provides sufficient space to completely avoid the need for
overlapping address space. Since allocations in IPv6 are based on overlapping address space. Since allocations in IPv6 are based on
subnets rather than hosts a reasonable way to look at the pool is subnets rather than hosts a reasonable way to look at the pool is
that there are about 17*10^18 unique subnet values where sparse that there are about 17*10^18 unique subnet values where sparse
allocation practice within those provides for new opportunities such allocation practice within those provides for new opportunities such
as SEND 3971 [13]. As previously discussed, the serious as SEND 3971 [17]. As previously discussed, the serious
disadvantages of ambiguous address space have been well documented, disadvantages of ambiguous address space have been well documented,
and with sufficient space there is no need to continue the and with sufficient space there is no need to continue the
increasingly aggressive conservation practices that are necessary increasingly aggressive conservation practices that are necessary
with IPv4. While IPv6 allocation policies and ISP business practice with IPv4. While IPv6 allocation policies and ISP business practice
will continue to evolve, the recommendations in RFC 3177 are based on will continue to evolve, the recommendations in RFC 3177 are based on
the technical potential of the vast IPv6 address space. That the technical potential of the vast IPv6 address space. That
document demonstrates that there is no resource limitation which will document demonstrates that there is no resource limitation which will
require the adoption of the IPv4 workaround of ambiguous space behind require the adoption of the IPv4 workaround of ambiguous space behind
a NAT. As an example of the direct contrast, many expansion oriented a NAT. As an example of the direct contrast, many expansion oriented
IPv6 deployment scenarios result in multiple IPv6 addresses per IPv6 deployment scenarios result in multiple IPv6 addresses per
device, as opposed to the constriction of IPv4 scenarios where device, as opposed to the constriction of IPv4 scenarios where
multiple devices are forced to share a scarce global address through multiple devices are forced to share a scarce global address through
a NAT. a NAT.
4.7. Multihoming and Renumbering 4.7 Multihoming and Renumbering
IPv6 was designed to allow sites and hosts to run with several IPv6 was designed to allow sites and hosts to run with several
simultaneous CIDR allocated prefixes, and thus with several simultaneous CIDR allocated prefixes, and thus with several
simultaneous ISPs. An address selection mechanism [10] is specified simultaneous ISPs. An address selection mechanism [13]is specified
so that hosts will behave consistently when several addresses are so that hosts will behave consistently when several addresses are
simultaneously valid. The fundamental difficulty that IPv4 has in simultaneously valid. The fundamental difficulty that IPv4 has in
regard to multiple addresses therefore does not apply to IPv6. IPv6 regard to multiple addresses therefore does not apply to IPv6. IPv6
sites can and do run today with multiple ISPs active, and the sites can and do run today with multiple ISPs active, and the
processes for adding, removing, and renumbering active prefixes at a processes for adding, removing, and renumbering active prefixes at a
site have been documented in [14] and [21]. However, multihoming and site have been documented in [18]and [22]. However, multihoming and
renumbering remain technically challenging even with IPv6 with renumbering remain technically challenging even with IPv6 with
regards to, for instance, session continuity across multihoming regards to session continuity across multihoming events or
events or interactions with ingress filtering (but see the Gap interactions with ingress filtering (see the Gap Analysis below).
Analysis below).
The IPv6 address space allocated by the ISP will be dependent upon The IPv6 address space allocated by the ISP will be dependent upon
the connecting Service provider. This will likely result in a the connecting Service provider. This will likely result in a
renumbering effort when the network changes between service renumbering effort when the network changes between service
providers. When changing ISPs or ISPs readjusting their addressing providers. When changing ISPs or ISPs readjusting their addressing
pool, DHCP-PD [11] can be used as an almost zero- touch external pool, DHCP-PD [14]can be used as an almost zero- touch external
mechanism for prefix change in conjunction with a ULA prefix for mechanism for prefix change in conjunction with a ULA prefix for
internal connection stability. With appropriate management of the internal connection stability. With appropriate management of the
lifetime values and overlap of the external prefixes, a smooth make- lifetime values and overlap of the external prefixes, a smooth make-
before-break transition is possible as existing communications will before-break transition is possible as existing communications will
continue on the old prefix as long as it remains valid, while any new continue on the old prefix as long as it remains valid, while any new
communications will use the new prefix. communications will use the new prefix.
5. Case Studies 5 Case Studies
In presenting these case studies we have chosen to consider In presenting these case studies we have chosen to consider
categories of network divided first according to their function categories of network divided first according to their function
either as carrier/ISP networks or end user (such as enterprise) either as carrier/ISP networks or end user (such as enterprise)
networks with the latter category broken down according to the number networks with the latter category broken down according to the number
of connected end hosts. For each category of networks we can use of connected end hosts. For each category of networks we can use
IPv6 Network Architecture Protection to achieve a secure and flexible IPv6 Network Architecture Protection to achieve a secure and flexible
infrastructure, which provides an enhanced network functionality in infrastructure, which provides an enhanced network functionality in
comparison with the usage of address translation. comparison with the usage of address translation.
o Medium/Large Private Networks (typically >10 connections) o Medium/Large Private Networks (typically >10 connections)
o Small Private Networks (typically 1 to 10 connections) o Small Private Networks (typically 1 to 10 connections)
o Single User Connection (typically 1 connection) o Single User Connection (typically 1 connection)
o ISP/Carrier Customer Networks o ISP/Carrier Customer Networks
5.1. Medium/large private networks 5.1 Medium/large private networks
The majority of private enterprise, academic, research, or government The majority of private enterprise, academic, research, or government
networks fall into this category. Many of these networks have one or networks fall into this category. Many of these networks have one or
more exit points to the Internet. Though these organizations have more exit points to the Internet. Though these organizations have
sufficient resources to acquire addressing independence when using sufficient resources to acquire addressing independence when using
IPv4 there are several reasons why they might choose to use NAT in IPv4 there are several reasons why they might choose to use NAT in
such a network. For the ISP there is no need to import the IPv4 such a network. For the ISP there is no need to import the IPv4
address range from the remote end-customer, which facilitates IPv4 address range from the remote end-customer, which facilitates IPv4
route summarization. The customer can use a larger IPv4 address route summarization. The customer can use a larger IPv4 address
range (probably with less-administrative overhead) by the use of RFC range (probably with less-administrative overhead) by the use of RFC
skipping to change at page 24, line 46 skipping to change at page 25, line 20
access between local and external hosts to those local hosts being access between local and external hosts to those local hosts being
authorized for this capability. authorized for this capability.
