draft-ietf-v6ops-nap-02.txt   draft-ietf-v6ops-nap-03.txt 
Network Working Group G. Van de Velde Network Working Group G. Van de Velde
Internet-Draft T. Hain Internet-Draft T. Hain
Expires: April 25, 2006 R. Droms Expires: January 1, 2007 R. Droms
Cisco Systems Cisco Systems
B. Carpenter B. Carpenter
IBM Corporation IBM Corporation
E. Klein E. Klein
Tel Aviv University Tel Aviv University
October 22, 2005 June 30, 2006
IPv6 Network Architecture Protection IPv6 Network Architecture Protection
<draft-ietf-v6ops-nap-02.txt> <draft-ietf-v6ops-nap-03.txt>
Status of this Memo Status of this Memo
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skipping to change at page 1, line 39 skipping to change at page 1, line 39
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). 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 does not support
NAT by design and this document shows how Network Architecture NAT by design and this document shows how Network Architecture
Protection (NAP) using IPv6 can provide the same or more benefits Protection (NAP) using IPv6 can provide the same or more benefits
without the need for NAT. 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 . . . . . . . 6 2. Perceived Benefits of NAT and its Impact on IPv4 . . . . . . . 7
2.1. Simple Gateway between Internet and Private Network . . . 6 2.1. Simple Gateway between Internet and Private Network . . . 7
2.2. Simple Security due to Stateful Filter Implementation . . 6 2.2. Simple Security due to Stateful Filter Implementation . . 7
2.3. User/Application tracking . . . . . . . . . . . . . . . . 7 2.3. User/Application tracking . . . . . . . . . . . . . . . . 8
2.4. Privacy and Topology Hiding . . . . . . . . . . . . . . . 8 2.4. Privacy and Topology Hiding . . . . . . . . . . . . . . . 9
2.5. Independent Control of Addressing in a Private Network . . 9 2.5. Independent Control of Addressing in a Private Network . 10
2.6. Global Address Pool Conservation . . . . . . . . . . . . . 9 2.6. Global Address Pool Conservation . . . . . . . . . . . . . 10
2.7. Multihoming and Renumbering with NAT . . . . . . . . . . . 10 2.7. Multihoming and Renumbering with NAT . . . . . . . . . . . 11
3. Description of the IPv6 Tools . . . . . . . . . . . . . . . . 10 3. Description of the IPv6 Tools . . . . . . . . . . . . . . . . 12
3.1. Privacy Addresses (RFC 3041) . . . . . . . . . . . . . . . 10 3.1. Privacy Addresses (RFC 3041) . . . . . . . . . . . . . . . 12
3.2. Unique Local Addresses . . . . . . . . . . . . . . . . . . 11 3.2. Unique Local Addresses . . . . . . . . . . . . . . . . . . 13
3.3. DHCPv6 Prefix Delegation . . . . . . . . . . . . . . . . . 12 3.3. DHCPv6 Prefix Delegation . . . . . . . . . . . . . . . . . 14
3.4. Untraceable IPv6 Addresses . . . . . . . . . . . . . . . . 12 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 . . . . . . . . . . . . . . . . . . . . . . . 13 Benefits of NAT . . . . . . . . . . . . . . . . . . . . . . . 14
4.1. Simple Gateway between Internet and Internal Network . . . 13 4.1. Simple Gateway between Internet and Internal Network . . . 14
4.2. IPv6 and Simple Security . . . . . . . . . . . . . . . . . 13 4.2. IPv6 and Simple Security . . . . . . . . . . . . . . . . . 15
4.3. User/Application Tracking . . . . . . . . . . . . . . . . 15 4.3. User/Application Tracking . . . . . . . . . . . . . . . . 17
4.4. Privacy and Topology Hiding using IPv6 . . . . . . . . . . 15 4.4. Privacy and Topology Hiding using IPv6 . . . . . . . . . . 17
4.5. Independent Control of Addressing in a Private Network . . 16 4.5. Independent Control of Addressing in a Private Network . 20
4.6. Global Address Pool Conservation . . . . . . . . . . . . . 17 4.6. Global Address Pool Conservation . . . . . . . . . . . . . 20
4.7. Multihoming and Renumbering . . . . . . . . . . . . . . . 17 4.7. Multihoming and Renumbering . . . . . . . . . . . . . . . 21
5. Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . 18 5. Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1. Medium/large private networks . . . . . . . . . . . . . . 18 5.1. Medium/large private networks . . . . . . . . . . . . . . 22
5.2. Small Private Networks . . . . . . . . . . . . . . . . . . 20 5.2. Small Private Networks . . . . . . . . . . . . . . . . . . 23
5.3. Single User Connection . . . . . . . . . . . . . . . . . . 21 5.3. Single User Connection . . . . . . . . . . . . . . . . . . 25
5.4. ISP/Carrier Customer Networks . . . . . . . . . . . . . . 22 5.4. ISP/Carrier Customer Networks . . . . . . . . . . . . . . 25
6. IPv6 Gap Analysis . . . . . . . . . . . . . . . . . . . . . . 23 6. IPv6 Gap Analysis . . . . . . . . . . . . . . . . . . . . . . 26
6.1. Subnet Topology Masking . . . . . . . . . . . . . . . . . 23 6.1. Simple Security . . . . . . . . . . . . . . . . . . . . . 27
6.2. Minimal Traceability of Privacy Addresses . . . . . . . . 23 6.2. Subnet Topology Masking . . . . . . . . . . . . . . . . . 27
6.3. Renumbering Procedure . . . . . . . . . . . . . . . . . . 23 6.3. Minimal Traceability of Privacy Addresses . . . . . . . . 27
6.4. Site Multihoming . . . . . . . . . . . . . . . . . . . . . 24 6.4. Site Multihoming . . . . . . . . . . . . . . . . . . . . . 28
6.5. Untraceable Addresses . . . . . . . . . . . . . . . . . . 24 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 8. Security Considerations . . . . . . . . . . . . . . . . . . . 28
8. Security Considerations . . . . . . . . . . . . . . . . . . . 24 9. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 28
9. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 24 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25 11.1. Normative References . . . . . . . . . . . . . . . . . . . 29
11.1. Normative References . . . . . . . . . . . . . . . . . . . 25 11.2. Informative References . . . . . . . . . . . . . . . . . . 30
11.2. Informative References . . . . . . . . . . . . . . . . . . 26
Appendix A. Additional Benefits due to Native IPv6 and Appendix A. Additional Benefits due to Native IPv6 and
Universal Unique Addressing . . . . . . . . . . . . . 27 Universal Unique Addressing . . . . . . . . . . . . 31
A.1. Universal Any-to-Any Aonnectivity . . . . . . . . . . . . 27 A.1. Universal Any-to-Any Connectivity . . . . . . . . . . . . 31
A.2. Auto-configuration . . . . . . . . . . . . . . . . . . . . 27 A.2. Auto-configuration . . . . . . . . . . . . . . . . . . . . 31
A.3. Native Multicast Services . . . . . . . . . . . . . . . . 28 A.3. Native Multicast Services . . . . . . . . . . . . . . . . 32
A.4. Increased Security Protection . . . . . . . . . . . . . . 28 A.4. Increased Security Protection . . . . . . . . . . . . . . 32
A.5. Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 29 A.5. Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 33
A.6. Merging Networks . . . . . . . . . . . . . . . . . . . . . 29 A.6. Merging Networks . . . . . . . . . . . . . . . . . . . . . 33
A.7. Community of interest . . . . . . . . . . . . . . . . . . 29 A.7. Community of interest . . . . . . . . . . . . . . . . . . 33
Appendix B. Revision history . . . . . . . . . . . . . . . . . . 30 Appendix B. Revision history . . . . . . . . . . . . . . . . . . 34
B.1. Changes from *-vandevelde-v6ops-nap-00 to B.1. Changes from *-vandevelde-v6ops-nap-00 to
*-vandevelde-v6ops-nap-01 . . . . . . . . . . . . . . . . 30 *-vandevelde-v6ops-nap-01 . . . . . . . . . . . . . . . . 34
B.2. Changes from *-vandevelde-v6ops-nap-01 to B.2. Changes from *-vandevelde-v6ops-nap-01 to
*-ietf-v6ops-nap-00 . . . . . . . . . . . . . . . . . . . 30 *-ietf-v6ops-nap-00 . . . . . . . . . . . . . . . . . . . 34
B.3. Changes from *-ietf-v6ops-nap-00 to *-ietf-v6ops-nap-01 . 30 B.3. Changes from *-ietf-v6ops-nap-00 to *-ietf-v6ops-nap-01 . 34
B.4. Changes from *-ietf-v6ops-nap-01 to *-ietf-v6ops-nap-02 . 30 B.4. Changes from *-ietf-v6ops-nap-01 to *-ietf-v6ops-nap-02 . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 35 B.5. Changes from *-ietf-v6ops-nap-02 to *-ietf-v6ops-nap-03 . 38
Intellectual Property and Copyright Statements . . . . . . . . . . 36 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41
Intellectual Property and Copyright Statements . . . . . . . . . . 42
1. Introduction 1. Introduction
Although there are many perceived benefits to Network Address There have been periodic claims that IPv6 will require a Network
Translation (NAT), its primary benefit of "amplifying" available Address Translation (NAT), because in IPv4 people use NAT to
address space is not needed in IPv6. The serious disadvantages of accomplish that person's preferred task. This document will explain
ambiguous "private" address space and of Network Address Translation why those pronouncements are false by showing how to accomplish the
(NAT) [1][5] have been well documented [4][6]. However, given its task goal without address translation. Although there are many
wide market acceptance NAT undoubtedly has some perceived benefits. perceived benefits to NAT, its primary benefit of "amplifying"
Indeed, in an Internet model based on universal any-to-any available address space is not needed in IPv6. The serious
connectivity, product marketing departments have driven a perception disadvantages and impact on applications by ambiguous address space
hat some connectivity and security concerns can only be solved by and Network Address Translation [1] [5] have been well documented [4]
using a NAT device or by using logically separated Local Area Network [6] so there will not be much additional discussion here. However,
(LAN) address spaces. This document describes the reasons for given its wide deployment NAT undoubtedly has some perceived
utilizing a NAT device in an IPv4 environment that are regularly benefits, though the bulk of those using it have not evaluated the
cited in marketing pronouncements. It then shows how these needs can technical trade-offs. Indeed, product marketing departments have
be met without using NAT in an IPv6 network. Some of the IPv6 effectively driven a perception that some connectivity and security
solutions offer advantages beyond the equivalent IPv4 NAT solution. concerns can only be solved by using a NAT device, without any
The use of the facilities from IPv6 described in this document avoids mention of the negative impacts on applications. This is amplified
the negative impacts of address translation. through the widespread sharing of vendor best practice documents and
sample configurations that do not differentiate the translation
function of address expansion from the state function of limiting
connectivity.
As far as security and privacy is concerned, this document considers This document describes the goals for utilizing a NAT device in an
IPv4 environment that are regularly cited as solutions for perceived
problems. It then shows how these needs can be met without using the
header modification feature of NAT in an IPv6 network. It should be
noted that this document is 'informational', as it discusses
approaches that will work to accomplish the goals. It is
specifically not a BCP that is recommending any one approach.
