Internet DRAFT - draft-gont-6man-address-usage-recommendations
draft-gont-6man-address-usage-recommendations
IPv6 maintenance Working Group (6man) F. Gont
Internet-Draft SI6 Networks / UTN-FRH
Intended status: Informational G. Gont
Expires: September 10, 2020 SI6 Networks
C. Huitema
Private Octopus Inc.
March 9, 2020
Problem Statement Regarding IP Address Usage
draft-gont-6man-address-usage-recommendations-05
Abstract
This document analyzes the security and privacy implications of IPv6
addresses based on a number of properties (such as address scope,
stability, and usage type), and identifies gaps that currently
prevent systems and applications from leveraging the increased
flexibility and availability of IPv6 addresses.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. IPv6 Address Properties . . . . . . . . . . . . . . . . . . . 4
4.1. Address Scope Considerations . . . . . . . . . . . . . . 4
4.2. Address Stability Considerations . . . . . . . . . . . . 5
4.3. Usage Type Considerations . . . . . . . . . . . . . . . . 6
5. Default Address Selection in IPv6 . . . . . . . . . . . . . . 8
6. Current Possible Approaches for IPv6 Address Usage . . . . . 9
6.1. Incoming communications . . . . . . . . . . . . . . . . . 9
6.2. Outgoing communications . . . . . . . . . . . . . . . . . 10
7. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Issues Associated with Sub-optimal IPv6 Address Usage . . 10
7.1.1. Correlation of Network Activity . . . . . . . . . . . 10
7.1.2. Testing for the Presence of Node in the Network . . . 11
7.1.3. Unexpected Address Discovery . . . . . . . . . . . . 11
7.1.4. Availability Outside the Expected Scope . . . . . . . 12
7.2. Current Limitations in the Address Selection APIs . . . . 12
7.3. Sub-optimal IPv6 Address Configuration . . . . . . . . . 13
7.4. Sub-optimal IPv6 Address Usage . . . . . . . . . . . . . 13
7.5. Operational Considerations . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9. Security Considerations . . . . . . . . . . . . . . . . . . . 14
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
11.1. Normative References . . . . . . . . . . . . . . . . . . 15
11.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
IPv6 addresses may differ in a number of properties, such as address
scope (e.g. link-local vs. global), stability (e.g. stable addresses
vs. temporary addresses), and intended usage type (outgoing
communications vs. incomming communications). While often
overlooked, these properties have impact on areas such as security,
privacy, and performance.
IPv6 hosts typically configure a number of IPv6 addresses of
different properties. For example, a host may configure one stable
and one temporary address per each autoconfiguration prefix
advertised on the local network. Currently, the addresses to be
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configured typically depend on local system policy, with the
aforementioned policy being static and irrespective of the network
the host attaches to. This "one size fits all" approach limits the
ability of systems and applications of fully-leveraging the increased
flexibility and availability of IPv6 addresses.
Each application running on a given system may have its own set of
requirements or expectations for the properties of the IPv6 addresses
to be employed. For example, an application meaning to offer a
public service might expect to employ global stable addresses for
such purpose, while a privacy-sensible client application might
prefer short-lived temporary addresses, or might even expect to
employ single-use ("throw-away") IPv6 addresses when connecting to
public servers. However, the subtetlies associated with IPv6
addresses (and associated properties) are often ignored by
application programmers and, in any case, current APIs (such as the
BSD Sockets API) tend to be very limited in the amount of control
they give applications to select the most appropriate IPv6 addresses
for a given task, thus limiting a programmer's ability to leverage
IPv6 address availability and properties.
This document analyzes the impact of a number of properties of IPv6
addresses on areas such as security and privacy, and analyzes how
IPv6 addresses are curently generated and employed by different
operating systems and applications. Finally, it provides a problem
statement by identifying and analyzing gaps that prevent systems and
applications from fully-leveraging IPv6 addressing capabilities,
setting the basis for new work that could fill those gaps.
