draft-ietf-v6ops-addr-select-ps-01.txt   draft-ietf-v6ops-addr-select-ps-02.txt 
IPv6 Operations Working Group A. Matsumoto IPv6 Operations Working Group A. Matsumoto
Internet-Draft T. Fujisaki Internet-Draft T. Fujisaki
Intended status: Informational NTT Intended status: Standards Track NTT
Expires: October 7, 2007 R. Hiromi Expires: April 13, 2008 R. Hiromi
K. Kanayama K. Kanayama
Intec Netcore Intec Netcore
April 5, 2007 October 11, 2007
Problem Statement of Default Address Selection in Multi-prefix Problem Statement of Default Address Selection in Multi-prefix
Environment: Operational Issues of RFC3484 Default Rules Environment: Operational Issues of RFC3484 Default Rules
draft-ietf-v6ops-addr-select-ps-01.txt draft-ietf-v6ops-addr-select-ps-02.txt
Status of this Memo Status of this Memo
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applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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skipping to change at page 1, line 38 skipping to change at page 1, line 38
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on October 7, 2007. This Internet-Draft will expire on April 13, 2008.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
Abstract Abstract
One physical network can carry multiple logical networks. Moreover, One physical network can carry multiple logical networks. Moreover,
we can use multiple physical networks at the same time in a host. In we can use multiple physical networks at the same time in a host. In
that environment, end-hosts might have multiple IP addresses and be that environment, end hosts might have multiple IP addresses and be
required to use them selectively. Without an appropriate source/ required to use them selectively. Without an appropriate source/
destination address selection mechanism, the host will experience destination address selection mechanism, the host will experience
some trouble in the communication. RFC 3484 defines both the source some trouble in communication. RFC 3484 defines both the source and
and destination address selection algorithms, but the multi-prefix destination address selection algorithms, but the multi-prefix
environment considered here needs additional rules beyond the default environment considered here needs additional rules beyond those of
operation. This document describes the possible problems that end- the default operation. This document describes the possible problems
hosts could encounter in an environment with multiple logical that end hosts could encounter in an environment with multiple
networks. logical networks.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Scope of this document . . . . . . . . . . . . . . . . . . 3 1.1. Scope of this document . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Source Address Selection . . . . . . . . . . . . . . . . . 3 2.1. Source Address Selection . . . . . . . . . . . . . . . . . 3
2.1.1. Multiple Routers on Single Interface . . . . . . . . . 4 2.1.1. Multiple Routers on Single Interface . . . . . . . . . 4
2.1.2. Ingress Filtering Problem . . . . . . . . . . . . . . 5 2.1.2. Ingress Filtering Problem . . . . . . . . . . . . . . 5
2.1.3. Half-Closed Network Problem . . . . . . . . . . . . . 5 2.1.3. Half-Closed Network Problem . . . . . . . . . . . . . 5
skipping to change at page 2, line 35 skipping to change at page 2, line 35
2.2. Destination Address Selection . . . . . . . . . . . . . . 8 2.2. Destination Address Selection . . . . . . . . . . . . . . 8
2.2.1. IPv4 or IPv6 prioritization . . . . . . . . . . . . . 8 2.2.1. IPv4 or IPv6 prioritization . . . . . . . . . . . . . 8
2.2.2. ULA and IPv4 dual-stack environment . . . . . . . . . 9 2.2.2. ULA and IPv4 dual-stack environment . . . . . . . . . 9
2.2.3. ULA or Global Prioritization . . . . . . . . . . . . . 10 2.2.3. ULA or Global Prioritization . . . . . . . . . . . . . 10
3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4. Security Considerations . . . . . . . . . . . . . . . . . . . 11 4. Security Considerations . . . . . . . . . . . . . . . . . . . 11
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Normative References . . . . . . . . . . . . . . . . . . . 12 6.1. Normative References . . . . . . . . . . . . . . . . . . . 12
6.2. Informative References . . . . . . . . . . . . . . . . . . 12 6.2. Informative References . . . . . . . . . . . . . . . . . . 12
Appendix A. Appendix. Revision History . . . . . . . . . . . . . 12 Appendix A. Appendix. Revision History . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . . . 14 Intellectual Property and Copyright Statements . . . . . . . . . . 15
1. Introduction 1. Introduction
One physical network can carry multiple logical networks. In that One physical network can carry multiple logical networks. In that
case, an end-host has multiple IP addresses. In the IPv4-IPv6 dual case, an end-host has multiple IP addresses. In the IPv4-IPv6 dual
stack environment or in a site connected to both ULA [RFC4193] and stack environment or in a site connected to both a ULA [RFC4193] and
Global scope networks, an end-host has multiple IP addresses. These Global scope networks, an end-host has multiple IP addresses. These
are examples of the networks that we focus on in this document. In are examples of networks that we focus on in this document. In such
such an environment, an end-host will encounter some communication an environment, an end-host will encounter some communication
trouble. trouble.