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 trying to penetrate your network, or having a such as having a hacker or a worm infected machine outside trying to
worm infected machine outside your network trying to attack it. Some penetrate and attack the local network. Some are local such as a
are local such as a disgruntled employee disrupting business disgruntled employee disrupting business operations, or the
operations, or the unintentional negligence of a user downloading unintentional negligence of a user downloading some malware which
some malware which then proceeds to attack any device on the LAN. then proceeds to attack from within. Some may be inherent in the
Some may be inherent in the device hardware ("embedded") such as device hardware ("embedded") such as having some firmware in a
having some firmware in a domestic appliance "call home" to its domestic appliance "call home" to its manufacturer without the user's
manufacturer without the user's consent. consent.
This document describes several techniques that may be combined on an Another consideration discussed is the view that NAT can be used to
IPv6 site to protect the integrity of its network architecture. fulfill the goals of a security policy. At a technical level the
These techniques, known collectively as Network Architecture translation process fundamentally can not produce security because
Protection (NAP), retain the concept of a well defined boundary mangling the address in the header does not fulfill any useful
between "inside" and "outside" the private network, and allow security functions; in fact it breaks the ability to produce an audit
firewalling, topology hiding, and privacy. NAP will achieve these trail which is a fundamental security tool. That said, the artifacts
security goals without address translation whilst maintaining any-to- of NAT devices do provide some value.
any connectivity. 1. The need to establish state before anything gets through from
outside to inside solves one set of problems.
2. The need to stop receiving any packets when finished with a flow
solves a set of problems
3. the need to appear to be attached at the edge of the network
solves a set of problems
4. and the ability to have addresses that are not publicly routed
solves yet another set (mostly changes where the state is and
scale requirements for the first one).
This document describes several techniques that may be combined in an
IPv6 deployment to protect the integrity of its network architecture.
It will focus on the 'how to accomplish a goal' perspective, leaving
most of the 'why that goal' perspective for other documents. These
techniques, known collectively as Network Architecture Protection
(NAP), retain the concept of a well defined boundary between "inside"
and "outside" the private network, and allow firewalling, topology
hiding, and privacy. NAP will achieve these security goals without
address translation whilst 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 NAT with a following table. It presents the marketed "benefits" of IPv4+NAT
cross-reference of how those are delivered in both the IPv4 and IPv6 with a cross-reference of how those are delivered in both the IPv4
environments. and IPv6 environments.
benefit 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 |
+------------------|-----------------------|-----------------------+ +------------------|-----------------------|-----------------------+
| Simple Security | Filtering side | Explicit Context | | Simple Security | Filtering side | Explicit Context |
| | effect due to lack | Based Access Control | | | effect due to lack | Based Access Control |
skipping to change at page 5, line 30 skipping to change at page 6, line 30
| tracking | | | | tracking | | |
| | see section 2.3 | see section 4.3 | | | see section 2.3 | see section 4.3 |
+------------------|-----------------------|-----------------------+ +------------------|-----------------------|-----------------------+
| End-system | NAT transforms | Temporary use | | End-system | NAT transforms | Temporary use |
| privacy | device ID bits in | privacy addresses | | privacy | device ID bits in | privacy addresses |
| | the address | | | | the address | |
| | see section 2.4 | see section 4.4 | | | see section 2.4 | see section 4.4 |
+------------------|-----------------------|-----------------------+ +------------------|-----------------------|-----------------------+
| Topology hiding | NAT transforms | Untraceable addresses| | Topology hiding | NAT transforms | Untraceable addresses|
| | subnet bits in the | using IGP host routes| | | subnet bits in the | using IGP host routes|
| | address | /or MIPv6 tunnels for| | | address | /or MIPv6 tunnels |
| | | stationary systems |
| | see section 2.4 | see section 4.4 | | | see section 2.4 | see section 4.4 |
+------------------|-----------------------|-----------------------+ +------------------|-----------------------|-----------------------+
| Addressing | RFC 1918 | RFC 3177 & ULA | | Addressing | RFC 1918 | RFC 3177 & 4193 |
| Autonomy | | | | Autonomy | see section 2.5 | see section 4.5 |
| | see section 2.5 | see section 4.5 |
+------------------|-----------------------|-----------------------+ +------------------|-----------------------|-----------------------+
| Global Address | RFC 1918 | 340,282,366,920,938, | | Global Address | RFC 1918 | 17*10^18 subnets |
| Pool | | 463,463,374,607,431, | | Pool | << 2^48 application | 3.4*10^38 addresses |
| Conservation | | 768,211,456 | | Conservation | end points | full port list / addr |
| | | (3.4*10^38) addresses| | | topology restricted | unrestricted topology |
| | see section 2.6 | see section 4.6 | | | see section 2.6 | see section 4.6 |
+------------------|-----------------------|-----------------------+ +------------------|-----------------------|-----------------------+
| 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 NAP can provide each of them. It detail, and then shows how IPv6 NAP can provide each of them. It
concludes with a IPv6 NAP case study and a gap analysis of work that concludes with a IPv6 NAP case study and a gap analysis of work that
remains to be done for a complete NAP solution. remains to be done for a complete NAP 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 as extolled by product marketing. The goal of of the use of IPv4 NAT. The goal of this description is not to
this description is not to analyze these benefits or discuss the analyze these benefits or the accuracy of the perception (detailed
accuracy of the perception (detailed discussions in [4]), but to discussions in [4]), but to describe the deployment requirements and
describe the deployment requirements and set a context for the later set a context for the later descriptions of the IPv6 approaches for
descriptions of the IPv6 approaches for dealing with those dealing with those requirements.
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 any kind of address A NAT device can connect a private network with addresses allocated
(ambiguous [RFC 1918] or global registered address) towards the from any part of the space (ambiguous [RFC 1918] or global registered
Internet. The address space of the private network can be built from & unregistered address) towards the Internet, though extra effort is
globally unique addresses, from ambiguous address space or from both needed when the same range exists on both sides of the NAT. The
simultaneously. Without needing specific configuration, the NAT address space of the private network can be built from globally
device enables access between the client side of a distributed unique addresses, from ambiguous address space or from both
client-server application in the private network and the server side simultaneously. In the simple case of private use addresses, without
in the public Internet. needing specific configuration the NAT device enables access between
the client side of a distributed client-server application in the
private network and the server side located in the public Internet.
Wide-scale deployments have shown that using NAT to attach a private Wide-scale deployments have shown that using NAT to act as a simple
IPv4 network to the Internet is simple and practical for the non- gateway attaching a private IPv4 network to the Internet is simple
technical end user. Frequently a simple user interface, or even a and practical for the non-technical end user. Frequently a simple
default configuration is sufficient for configuring both device and user interface, or even a default configuration is sufficient for
application access rights. configuring both device and application access rights.
Additionally, thanks to successful marketing campaigns it is This simplicity comes at a price as the resulting topology puts
perceived by end users that their equipment is protected from the restrictions on applications. The NAT simplicity works well when the
malicious entities and attackers on the public IPv4 Internet. applications are limited to a client/server model with the server
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
technologies must be available. These helper technologies are
frequently complex to develop and manage, creating a hidden cost to
this 'simple gateway'.
2.2. Simple Security due to Stateful Filter Implementation 2.2. Simple Security due to Stateful Filter Implementation
A firewall doesn't fully secure a network, because many attacks come
from inside or are at a layer higher than the firewall can protect
against. In the final analysis, every system has to be responsible
for its own security, and every process running on a system has to be
robust in the face of challenges like stack overflows etc. What a
firewall does is prevent a network administration from having to pay
for bandwidth to carry unauthorized traffic, and in so doing reduce
the probability of certain kinds of attacks across the protected
boundary.
A distributed security mechanism to protect the end-systems may help
in the above situation; however, to deploy such a system is quite
complex and may depend upon behaviour per operating system and
release version. Also it will only be reliable if a mechanism such
as 'trusted computing' is implemented in the end-system; without this
enhancement administrators will be unwilling to trust the behavior of
end-systems. As a result it will probably not be available in the
next couple of years for end-user organizations. End-system-only
security mechanisms do not protect the network infrastructure from
being misused for transit, or against Distributed Denial of Service
(DDOS) attacks against individual systems inside: and this is the
area where a NAT device is perceived to provide some protection.
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 host in general and on any cannot exploit this state to attack a specific host on any other
port. This benefit may be partially real, however, experienced port, though in the port overload case of NAPT attacking all active
hackers are well aware of NAT devices and are very familiar with ports will impact a potentially wide number of hosts. This benefit
private address space, and have devised methods of attack (such as may be partially real, however, experienced hackers are well aware of
trojan horses) that readily penetrate NAT boundaries. For these NAT devices and are very familiar with private address space, and
reasons the sense of security provided by NAT is actually an have devised methods of attack (such as trojan horses) that readily
illusion. penetrate NAT boundaries. For these reasons the sense of security
provided by NAT is actually an illusion.
Address translation does not provide security in itself; for example, The act of address translation does not provide security in itself;
consider a configuration with static NAT translation and all inbound for example, consider a configuration with static NAT translation and
ports translating to a single machine. In such a scenario the all inbound ports translating to a single machine. In such a
security risk for that machine is identical to the case with no NAT scenario the security risk for that machine is identical to the case
device in the communication path. As result there is no specific with no NAT device in the communication path. As result there is no
security value in the address translation function. The perceived specific security value in the address translation function. The
security comes from the lack of pre-established or permanent mapping perceived security of NAT comes from the lack of pre- established or
state. Dynamically establishing state in response to internal permanent mapping state. Dynamically establishing state in response
requests reduces the threat of unexpected external connections to to internal requests reduces the threat of unexpected external
internal devices. connections to internal devices. This role, often marketed as a
firewall, is really an arbitrary artifact while a real firewall has
explicit 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 a simple router. In situations where two or
more devices need to host the same application this complexity shifts more devices need to host the same application or otherwise use the
from difficult to impossible. same public port this complexity shifts from difficult to impossible.
2.3. User/Application tracking 2.3. User/Application tracking
Although NATs create temporary state for active sessions, in general One usage of NAT is for the local network administrator to track user
they provide limited capabilities for the administrator of the NAT to and application traffic. Although NATs create temporary state for
gather information about who in the private network is requesting active sessions, in general they provide limited capabilities for the
access to which Internet location. This could in theory be done by administrator of the NAT to gather information about who in the
logging the network address translation details of the private and private network is requesting access to which Internet location.
the public addresses from the NAT device's state database. This is done by periodically logging the network address translation
details of the private and the public addresses from the NAT device's
state database.
The checking of this database is not always a simple task, especially The subsequent checking of this database is not always a simple task,
if Port Address Translation is used. It also has an unstated especially if Port Address Translation is used. It also has an
assumption that the administrative instance has a mapping between an unstated assumption that the administrative instance has a mapping
IPv4-address and a network element or user at all times, or the between a private IPv4-address and a network element or user at all
administrator has a time-correlated list of the address/port times, or the administrator has a time-correlated list of the
mappings. address/port mappings.
2.4. Privacy and Topology Hiding 2.4. Privacy and Topology Hiding
The goal of 'topology hiding' is to provide devices on the private One goal of 'topology hiding' is to prevent external entities from
network with an identifier (IPv4 address) which an entity outside the making a correlation between the topological location of devices on
network can use to communicate with or to reference the private the local network. The ability of NAT to provide Internet access to
network devices in protocols but prevents the external entity making a large community of users by the use of a single (or a few) global
a correlation between the topological location of the private device IPv4 routable addresses offers a simple mechanism to hide the
and the address on the local network. internal topology of a network. In this scenario the large community
will be represented in the Internet by a single (or a few) IPv4
The ability of NAT to provide Internet access to a large community of address(es).
users by the use of a single (or a few) global IPv4 routable
addresses offers a simple mechanism to hide the internal topology of
a network. In this scenario the large community will be represented
in the Internet by a single (or a few) IPv4 address(es).