The use of permanent ULA addresses on a site provides the benefit The use of permanent ULA addresses on a site provides the benefit
that even if an enterprise would change its ISP, the renumbering will that even if an enterprise would change its ISP, the renumbering will
only affect those devices that have a wish to connect beyond the only affect those devices that have a wish to connect beyond the
site. Internal servers and services would not change their allocated site. Internal servers and services would not change their allocated
IPv6 ULA address, and the service would remain available even during IPv6 ULA address, and the service would remain available even during
global address renumbering. global address renumbering.
5.2. Small Private Networks 5.2 Small Private Networks
Also known as SOHO (Small Office/Home Office) networks, this category Also known as SOHO (Small Office/Home Office) networks, this category
describes those networks which have few routers in the topology, and describes those networks which have few routers in the topology, and
usually have a single network egress point. Typically these networks usually have a single network egress point. Typically these networks
are: are:
o connected via either a dial-up connection or broadband access o connected via either a dial-up connection or broadband access
o don't have dedicated Network Operation Center (NOC) o don't have dedicated Network Operation Center (NOC)
o and through economic pressure are typically forced today to use o and through economic pressure are typically forced today to use
NAT NAT
skipping to change at page 26, line 28 skipping to change at page 27, line 5
with IPv4 to provide RFC 1918 addresses, in this environment the ISP with IPv4 to provide RFC 1918 addresses, in this environment the ISP
will not be motivated to allocate private addresses towards the will not be motivated to allocate private addresses towards the
single user connection because there are enough global addresses single user connection because there are enough global addresses
available at essentially the same cost. Also it will be likely that available at essentially the same cost. Also it will be likely that
the single device wants to mask its identity to the called party or the single device wants to mask its identity to the called party or
its attack profile over a shorter time window than the life of the its attack profile over a shorter time window than the life of the
ISP attachment, so it will need to enable IPv6 privacy extensions ISP attachment, so it will need to enable IPv6 privacy extensions
which in turn leads to the need for a minimum allocation of a /64 which in turn leads to the need for a minimum allocation of a /64
prefix rather than a single address. prefix rather than a single address.
5.3. Single User Connection 5.3 Single User Connection
This group identifies the users which are connected via a single IPv4 This group identifies the users which are connected via a single IPv4
address and use a single piece of equipment (PC, PDA, etc.). This address and use a single piece of equipment (PC, PDA, etc.). This
user may get an ambiguous IPv4 address (frequently imposed by the user may get an ambiguous IPv4 address (frequently imposed by the
ISP) from the service provider which is based on RFC 1918. If ISP) from the service provider which is based on RFC 1918. If
ambiguous addressing is utilized, the service provider will execute ambiguous addressing is utilized, the service provider will execute
NAT on the allocated IPv4 address for global Internet connectivity. NAT on the allocated IPv4 address for global Internet connectivity.
This also limits the Internet capability of the equipment to being This also limits the Internet capability of the equipment to being
mainly a receiver of Internet data, and makes it quite hard for the mainly a receiver of Internet data, and makes it quite hard for the
equipment to become a world wide Internet server (i.e. HTTP, FTP, equipment to become a world wide Internet server (i.e. HTTP, FTP,
skipping to change at page 27, line 5 skipping to change at page 27, line 30
equipment (PC, PDA, etc.). equipment (PC, PDA, etc.).
In IPv6 world the assumption is that there is unrestricted In IPv6 world the assumption is that there is unrestricted
availability of a large amount of globally routable and unique IPv6 availability of a large amount of globally routable and unique IPv6
addresses. The ISP will not be motivated to allocate private addresses. The ISP will not be motivated to allocate private
addresses towards the single user connection because he has enough addresses towards the single user connection because he has enough
global addresses available, if scarcity was the motivation with IPv4 global addresses available, if scarcity was the motivation with IPv4
to provide RFC 1918 addresses. If the single user wants to mask his to provide RFC 1918 addresses. If the single user wants to mask his
identity, he may choose to enable IPv6 privacy extensions. identity, he may choose to enable IPv6 privacy extensions.
5.4. ISP/Carrier Customer Networks 5.4 ISP/Carrier Customer Networks
This group refers to the actual service providers that are providing This group refers to the actual service providers that are providing
the IP access and transport services. They tend to have three the IP access and transport services. They tend to have three
separate IP domains that they support: separate IP domains that they support:
o For the first they fall into the Medium/large private networks o For the first they fall into the Medium/large private networks
category (above) for their own internal networks, LANs etc. category (above) for their own internal networks, LANs etc.
o The second is the Operations network which addresses their o The second is the Operations network which addresses their
backbone and access switches, and other hardware, this is separate backbone and access switches, and other hardware, this is separate
for both engineering reasons as well as simplicity in managing the for both engineering reasons as well as simplicity in managing the
security of the backbone. security of the backbone.
skipping to change at page 27, line 45 skipping to change at page 28, line 21
be consistent with the DNS PTR records. As scarcity of IPv6 be consistent with the DNS PTR records. As scarcity of IPv6
addresses is not a concern, it will be possible for the ISP to addresses is not a concern, it will be possible for the ISP to
provide global routable IPv6 prefixes without a requirement for provide global routable IPv6 prefixes without a requirement for
address translation. An ISP may for commercial reasons still decide address translation. An ISP may for commercial reasons still decide
to restrict the capabilities of the end users by other means like to restrict the capabilities of the end users by other means like
traffic and/or route filtering etc. traffic and/or route filtering etc.