Inappropriate source address selection at the end-host causes Inappropriate source address selection at the end-host causes
unexpected asymmetric routing or filtering by a router on the way unexpected asymmetric routing, filtering by a router or discarding of
back or discard due to there being no route to the host. packets bacause there is no route to the host.
Considering a multi-prefix environment, the destination address Considering a multi-prefix environment, destination address selection
selection is also important for correct communication establishment. is also important for correct or better communication establishment.
The key to the appropriate process will come from the way to
configure the source address and destination address to the
interfaces at the end-hosts by the network policy of the site.
RFC 3484 [RFC3484] defines both source and destination address RFC 3484 [RFC3484] defines both source and destination address
selection algorithms. In most cases, the host will be able to selection algorithms. In most cases, the host will be able to
communicate with the targeted host using the algorithms. But there communicate with the targeted host using the algorithms. However,
are still problematic cases such as when multiple default routes are there are still problematic cases such as when multiple default
supplied. This document describes such possibilities of false routes are supplied. This document describes such possibilities of
dropping during address selection. incorrect address selection, which leads to dropping packets and
communication failure.
In addition, the provision of an address policy table is an important In addition, the provision of an address policy table is an important
matter. RFC 3484 describes all the algorithms for setting the matter. RFC 3484 describes all the algorithms for setting the
address policy table but it makes no mention of the provisions of address policy table but address policy provisions are not mentioned.
address policy and does not define how to set it except manually. RFC 3484 only defines how to configure the address policy table
manually.
1.1. Scope of this document 1.1. Scope of this document
There has been a lot of discussion about "multiple addresses/ There has been a lot of discussion about "multiple addresses/
prefixes" but the multi-homing issues for redundancy are out of our prefixes" but the multi-homing techniques for achieving redundancy
scope. Cooperation with a mechanism like shim6 is rather desirable. are out of our scope. Cooperation with a mechanism like shim6 is
We focus on an end-site network environment. The scope of this rather desirable. We focus on an end-site network environment. The
document is to sort out problematic cases of false dropping of the scope of this document is to sort out problematic cases of false
address selection within a multi-prefix environment. dropping of the address selection within a multi-prefix environment.
2. Problem Statement 2. Problem Statement
2.1. Source Address Selection 2.1. Source Address Selection
2.1.1. Multiple Routers on Single Interface 2.1.1. Multiple Routers on Single Interface
================== ==================
| Internet | | Internet |
================== ==================
skipping to change at page 4, line 32 skipping to change at page 4, line 32
| | | |
-----+-+-----+------ -----+-+-----+------
| |
+-+----+ 2001:db8:1000:1::EUI64 +-+----+ 2001:db8:1000:1::EUI64
| Host | 2001:db8:8000:1::EUI64 | Host | 2001:db8:8000:1::EUI64
+------+ +------+
[Fig. 1] [Fig. 1]
Generally speaking, there is no interaction between next-hop Generally speaking, there is no interaction between next-hop
determination and address selection. In this example, when Host determination and address selection. In this example, when a Host
sends a packet via Gateway1, the Host does not necessarily choose the sends a packet via Gateway1, the Host does not necessarily choose
address 2001:db8:1000:1::EUI64 given by Gateway1 as the source address 2001:db8:1000:1::EUI64 given by Gateway1 as the source
address. This causes the same problem as described in the next address. This causes the same problem as described in the next
section 'Ingress Filtering Problem'. section 'Ingress Filtering Problem'.