The use of NAT then results in a user behind a NAT gateway actually The use of NAT then results in a user behind a NAT gateway actually
appearing on the Internet as a user inside the NAT box itself; i.e., appearing from the Internet as a user inside the NAT box itself;
the IPv4 address that appears on the Internet is only sufficient to i.e., the IPv4 address that appears on the Internet is only
identify the NAT. When concealed behind a NAT it is impossible to sufficient to identify the NAT so all internal nodes appear to exist
tell from the outside which member of a family, which customer of an at the demarcation edge. When concealed behind a NAT it is
Internet cafe, or which employee of a company generated or received a impossible to tell from the outside which member of a family, which
particular packet. Thus, although NATs do nothing to provide customer of an Internet cafe, or which employee of a company
application level privacy, they do prevent the external tracking and generated or received a particular packet. Thus, although NATs do
profiling of individual host computers by means of their IP nothing to provide application level privacy, they do prevent the
addresses, usually known as 'device profiling'. At the same time a external tracking and profiling of individual systems by means of
NAT creates a smaller pool of addresses for a much more focused point their IP addresses, usually known as 'device profiling'.
of attack.
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
scan the entire local network but can instead concentrate on the
active ports associated with the NAT adress. By periodically
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
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 enterprises prefer to hide as much as possible of their internal Some network managers prefer to hide as much as possible of their
network topology from outsiders. Mostly this is achieved by blocking internal network topology from outsiders as a useful precaution to
"traceroute" etc., but NAT of course entirely hides the internal mitigate scanning attacks. Mostly this is achieved by blocking
subnet topology, which some network managers believe is a useful "traceroute" etc., though NAT entirely hides the internal subnet
precaution to mitigate scanning attacks. Scanning for IPv6 can be topology. Scanning is a particular concern in IPv4 networks because
much harder in comparison with IPv4 as described in [18]. the subnet size is small enough that once the topology is known it is
easy to find all the hosts, then start scanning them for vulnerable
Once a list of available devices and IP addresses has been mapped, a ports. Once a list of available devices has been mapped, a port-scan
port-scan on these IP addresses can be performed. Scanning works by on these IP addresses can be performed. Scanning works by tracking
tracking which ports do not receive unreachable errors from either which ports do not receive unreachable errors from either the
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 initiating attacks 80. Any vulnerable open ports could be used for access to an end
on an end system. 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 take benefit from using the address space
defined in RFC 1918 to enlarge the available addressing space for defined in RFC 1918 to enlarge the available addressing space for
their private network, and at the same time reduce their need for their private network, and at the same time reduce their need for
globally routable addresses. This type of local control of address globally routable addresses. This type of local control of address
resources allows a clean and hierarchical addressing structure in the resources allows a sufficiently large pool for a clean and
network. hierarchical addressing structure in the local network.
Another benefit is due to the usage of independent addresses on Another benefit is due to the usage of independent addresses on
majority of the network infrastructure there is an increased ability majority of the network infrastructure there is an increased ability
to change provider with less operational difficulties. to change provider with less operational difficulties.
Section 2.7 describes some disadvantages that appear if independent Section 2.7 describes some disadvantages that appear if independent
networks using [RFC1918] addresses have to be merged. networks using [RFC1918] addresses have to be merged.
2.6. Global Address Pool Conservation 2.6. Global Address Pool Conservation
Due to the ongoing depletion of the IPv4 address range, the remaining While the widespread use of IPv4+NAT has reduced the potential
pool of unallocated IPv4 addresses is below 30%. While mathematical consumption rate, the ongoing depletion of the IPv4 address range has
models based on historical IPv4 prefix consumption periodically already taken the remaining pool of unallocated IPv4 addresses below
attempt to predict the future exhaustion date of the IPv4 address 25%. While mathematical models based on historical IPv4 prefix
pool, a direct result of this continuous resource consumption is that consumption periodically attempt to predict the future exhaustion
the administrative overhead for acquiring globally unique IPv4 date of the IPv4 address pool, a direct result of this continuous
addresses will continue increasing in direct response to tightening resource consumption is that the administrative overhead for
allocation policies. In response to the increasing administrative acquiring globally unique IPv4 addresses will continue increasing in
overhead many Internet Service Providers (ISPs) have already resorted direct response to tightening allocation policies.
to the ambiguous addresses defined in RFC 1918 behind a NAT for the
various services they provide as well as connections for their end In response to the increasing administrative overhead many Internet
customers. This happens even though that private address-space is Service Providers (ISPs) have already resorted to the ambiguous
strictly limited in size. In turn this has restricted the number of addresses defined in RFC 1918 behind a NAT for the various services
and types of applications that can be deployed by these ISPs and they provide as well as connections for their end customers. This
their customers. Forced into this limiting situation such customers happens even though the private use address-space is strictly limited
can rightly claim that despite the optimistic predictions of in size. Some deployments have already outgrown that space and have
mathematical models the global pool of IPv4 addresses is effectively begun cascading NAT to continue expanding, though this practice
already exhausted, especially for larger enterprises. eventually breaks down over routing ambiguity. Additionally, while
we are unlikely to know the full extent of the practice (because it
is hidden behind a nat), service providers have been known to
announce previously unallocated public space to their customers (to
avoid the problems associated with the same address space appearing
on both sides), only to find that once that space was formally
allocated and being publicly announced their customers couldn't reach
the registered networks.
The number of and types of applications that can be deployed by these
ISPs and their customers is restricted by the ability to overload the
port range on the public side of the most public NAT in the path.
The limit of this approach is something substantially less than 2^48
possible active **application** endpoints (approximately [2^32 minus
2^29] * [2* 2^16 minus well known port space]), as distinct from
addressable devices each with their own application endpoint range.
Those who advocate layering of NAT frequently forget to mention that
there are topology restrictions placed on the applications. Forced
into this limiting situation such customers can rightly claim that
despite the optimistic predictions of mathematical models, the global
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, making a network multihomed is quite different functions. However these are argued together as
often a transitional state required as part of network renumbering, reasons for using NAT, because making a network multihomed is often a
and NAT interacts with both in the same way. transitional state required as part of network renumbering, and NAT
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
[14] and/or readily change its CIDR prefix. Unfortunately, IPv4 was [15] 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 huge problems due to address translation it will create huge problems due to
administrative difficulties of overlapping address speaces 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 NAP solution to emulate the protection features associated with the NAP solution to replace the protection features associated with
IPv4 NAT. IPv4 NAT.
The reader must clearly distinguish between features of IPv6 that
were fully defined when this document was drafted and those that were
potential features that still required more work to define them. The
latter are summarized later in the 'Gap Analysis' section of this
document. However, we do not distinguish in this document between
fully defined features of IPv6 and those that were already widely
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 profiling, for example by web sites that are accessed from the device
device; IPv6 privacy addresses were defined to provide that as it moves around the Internet. IPv6 privacy addresses were defined
capability. IPv6 addresses consist of a routing prefix, subnet-id to provide that capability. IPv6 addresses consist of a routing
part (SID) and an interface identifier part (IID). For interfaces prefix, subnet-id part (SID) and an interface identifier part (IID).
that contain embedded IEEE Link Identifiers the interface identifier As originally defined, IPv6 stateless address auto-configuration
is typically derived from it, though this practice facilitates (SLAAC) will typically embed the IEEE Link Identifier of the
tracking and profiling of a device as it moves around the Internet. interface as the IID part, though this practice facilitates tracking
RFC 3041 describes an extension to IPv6 stateless address and profiling of a device through the consistent IID. RFC 3041 [7]
autoconfiguration (SLAAC) for interfaces [7]. Use of the privacy describes an extension to SLAAC to enhance device privacy. Use of
address extension causes nodes to generate global-scope addresses the privacy address extension causes nodes to generate global-scope
from interface identifiers that change over time, even in cases where addresses from interface identifiers that change over time,
the interface contains an embedded IEEE link identifier. Changing consistent with system administrator policy. Changing the interface
the interface identifier (thus the global-scope addresses generated identifier (thus the global-scope addresses generated from it) over
from it) over time makes it more difficult for eavesdroppers and time makes it more difficult for eavesdroppers and other information
other information collectors to identify when addresses used in collectors to identify when addresses used in different transactions
different transactions actually correspond to the same node. A actually correspond to the same node. A relatively short valid
relatively short valid lifetime for the privacy address also has the lifetime for the privacy address also has the side effect of reducing
side effect of reducing the attack profile of a device, as it is not the attack profile of a device, as it is not directly attackable once
directly attackable once it stops answering at the temporary use it stops answering at the temporary use address.
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 addresses is expected to be from end-systems running stateless auto-
autoconfiguration, 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
then remembering that for future queries. This would allow using in a request, then remembering that for future queries. This would
them in DNS for registered services since the assumption of a server allow using them in DNS for registered services since the assumption
based deployment would be a persistent value that minimizes DNS of a DHCP server based deployment would be a persistent value that
churn. A DHCP based deployment would also allow for local policy to minimizes DNS churn. A DHCP based deployment would also allow for
periodically change the entire collection of end device addresses local policy to periodically change the entire collection of end
while maintaining some degree of central knowledge and control over device addresses while maintaining some degree of central knowledge
which addresses should be in use at any point in time. and control over which addresses should be in use at any point in
time.
Randomizing the IID, as defined in RFC 3041, only precludes tracking Randomizing the IID, as defined in RFC 3041, is effectively a sparse
of the lower 64 bits of the IPv6 address. Masking of the subnet ID allocation technique which only precludes tracking of the lower 64
will require additional approaches as discussed below in 3.4. bits of the IPv6 address. Masking of the subnet ID will require
Additional considerations are discussed in [17]. additional approaches as discussed below in 3.4. Additional
considerations are discussed in [18].
3.2. Unique Local Addresses 3.2. Unique Local Addresses
Local network and application services stability during periods of Achieving the goal of autonomy, that many perceive as a value of NAT,
intermittent connectivity between one or more providers requires is required for local network and application services stability
address management autonomy. Such autonomy in a single routing during periods of intermittent connectivity or moving between one or
prefix environment would lead to massive expansion of the global more providers. Such autonomy in a single routing prefix environment
routing tables, so IPv6 provides for simultaneous use of multiple would lead to massive expansion of the global routing tables (as seen
prefixes. The Unique Local Address prefix (ULA) [13] has been set in IPv4), so IPv6 provides for simultaneous use of multiple prefixes.
aside for use in local communications. The ULA address prefix for The Unique Local Address prefix (ULA) [14] has been set aside for use
any network is routable over a locally defined collection of routers. in local communications. The ULA address prefix for any network is
These prefixes are not intended to be routed on the public global routable over a locally defined collection of routers. These
Internet; large scale inter-domain distribution of routes to ULA prefixes are not intended to be routed on the public global Internet
prefixes would have a negative impact on global route aggregation. as large scale inter-domain distribution of routes for ULA prefixes
would have a negative impact on global route aggregation.
ULAs have the following characteristics: ULAs have the following characteristics:
o 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 any address conflicts or requiring renumbering without creating address conflicts or requiring renumbering of
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 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 local routes and packets.
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 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. Mixing the two kinds of addresses is likely to lead to addresses to assure stability. The policy table defined in [10]
undeliverable packets. is one way to bias this selection, by giving higher preference to
FC00::/7 over 2001::/3. Mixing the two kinds of addresses may
lead to undeliverable packets during times of instability, but
that mixing is not likely to happen when the rules of RFC 3484 are
followed.