If the carrier network is a mobile provider, then IPv6 is encouraged If the carrier network is a mobile provider, then IPv6 is encouraged
in comparison with the combination of IPv4+NAT for 3GPP attached in comparison with the combination of IPv4+NAT for 3GPP attached
devices. When looking in chapter 2.3 of RFC3314 'Recommendations for devices. When looking in chapter 2.3 of RFC3314 'Recommendations for
IPv6 in 3GPP Standards' [17]it is found that the IPv6 WG recommends IPv6 in 3GPP Standards' [11]it is found that the IPv6 WG recommends
that one or more /64 prefixes should be assigned to each primary PDP that one or more /64 prefixes should be assigned to each primary PDP
context. This will allow sufficient address space for a 3GPP- context. This will allow sufficient address space for a 3GPP-
attached node to allocate privacy addresses and/or route to a multi- attached node to allocate privacy addresses and/or route to a multi-
link subnet, and will discourage the use of NAT within 3GPP-attached link subnet, and will discourage the use of NAT within 3GPP-attached
devices. devices.
6. IPv6 Gap Analysis 6 IPv6 Gap Analysis
Like IPv4 and any major standards effort, IPv6 standardization work Like IPv4 and any major standards effort, IPv6 standardization work
continues as deployments are ongoing. This section discusses several continues as deployments are ongoing. This section discusses several
topics for which additional standardization, or documentation of best topics for which additional standardization, or documentation of best
practice, is required to fully realize the benefits of NAP6. None of practice, is required to fully realize the benefits or provide
these items are show-stoppers for immediate usage of NAP6 in optimizations when deploying NAP6. From a standardization
scenarios where there are no current gaps. perspective there is no obstacle to immediate deployment of the NAP6
approach in many scenarios, though product implimentations may lag
the standardization efforts. That said, the list below identifies
additional work that should be undertaken to cover the missing
scenarios.
6.1. Simple Security 6.1 Simple Security
Firewall traversal by dynamic pinhole management requires further Firewall traversal by dynamic pinhole management requires further
study. Several partial solutions exist including ICE [23], UPNP study. Several partial solutions exist including ICE [24], UPNP
[24], as well as alternative proposals for Service Provider based [25]. Alternative approaches are looking to define service provider
control. The basic security provided by a stateful firewall will mediated pinhole management, where things like voice call signaling
require some degree of default configuration and automation to mask could dynamically establish pinholes based on predefined
the technical complexity from a consumer who merely wants a secure authentication rules. The basic security provided by a stateful
environment with working applications. There is no reason a stateful firewall will require some degree of default configuration and
IPv6 firewall product cannot be shipped with the equivalent default automation to mask the technical complexity from a consumer who
protection that is offered by today's IPv4/NAT products. merely wants a secure environment with working applications. There
is no reason a stateful IPv6 firewall product cannot be shipped with
default protection that is equal to or better than that offered by
today's IPv4/NAT products.
6.2. Subnet Topology Masking 6.2 Subnet Topology Masking
There really is no functional gap here as a centrally assigned pool There really is no functional standards gap here as a centrally
of addresses in combination with host routes in the IGP is an assigned pool of addresses in combination with host routes in the IGP
effective way to mask topology for smaller deployments. If necessary is an effective way to mask topology for smaller deployments. If
a best practice document could be developed describing the necessary a best practice document could be developed describing the
interaction between DHCP and various IGPs which would in effect interaction between DHCP and various IGPs which would in effect
define Untraceable Addresses. define Untraceable Addresses.
As an alternative for larger deployments, there is no gap in the HA As an alternative for larger deployments, there is no gap in the HA
tunneling approach when firewalls are configured to block outbound tunneling approach when firewalls are configured to block outbound
binding update messages. A border Home Agent using internal binding update messages. A border Home Agent using internal
tunneling to the logical mobile node (potentially rack mounted) can tunneling to the logical mobile (potentially rack mounted) node can
completely mask all internal topology, while avoiding the strain from completely mask all internal topology, while avoiding the strain from
a large number of host routes in the IGP. Some optimization work a large number of host routes in the IGP. Some optimization work
could be done in Mobile IP to define a policy message where a mobile could be done in Mobile IP to define a policy message where a mobile
node would learn from the Home Agent that it should not try to inform node would learn from the Home Agent that it should not try to inform
its correspondent about route optimization and thereby expose its its correspondent about route optimization and thereby expose its
real location. This optimization which reduces the load on the real location. This optimization, which reduces the load on the
firewall would result in less optimal internal traffic routing as firewall, would result in less optimal internal traffic routing as
that would also transit the HA. Trade-off's for this optimization that would also transit the HA unless ULAs were used internally.
work should be investigated in the IETF. Trade-off's for this optimization work should be investigated in the
IETF.
6.3. Minimal Traceability of Privacy Addresses 6.3 Minimal Traceability of Privacy Addresses
Privacy addresses [7] may certainly be used to limit the traceability Privacy addresses [9]may certainly be used to limit the traceability
of external traffic flows back to specific hosts, but lacking a of external traffic flows back to specific hosts, but lacking a
topology masking component above they would still reveal the subnet topology masking component above they would still reveal the subnet
address bits. For complete privacy a best practice document address bits. For complete privacy a best practice document
describing the combination of privacy addresses with topology masking describing the combination of privacy addresses with topology masking
may be required. This work remains to be done, and should be pursued may be required. This work remains to be done, and should be pursued
by the IETF. by the IETF.
6.4. Site Multihoming 6.4 Site Multihoming
This complex problem has never been completely solved for IPv4, which This complex problem has never been completely solved for IPv4, which
is exactly why NAT has been used as a partial solution. For IPv6, is exactly why NAT has been used as a partial solution. For IPv6,
after several years of work, the IETF has converged on an after several years of work, the IETF has converged on an
architectural approach intended with service restoration as initial architectural approach intended with service restoration as initial
aim [22]. When this document was drafted, the IETF was actively aim [23]. When this document was drafted, the IETF was actively
defining the details of this approach to the multihoming problem. defining the details of this approach to the multihoming problem.
The approach appears to be most suitable for small and medium sites, The approach appears to be most suitable for small and medium sites,
though it will conflict with existing firewall state procedures. At though it will conflict with existing firewall state procedures. At
this time there are also active discussions in the address registries this time there are also active discussions in the address registries
investigating the possibility of assigning provider-independent investigating the possibility of assigning provider-independent
address space. Their challenge is finding a reasonable metric for address space. Their challenge is finding a reasonable metric for
limiting the number of organizations that would qualify for a global limiting the number of organizations that would qualify for a global
routing entry. Additional work appears to be necessary to satisfy routing entry. Additional work appears to be necessary to satisfy
the entire range of requirements. the entire range of requirements.