2. Terminology
This document employs the definitions of "public address", "stable
address", and "temporary address" from Section 2 of [RFC7721].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. Background
Predictable IPv6 addresses result in a number of security and privacy
implications. For example, [Barnes2012] discusses how patterns in
network prefixes can be leveraged for IPv6 address scanning. On the
other hand, [RFC7707], [RFC7721] and [RFC7217] discuss the security
and privacy implications of predictable IPv6 Interface Identifiers
(IIDs).
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Given the aforementioned previous work in this area, and the formal
specification update produced by [RFC8064], we expect (and assume in
the rest of this document) that implementations have replaced any
schemes that produce predictable addresses with alternative schemes
that avoid such patterns (e.g., RFC7217 in replacement of the
traditional SLAAC addresses that embed link-layer addresses).
4. IPv6 Address Properties
There are three parameters that affect the security and privacy
properties of an IPv6 address:
o Scope
o Stability
o Usage type (client-like "outgoing connections" vs. server-like
"incoming connections")
Section 4.1, Section 4.2, and Section 4.3 discuss the security and
privacy implications (and associated tradeoffs) of the scope,
stability and usage type properties of IPv6 addresses, respectively.
Additionally, IPv6 address usage has a number of operational
considerations; these are discussed n Section 7.5.
4.1. Address Scope Considerations
The IPv6 address scope can, in some scenarios, limit the attack
exposure of a node as a result of the implicit isolation provided by
a non-global address scope. For example, a node that only employs
link-local addresses may, in principle, only be exposed to attack
from other nodes in the local link. Hosts employing only Unique
Local Addresses (ULAs) may be more isolated from attack than those
employing Global Unicast Addresses (GUAs), assuming that proper
packet filtering is enforced at the network edge.
The potential protection provided by a non-global addresses should
not be regarded as a complete security strategy, but rather as a form
of "prophylactic" security (see
[I-D.gont-opsawg-firewalls-analysis]).
We note that the use of non-global addresses is usually limited to a
reduced type of applications/protocols that e.g. are only meant to
operate on a reduced scope, and hence their applicability may be
limited.
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A discussion of ULA usage considerations can be found in
[I-D.ietf-v6ops-ula-usage-considerations].
4.2. Address Stability Considerations
The stability of an address has two associated security/privacy
implications:
o Ability of an attacker to correlate network activity
o Exposure to attack
For obvious reasons, an address that is employed for multiple
communication instances allows the aforementioned network activities
to be correlated. The longer an address is employed (i.e., the more
stable it is), the longer such correlation will be possible. In the
worst-case scenario, a stable address that is employed for multiple
communication instances over time will allow all such activities to
be correlated. On the other hand, if a host were to generate (and
eventually "throw away") one new address for each communication
instance (e.g., TCP connection), network activity correlation would
be mitigated.
NOTE:
The use of constant IIDs (as in traditional SLAAC) result in
addresses that, while not constant as a whole (since the prefix
changes), contain a globally-unique value that leaks out the node
"identity". Such addresses result in the worst possible security
and privacy implications, and their use has been deprecated by
[RFC8064].
Typically, when it comes to attack exposure, the longer an address is
employed the longer an attacker is exposed to attacks (e.g. an
attacker has more time to find the address in the first place
[RFC7707]). While such exposure is traditionally associated with the
stability of the address, the usage type of the address (see
Section 4.3) may also have an impact on attack exposure.
A popular approach to mitigate network activity correlation is the
use of "temporary addresses" [RFC4941]. Temporary addresses are
typically configured and employed along with stable addresses, with
the temporary addresses employed for outgoing communications, and the
stable addresses employed for incoming communications.
NOTE:
Ongoing work [I-D.gont-6man-non-stable-iids] aims at updating
[RFC4941] such that temporary addresses can be employed without
the need to configure stable addresses.
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We note that the extent to which temporary addresses provide improved
mitigation of network activity correlation and/or reduced attack
exposure may be questionable and/or limited in some scenarios. For
example, a temporary address that is reachable for, say, a few hours
has a questionable "reduced exposure" (particularly when automated
attack tools do not typically require such a long period of time to
complete their task). Similarly, if network activity can be
correlated for the life of such address (e.g., on the order of
several hours), such period of time might be long enough for the
attacker to correlate all the network activity he is meaning to
correlate.