3.3. DHCPv6 Prefix Delegation 3.3. DHCPv6 Prefix Delegation
The Prefix Delegation (DHCP-PD) options [11] provide a mechanism for One of the functions of a simple gateway is managing the local use
automated delegation of IPv6 prefixes using the Dynamic Host address range. The Prefix Delegation (DHCP-PD) options [11] provide
Configuration Protocol (DHCP) [9]. This mechanism (DHCP-PD) is a mechanism for automated delegation of IPv6 prefixes using the
intended for delegating a long-lived prefix from a delegating router Dynamic Host Configuration Protocol (DHCP) [9]. This mechanism
(incorporating a DHCPv6 server) to a requesting router, possibly (DHCP-PD) is intended for delegating a long-lived prefix from a
across an administrative boundary, where the delegating router does delegating router (possibly incorporating a DHCPv6 server) to a
not require knowledge about the topology of the links in the network requesting router, possibly across an administrative boundary, where
to which the prefixes will be assigned. the delegating router does not require knowledge about the topology
of the links in the network to which the prefixes will be assigned.
3.4. Untraceable IPv6 Addresses 3.4. Untraceable IPv6 Addresses
These should be globally routable IPv6 addresses which can be
randomly and independently assigned to IPv6 devices.
The random assignment is intended to mislead the outside world about
the structure of the local network. However the local network needs
to maintain a correlation between the location of the device and the
untraceable IPv6 address. This correlation could be done by
generating IPv6 host route entries or by utilizing an indirection
device such as a Mobile IPv6 Home Agent.
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.
These should be globally routable IPv6 addresses which can be
randomly and independently assigned to IPv6 devices. The random
assignment is intended to mislead the outside world about the
structure of the local network. However the local network needs to
maintain a correlation between the location of the device and the
untraceable IPv6 address. For smaller deployments this correlation
could be done by generating IPv6 host route entries, or for larger
ones by utilizing an indirection device such as a Mobile IPv6 Home
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 could 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 to communicate amongst connectivity. This would allow local nodes to communicate amongst
themselves prior to establishing a global connection. If the network themselves independent of the state of a global connection. If the
happened to concatenate with another local network, this is highly network happened to concatenate with another local network, the
unlikely to result in address collisions. A more secure network randomness in ULA creation is highly unlikely to result in address
environment can be established by having the referenced ULA addresses collisions.
statically configured on the network devices as this decreases the
dynamic aspects of the network, however the operational overhead is
increased.
With external connectivity the simple gateway could also use DHCP-PD With external connectivity the simple gateway should use DHCP-PD to
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 will always use the global IPv6
addresses [9] derived from this prefix delegation. It should be addresses derived from this prefix delegation. It should be noted
noted that the address selection policy table in end-systems needs to that the address selection policy table in end-systems defined in RFC
be correctly set up so that true global prefixes are distinguished 3484 should be configured to prefer the ULA prefix range over the
from ULAs and will be used for the source address in preference when DHCP-PD prefix range when the goal is to keep local communications
the destination is not a ULA. stable during periods of transient external connectivity.
In the very simple case there is no explicit routing protocol and a In the very simple case there is no explicit routing protocol on
single default route is used out to the global Internet. A slightly either side of the gateway, and a single default route is used
more complex case might involve local routing protocols, but with the internally pointing out to the global Internet. A slightly more
entire local network sharing a common global prefix there would still complex case might involve local internal routing protocols, but with
not be a need for an external routing protocol as a default route the entire local network sharing a common global prefix there would
would continue to be consistent with the connectivity. 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
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 is similar to that of an IPv4 host
directly connected towards the Internet. The use of firewall and directly connected towards the Internet. The use of firewall and
Intrusion Detection Systems (IDS) is recommended. A proxy may be Intrusion Detection Systems (IDS) is recommended for those that want
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 transparancy 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 the profile since the node will not respond to the address once its
address is no longer valid. lifetime becomes invalid.
2. IPsec is a mandatory service for IPv6 implementations. IPsec 2. IPsec is a mandatory service for IPv6 implementations. IPsec
functions to prevent session hijacking, prevent content functions to authenticate the correspondent, prevent session
tampering, and optionally masks the packet contents. While IPsec hijacking, prevent content tampering, and optionally masks the
might be available in IPv4 implementations, deployment in NAT packet contents. While IPsec might be available in IPv4
implementations and works the same way, deployment in NAT
environments either breaks the protocol or requires complex environments either breaks the protocol or requires complex
helper services with limited functionality or efficiency. helper services with limited functionality or efficiency.
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 an effective network ping sweep and resulting IID) will make a complete subnet ping sweep virtually impossible
port-scan virtually impossible due to the number of possible due to the potential number of combinations available. Reducing
combinations available, provided that IIDs are essentially the security threat of port scans on identified nodes requires
randomly distributed across the available space. This protection sparse distribution within the subnet to minimize the probability
is nullified if the attacker has no access to a local connection. of scans finding adjacent nodes. Provided that IIDs are
If an attacker has local access then he could use ND [3] and essentially randomly distributed across the available space,
ping6 to ff02::1 to detect local neighbors. (Of course, a address scanning based attacks will effectively fail. This
locally connected attacker has many scanning options with IPv4 as protection exists if the attacker has no direct access to the
well.) It is recommended for site administrators to take [18] specific subnet and therefore is trying to scan it remotely. If
into consideration to achieve the expected goal. This protection an attacker has local access then he could use ND [3] and ping6
will also be nullified if IIDs are configured in a group near the to the link-scope multicast ff02::1 to detect the IEEE based
start of the IID space. address of local neighbors, then apply the global prefix to those
to simplify its search (of course, a locally connected attacker
has many scanning options with IPv4 as well). This scanning
protection will be nullified if IIDs are configured in any
structured groupings within the IID space.
Assuming the network administrator is aware of [19] the increased
size of the IPv6 address will make topology probing much harder, and
almost impossible for IPv6 devices. The intention of topology
probing is to identify a selection of the available hosts inside an
enterprise. This mostly starts with a ping-sweep. Since the IPv6
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
the network, and virus/worm propagation will be thwarted in the
process. At full-rate full-duplex 40Gbps (400 times the typical
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.
IPv4 NAT was not developed as a security mechanism. Despite IPv4 NAT was not developed as a security mechanism. Despite
marketing messages to the contrary it is not a security mechanism, marketing messages to the contrary it is not a security mechanism,
and hence it will offer some security holes while many people assume and hence it will offer some security holes while many people assume
their network is secure due to the usage of NAT. IPv6 security best their network is secure due to the usage of NAT. IPv6 security best
practices will avoid this kind of illusory security but can only do practices will avoid this kind of illusory security but can only
this if correctly configured firewalls and IDS systems are used at address the same threats if correctly configured firewalls and IDS
the perimeter where some IPv4 networks have relied on NATs. systems are used at the perimeter.
It must be noted that even a firewall doesn't fully secure
a network. Many attacks come from inside or are at a layer
higher than the firewall can protect against. In the final
analysis, every system has to be responsible for its own
security, and every process running on a system has to be
robust in the face of challenges like stack overflows etc.
What a firewall does is prevent a network administration
from having to pay for bandwidth to carry unauthorized
traffic, and in so doing reduce the probability of certain
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
connected home network, the DSL broadband gateway/router should be connected home network, the DSL 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 which provides a minimum set of connectivity default configuration where incoming traffic is limited to return
for users in the home network (e.g., just to external HTTP servers) traffic resulting from outgoing packets (sometimes known as
with incoming traffic limited to return traffic resulting from reflective session state). There should also be an easy interface
outgoing packets (sometimes known as reflective session state) with which allows users to create inbound 'pinholes' for specific purposes
an easy interface which allows users to create additional 'pinholes' such as online-gaming. Another consideration would be the capability
for specific purposes. 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 for oblivious users. be to make use of the IPv6 Internet more secure without increasing
the perceived complexity for users who just want to accomplish a
Assuming the network administrator is aware of [18] the increased task.
size of the IPv6 address will make topology probing much harder, and
almost impossible for IPv6 devices. The intention of topology
probing is to identify a selection of the available hosts inside an
enterprise. This mostly starts with a ping-sweep. Since the IPv6
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
the network, and virus/worm propagation will be thwarted in the
process. At full rate 40Gbps (400 times the typical 100Mbps LAN, and
13,000 times the typical DSL/Cable access link) it takes over 5000
years to scan a single 64 bit space.
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. This enhances the capability of data-flow two or more devices. This enhances the capability of data-flow
tracking for security audits compared with IPv4 NAT, because in IPv6 tracking for security audits compared with IPv4 NAT, because in IPv6
a flow between a sender and receiver will always be uniquely a flow between a sender and receiver will always be uniquely
identified due to the unique IPv6 source and destination addresses. identified due to the unique IPv6 source and destination addresses.
At the same time, this tracking is per address. In environments
where the goal is tracking back to the user, additional external
information will be necessary correlating a user with an address. In
the case of short lifetime privacy address usage, this external
information will need to be based on more stable information such as
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 pseudo-random privacy
addresses [RFC 3041] which are generated as required, so that a addresses [RFC 3041] which are generated as required, so that a
session can use an address that is valid only for a limited time. session can use an address that is valid only for a limited time.
Exactly as with IPv4 NAT, this only allows such a session to be This only allows such a session to be traced back to the subnet that
traced back to the subnet that originates it, but not immediately to originates it, but not immediately to the actual host, where IPv4 NAT
the actual host. 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 [RFC 3041] a casual When doing both subnet and IID randomization [RFC 3041] a casual
snooper won't be able to deduce much about the networks topology. snooper won't be able to deduce much about the networks topology.
The obtaining of a single address will tell the snooper very little The obtaining of a single address will tell the snooper very little
about other addresses. This is different from IPv4 where address about other addresses. This is different from IPv4 where address
space limitations cause this to be not true. In most usage cases space limitations cause this to be not true. In most usage cases
this concept should be sufficient for address privacy and topology this concept should be sufficient for address privacy and topology
hiding. hiding, with the cost being a more complex internal routing
configuration.
In the case where a network administrator wishes to fully conceal the As discussed in Section 3.1, there are multiple parts to the IPv6
internal IPv6 topology, and the majority of its host computer address, and different techniques to manage privacy for each which
addresses, a possible option is to run all internal traffic using may be combined to protect the entire address. In the case where a
Unique Local Addresses (ULA) since such packets can by definition network administrator wishes to fully isolate the internal IPv6
never exit the site. For hosts that do in fact need to generate topology, and the majority of its internal use addresses, one option
external traffic, by using multiple IPv6 addresses (ULAs and one or is to run all internal traffic using Unique Local Addresses (ULA).
more global addresses), it will be possible to hide and mask some or By definition this prefix block is not to be advertised into the
all of the internal network. As discussed in Section 3.1, there are public routing system, so without a routing path external traffic
multiple parts to the IPv6 address, and different techniques to will never reach the site. For the set of hosts that do in fact need
manage privacy for each. to interact externally, by using multiple IPv6 prefixes (ULAs and one
or more global addresses) all of the internal nodes that do not need
external connectivity, and the internally used addresses of those
that do will be masked from the outside. The policy table defined in
[10] provides a mechanism to bias the selection process when multiple
prefixes are in use such that the ULA would be preferred when the
correspondent is also local.