7. IANA Considerations 7 IANA Considerations
This document requests no action by IANA This document requests no action by IANA
8. Security Considerations 8 Security Considerations
While issues which are potentially security related are discussed While issues which are potentially security related are discussed
throughout the document, the approaches herein do not introduce any throughout the document, the approaches herein do not introduce any
new security concerns. Product marketing departments have widely new security concerns. Product marketing departments have widely
sold IPv4 NAT as a security tool and suppliers have been implementing sold IPv4 NAT as a security tool and suppliers have been implementing
address translation functionality in their firewalls, though the address translation functionality in their firewalls, though the
misleading nature of those claims has been previously documented in misleading nature of those claims has been previously documented in
[2] and [4]. [4]and [6].
This document defines IPv6 approaches which collectively achieve the This document defines IPv6 approaches which collectively achieve the
goals of the network manager without the negative impact on goals of the network manager without the negative impact on
applications or security that are inherent in a NAT approach. To the applications or security that are inherent in a NAT approach. While
degree that these techniques improve a network manager's ability to section 6 identifies additional optimization work, to the degree that
explicitly audit or control access, and thereby manage the overall these techniques improve a network manager's ability to explicitly
attack exposure of local resources, they act to improve local network audit or control access, and thereby manage the overall attack
exposure of local resources, they act to improve local network
security. security.
9. Conclusion 9 Conclusion
This document has described a number of techniques that may be This document has described a number of techniques that may be
combined on an IPv6 site to protect the integrity of its network combined on an IPv6 site to protect the integrity of its network
architecture. These techniques, known collectively as Network architecture. These techniques, known collectively as Network
Architecture Protection, retain the concept of a well defined Architecture Protection, retain the concept of a well defined
boundary between "inside" and "outside" the private network, and boundary between "inside" and "outside" the private network, and
allow firewalling, topology hiding, and privacy. However, because allow firewalling, topology hiding, and privacy. However, because
they preserve address transparency where it is needed, they achieve they preserve address transparency where it is needed, they achieve
these goals without the disadvantage of address translation. Thus, these goals without the disadvantage of address translation. Thus,
Network Architecture Protection in IPv6 can provide the benefits of Network Architecture Protection in IPv6 can provide the benefits of
IPv4 Network Address Translation without the corresponding IPv4 Network Address Translation without the corresponding
disadvantages. disadvantages.
The document has also identified a few ongoing IETF work items that The document has also identified a few ongoing IETF work items that
are needed to realize 100% of the benefits of NAP6. are needed to realize 100% of the benefits of NAP6.
10. Acknowledgements 10 Acknowledgements
Christian Huitema has contributed during the initial round table to Christian Huitema has contributed during the initial round table to
discuss the scope and goal of the document, while the European Union discuss the scope and goal of the document, while the European Union
IST 6NET project acted as a catalyst for the work documented in this IST 6NET project acted as a catalyst for the work documented in this
note. Editorial comments and contributions have been received from: note. Editorial comments and contributions have been received from:
Fred Templin, Chao Luo, Pekka Savola, Tim Chown, Jeroen Massar, Fred Templin, Chao Luo, Pekka Savola, Tim Chown, Jeroen Massar,
Salman Asadullah, Patrick Grossetete, Fred Baker, Jim Bound, Mark Salman Asadullah, Patrick Grossetete, Fred Baker, Jim Bound, Mark
Smith, Alain Durand, John Spence, Christian Huitema, Mark Smith, Smith, Alain Durand, John Spence, Christian Huitema, Mark Smith,
Elwyn Davies, Daniel Senie, Soininen Jonne, Lindqvist Erik Kurt and Elwyn Davies, Daniel Senie, Soininen Jonne, Lindqvist Erik Kurt and
other members of the v6ops WG. other members of the v6ops WG.
[1]
11. References 11. References
11.1. Normative References 11.1. Normative References
[1] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and E. [1] Bradner, S., "IETF Rights in Contributions", BCP 78, RFC 3978,
March 2005.
11.2. Informative References
[2] Fuller, V., Li, T., Yu, J., and K. Varadhan, "Classless Inter-
Domain Routing (CIDR): an Address Assignment and Aggregation
Strategy", RFC 1519, September 1993.
[3] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and E.
Lear, "Address Allocation for Private Internets", BCP 5, Lear, "Address Allocation for Private Internets", BCP 5,
RFC 1918, February 1996. RFC 1918, February 1996.
[2] Srisuresh, P. and M. Holdrege, "IP Network Address Translator [4] Srisuresh, P. and M. Holdrege, "IP Network Address Translator
(NAT) Terminology and Considerations", RFC 2663, August 1999. (NAT) Terminology and Considerations", RFC 2663, August 1999.
[3] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery [5] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery
for IP Version 6 (IPv6)", RFC 2461, December 1998. for IP Version 6 (IPv6)", RFC 2461, December 1998.
[4] Hain, T., "Architectural Implications of NAT", RFC 2993, [6] Hain, T., "Architectural Implications of NAT", RFC 2993,
November 2000. November 2000.
[5] Srisuresh, P. and K. Egevang, "Traditional IP Network Address [7] Srisuresh, P. and K. Egevang, "Traditional IP Network Address
Translator (Traditional NAT)", RFC 3022, January 2001. Translator (Traditional NAT)", RFC 3022, January 2001.
[6] Holdrege, M. and P. Srisuresh, "Protocol Complications with the [8] Holdrege, M. and P. Srisuresh, "Protocol Complications with the
IP Network Address Translator", RFC 3027, January 2001. IP Network Address Translator", RFC 3027, January 2001.
[7] Narten, T. and R. Draves, "Privacy Extensions for Stateless [9] Narten, T. and R. Draves, "Privacy Extensions for Stateless
Address Autoconfiguration in IPv6", RFC 3041, January 2001. Address Autoconfiguration in IPv6", RFC 3041, January 2001.