2.1.2. Ingress Filtering Problem 2.1.2. Ingress Filtering Problem
================== ==================
| Internet | | Internet |
================== ==================
| | | |
skipping to change at page 5, line 37 skipping to change at page 5, line 37
[Fig. 2] [Fig. 2]
When a relatively small site, which we call a "customer network", is When a relatively small site, which we call a "customer network", is
attached to two upstream ISPs, each ISP delegates a network address attached to two upstream ISPs, each ISP delegates a network address
block, which is usually /48, and a host has multiple IPv6 addresses. block, which is usually /48, and a host has multiple IPv6 addresses.
When the source address of an outgoing packet is not the one that is When the source address of an outgoing packet is not the one that is
delegated by an upstream ISP, there is a possibility that the packet delegated by an upstream ISP, there is a possibility that the packet
will be dropped at the ISP by its Ingress Filter. Ingress will be dropped at the ISP by its Ingress Filter. Ingress
filtering(uRPF: unicast Reverse Path Forwarding) is becoming more and filtering(uRPF: unicast Reverse Path Forwarding) is becoming more
more popular among ISPs in order to mitigate the damage of DoS popular among ISPs to mitigate the damage of DoS attacks.
attacks.
In this example, when the Gateway chooses the default route to ISP2 In this example, when the Gateway chooses the default route to ISP2
and the Host chooses 2001:db8:1000:1::EUI64 as the source address for and the Host chooses 2001:db8:1000:1::EUI64 as the source address for
packets sent to a host(2001:db8:2000::1) somewhere in the Internet, packets sent to a host (2001:db8:2000::1) somewhere on the Internet,
the packets may be dropped at ISP2 because of Ingress Filtering. the packets may be dropped at ISP2 because of Ingress Filtering.
2.1.3. Half-Closed Network Problem 2.1.3. Half-Closed Network Problem
You can see a second typical source address selection problem in a You can see a second typical source address selection problem in a
multihome site with global-closed mixed connectivity like the figure multihome site with global-closed mixed connectivity like in the
below. In this case, Host-A is in a multihomed network and has two figure below. In this case, Host-A is in a multihomed network and
IPv6 addresses, one delegated from each of the upstream ISPs. Note has two IPv6 addresses, one delegated from each of the upstream ISPs.
that ISP2 is a closed network and does not have connectivity to the Note that ISP2 is a closed network and does not have connectivity to
Internet. the Internet.
+--------+ +--------+
| Host-C | 2001:db8:a000::1 | Host-C | 2001:db8:a000::1
+-----+--+ +-----+--+
| |
============== +--------+ ============== +--------+
| Internet | | Host-B | 2001:db8:8000::1 | Internet | | Host-B | 2001:db8:8000::1
============== +--------+ ============== +--------+
| | | |
2001:db8:1000:/36 | | 2001:db8:8000::/36 2001:db8:1000:/36 | | 2001:db8:8000::/36
skipping to change at page 6, line 33 skipping to change at page 6, line 32
| 2001:db8:1000:1::/64 | 2001:db8:1000:1::/64
| 2001:db8:8000:1::/64 | 2001:db8:8000:1::/64
------+---+---------- ------+---+----------
| |
+--+-----+ 2001:db8:1000:1::EUI64 +--+-----+ 2001:db8:1000:1::EUI64
| Host-A | 2001:db8:8000:1::EUI64 | Host-A | 2001:db8:8000:1::EUI64
+--------+ +--------+
[Fig. 3] [Fig. 3]
You don't need two physical network connection here. The connection You do not need two physical network connections here. The
from Gateway to ISP2 can be a logical link over ISP1 and the connection from the Gateway to ISP2 can be a logical link over ISP1
Internet. and the Internet.
When Host-A starts the connection to Host-B in ISP2, the source When Host-A starts the connection to Host-B in ISP2, the source
address of a sending packet will be the one delegated from ISP2, that address of a packet that has been sent will be the one delegated from
is 2001:db8:8000:1::EUI64, because of rule 8 (longest matching ISP2, that is 2001:db8:8000:1::EUI64, because of rule 8 (longest
prefix) in RFC 3484. matching prefix) in RFC 3484.