There are two possible scenarios for the extreme situation when a There are other scenarios for the extreme situation when a network
network manager also wishes to fully conceal the internal IPv6 manager also wishes to fully conceal the internal IPv6 topology. In
topology. 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
exist at the edge of the network, just as they would when behind a
NAT.
o One could use explicit host routes and remove the correlation o One approach uses explicit host routes in the IGP to remove the
between location and IPv6 address. This solution does however external correlation between physical topology attachment point
show severe scalability issues. and end-to-end IPv6 address. In the figure below the hosts would
o The other technology to fully hide the internal topology would be be allocated prefixes from one or more logical subnets, and would
to use a tunneling mechanism. Mobile IPv6 without route inject host routes to internally identify their real attachment
optimization is one example. In this example the public facing point. This solution does however show severe scalability issues
addresses are indirected via an edge Home Agent (HA). This and requires hosts to participate in the IGP, as well as having
indirection method truly masks the internal topology as all nodes the firewall block all external to internal traceroute for the
with global access appear to share a common prefix. The downside logical subnet. The specific limitations are dependent on the IGP
of using this method is that it makes usage of middleware like a protocol, the physical topology, and the stability of the system.
Home Agent (HA). 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).
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. While turning off all binding updates 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 updates at the
firewall. Another approach for the internal routes would be to
use the policy table of RFC 3484 to bias a ULA prefix as preferred
internally, leaving the Home Address external for use. The
downsides of using the MIPv6 tunneling method is that it makes
usage of middleware like a Home Agent (HA) and consumes slightly
more bandwidth for the 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. 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
|
\
|
+------------------+
| Simple Gateway |-+-+-+-+-+-+-+-+--
| or Home Agent | Logical subnets
| |-+-+-+-+-+-+-+-+--
+------------------+ for topology
| hidden nodes
|
Real internal -------------+-
topology | |
| -+----------
-----------+--------+
|
|
|
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. Nodes that need access to the public Internet the public Internet because nodes that need access to the public
may have a ULA for local use, and will have a global use address Internet will have a global use address as well. When using IPv6,
because the global use IPv6 address space is not a scarce resource the need to ask for more address space will become far less likely
like the global use IPv4 space. While global IPv6 allocation policy due to the increased size of the subnets, along with an allocation
is managed through the Regional Internet Registries, it is expected policy that recognizes table fragmentation is also an important
that they will continue with derivatives of [RFC 3177] for the consideration. While global IPv6 allocation policy is managed
foreseeable future. through the Regional Internet Registries, it is expected that they
will continue with derivatives of [8] for the foreseeable future so
When using IPv6, the need to ask for more address space will become the number of subnet prefixes available to an organization should not
far less likely due to the increased size of the subnets. These be a limitation which would create an artificial demand for NAT.
subnets typically allow 2^64 addresses per subnet and an enterprise
will typically receive a /48 which allows segmentation into at least
2^16 different subnets.
The ongoing subnet size maintenance may become simpler when IPv6 Ongoing subnet address maintenance may become simpler when IPv6
technology is utilised. If IPv4 address space is optimised one has technology is utilized. Under IPv4 address space policy restrictions
to look periodically into the number of hosts on a segment and the each subnet must be optimized, so one has to look periodically into
subnet size allocated to the segment; an enterprise today may have a the number of hosts on a segment and the subnet size allocated to the
mix of /28 - /23 size subnets for example, and may shrink/grow these segment and rebalance. For example an enterprise today may have a
as their network user base changes. For IPv6 all subnets have /64 mix of IPv4 /28 - /23 size subnets, and may shrink/grow these as
prefixes. their network user base changes. For IPv6 all subnets have /64
prefixes which will reduce the operational and configuration
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, overlapping address space. Since allocations in IPv6 are based on
340,282,366,920,938,463,463,374,607,431,768,211,456 (3.4*10^38) total subnets rather than hosts a reasonable way to look at the pool is
possible addresses. As previously discussed, the serious that there are about 17*10^18 unique subnet values where sparse
allocation practice within those provides for new opportunities such
as SEND 3971 [12]. 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. multiple devices are forced to share a scarce global address through
a NAT.
4.7. Multihoming and Renumbering 4.7. Multihoming and Renumbering
Multihoming and renumbering remain technically challenging with IPv6 Multihoming and renumbering remain technically challenging with IPv6
(see the Gap Analysis below). However, IPv6 was designed to allow (see the Gap Analysis below). However, IPv6 was designed to allow
sites and hosts to run with several simultaneous CIDR-like prefixes sites and hosts to run with several simultaneous CIDR allocated
and thus with several simultaneous ISPs. An address selection prefixes, and thus with several simultaneous ISPs. An address
mechanism [10] is specified so that hosts will behave consistently selection mechanism [10] is specified so that hosts will behave
when several addresses are simultaneously valid. The fundamental consistently when several addresses are simultaneously valid. The
difficulty that IPv4 has in this regard therefore does not apply to fundamental difficulty that IPv4 has in regard to multiple addresses
IPv6. IPv6 sites can and do run today with multiple ISPs active, and therefore does not apply to IPv6. IPv6 sites can and do run today
the processes for adding and removing active prefixes at a site have with multiple ISPs active, and the processes for adding, removing,
been documented [12] and [19]. and renumbering active prefixes at a site have been documented in
[13] and [20].
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 may result in a renumbering the connecting Service provider. This will likely result in a
effort if the network changes from Service Provider. When changing renumbering effort when the network changes between service
ISPs or ISPs readjusting their addressing pool, DHCP-PD [11] can be providers. When changing ISPs or ISPs readjusting their addressing
used as an almost zero-touch external mechanism for prefix change in pool, DHCP-PD [11] can be used as an almost zero- touch external
conjunction with a ULA prefix for internal connection stability. mechanism for prefix change in conjunction with a ULA prefix for
With appropriate management of the lifetime values and overlap of the internal connection stability. With appropriate management of the
external prefixes, a smooth make-before-break transition is possible lifetime values and overlap of the external prefixes, a smooth make-
as existing communications will continue on the old prefix as long as before-break transition is possible as existing communications will
it remains valid, while any new communications will use the new continue on the old prefix as long as it remains valid, while any 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 of these category of networks we of connected end hosts. For each category of networks we can use
can use IPv6 Network Architecture Protection to achieve a secure and IPv6 Network Architecture Protection to achieve a secure and flexible
flexible infrastructure, which provides an enhanced network infrastructure, which provides an enhanced network functionality in
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 networks fall into this category. The majority of private enterprise, academic, research, or government
Many of these networks have one or more exit points to the Internet. networks fall into this category. Many of these networks have one or
Though these organizations have sufficient resources to acquire more exit points to the Internet. Though these organizations have
addressing independence when using IPv4 there are several reasons why sufficient resources to acquire addressing independence when using
they might choose to use NAT in such a network. For the ISP there is IPv4 there are several reasons why they might choose to use NAT in
no need to import the IPv4 address range from the remote end- such a network. For the ISP there is no need to import the IPv4
customer, which facilitates IPv4 route summarization. The customer address range from the remote end-customer, which facilitates IPv4
can use a larger IPv4 address range (probably with less- route summarization. The customer can use a larger IPv4 address
administrative overhead) by the use of RFC 1918 and NAT. The range (probably with less-administrative overhead) by the use of RFC
customer also reduces the overhead in changing to a new ISP, because 1918 and NAT. The customer also reduces the overhead in changing to
the addresses assigned to devices behind the NAT do not need to be a new ISP, because the addresses assigned to devices behind the NAT
changed when the customer is assigned a different address by a new do not need to be changed when the customer is assigned a different
ISP. By using address translation one avoids the need for network address by a new ISP. By using address translation in IPv4 one
renumbering. Finally, the customer can provide privacy for its hosts avoids the expensive process of network renumbering. Finally, the
and the topology of its internal network if the internal addresses customer can provide privacy for its hosts and the topology of its
are mapped through NAT. internal network if the internal addresses are mapped through NAT.
It is expected that there will be enough IPv6 addresses available for It is expected that there will be enough IPv6 addresses available for
all networks and appliances for the foreseeable future. The basic all networks and appliances for the foreseeable future. The basic
IPv6 address range an ISP allocates for a private network is large IPv6 address range an ISP allocates for a private network is large
enough (currently /48) for most of the medium and large enterprises, enough (currently /48) for most of the medium and large enterprises,
while for the very large private enterprise networks address-ranges while for the very large private enterprise networks address-ranges
can be concatenated. A single /48 allocation provides an enterprise can be concatenated. The goal of this assignment mechanism is to
network with 65536 different /64 prefixes. decrease the total amount of entries in the public Internet routing
table. A single /48 allocation provides an enterprise network with
The summarization benefit for the ISP results from the IPv6 65536 different /64 subnet prefixes.
allocation rules. This means that the ISP will provide the
enterprise with an IPv6 address-range (typically one or multiple
range(s) of '/48') from its RIR assigned IPv6 address-space. The
goal of this assignment mechanism is to decrease the total amount of
entries in the internet routing table. If the ISP adopts appropriate
policies there is high probability that an enterprise requiring
additional space could acquire an adjacent address block.
To mask the identity of a user on a network of this type, the usage To mask the identity of a user on a network of this type, the usage
of IPv6 privacy extensions may be advised. This technique is useful of IPv6 privacy extensions may be advised. This technique is useful
when an external element wants to track and collect all information when an external element wants to track and collect all information
sent and received by a certain host with known IPv6 address. Privacy sent and received by a certain host with known IPv6 address. Privacy
extensions add a random factor to the host part of an IPv6 address extensions add a random time-limited factor to the host part of an
and will make it very hard for an external element to keep IPv6 address and will make it very hard for an external element to
correlating the IPv6 address to a host on the inside network. The keep correlating the IPv6 address to a specific host on the inside
usage of IPv6 privacy extensions does not mask the internal network network. The usage of IPv6 privacy extensions does not mask the
structure of an enterprise network. internal network structure of an enterprise network.
If there is need to mask the internal structure towards the external When there is need to mask the internal structure towards the
IPv6 internet, then some form of 'untraceable' addresses may be used. external IPv6 Internet, then some form of 'untraceable' addresses may
These addresses will be derived from a local pool, and may be be used. These addresses will appear to exist at the external edge
assigned to those hosts for which topology masking is required or of the network, and may be assigned to those hosts for which topology
which want to reach the IPv6 Internet or other external networks. masking is required or which want to reach the IPv6 Internet or other
The technology to assign these addresses to the hosts could be based external networks. The technology to assign these addresses to the
on DHCPv6. To complement the 'Untraceable' addresses it is needed to hosts could be based on DHCPv6 or static configuration. To
have at least awareness of the IPv6 address location when routing an complement the 'Untraceable' addresses it is needed to have at least
IPv6 packet through the internal network. This could be achieved by awareness of the IPv6 address location when routing an IPv6 packet
'route-injection' in the network infrastructure. This route- through the internal network. This could be achieved by 'host based
route- injection' in the local network infrastructure. This route-
injection could be done based on /128 host-routes to each device that injection could be done based on /128 host-routes to each device that
wants to connect to the Internet using an untraceable address. This wants to connect to the Internet using an untraceable address. This
will provide the most dynamic masking, but will have a scalability will provide the most dynamic masking, but will have a scalability
limitation, as an IGP is typically not designed to carry many limitation, as an IGP is typically not designed to carry many
thousands of IPv6 prefixes. A large enterprise may have thousands of thousands of IPv6 prefixes. A large enterprise may have thousands of
hosts willing to connect to the Internet. Less flexible masking hosts willing to connect to the Internet.
could be to have time-based IPv6 prefixes per link or subnet. This
may reduce the amount of route entries in the IGP by a significant
factor, but has as trade-off that masking is time and subnet based.