[8] IAB and IESG, "IAB/IESG Recommendations on IPv6 Address [10] IAB and IESG, "IAB/IESG Recommendations on IPv6 Address
Allocations to Sites", RFC 3177, September 2001. Allocations to Sites", RFC 3177, September 2001.
[9] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. [11] Wasserman, M., "Recommendations for IPv6 in Third Generation
Partnership Project (3GPP) Standards", RFC 3314,
September 2002.
[12] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M.
Carney, "Dynamic Host Configuration Protocol for IPv6 Carney, "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003. (DHCPv6)", RFC 3315, July 2003.
[10] Draves, R., "Default Address Selection for Internet Protocol [13] Draves, R., "Default Address Selection for Internet Protocol
version 6 (IPv6)", RFC 3484, February 2003. version 6 (IPv6)", RFC 3484, February 2003.
[11] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host [14] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host
Configuration Protocol (DHCP) version 6", RFC 3633, Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003. December 2003.
[12] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M. [15] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.
Stenberg, "UDP Encapsulation of IPsec ESP Packets", RFC 3948, Stenberg, "UDP Encapsulation of IPsec ESP Packets", RFC 3948,
January 2005. January 2005.
[13] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure [16] Savola, P. and B. Haberman, "Embedding the Rendezvous Point
(RP) Address in an IPv6 Multicast Address", RFC 3956,
November 2004.
[17] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005. Neighbor Discovery (SEND)", RFC 3971, March 2005.
[14] Baker, F., Lear, E., and R. Droms, "Procedures for Renumbering [18] Baker, F., Lear, E., and R. Droms, "Procedures for Renumbering
an IPv6 Network without a Flag Day", RFC 4192, September 2005. an IPv6 Network without a Flag Day", RFC 4192, September 2005.
[15] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast [19] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005. Addresses", RFC 4193, October 2005.
11.2. Informative References [20] Dupont, F. and P. Savola, "RFC 3041 Considered Harmful
[16] Fuller, V., Li, T., Yu, J., and K. Varadhan, "Classless Inter-
Domain Routing (CIDR): an Address Assignment and Aggregation
Strategy", RFC 1519, September 1993.
[17] Wasserman, M., "Recommendations for IPv6 in Third Generation
Partnership Project (3GPP) Standards", RFC 3314,
September 2002.
[18] Savola, P. and B. Haberman, "Embedding the Rendezvous Point
(RP) Address in an IPv6 Multicast Address", RFC 3956,
November 2004.
[19] Dupont, F. and P. Savola, "RFC 3041 Considered Harmful
(draft-dupont-ipv6-rfc3041harmful-05.txt)", June 2004. (draft-dupont-ipv6-rfc3041harmful-05.txt)", June 2004.
[20] Chown, T., "IPv6 Implications for TCP/UDP Port Scanning (chown- [21] Chown, T., "IPv6 Implications for TCP/UDP Port Scanning (chown-
v6ops-port-scanning-implications-01.txt)", July 2004. v6ops-port-scanning-implications-01.txt)", July 2004.
[21] Chown, T., Tompson, M., Ford, A., and S. Venaas, "Things to [22] Chown, T., Tompson, M., Ford, A., and S. Venaas, "Things to
think about when Renumbering an IPv6 network think about when Renumbering an IPv6 network
(draft-chown-v6ops-renumber-thinkabout-03)", October 2004. (draft-chown-v6ops-renumber-thinkabout-03)", October 2004.
[22] Huston, G., "Architectural Commentary on Site Multi-homing [23] Huston, G., "Architectural Commentary on Site Multi-homing
using a Level 3 Shim (draft-ietf-shim6-arch-00.txt)", using a Level 3 Shim (draft-ietf-shim6-arch-00.txt)",
July 2004. July 2004.
[23] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A [24] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A
Methodology for Network Address Translator (NAT) Traversal for Methodology for Network Address Translator (NAT) Traversal for
Offer/Answer Protocols (draft-ietf-mmusic-ice-11)", Offer/Answer Protocols (draft-ietf-mmusic-ice-11)",
October 2006. October 2006.
[24] "UPNP Web Site, "Universal Plug and Play Web Site", Web Site [25] "UPNP Web Site, "Universal Plug and Play Web Site", Web Site
http://www.upnp.org/", July 2005. http://www.upnp.org/", July 2005.
Appendix A. Additional Benefits due to Native IPv6 and Universal Unique Appendix A Additional Benefits due to Native IPv6 and Universal Unique
Addressing Addressing
The users of native IPv6 technology and global unique IPv6 addresses The users of native IPv6 technology and global unique IPv6 addresses
have the potential to make use of the enhanced IPv6 capabilities, in have the potential to make use of the enhanced IPv6 capabilities, in
addition to the benefits offered by the IPv4 technology. addition to the benefits offered by the IPv4 technology.
A.1. Universal Any-to-Any Connectivity A.1 Universal Any-to-Any Connectivity
One of the original design points of the Internet was any-to-any One of the original design points of the Internet was any-to-any
connectivity. The dramatic growth of Internet connected systems connectivity. The dramatic growth of Internet connected systems
coupled with the limited address space of the IPv4 protocol spawned coupled with the limited address space of the IPv4 protocol spawned
address conservation techniques. NAT was introduced as a tool to address conservation techniques. NAT was introduced as a tool to
reduce demand on the limited IPv4 address pool, but the side effect reduce demand on the limited IPv4 address pool, but the side effect
of the NAT technology was to remove the any-to-any connectivity of the NAT technology was to remove the any-to-any connectivity
capability. By removing the need for address conservation (and capability. By removing the need for address conservation (and
therefore NAT), IPv6 returns the any-to-any connectivity model and therefore NAT), IPv6 returns the any-to-any connectivity model and
removes the limitations on application developers. With the freedom removes the limitations on application developers. With the freedom
skipping to change at page 33, line 11 skipping to change at page 34, line 5
applications, IPv6 embedded IPsec communication between two applications, IPv6 embedded IPsec communication between two
communicating devices, instant messaging, Internet telephony, etc..) communicating devices, instant messaging, Internet telephony, etc..)
rather than focusing on discovering and traversing the increasingly rather than focusing on discovering and traversing the increasingly
complex NAT environment. complex NAT environment.