In order to better mitigate network activity correlation and/or
possibly reduce host exposure, an implementation might want to either
reduce the preferred lifetime of a temporary address, or even better,
generate one new temporary address for each new transport protocol
instance. However, the associated lifetime/stability of an address
may have a negative impact on the network. For example, if a node
were to employ "throw away" IPv6 addresses, or employ temporary
addresses [RFC4941] with a short preferred lifetime, local nodes
might need to maintain too many entries in their Neighbor Cache, and
a number of devices (possibly enforcing security policies) might also
need to cope with such additional state.
Additionally, enforcing a maximum lifetime on IPv6 addresses may
cause long-lived TCP connections to fail. For example, an address
becoming "Invalid" (after transitioning through the "Preferred" and
"Deprecated" states) would cause the TCP connections employing them
to break. This, in turn, would cause e.g. long-lived SSH sessions to
break/fail.
In some scenarios, attack exposure may be reduced by limiting the
usage of temporary addresses to outgoing connections, and prevent
such addresses from being used for incoming connections (please see
Section 4.3).
4.3. Usage Type Considerations
A node that employs one of its addresses to communicate with an
external server (i.e., to perform an "outgoing connection") may cause
such address to become exposed to attack. For example, once the
external server receives an incoming connection, the corresponding
server might launch an attack against the aforementioned address. A
real-world instance of this type of scenario has been documented in
[Hein].
However, we note that employing an IPv6 address for outgoing
communications need not increase the exposure of local services to
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other parties. For example, nodes could employ temporary addresses
only for outgoing connections, but not for incoming connections.
Thus, external nodes that learn about client's addresses could not
really leverage such addresses for actively contacting the clients.
There are multiple ways in which this could possibly be achieved,
with different implications. Namely:
o Run a host-based or network-based firewall
o Bind services to specific (explicit) addresses
o Bind services only to stable addresses
A client could simply run a host-based firewall that only allows
incoming connections on the stable addresses. This is clearly more
of an operational way of achieving the desired functionality, and may
require good firewall/host integration (e.g., the firewall should be
able to tell stable vs. temporary addresses), may require the client
to run additional firewall software for this specific purpose, etc.
In other scenarios, a network-based firewall could be configured to
allow outgoing communications from all internal addresses, but only
allow incoming communications to stable addresses. For obvious
reasons, this is generally only applicable to networks where incoming
communications are allowed to a limited number of hosts/servers.
Services could be bound to specific (explicit) addresses, rather than
to all locally-configured addresses. However, there are a number of
short-comings associated with this approach. Firstly, an application
would need to be able to learn all of its addresses and associated
stability properties, something that tends to be non-trivial and non-
portable, and that also makes applications protocol-dependent,
unnecessarily. Secondly, the BSD Sockets API does not really allow a
socket to be bound to a subset of the node's addresses. That is,
sockets can be bound to a single address or to all available
addresses (wildcard), but not to a subset of all the configured
addresses.
Binding services only to stable addresses provides a clean separation
between addresses employed for client-like outgoing connections and
server-like incoming connections. However, we currently lack an
appropriate API for nodes to be able to specify that a socket should
only be bound to stable addresses.
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5. Default Address Selection in IPv6
Applications use system API's to select the IPv6 addresses that will
be used for incoming and outgoing connections. These choices have
consequences in terms of privacy, security, stability and
performance.
Default Address Selection for IPv6 is specified in [RFC6724]. The
selection starts with a set of potential destination addresses, such
as returned by getaddrinfo(), and the set of potential source
addresses currently configured for the selected interfaces. For each
potential destination address, the algorithm will select the source
address that provides the best route to the destination, while
choosing the appropriate scope and preferring temporary addresses.
The algorithm will then select the destination address, while giving
a preference to reachable addresses with the smallest scope. The
selection may be affected by system settings. We note that [RFC6724]
only applies for outgoing connections, such as those made by clients
trying to use services offered by other hosts.