The dynamic allocation of 'Untraceable' addresses can also limit the An alternative for larger deployments is to leverage the tunneling
IPv6 access between local and external hosts to those local hosts aspect of MIPv6 even for non-mobile devices. With the logical subnet
being authorized for this capability. Dynamically allocated being allocated as attached to the edge Home Agent, the real
'Untraceable' addresses may also facilitate and simplify the attachment and internal topology are masked from the outside.
connectivity to the outside networks during renumbering, because the Dropping outbound binding updates at the firewall is also necessary
existing IPv6 central address pool could be swapped for the newly to avoid leaking the attachment information.
allocated IPv6 address pool.
Less flexible masking could be to have time-based IPv6 prefixes per
link or subnet. This may reduce the amount of route entries in the
IGP by a significant factor, but has as trade-off that masking is
time and subnet based which will complicate auditing systems. The
dynamic allocation of 'Untraceable' addresses can also limit the IPv6
access between local and external hosts to those local hosts being
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
skipping to change at page 20, line 40 skipping to change at page 24, line 22
blocks, or IPv4 prefixes that are static over time, due to the larger blocks, or IPv4 prefixes that are static over time, due to the larger
public address pool each of those requires. public address pool each of those requires.
As a direct response to explicit charges per public address most of As a direct response to explicit charges per public address most of
this category has deployed NAPT (port demultiplexing NAT) to minimize this category has deployed NAPT (port demultiplexing NAT) to minimize
the number of addresses in use. Unfortunately this also limits the the number of addresses in use. Unfortunately this also limits the
Internet capability of the equipment to being mainly a receiver of Internet capability of the equipment to being mainly a receiver of
Internet data (client), and makes it quite hard for the equipment to Internet data (client), and makes it quite hard for the equipment to
become a world wide Internet server (i.e. HTTP, FTP, etc.) due to become a world wide Internet server (i.e. HTTP, FTP, etc.) due to
the stateful operation of the NAT equipment. Even when there is the stateful operation of the NAT equipment. Even when there is
sufficient technical knowledge to manage the NAT to enable a server, sufficient technical knowledge to manage the NAT to enable external
only one server of any given protocol type is possible per address, access to a server, only one server can be mapped per protocol/
and then only when the address from the ISP is public. port-number per address, and then only when the address from the ISP
is publicly routed. When there is an upstream NAT providing private
address space to the ISP side of the private NAT, additional
negotiation with the ISP will be necessary to provide an inbound
mapping, if that is even possible.
When deploying IPv6 NAP in this environment, there are two approaches When deploying IPv6 NAP in this environment, there are two approaches
possible with respect to IPv6 addressing. possible with respect to IPv6 addressing.
o DHCPv6 Prefix-Delegation o DHCPv6 Prefix-Delegation
o ISP provides a static IPv6 address-range o ISP provides a static IPv6 address-range
For the DHCPv6-PD solution, a dynamic address allocation approach is For the DHCPv6-PD solution, a dynamic address allocation approach is
chosen. By means of the enhanced DHCPv6 protocol it is possible to chosen. By means of the enhanced DHCPv6 protocol it is possible to
have the ISP push down an IPv6 prefix range automatically towards the have the ISP push down an IPv6 prefix range automatically towards the
small private network and populate all interfaces in that small small private network and populate all interfaces in that small
skipping to change at page 21, line 29 skipping to change at page 25, line 15
While a full prefix is expected to be the primary deployment model While a full prefix is expected to be the primary deployment model
there may be cases where the ISP provides a single IPv6 address for there may be cases where the ISP provides a single IPv6 address for
use on a single piece of equipment (PC, PDA, etc.). This is expected use on a single piece of equipment (PC, PDA, etc.). This is expected
to be rare though, because in the IPv6 world the assumption is that to be rare though, because in the IPv6 world the assumption is that
there is an unrestricted availability of a large amount of globally there is an unrestricted availability of a large amount of globally
routable and unique address space. If scarcity was the motivation routable and unique address space. If scarcity was the motivation
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 if the single device available at essentially the same cost. Also it will be likely that
wants to mask its identity to the called party or its attack profile the single device wants to mask its identity to the called party or
over a short time window it will need to enable IPv6 privacy its attack profile over a shorter time window than the life of the
extensions, which in turn leads to the need for a minimum allocation ISP attachment, so it will need to enable IPv6 privacy extensions
of a /64 prefix rather than a single address. which in turn leads to the need for a minimum allocation of a /64
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,
etc.) due to the stateful operation of the NAT equipment. etc.) due to the stateful operation of the NAT equipment.
When using IPv6 NAP, this group will identify the users which are When using IPv6 NAP, this group will identify the users which are
connected via a single IPv6 address and use a single piece of connected via a single IPv6 address and use a single piece of
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 IPv4 access and transport services. They tend to have three the IP access and transport services. They tend to have three
separate IPv4 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.
o The third is the IP addresses (single or blocks) that they assign o The third is the IP addresses (single or blocks) that they assign
to customers. These can be registered addresses (usually given to to customers. These can be registered addresses (usually given to
category 5.1 and 5.2 and sometimes 5.3) or can be from a pool of category 5.1 and 5.2 and sometimes 5.3) or can be from a pool of
RFC 1918 addresses used with NAT for single user connections. RFC 1918 addresses used with IPv4 NAT for single user connections.
Therefore they can actually have two different NAT domains that Therefore they can actually have two different NAT domains that
are not connected (internal LAN and single user customers). are not connected (internal LAN and single user customers).
When IPv6 NAP is utilized in these three domains then for the first When IPv6 NAP is utilized in these three domains then for the first
category it will be possible to use the same solutions as described category it will be possible to use the same solutions as described
in Section 5.1. The second domain of the ISP/carrier is the in Section 5.1. The second domain of the ISP/carrier is the
Operations network. This environment tends to be a closed Operations network. This environment tends to be a closed
environment, and consequently communication can be done based on ULA environment, and consequently communication can be done based on ULA
addresses, however, in this environment, stable IPv6 Provider addresses, however, in this environment, stable IPv6 Provider
Independent addresses can be used in preference to ULA addresses. Independent addresses can be used. This would give a solid and
This would give a solid and scalable configuration with respect to a scalable configuration with respect to a local IPv6 address plan. By
local IPv6 address plan. By the usage of proper network edge the usage of proper network edge filters, outside access to the
filters, outside access to the closed environment can be avoided. closed environment can be avoided. The third is the IPv6 addresses
The third is the IPv6 addresses that ISP/carrier network assign to that ISP/carrier network assign to customers. These will typically
customers. These will typically be assigned with prefix lengths be assigned with prefix lengths terminating on nibble boundaries to
terminating on nibble boundaries to be consistent with the DNS PTR be consistent with the DNS PTR records. As scarcity of IPv6
records. As scarcity of IPv6 addresses is not a concern, it will be addresses is not a concern, it will be possible for the ISP to
possible for the ISP to provide global routable IPv6 prefixes without provide global routable IPv6 prefixes without a requirement for
a requirement for address translation. An ISP may for commercial address translation. An ISP may for commercial reasons still decide
reasons still decide to restrict the capabilities of the end users by to restrict the capabilities of the end users by other means like
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' [15] it is found that the IPv6 WG recommends IPv6 in 3GPP Standards' [16] 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 NAP. None of practice, is required to fully realize the benefits of NAP. None of
these items are show-stoppers for immediate usage of NAP in roles these items are show-stoppers for immediate usage of NAP in roles
where there are no current gaps. where there are no current gaps.
6.1. Subnet Topology Masking 6.1. Simple Security
Dynamic pinhole management is an area for further study. Several
partial solutions exist including ICE, UPNP, as well as alternative
proposals for Service Provider based control. The 'simple' aspect of
the security provided by a stateful firewall will require some degree
of automation to mask the technical complexity from the consumer that
only wants a secure environment with working applications.
6.2. Subnet Topology Masking
There really is no functional gap here as a centrally assigned pool There really is no functional gap here as a centrally assigned pool
of addresses in combination with host routes in the IGP is an of addresses in combination with host routes in the IGP is an
effective way to mask topology. If necessary a best practice effective way to mask topology for smaller deployments. If necessary
document could be developed describing the interaction between DHCP a best practice document could be developed describing the
and various IGPs which would in effect define Untraceable Addresses. interaction between DHCP and various IGPs which would in effect
define Untraceable Addresses.
As an alternative, some work in Mobile IP to define a policy message As an alternative for larger deployments, there is no gap in the HA
where a mobile node would learn from the Home Agent. It should not tunneling approach when firewalls are configured to block outbound
try to inform its correspondent about route optimization and thereby binding update messages. A border Home Agent using internal
expose its real location. A border Home Agent using internal tunneling to the logical mobile node (potentially rack mounted) can
tunneling to the logical mobile node (potentially static) 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. This work should be a large number of host routes in the IGP. Some optimization work
pursued in the IETF. 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
its correspondent about route optimization and thereby expose its
real location. This optimization which reduces the load on the
firewall would result in less optimal internal traffic routing as
that would also transit the HA. Trade-off's for this optimization
work should be investigated in the IETF.
6.2. Minimal Traceability of Privacy Addresses 6.3. Minimal Traceability of Privacy Addresses
Privacy addresses (RFC 3041) may certainly be used to limit the Privacy addresses (RFC 3041) may certainly be used to limit the
traceability of external traffic flows back to specific hosts, but traceability of external traffic flows back to specific hosts, but
lacking a topology masking component above they would still reveal lacking a topology masking component above they would still reveal
the subnet address bits. For complete privacy a best practice the subnet address bits. For complete privacy a best practice
document describing the combination of privacy addresses with document describing the combination of privacy addresses with
topology masking may be required. This work remains to be done, and topology masking may be required. This work remains to be done, and
should be pursued by the IETF. should be pursued by the IETF.
6.3. Renumbering Procedure
Documentation of site renumbering procedures [12] is completed and is
in the RFC-editor's queue. It should also be noticed that ULAs may
help here too, since a change of ISP prefix will only affect hosts
that need an externally routeable address as well as an ULA.
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' work, the IETF has converged on an architectural after several years of work, the IETF has converged on an
approach intended with service restoration as initial aim [20]. architectural approach intended with service restoration as initial
Again, ULAs may help since they will provide stable addressing for aim [21]. When this document was drafted, the IETF was actively
internal communications that are not affected by multihoming. defining the details of this approach to the multihoming problem.
The approach appears to be most suitable for small and medium sites,
6.5. Untraceable Addresses though it will conflict with firewall state procedures. At this time
there are also active discussions in the address registries
The details of the untraceable addresses, along with any associated investigating the possibility of assigning provider-independent
mechanisms such as route injection, must be worked out and specified. address space. Their challenge is finding a reasonable metric for
limiting the number of organizations that would qualify for a global
routing entry. Additional work appears to be necessary to satisfy
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
RFC 2663 [2] and RFC 2993 [4]. [2] and [4].
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. To the
degree that these techniques improve a network manager's ability to degree that these techniques improve a network manager's ability to
explicitly know about or control access, and thereby manage the explicitly audit or control access, and thereby manage the overall
overall attack exposure of local resources, they act to improve local attack exposure of local resources, they act to improve local network
network security. In particular the explicit nature of a content security. In particular the explicit nature of a content aware
aware firewall in NAP will be a vast security improvement over the firewall in NAP will be a vast security improvement over the NAT
NAT artifact where lack of translation state has been widely sold as artifact where lack of translation state has been widely sold as a
a form of protection. form of protection.