It will also allow application and service developers to rethink the It will also allow application and service developers to rethink the
security model involved with any-to-any connectivity, as the current security model involved with any-to-any connectivity, as the current
edge firewall solution in IPv4 may not be sufficient for any- to-any edge firewall solution in IPv4 may not be sufficient for any- to-any
service models. service models.
A.2. Auto-configuration A.2 Auto-configuration
IPv6 offers a scalable approach to minimizing human interaction and IPv6 offers a scalable approach to minimizing human interaction and
device configuration. Whereas IPv4 implementations require touching device configuration. Whereas IPv4 implementations require touching
each end system to indicate the use of DHCP vs. a static address and each end system to indicate the use of DHCP vs. a static address and
management of a server with the pool size large enough for the management of a server with the pool size large enough for the
potential number of connected devices, IPv6 uses an indication from potential number of connected devices, IPv6 uses an indication from
the router to instruct the end systems to use DHCP or the stateless the router to instruct the end systems to use DHCP or the stateless
auto configuration approach supporting a virtually limitless number auto configuration approach supporting a virtually limitless number
of devices on the subnet. This minimizes the number of systems that of devices on the subnet. This minimizes the number of systems that
require human interaction as well as improves consistency between all require human interaction as well as improves consistency between all
the systems on a subnet. In the case that there is no router to the systems on a subnet. In the case that there is no router to
provide this indication, an address for use only on the local link provide this indication, an address for use only on the local link
will be derived from the interface media layer address. will be derived from the interface media layer address.
A.3. Native Multicast Services A.3 Native Multicast Services
Multicast services in IPv4 were severely restricted by the limited Multicast services in IPv4 were severely restricted by the limited
address space available to use for group assignments and an implicit address space available to use for group assignments and an implicit
locally defined range for group membership. IPv6 multicast corrects locally defined range for group membership. IPv6 multicast corrects
this situation by embedding explicit scope indications as well as this situation by embedding explicit scope indications as well as
expanding to 4 billion groups per scope. In the source specific expanding to 4 billion groups per scope. In the source specific
multicast case, this is further expanded to 4 billion groups per multicast case, this is further expanded to 4 billion groups per
scope per subnet by embedding the 64 bits of subnet identifier into scope per subnet by embedding the 64 bits of subnet identifier into
the multicast address. the multicast address.
IPv6 allows also for innovative usage of the IPv6 address length, and IPv6 allows also for innovative usage of the IPv6 address length, and
makes it possible to embed the multicast 'Rendezvous Point' (or RP) makes it possible to embed the multicast 'Rendezvous Point' (or RP)
[18] directly in the IPv6 multicast address when using ASM multicast. [16]directly in the IPv6 multicast address when using ASM multicast.
This is not possible with limited size of the IPv4 address. This This is not possible with limited size of the IPv4 address. This
approach also simplifies the multicast model considerably, making it approach also simplifies the multicast model considerably, making it
easier to understand and deploy. easier to understand and deploy.
A.4. Increased Security Protection A.4 Increased Security Protection
The security protection offered by native IPv6 technology is more The security protection offered by native IPv6 technology is more
advanced than IPv4 technology. There are various transport advanced than IPv4 technology. There are various transport
mechanisms enhanced to allow a network to operate more securely with mechanisms enhanced to allow a network to operate more securely with
less performance impact: less performance impact:
o IPv6 has the IPsec technology directly embedded into the IPv6 o IPv6 has the IPsec technology directly embedded into the IPv6
protocol. This allows for simpler peer-to-peer authentication and protocol. This allows for simpler peer-to-peer authentication and
encryption, once a simple key/trust management model is developed, encryption, once a simple key/trust management model is developed,
while the usage of some other less secure mechanisms is avoided while the usage of some other less secure mechanisms is avoided
(i.e. md5 password hash for neighbor authentication). (i.e. md5 password hash for neighbor authentication).
o On a local network, any user will have more security awareness. o While a firewall is specifically designed to disallow applicaions
This awareness will motivate the usage of simple firewall based on local policy, they do not interfere with those that are
applications/devices to be inserted on the border between the allowed. This is a security improvement over NAT, where the work-
external network and the local (or home network) as there is no arounds to enable applications allowed by local policy are
Address Translator and hence no false safety perception. effectively architected man-in-the-middle attacks on the packets
which precludes end-to-end auditing or IP level identification.
o All flows on the Internet will be better traceable due to a unique o All flows on the Internet will be better traceable due to a unique
and globally routable source and destination IPv6 address. This and globally routable source and destination IPv6 address. This
may facilitate an easier methodology for back-tracing DoS attacks may facilitate an easier methodology for back-tracing DoS attacks
and avoid illegal access to network resources by simpler traffic and avoid illegal access to network resources by simpler traffic
filtering. filtering.
o The usage of private address-space in IPv6 is now provided by o The usage of private address-space in IPv6 is now provided by
Unique Local Addresses, which will avoid conflict situations when Unique Local Addresses, which will avoid conflict situations when
merging networks and securing the internal communication on a merging networks and securing the internal communication on a
local network infrastructure due to simpler traffic filtering local network infrastructure due to simpler traffic filtering
policy. policy.
o The technology to enable source-routing on a network o The technology to enable source-routing on a network
infrastructure has been enhanced to allow this feature to infrastructure has been enhanced to allow this feature to
function, without impacting the processing power of intermediate function, without impacting the processing power of intermediate
network devices. The only devices impacted with the source- network devices. The only devices impacted with the source-
routing will be the source and destination node and the routing will be the source and destination node and the
intermediate source-routed nodes. This impact behavior is intermediate source-routed nodes. This impact behavior is
different if IPv4 is used, because then all intermediate devices different if IPv4 is used, because then all intermediate devices
would have had to look into the source- route header. would have had to look into the source- route header.