We note that [RFC6724] selects IPv6 addresses from all the currently
available addresses on the host, and there is currently no way for an
application to indicate expected or desirable properties for the IPv6
source addresses employed for such outgoing communications. For
example, a privacy-sensitive application might want that each
outgoing communication instance employs a new, single-use IPv6
address, or to employ a new reusable address that is not employed or
reusable by any other application on the host. Reuse of an IPv6
address by an application would allow the correlation of all network
activities corresponding to such application as being performed by
the same host, while reuse of an IPv6 address by multiple different
applications would allow the correlation of all such network
activities as being performed by the host with such IPv6 address.
When devices provide a service, the common pattern is to just wait
for connections over all addresses configured on the device. For
example, applications using the BSD Sockets API will commonly bind()
the listening socket to the undefined address. This long-established
behavior is appropriate for devices providing public services, but
may have unexpected results for devices providing semi-private
services, such as various forms of peer-to-peer or local-only
applications.
This behavior leads to three problems: device tracking, discussed in
Section 7.1.2; unexpected address discovery, discussed in
Section 7.1.3; and availability outside the expected scope, discussed
in Section 7.1.4. These problems are caused in part by the
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limitations of available address selection API, presented in
Section 7.2.
6. Current Possible Approaches for IPv6 Address Usage
6.1. Incoming communications
There are a number of ways in which a system or network may affect
which address (and how) may be employed for different services and
cases. Namely,
o TCP/IP stack address filtering
o Application-based address filtering
o Firewall-based address filtering
Clearly, the most elegant approach for address selection is for
applications to be able to specify the properties of the addresses
they are willing to employ by means of an API, such the TCP/IP stack
itself can "filter" which addresses are allowed to be employed for
the given service/application. This relieves the application from
dealing with low level details of networking, improves portability,
and avoids duplicate code in applications. However, constraints in
the current APIs (see Section 7.2) may limit the ability of
application progremmers for leveraging this technique.
Another possible approach is for applications to e.g. bind services
to all available addresses, and perform the associated selection/
filtering at the application level. While possible this has a number
of drawbacks. Firstly, it would require applications to deal with
low-level networking details, require that all the associated code be
duplicated in all applications, and also negatively affect
portability. Besides, performing address/selection filtering at the
application level may not mitigate some possible threats. For
example, port scanning will still be possible, since the
aforementioned filtering will only be performed e.g. once UDP packets
are received or TCP connections are established.
Finally, a firewall may be employed to filter addresses based on
their intended usage. For example, a firewall may block incoming
requests to all addresses except to some whitelisted addresses (such
as the stable addresses of the node). This technique not only
requires the use of a firewall (which may or may not be present), but
also implies knowledge of the firewall regarding the desired
properties of the addresses that each application/service is intended
to use.
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6.2. Outgoing communications
An application might be able to obtain the list of currently-
configured addresses, and subsequently select an address with desired
properties, and explicitly "bind" the address to the socket, to
override the default source address selection.
However, this approach is problematic for a number of reasons.
Firstly, there is no portable way of obtaining the list of currently-
configured addresses on the local node, and even less to check for
properties such "valid lifetime". Secondly, as discussed in
Section 6.1, it would require application programmers to understand
all the subtetiles associated with IPv6 addressing, and would also
lead to duplicate code on all applications. Finally, applications
would be limited to use already-configured addresses and unable to
trigger the generation of new addresses where desirable (e.g. the
genration of a new temporary address for this application instance or
communication instance).
7. Problem Statement
This section elaborates the problem statement on IPv6 address usage.
Section 7.1 describes the security and privacy implications of
improper IPv6 address usage, while Section 7.2, Section 7.4,
Section 7.3, analyze the possible root of such improper address
usage, suggesting possible future work.