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
skipping to change at page 26, line 25 skipping to change at page 30, line 25
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 [10] 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 [11] 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] Baker, F., "Procedures for Renumbering an IPv6 Network without [12] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
a Flag Day", draft-ietf-v6ops-renumbering-procedure-05 (work in Neighbor Discovery (SEND)", RFC 3971, March 2005.
progress), March 2005.
[13] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast [13] Baker, F., Lear, E., and R. Droms, "Procedures for Renumbering
Addresses", draft-ietf-ipv6-unique-local-addr-09 (work in an IPv6 Network without a Flag Day", RFC 4192, September 2005.
progress), January 2005.
[14] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
11.2. Informative References 11.2. Informative References
[14] Fuller, V., Li, T., Yu, J., and K. Varadhan, "Classless Inter- [15] Fuller, V., Li, T., Yu, J., and K. Varadhan, "Classless Inter-
Domain Routing (CIDR): an Address Assignment and Aggregation Domain Routing (CIDR): an Address Assignment and Aggregation
Strategy", RFC 1519, September 1993. Strategy", RFC 1519, September 1993.
[15] Wasserman, M., "Recommendations for IPv6 in Third Generation [16] Wasserman, M., "Recommendations for IPv6 in Third Generation
Partnership Project (3GPP) Standards", RFC 3314, Partnership Project (3GPP) Standards", RFC 3314,
September 2002. September 2002.
[16] Savola, P. and B. Haberman, "Embedding the Rendezvous Point [17] Savola, P. and B. Haberman, "Embedding the Rendezvous Point
(RP) Address in an IPv6 Multicast Address", RFC 3956, (RP) Address in an IPv6 Multicast Address", RFC 3956,
November 2004. November 2004.
[17] Dupont, F. and P. Savola, "RFC 3041 Considered Harmful [18] 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.
[18] Chown, T., "IPv6 Implications for TCP/UDP Port Scanning (chown- [19] Chown, T., "IPv6 Implications for TCP/UDP Port Scanning
v6ops- port-scanning-implications-01.txt)", July 2004. (chown-v6ops-port-scanning-implications-01.txt)", July 2004.
[19] Chown, T., Tompson, M., Ford, A., and S. Venaas, "Things to [20] 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.
[20] Huston, G., "Architectural Commentary on Site Multi-homing [21] 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.
Appendix A. Additional Benefits due to Native IPv6 and Universal Unique Appendix A. Additional Benefits due to Native IPv6 and Universal
Addressing Unique 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 Aonnectivity 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
to innovate unconstrained by NAT traversal efforts, developers will to innovate unconstrained by NAT traversal efforts, developers will
be able to focus on new advanced network services (i.e. peer-to-peer be able to focus on new advanced network services (i.e. peer-to-peer
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 on the local link only 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 'Rendez-Vous Point' (or RP) makes it possible to embed the multicast 'Rendezvous Point' (or RP)
[16] directly in the IPv6 multicast address when using ASM multicast. [17] 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 encryption and protocol. This allows for simpler peer-to-peer authentication and
authentication, once a simple key/trust management model is encryption, once a simple key/trust management model is developed,
developed, while the usage of some other less secure mechanisms is while the usage of some other less secure mechanisms is avoided
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 On a local network, any user will have more security awareness.
This awareness will motivate the usage of simple firewall This awareness will motivate the usage of simple firewall
applications/devices to be inserted on the border between the applications/devices to be inserted on the border between the
external network and the local (or home network) as there is no external network and the local (or home network) as there is no
Address Translater and hance no false safety perception. Address Translator and hence no false safety perception.
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.
skipping to change at page 29, line 29 skipping to change at page 33, line 29
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 legitimate usage of RFC 1918 network infrastructure due to the usage of RFC 1918 private
private addressing. This potential overlap in address space may addressing. This potential overlap in address space may complicate a
complicate a merge of two and more networks dramatically due to the merge of two and more networks dramatically due to the additional
additional IPv4 renumbering effort. i.e. when the first network has a IPv4 renumbering effort. i.e. when the first network has a service
service running (NTP, DNS, DHCP, HTTP, etc..) which need to be running (NTP, DNS, DHCP, HTTP, etc..) which need to be accessed by
accessed by the 2nd merging network. Similar address conflicts can the 2nd merging network. Similar address conflicts can happen when
happen when two network devices from these merging networks want to two network devices from these merging networks want to communicate.
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.
A.7. Community of interest A.7. Community of interest
Although some Internet-enabled devices will function as fully-fledged Although some Internet-enabled devices will function as fully-
Internet hosts, it is believed that many will be operated in a highly fledged Internet hosts, it is believed that many will be operated in
restricted manner functioning largely or entirely within a Community a highly restricted manner functioning largely or entirely within a
of Interest. By Community of Interest we mean a collection of hosts Community of Interest. By Community of Interest we mean a collection
that are logically part of a group reflecting their ownership or of hosts that are logically part of a group reflecting their
function. Typically, members of a Community of Interest need to ownership or function. Typically, members of a Community of Interest
communicate within the community but should not be generally need to communicate within the community but should not be generally
accessible on the Internet. They want the benefits of the accessible from the public Internet. They want the benefits of the
connectivity provided by the Internet, but do not want to be exposed connectivity provided by the Internet, but do not want to be exposed
to the rest of the world. This functionality will be available to the rest of the world. The ability in NAP to virtualize the
through the usage of NAP and native IPv6 dataflows, without any topology and mask portions of it is applied to the community,
stateful device in the middle. It will also allow to build virtual creating arbitrary groupings. It will also allow building virtual
organization networks on the fly, which is very difficult to do in organization networks on the fly, which is very difficult to do in
IPv4+NAT scenarios. IPv4+NAT scenarios.
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 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 *-ietf- o Change of Draft name from *-vandevelde-v6ops-nap-01.txt to *-
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 capitelized. 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 transaltion 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
o Section 2.2: changed 'provided by NAT are actually ' into o Section 2.2: changed 'provided by NAT are actually ' into
'provided by NAT is actually' 'provided by NAT is actually'
o Section 2.2: para 3: s/actually false/actually an illusion/ o Section 2.2: para 3: s/actually false/actually an illusion/
o Section 2.2: para 2: added 'Also it will only be reliable if a o Section 2.2: para 2: added 'Also it will only be reliable if a
skipping to change at page 31, line 20 skipping to change at page 35, line 20
device's state/ device's state/
o Section 2.4: para1: clarified the definition of topology hiding o Section 2.4: para1: clarified the definition of topology hiding
o Section 2.4: last sentence of next-to-last paragraph, added o Section 2.4: last sentence of next-to-last paragraph, added
punctuation at end of sentence. punctuation at end of sentence.
o Section 2.4: added first line: When mentioning 'topology hiding' o Section 2.4: added first line: When mentioning 'topology hiding'
the goal is to make a reference that an entity outside the network the goal is to make a reference that an entity outside the network
can not make a correlation between the location of a device and can not make a correlation between the location of a device and
the address of a device on the local network. the address of a device on the local network.
o Section 2.4: para 1: s/reflected/represented/ o Section 2.4: para 1: s/reflected/represented/
o Section 2.5: last par: added reference: 'Section 2.7 describes o Section 2.5: last par: added reference: 'Section 2.7 describes
some disadvantages that appear if independednt networks using some disadvantages that appear if independent networks using
[RFC1918] addresses have to be merged.' [RFC1918] addresses have to be merged.'
o Section 2.6: Added text that private address-space is not o Section 2.6: Added text that private address-space is not
limitless limitless
o Section 2.6: Various editorial changes o Section 2.6: Various editorial changes
o Section 2.7: Para 1 editorial revised o Section 2.7: Para 1 editorial revised
o Section 2.7: last para: s/This solution/The addition of an extra o Section 2.7: last para: s/This solution/The addition of an extra
NAT as a solution/ NAT as a solution/
o Section 2.7: s/highly desirable to be/highly desirable due to o Section 2.7: s/highly desirable to be/highly desirable due to
resiliency and load-balancing to be/ resiliency and load-balancing to be/
o Section 2.7: added text on the reason why there are overlapping o Section 2.7: added text on the reason why there are overlapping
addresses addresses
o Section 2.7: last para: s/merged address space/overlapping address o Section 2.7: last para: s/merged address space/overlapping address
speaces in the merged networks/ spaces in the merged networks/
o Section 3.1: Para 1 editorial changes o Section 3.1: Para 1 editorial changes
o Section 3.1: s/by contacted web sites, so IPv6/by web sites that o Section 3.1: s/by contacted web sites, so IPv6/by web sites that
are accessed from the device: IPv6 / are accessed from the device: IPv6 /
o Section 3.1: s/as that would have a serious negative impact on o Section 3.1: s/as that would have a serious negative impact on
global routing/as that would have a negative effect on global global routing/as that would have a negative effect on global
route aggregation route aggregation
o Section 3.2: s3.2: Par 1 editorial revised and noted that ULA in o Section 3.2: s3.2: Par 1 editorial revised and noted that ULA in
global routing table is not scalable global routing table is not scalable
o Section 3.2: s3.2: Noted that it is not always interresting to mix o Section 3.2: s3.2: Noted that it is not always interesting to mix
ULA with global as that may lead to SAS issues ULA with global as that may lead to SAS issues
o Section 3.3: last para: s/delegating router/delegating router o Section 3.3: last para: s/delegating router/delegating router
(incorporating a DHCPv6 server)/, s/across an administrative/ (incorporating a DHCPv6 server)/, s/across an administrative/
possibly across an administrative/ possibly across an administrative/
o Section 3.4: Changed: 'random assignment has as purpose' to o Section 3.4: Changed: 'random assignment has as purpose' to
'random assignment has a purpose' 'random assignment has a purpose'
o Section 3.4: para 2: Replace first sentence with: 'The random o Section 3.4: para 2: Replace first sentence with: 'The random
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.' structure of the local network.'
o Section 3.4: para 2: s/there is a correlation/needs to maintain a o Section 3.4: para 2: s/there is a correlation/needs to maintain a
correlation/ correlation/
o Section 3.4: para 2: s/like a/such as a/ o Section 3.4: para 2: s/like a/such as a/
o Section 3.4: para 3: s/unpredictable/amorphous/, s/or from o Section 3.4: para 3: s/unpredictable/amorphous/, s/or from
mapping/and from mapping of/ mapping/and from mapping of/
o Section 3.4: para 3: s/are reachable on/are allocated to devices o Section 3.4: para 3: s/are reachable on/are allocated to devices
on/ on/
o Section 3.4: para 3: s/belonging to the same subnet next to each o Section 3.4: para 3: s/belonging to the same subnet next to each
other/belonging to devices adjacent to each other on the same other/belonging to devices adjacent to each other on the same
subnet/ subnet/
o Section 3.4: s/aggregation device/indirection device/ o Section 3.4: s/aggregation device/indirection device/
o Section 4.1: splitted the 1 section up into 2 separate sections o Section 4.1: split the 1 section up into 2 separate sections
o Section 4.1: s/ End node connections involving other nodes on the o Section 4.1: s/ End node connections involving other nodes on the
global Internet will always use the global IPv6 addresses [9] global Internet will always use the global IPv6 addresses [9]
derived from this prefix delegation./ End node connections derived from this prefix delegation./ End node connections
involving other nodes on the global Internet will always use the involving other nodes on the global Internet will always use the
global IPv6 addresses [9] derived from this prefix delegation. It global IPv6 addresses [9] derived from this prefix delegation. It
should be noted that the policy table needs to be correctly set up should be noted that the policy table needs to be correctly set up
so that true global prefixes are distinguished from ULAs and will so that true global prefixes are distinguished from ULAs and will
be used for the source address in preference when the destination be used for the source address in preference when the destination
is not a ULA/ is not a ULA/
o Section 4.1: A more secure network environment can be established o Section 4.1: A more secure network environment can be established
by having the referenced ULA addresses statically configured on by having the referenced ULA addresses statically configured on
the network devices as this decreases the dynamic aspects of the the network devices as this decreases the dynamic aspects of the
network, however the operational overhead is increased. network, however the operational overhead is increased.