Host-C is located somewhere in the Internet and has an IPv6 address Host-C is located somewhere on the Internet and has IPv6 address
2001:db8:a000::1. When Host-A sends a packet to Host-C, the longest 2001:db8:a000::1. When Host-A sends a packet to Host-C, the longest
matching algorithm chooses 2001:db8:8000:1::EUI64 for the source matching algorithm chooses 2001:db8:8000:1::EUI64 for the source
address. In this case, the packet goes through ISP1 and may be address. In this case, the packet goes through ISP1 and may be
filtered by ISP1's ingress filter. Even if the packet is fortunately filtered by ISP1's ingress filter. Even if the packet is not
not filtered by ISP1, a return packet from Host-C cannot possibly be filtered by ISP1, a return packet from Host-C cannot possibly be
delivered to Host-A because the return packet is destined for 2001: delivered to Host-A because the return packet is destined for 2001:
db8:8000:1::EUI64, which is closed from the Internet. db8:8000:1::EUI64, which is closed from the Internet.
What is important is that each host chooses a correct source address The important point is that each host chooses a correct source
for a given destination address as far as NAT does not exist in the address for a given destination address as long as NAT does not exist
IPv6 world. in the IPv6 world.
2.1.4. Combined Use of Global and ULA 2.1.4. Combined Use of Global and ULA
============ ============
| Internet | | Internet |
============ ============
| |
| |
+----+----+ +----+----+
| ISP | | ISP |
skipping to change at page 7, line 33 skipping to change at page 7, line 31
fd01:2:3:200:/64 | | fd01:2:3:100:/64 fd01:2:3:200:/64 | | fd01:2:3:100:/64
-----+--+- -+--+---- -----+--+- -+--+----
| | | |
fd01:2:3:200::EUI64 | | 2001:db8:a:100::EUI64 fd01:2:3:200::EUI64 | | 2001:db8:a:100::EUI64
+----+----+ +-+----+ fd01:2:3:100::EUI64 +----+----+ +-+----+ fd01:2:3:100::EUI64
| Printer | | Host | | Printer | | Host |
+---------+ +------+ +---------+ +------+
[Fig. 4] [Fig. 4]
As NAP [I-D.ietf-v6ops-nap] describes, using ULA may be beneficial in As NAP [I-D.ietf-v6ops-nap] describes, using a ULA may be beneficial
some scenarios. If ULA is used for internal communication, packets in some scenarios. If the ULA is used for internal communication,
with ULA addresses need to be filtered at Gateway. packets with ULA need to be filtered at the Gateway.
There is no serious problem related to address selection in this There is no serious problem related to address selection in this
case, thanks to the unlikeness of ULA and Global Unicast Address for case, because of the dissimilarity between the ULA and the Global
now. RFC 3484's longest matching rule chooses the correct address Unicast Address. The longest matching rule of RFC 3484 chooses the
for both intra-site and extra-site communication. correct address for both intra-site and extra-site communication.
In a few years, however, the longest matching rule will not be able In a few years, however, the longest matching rule will not be able
to choose the correct address anymore: the moment the assignment of to choose the correct address anymore. That is the moment when the
those Global Unicast Addresses whose beginning bit is 1 starts. In assignment of those Global Unicast Addresses starts, where the first
RFC 4291 [RFC4291], almost all the space of IPv6, including those bit is 1. In RFC 4291 [RFC4291], almost all address spaces of IPv6,
with beginning bit 1, is assigned as Global Unicast Addresses. including those whose first bit is 1, are assigned as Global Unicast
Addresses.
2.1.5. Site Renumbering 2.1.5. Site Renumbering
RFC 4192 [RFC4192] describes a recommended procedure for renumbering RFC 4192 [RFC4192] describes a recommended procedure for renumbering
a network from one prefix to another. An auto-configured address has a network from one prefix to another. An autoconfigured address has
a lifetime, so by stopping advertisement of the old prefix it is a lifetime, so by stopping advertisement of the old prefix, the
eventually invalidated. autoconfigured address is eventually invalidated.
However, it takes a long time to invalidate the old prefix. You However, invalidating the old prefix takes a long time. You cannot
cannot stop routing to the old prefix as long as the old prefix is stop routing to the old prefix as long as the old prefix is not
not deprecated. This issue can be a tough issue for ISP network removed from the host. This can be a tough issue for ISP network
administrator. administrators.