A.5. Mobility A.5 Mobility
Anytime, anywhere, universal access requires MIPv6 services in Anytime, anywhere, universal access requires MIPv6 services in
support of mobile nodes. While a Home Agent is required for initial support of mobile nodes. While a Home Agent is required for initial
connection establishment in either protocol version, IPv6 mobile connection establishment in either protocol version, IPv6 mobile
nodes are able to optimize the path between them using the MIPv6 nodes are able to optimize the path between them using the MIPv6
option header while IPv4 mobile nodes are required to triangle route option header while IPv4 mobile nodes are required to triangle route
all packets. In general terms this will minimize the network all packets. In general terms this will minimize the network
resources used and maximize the quality of the communication. resources used and maximize the quality of the communication.
A.6. Merging Networks A.6 Merging Networks
When two IPv4 networks want to merge it is not guaranteed that both When two IPv4 networks want to merge it is not guaranteed that both
networks would be using different address-ranges on some parts of the networks would be using different address-ranges on some parts of the
network infrastructure due to the usage of RFC 1918 private network infrastructure due to the usage of RFC 1918 private
addressing. This potential overlap in address space may complicate a addressing. This potential overlap in address space may complicate a
merge of two and more networks dramatically due to the additional merge of two and more networks dramatically due to the additional
IPv4 renumbering effort. i.e. when the first network has a service IPv4 renumbering effort. i.e. when the first network has a service
running (NTP, DNS, DHCP, HTTP, etc..) which need to be accessed by running (NTP, DNS, DHCP, HTTP, etc..) which need to be accessed by
the 2nd merging network. Similar address conflicts can happen when the 2nd merging network. Similar address conflicts can happen when
two network devices from these merging networks want to communicate. two network devices from these merging networks want to communicate.
With the usage of IPv6 the addressing overlap will not exist because With the usage of IPv6 the addressing overlap will not exist because
of the existence of the Unique Local Address usage for private and of the existence of the Unique Local Address usage for private and
local addressing. local addressing.
Appendix B. Revision history Appendix B Revision history
B.1. Changes from *-vandevelde-v6ops-nap-00 to B.1 Changes from *-vandevelde-v6ops-nap-00 to *-vandevelde-v6ops-nap-01
*-vandevelde-v6ops-nap-01
o Document introduction has been revised and overview table added o Document introduction has been revised and overview table added
o Comments and suggestions from nap-00 draft have been included. o Comments and suggestions from nap-00 draft have been included.
o Initial section of -00 draft 2.6 and 4.6 have been aggregated into o Initial section of -00 draft 2.6 and 4.6 have been aggregated into
a new case study section 5. a new case study section 5.
o The list of additional IPv6 benefits has been placed into o The list of additional IPv6 benefits has been placed into
appendix. appendix.
o new security considerations section added. o new security considerations section added.
o GAP analysis revised. o GAP analysis revised.
o Section 2.6 and 4.6 have been included. o Section 2.6 and 4.6 have been included.
B.2. Changes from *-vandevelde-v6ops-nap-01 to *-ietf-v6ops-nap-00 B.2 Changes from *-vandevelde-v6ops-nap-01 to *-ietf-v6ops-nap-00
o Change of Draft name from *-vandevelde-v6ops-nap-01.txt to *- o Change of Draft name from *-vandevelde-v6ops-nap-01.txt to *-
ietf-v6ops-nap-00.txt. ietf-v6ops-nap-00.txt.
o Editorial changes. o Editorial changes.
B.3. Changes from *-ietf-v6ops-nap-00 to *-ietf-v6ops-nap-01 B.3 Changes from *-ietf-v6ops-nap-00 to *-ietf-v6ops-nap-01
o Added text in Chapter 2.2 and 4.2 to address more details on o Added text in Chapter 2.2 and 4.2 to address more details on
firewall and proxy firewall and proxy
o Revised Eric Klein contact details o Revised Eric Klein contact details
o Added note in 4.2 that control over the proposed statefull-filter o Added note in 4.2 that control over the proposed statefull-filter
should be by a simple user-interface should be by a simple user-interface
B.4. Changes from *-ietf-v6ops-nap-01 to *-ietf-v6ops-nap-02 B.4 Changes from *-ietf-v6ops-nap-01 to *-ietf-v6ops-nap-02
o General Note: Header more consistent capitalized. o General Note: Header more consistent capitalized.
o Section 1: para 3: s/...and privacy and will... translation./ o Section 1: para 3: s/...and privacy and will... translation./
...and privacy. NAP will achieve these security goals without ...and privacy. NAP will achieve these security goals without
address translation whilst maintaining any-to-any connectivity./ address translation whilst maintaining any-to-any connectivity./
o Section 1: Various editorial changes happened o Section 1: Various editorial changes happened
o Section 2.1: Changed: 'Frequently a simple user interface is o Section 2.1: Changed: 'Frequently a simple user interface is
sufficient for configuring'. into 'Frequently a simple user sufficient for configuring'. into 'Frequently a simple user
interface, or no user interface is sufficient' interface, or no user interface is sufficient'
o Section 2.2: (Simple Security ) Better not to use the word -evil- o Section 2.2: (Simple Security ) Better not to use the word -evil-
in the text in the text
skipping to change at page 39, line 35 skipping to change at page 40, line 31
ULA specification is in the RFC-editor queue. ULA specification is in the RFC-editor queue.
o Section 6.3: (Minimal Traceability) Better to say "topology o Section 6.3: (Minimal Traceability) Better to say "topology
masking _may be_ required" instead of "is required", because masking _may be_ required" instead of "is required", because
whether this is needed or not is a value judgment. whether this is needed or not is a value judgment.
o Section 6.4: (Renumbering Procedure) Renumbering procedure is in o Section 6.4: (Renumbering Procedure) Renumbering procedure is in
RFC queue. The section corrected in the current state? RFC queue. The section corrected in the current state?
o Section 6.4: s/well solved/completely solved/ o Section 6.4: s/well solved/completely solved/
o In general the whole chapter 6 has been revised to reflect current o In general the whole chapter 6 has been revised to reflect current
status status
B.5. Changes from *-ietf-v6ops-nap-02 to *-ietf-v6ops-nap-03 B.5 Changes from *-ietf-v6ops-nap-02 to *-ietf-v6ops-nap-03
o Editorial changes in response to IESG review comments and o Editorial changes in response to IESG review comments and
questions. questions.