o Section 4.2:Added note that IID should be randomized for port-scan o Section 4.2: Added note that IID should be randomized for port-
protection scan protection
o Section 4.2: Removed text: This is an automated procedure of o Section 4.2: Removed text: This is an automated procedure of
sending Internet Control Message Protocol (ICMP) echo requests sending Internet Control Message Protocol (ICMP) echo requests
(also known as PINGs) to a range of IP addresses and recording (also known as PINGs) to a range of IP addresses and recording
replies. This can enable an attacker to map the network. replies. This can enable an attacker to map the network.
o Section 4.2: paragraph beginning: "This simple rule...". The o Section 4.2: paragraph beginning: "This simple rule...". The
first sentence in this paragraph was overly-long. The sentence first sentence in this paragraph was overly-long. The sentence
has been fragmented has been fragmented
o Section 4.2: para 1: s/similar as for an/similar to that of an/ o Section 4.2: para 1: s/similar as for an/similar to that of an/
o Section 4.2: para 1: s/Internet, and firewall and IDS systems are/ o Section 4.2: para 1: s/Internet, and firewall and IDS systems are/
Internet. The use of firewall and Intrusion Detection Systems Internet. The use of firewall and Intrusion Detection Systems
skipping to change at page 33, line 20 skipping to change at page 37, line 20
best practices are trying to achieve./IPv6 security best practices best practices are trying to achieve./IPv6 security best practices
will avoid this kind of illusory security but can only do this if will avoid this kind of illusory security but can only do this if
correctly configured firewalls and IDS systems are used at the correctly configured firewalls and IDS systems are used at the
perimeter where some IPv4 networks have relied on NATs. perimeter where some IPv4 networks have relied on NATs.
o Section 4.2: s/ It is recommended for site administrators to take o Section 4.2: s/ It is recommended for site administrators to take
[17] into consideration to achieve the expected goal./ It is [17] into consideration to achieve the expected goal./ It is
recommended for site administrators to take [17] into recommended for site administrators to take [17] into
consideration to achieve the expected goal. This protection will consideration to achieve the expected goal. This protection will
also be nullified if IIDs are configured in a group near the start also be nullified if IIDs are configured in a group near the start
of the IID space./ of the IID space./
o Section 4.2: Removed the example study and added complementiory o Section 4.2: Removed the example study and added complementary
text to describe a potential behavior text to describe a potential behavior
o Section 4.4: rewrite of the section to reduce the importance of o Section 4.4: rewrite of the section to reduce the importance of
the MIpv^ and tunneled solution the MIPv6 and tunneled solution
o Section 4.4: (Privacy and Topology Hiding) Mobile IP is suggested o Section 4.4: (Privacy and Topology Hiding) Mobile IP is suggested
in the text, however text is added that any kind of tunneling in the text, however text is added that any kind of tunneling
should do the trick. should do the trick.
o Section 4.4: para 2: after 'As discussed above' inserted '(see o Section 4.4: para 2: after 'As discussed above' inserted '(see
Section 3.1)' Section 3.1)'
o Section 4.4: para 3: s/consolidated on/indirected via/ o Section 4.4: para 3: s/consolidated on/indirected via/
o Section 4.4: para 3: s/topololgy masked/each topology masked/ o Section 4.4: para 3: s/topololgy masked/each topology masked/
o Section 4.4: para 3: Expanded acronym COA o Section 4.4: para 3: Expanded acronym COA
o Section 4.4: para 3: s/rack mounted/static/ o Section 4.4: para 3: s/rack mounted/static/
o Section 4.4: Rephrasing of text happened in this section o Section 4.4: Rephrasing of text happened in this section
o Section 4.5: change: "so that a NAT is not required" to: "so that o Section 4.5: change: "so that a NAT is not required" to: "so that
IPv6 address translation is not required". IPv6 address translation is not required".
o Section 4.5: changed 'periodically to look' into 'to look o Section 4.5: changed 'periodically to look' into 'to look
periodically' periodically'
o Section 4.5: change: "2^64 hosts" to: "2^64 addresses". o Section 4.5: change: "2^64 hosts" to: "2^64 addresses".
o Section 4.5: Removed the statement '(or even defined) o Section 4.5: Removed the statement '(or even defined)
o Section 4.6: last para: s/which will lead to the IPv4 practice/ o Section 4.6: last para: s/which will lead to the IPv4 practice/
which will require the adoption of the IPv4 workaround/ which will require the adoption of the IPv4 workaround/
o Section 4.6: s/the IPv4 constricting scenarios of multiple devices o Section 4.6: s/the IPv4 constricting scenarios of multiple devices
sharing a/the constriction of IPv4 scenarios where multiple devies sharing a/the constriction of IPv4 scenarios where multiple
are forced to share a/ devices are forced to share a/
o Section 4.7: s/as the zero-touch external/as an almost zero-touch o Section 4.7: s/as the zero-touch external/as an almost zero-touch
external/ external/
o Section 5: Replaced first three sentences with: In presenting o Section 5: Replaced first three sentences with: In presenting
these case studies we have chosen to consider categories of these case studies we have chosen to consider categories of
network divided first according to their function either as network divided first according to their function either as
carrier/ISP networks or end user (such as enterprise) networks carrier/ISP networks or end user (such as enterprise) networks
with the latter category broken down according to the number of with the latter category broken down according to the number of
connected end hosts. connected end hosts.
o Section 5: bullet points: s/connection/connected end hosts/ o Section 5: bullet points: s/connection/connected end hosts/
o Section 5.1: s/addressing independence/addressing independence o Section 5.1: s/addressing independence/addressing independence
when using IPv4/ when using IPv4/
o Section 5.1: last para: s/is only affecting/will only affect/ o Section 5.1: last para: s/is only affecting/will only affect/
o Section 5.1: changed 'alloaction' into 'allocation' o Section 5.1: changed 'allocation' into 'allocation'
o Section 5.1: changed: '(typically a one or' into '(typically one o Section 5.1: changed: '(typically a one or' into '(typically one
or' or'
o section 5.1: changed: s/allocation/assignment/ in one of the o section 5.1: changed: s/allocation/assignment/ in one of the
paragraphs paragraphs
o section 5.2: para 1: s?is too long?is too long (very often just a o section 5.2: para 1: s?is too long?is too long (very often just a
/32 just giving a single address)? /32 just giving a single address)?
o Section 5.4: (Case study: ISP networks) ULA usage for ISP/ o Section 5.4: (Case study: ISP networks) ULA usage for ISP/
Carrier-grade networks is mentioned in the draft, while it was Carrier-grade networks is mentioned in the draft, while it was
suggested that for these NW the PI addresses are already very suggested that for these NW the PI addresses are already very
stable and they should be qualified for setting up proper stable and they should be qualified for setting up proper
skipping to change at page 35, line 5 skipping to change at page 38, line 35
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
o Editorial changes in response to IESG review comments and
questions.
o Introduction: clarified impact & goal for limited additional NAT
discussion here / modified tone wrt marketing / grammar cleanup
o Introduction: s/market acceptance/deployment
o Introduction: noted that users do not evaluate technical trade-
offs and that marketing does not mention the downside of address
translation
o Introduction: added paragraph about why nat != security
o Table1: s/benefit/Goal/ s/ULA/4193/ removed long numeric string /
added app end points & number of subnets
o Section 2: tone reduction about marketing
o Section 2.1: grammar cleanup / clarified point about use of public
space / added paragraph about topology restrictions / removed last
paragraph about security
o Section 2.2: moved paragraph about firewalls to 4.2 / deleted
discussion about distributed security / clarified point about port
overload
o Section 2.3: Added opening sentence to explain the goal of the
section / changed comment about theory to an absolute / qualified
logging and checking times
o Section 2.4: deleted confusing/redundant comments about identifier
/ clarified point about nodes appearing to be at the edge / added
clarification that focused scanning on the port range reaches
active nodes
o Section 2.5: clarified that the reason for autonomy is large space
& impact was on the local network
o Section 2.6: clarified point about reduction of IPv4 consumption
rate / s/30%/25% / added point about limitations of cascaded nat /
added para about limited app endpoints as well as topology
restrictions
o Section 2.7: clarification about why multihoming & renumbering are
discussed together / point about sparse allocation / s/speaces/
spaces
o Section 3: s/emulate/replace / added para about 'gaps' being
discussed later
o Section 3.1: Cleaned up description of SLAAC & 3041 / specified
server as DHCP / added comment about sparse allocation
o Section 3.2: grammar cleanup / updated reference from ID to RFC
4193 / added point about policy table in 3484 to bias ULA over ISP
prefix
o Section 3.3: Clarification about goal for section
o Section 3.4: reorder paragraphs to put goal up front
o Section 4.1: s/could/should/ s/prior to establishing/independent
of the state of / clarified why concatenation would not collide /
another comment about the 3484 table for ULA biasing / clarified
point about lack of routing protocol
o Section 4.2: clarified point about firewall at boundary /
clarified point about valid lifetime / clarified point that IPsec
works the same w/o NAT / added point about authenticating
correspondent / clarified that the scanning threat is addresses as
ports are the same once an address is known / rearranged paragraph
to keep scanning thread together / inserted firewall discussion
moved from 2.2 / clarified role of simple firewall / added comment
about service provider mediated pinhole management
o Section 4.3: added paragraph about tracking privacy address use
o Section 4.4: clarified point about tracking wrt NAT / added
comment about IGP complexity / s/conceal/isolate/ s/possible/
potential/ reworded ULA description which was technically
backwards / additional description of the goal / added picture and
referenced it from descriptions converted options to descriptive
list / added discussion about blocking binding updates / added
vlan option / s/would be to use/uses to make it clear this already
works / para 2 s/prefixes/addresses and replaced last part of the
sentence to clarify what was being hidden.
o Section 4.5: Grammar cleanup / clarification about policy
o Section 4.6: replaced long number string with power qnty of
subnets / added reference to new capabilities like SEND
o Section 4.7: s/CIDR-like/CIDR allocated/ s/this/to multiple
addresses/ s/may/will likely/ s/if/when/ s/from SP/between sp/
Updated reference for renumbering proceedure to RFC 4192
o Section 5: d/of these/
o Section 5.1: s/private enterprise/private enterprise, academic,
research, or government / deleted redundant discussion about /48
allocation / added discussion about larger deployments using
tunneling /
o Section 5.2: clarification of overload on port vs. protocol /
added comment about upstream NAT / clarified 3041 use as short
timeframe
o Section 5.3: capitalize Internet
o Section 5.4: s/IPv4/IP as role is not version specific / deleted
comment about preference to ULA.
o Section 6.1: (security) inserted section discussing need for
dynamic pinhole management
o Section 6.2: (topology mask) added comment about deployment scale
/ added comment about firewall blocking BU / clarified point about
future work being an optimization to reduce firewall load
o Section 6.3: (tracability) grammar cleanup
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.6: deleted 'legitimate'
o Section A.7: clarified how NAP delivers community of interest
o Spell check
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
skipping to change at page 36, line 41 skipping to change at page 42, line 41
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
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