+-----+---+ +-----+---+
| Gateway | | Gateway |
+----+----+ +----+----+
| 2001:db8:b::/64 (new) | 2001:db8:b::/64 (new)
| 2001:db8:a::/64 (old) | 2001:db8:a::/64 (old)
------+---+---------- ------+---+----------
| |
+--+-----+ 2001:db8:b::EUI64 (new) +--+-----+ 2001:db8:b::EUI64 (new)
| Host-A | 2001:db8:a::EUI64 (old) | Host-A | 2001:db8:a::EUI64 (old)
+--------+ +--------+
[Fig. 5] [Fig. 5]
2.1.6. Multicast Source Address Selection 2.1.6. Multicast Source Address Selection
This case is an example of Site-local or Global prioritization. When This case is an example of Site-local or Global prioritization. When
you send a multicast packet across site-borders, the source address you send a multicast packet across site-borders, the source address
of the multicast packet must be a global scope address. The longest of the multicast packet must be a global scope address. The longest
matching algorithm, however, selects a ULA address if the sending matching algorithm, however, selects a ULA if the sending host has
host has both a ULA and a global address. both a ULA and a global address.
2.1.7. Temporary Address Selection 2.1.7. Temporary Address Selection
RFC 3041 [RFC3041] defines a Temporary Address. The usage of RFC 3041 [RFC3041] defines a Temporary Address. The usage of a
Temporary Address has both pros and cons. It is good for viewing Temporary Address has both pros and cons. That is good for viewing
web-pages or communicating with the general public, but it is bad for web pages or communicating with the general public, but that is bad
a service that uses address-based authentication and for logging for a service that uses address-based authentication and for logging
purpose. purposes.
It would be better if you could turn the temporary address on and If you could turn the temporary address on and off, that would be
off. It would also be better if you could switch its usage per better. If you could switch its usage per service(destination
service(destination address). The same situation can be found when address), that would also be better. The same situation can be found
using HA and CoA in MobileIP network. when using HA and CoA in a MobileIP network.
2.2. Destination Address Selection 2.2. Destination Address Selection
2.2.1. IPv4 or IPv6 prioritization 2.2.1. IPv4 or IPv6 prioritization
The default policy table gives IPv6 addresses higher precedence than The default policy table gives IPv6 addresses higher precedence than
IPv4 addresses. There seem to be many cases, however, where network IPv4 addresses. There seem to be many cases, however, where network
administrators want to control the address selection policy of end- administrators want to control the address selection policy of end-
hosts the other way around. hosts the other way around.
skipping to change at page 9, line 38 skipping to change at page 9, line 36
| 192.0.2.0/28 | 192.0.2.0/28
| |
------+---+---------- ------+---+----------
| |
+-+----+ 2001:db8:a:1:EUI64 +-+----+ 2001:db8:a:1:EUI64
| Host | 192.0.2.2 | Host | 192.0.2.2
+------+ +------+
[Fig. 6] [Fig. 6]
In the figure above, a site has native IPv4 and tunneled IPv6 In the figure above, a site has native IPv4 and tunneled-IPv6
connectivity. Therefore, the administrator may want to set a higher connectivity. Therefore, the administrator may want to set a higher
priority for using IPv4 than using IPv6 because the quality of the priority for using IPv4 than using IPv6 because the quality of the
tunnel network seems to be worse than that of the native transport. tunnel network seems to be worse than that of the native transport.
2.2.2. ULA and IPv4 dual-stack environment 2.2.2. ULA and IPv4 dual-stack environment
This is a special form of IPv4 and IPv6 prioritization. When an This is a special form of IPv4 and IPv6 prioritization. When an
enterprise has IPv4 Internet connectivity but does not yet have IPv6 enterprise has IPv4 Internet connectivity but does not yet have IPv6
Internet connectivity, and the enterprise wants to provide site-local Internet connectivity, and the enterprise wants to provide site-local
IPv6 connectivity, ULA is the best choice for site-local IPv6 IPv6 connectivity, a ULA is the best choice for site-local IPv6
connectivity. Each employee host will have both an IPv4 global or connectivity. Each employee host will have both an IPv4 global or
private address and a ULA. Here, when this host tries to connect to private address and a ULA. Here, when this host tries to connect to
Host-C that has registered both A and AAAA records in the DNS, the Host-C that has registered both A and AAAA records in the DNS, the
host will choose AAAA as the destination address and ULA for the host will choose AAAA as the destination address and the ULA for the
source address. This will clearly result in a connection failure. source address. This will clearly result in a connection failure.