o Introduction: clarified impact & goal for limited additional NAT o Introduction: clarified impact & goal for limited additional NAT
discussion here / modified tone wrt marketing / grammar cleanup discussion here / modified tone wrt marketing / grammar cleanup
o Introduction: s/market acceptance/deployment o Introduction: s/market acceptance/deployment
o Introduction: noted that users do not evaluate technical trade- o Introduction: noted that users do not evaluate technical trade-
offs and that marketing does not mention the downside of address offs and that marketing does not mention the downside of address
translation translation
o Introduction: added paragraph about why nat != security o Introduction: added paragraph about why nat != security
o Table1: s/benefit/Goal/ s/ULA/4193/ removed long numeric string / o Table1: s/benefit/Goal/ s/ULA/4193/ removed long numeric string /
skipping to change at page 41, line 35 skipping to change at page 42, line 34
o Section 6.2: (topology mask) added comment about deployment scale o Section 6.2: (topology mask) added comment about deployment scale
/ added comment about firewall blocking BU / clarified point about / added comment about firewall blocking BU / clarified point about
future work being an optimization to reduce firewall load future work being an optimization to reduce firewall load
o Section 6.3: (tracability) grammar cleanup o Section 6.3: (tracability) grammar cleanup
o Section 6.4: (renumbering) Cut section since it is no longer a gap o Section 6.4: (renumbering) Cut section since it is no longer a gap
o Section A.2: word order - moved 'only' o Section A.2: word order - moved 'only'
o Section A.6: deleted 'legitimate' o Section A.6: deleted 'legitimate'
o Section A.7: clarified how NAP delivers community of interest o Section A.7: clarified how NAP delivers community of interest
o Spell check o Spell check
B.6. Changes from *-ietf-v6ops-nap-03 to *-ietf-v6ops-nap-04 B.6 Changes from *-ietf-v6ops-nap-03 to *-ietf-v6ops-nap-04
o Editorial changes in response to IESG review comments and o Editorial changes in response to IESG review comments and
questions, as well as I-D nits. questions, as well as I-D nits.
o Changed the abreviation to NAP6 and the title from 'IPv6 Network o Changed the abreviation to NAP6 and the title from 'IPv6 Network
Address Protection' to 'Network Architecture Protection for IPv6' Address Protection' to 'Network Architecture Protection for IPv6'
o Introduction s/in/with o Introduction s/in/with
o Introduction s/Indeed, product marketing departments have o Introduction s/Indeed, product marketing departments have
effectively driven a perception that some connectivity/ Indeed, it effectively driven a perception that some connectivity/ Indeed, it
is often claimed that some connectivity and .../ is often claimed that some connectivity and .../
o Section 2.1 s/[RFC 1918]/xref... o Section 2.1 s/[RFC 1918]/xref...
o Section 2.5 s/[RFC1918]/xref... o Section 2.5 s/[RFC1918]/xref...
skipping to change at page 43, line 5 skipping to change at page 43, line 47
o Section 4.4 added comment about how a topology hidden node learns o Section 4.4 added comment about how a topology hidden node learns
its home address its home address
o Section 4.7 Rephrased section based on J. Arkko suggestion o Section 4.7 Rephrased section based on J. Arkko suggestion
o Section 6. s/roles/scenarios/ o Section 6. s/roles/scenarios/
o Section 6.1 rewritten section o Section 6.1 rewritten section
o Section 6.4 s/with firewall/with existing firewall o Section 6.4 s/with firewall/with existing firewall
o Section 8. removed last line of section o Section 8. removed last line of section
o Section A.7 Removed section to address suggestion from Cullen J. o Section A.7 Removed section to address suggestion from Cullen J.
o Author details: modified Brian Carpenter's address details o Author details: modified Brian Carpenter's address details
B.7 Changes from *-ietf-v6ops-nap-04 to *-ietf-v6ops-nap-05
o Editorial changes in response to IESG review comments and
questions, as well as I-D nits.
o Abstract s/does not support NAT by design/was designed with the
intention of making NAT unnecessary
o Introduction s/people/network administrators
o Introduction s/preferred task/needs
o Introduction s/goals for utilizing/uses of
o Introduction added or a manual on how to configure a network
o Introduction reworded discussion about security policy goals
o Introduction s/need/expiration of state
o Introduction s/the need/The ability for nodes
o Introduction s/allow/while allowing
o Introduction s/"benefits"/benefits
o Introduction s/a complete/an optimal
o Section 2.1 s/be available/also be deployed
o Section 2.2 added comment about one-size-fits-all answer
o Section 2.2 added discussion about better-than-nothing protection
o Section 2.4 changed context from 'a user' to 'a system'
o Section 2.5 s/take benefit from using/make use of
o Section 2.5 reordered wording about 'Another benefit...'
o Section 3.2 reordered wording of bullet 3
o Section 4.1 moved 3484 policy table discussion earlier in the
paragraph
o Section 4.2 moved qualifier from IPv4 host to IPv6 host
o Section 4.2 clarification wording changes in bullet 2
o Section 4.2 added reference to bullet 3
o Section 4.2 s/example, a DSL/example a DSL or Cable Modem
o Section 4.2 moved discussion about SP dynamic pinhole management
to 6.1
o Section 4.4 moved 3041 reference earlier in section
o Section 4.4 added sentence explaining figure and moved figure
ahead of bulleted list
o Section 4.7 s/to, for instance,/to
o Section 6 clarification that the gaps apply to standards efforts
and products may lag
o Section 6.1 inserted discussion about SP dynamic pinhole
management from 4.2
o Section 6.2 s/no functional gap/no functional standards gap
o Section 6.2 s/HA./HA unless ULAs were used internally.
o Section 8 s/To/While section 6 identifies additional optimization
work, to
o Section 11 made all references informative, added BCP 78 as
normative
o Appendix A4 reworded bullet 2
o
Authors' Addresses Authors' Addresses
Gunter Van de Velde Gunter Van de Velde
Cisco Systems Cisco Systems
De Kleetlaan 6a De Kleetlaan 6a
Diegem 1831 Diegem 1831
Belgium Belgium
Phone: +32 2704 5473 Phone: +32 2704 5473
Email: gunter@cisco.com Email: gunter@cisco.com
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