+--------+ +--------+
| Host-C | AAAA = 2001:db8::80 | Host-C | AAAA = 2001:db8::80
+-----+--+ A = 192.0.2.1 +-----+--+ A = 192.0.2.1
| |
============ ============
| Internet | | Internet |
============ ============
| no IPv6 connectivity | no IPv6 connectivity
skipping to change at page 10, line 36 skipping to change at page 10, line 34
------+---+---------- ------+---+----------
| |
+-+----+ fd01:2:3:4::100 (ULA) +-+----+ fd01:2:3:4::100 (ULA)
| Host | 192.0.2.245 | Host | 192.0.2.245
+------+ +------+
[Fig. 7] [Fig. 7]
2.2.3. ULA or Global Prioritization 2.2.3. ULA or Global Prioritization
It is very common to differentiate services by the client's source Differentiating services by the client's source address is very
address. IP-address-based authentication is an extreme example of common. IP-address-based authentication is an typical example of
this. Another typical example is a web service that has pages for this. Another typical example is a web service that has pages for
the public and internal pages for employees or involved parties. Yet the public and internal pages for employees or involved parties. Yet
another example is DNS zone splitting. another example is DNS zone splitting.
However, ULA and IPv6 global address both have global scope, and However, a ULA and IPv6 global address both have global scope, and
RFC3484 default rules do not specify which address should be given RFC3484 default rules do not specify which address should be given
priority. This point makes IPv6 implementation of address-based priority. This point makes IPv6 implementation of address-based
service differentiation a bit harder. service differentiation a bit harder.
+------+ +------+
| Host | | Host |
+-+--|-+ +-+--|-+
| | | |
===========|== ===========|==
| Internet | | | Internet | |
skipping to change at page 11, line 48 skipping to change at page 11, line 48
host must choose an appropriate destination and source address, which host must choose an appropriate destination and source address, which
cannot be achieved only by routers. cannot be achieved only by routers.
It should be noted that end-hosts must be informed about routing It should be noted that end-hosts must be informed about routing
policies of their upstream networks for appropriate address policies of their upstream networks for appropriate address
selection. A site administrator must consider every possible address selection. A site administrator must consider every possible address
false-selection problem and take countermeasures beforehand. false-selection problem and take countermeasures beforehand.
4. Security Considerations 4. Security Considerations
Address false-selection can lead to serious security problem, such as When an intermediate router performs policy routing (e.g. source
session hijack. However, it should be noted that address selection address based routing), inappropriate address selection causes
is eventually up to end-hosts. We have no means to enforce one unexpected routing. For example, in the network described in 2.1.3,
specific address selection policy to every end-host. So, a network when Host-A uses a default address selection policy and chooses an
administrator has to take countermeasures for unexpected address inappropriate address, a packet sent to VPN can be delivered to a
selection. location via the Internet. This issue can lead to packet
eavesdropping or session hijack.
As documented in the security consideration section in RFC 3484,
address selection algorithms expose a potential privacy concern.
When a malicious host can make a target host perform address
selection, the malicious host can know multiple addresses attached to
the target host. In a case like 2.1.4, if an attacker can make Host
to send a multicast packet and the Host performs the default address
selection algorithm, the attacker may be able to determine the ULAs
attached to the Host.
These security risks have roots in inappropriate address selection.
Therefore, if a countermeasure is taken, and hosts always select an
appropriate address that is suitable to a site's network structure
and routing, these risks can be avoided.
5. IANA Considerations 5. IANA Considerations
This document has no actions for IANA. This document has no actions for IANA.
6. References 6. References
6.1. Normative References 6.1. Normative References
[RFC3484] Draves, R., "Default Address Selection for Internet [RFC3484] Draves, R., "Default Address Selection for Internet
skipping to change at page 13, line 4 skipping to change at page 13, line 13
September 2005. September 2005.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006. Architecture", RFC 4291, February 2006.
Appendix A. Appendix. Revision History Appendix A. Appendix. Revision History
01: 01:
IP addresse notations changed to docmentation address. IP addresse notations changed to docmentation address.
Descriptoin of solutions deleted. Descriptoin of solutions deleted.
02:
Security considerations section rewritten according to comments
from SECDIR.
Authors' Addresses Authors' Addresses
Arifumi Matsumoto Arifumi Matsumoto
NTT PF Lab NTT PF Lab
Midori-Cho 3-9-11 Midori-Cho 3-9-11
Musashino-shi, Tokyo 180-8585 Musashino-shi, Tokyo 180-8585
Japan Japan
Phone: +81 422 59 3334 Phone: +81 422 59 3334
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