7.1. Issues Associated with Sub-optimal IPv6 Address Usage
7.1.1. Correlation of Network Activity
As discussed in [RFC7721], a node that reuses an IPv6 address for
multiple communication instances would allow the correlation of such
network activities. This could be the case when the same IPv6
address is employed by several instances of the same application
(e.g., a browser in "privacy" mode and a browser in "normal" mode),
or when the same IPv6 address is employed by two different
applications on the same node (e.g., a browser in "privacy" mode, and
an email client).
Particularly for privacy-sensitive applications, an application or
system might want to limit the usage of a given IPv6 address to a
single communication instance, a single application, a single user on
the system, etc. However, given current APIs, this is practically
impossible.
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7.1.2. Testing for the Presence of Node in the Network
The stable addresses recommended in [RFC8064] use stable IIDs defined
in [RFC7217]. One key part of that algorithm is that if a device
connects to a given network at different times, it will always
configure the same IPv6 addresses on that network. If the device
hosts a service ready to accept connections on that stable address,
adversaries can test the presence of the device on the network by
attempting connections to that stable address. Stable addresses used
by listening services will thus enable testing whether a specific
device is returning to a particular network, which in a number of
cases might be considered a privacy issue.
7.1.3. Unexpected Address Discovery
Systems like DNS-Based Service Discovery [RFC6763] allow clients to
discover services within a limited scope, that can be defined by a
domain name. These services are not advertised outside of that
scope, and thus do not expect to be discovered by random parties on
the Internet. However, such services may be easily discoverable if
they listen for connections to IPv6 addresses that a client process
also uses as source address when connecting to remote servers.
NOTE:
An example of such unexpected discovery is described in [Hein]. A
network manager observed scanning traffic directed at the
temporary addresses of local devices. The analysis in [Hein]
shows that the scanners learned the addresses by observing the
device contact an NTP service ([RFC5905]). The remote scanning
was possible because the local devices were also accepting
connections directed to the temporary addresses.
It is obvious from the example that the "attack surface" of the
services is increased because they are bond to the same IPv6
addresses that are also used by clients for outgoing communications
with remote systems. But the overlap between "client" and "server"
addresses is only one part of the problem. Suppose that a device
hosts both a video game and a home automation application. The video
game users will be able to discover the IPv6 address of the game
server. If the home automation server listens to the same IPv6
addresses, it is now exposed to connection attempts by all these
users. That, too, increases the attack surface of the home
automation server.
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7.1.4. Availability Outside the Expected Scope
The IPv6 addressing architecture [RFC4291] defines multiple address
scopes. In practice, devices are often configured with globally
reachable unicast addresses, link local addresses, and Unique Local
IPv6 Unicast Addresses (ULA) [RFC4193]. Availability outside the
expected scope happens when a service is expected to be only
available in some local scope, but inadvertently becomes available to
remote parties. That could happen for example if a service is meant
to be available only on a given link, but becomes reachable through
ULA or through globally reachable addresses, or if a service is meant
to be available only inside some organization's perimeter and becomes
reachable through globally reachable addresses. It will happen in
particular if a service intended for some local scope is programmed
to bind to "unspecified" addresses, which in practice means every
address configured for the device (please see Section 7.2).
7.2. Current Limitations in the Address Selection APIs
Application developers using the BSD Sockets API can "bind" a
listening socket to a specific address, and ensure that the
application is only reachable through that address. In theory,
careful selection of the binding address could mitigate the problems
described in Section 7.1. Binding services to temporary addresses
could mitigate the ability of an attacker from testing for the
presence of the node in the network. Binding different services to
different addresses could mitigate unexpected discovery. Binding
services to link local addresses or ULA could mitigate availability
outside the expected scope. However, explicitly managing addresses
adds significant complexity to the application development. It
requires that application developers master addressing architecture
subtleties, and implement logic that reacts adequately to
connectivity events and address changes. Experience shows that
application developers would probably prefer some much simpler
solution.
In addition, we should note that many application developers use high
level APIs that listen to TLS, HTTP, or some other application
protocol. These high level APIs seldom provide detailed access to
specific IP addresses, and typically default to listening to all
available addresses.
A more advanced API could allow an application programmer to select
desired properties in an address (scope, lifespan, etc.), such that
the best-suitable addresses are selected, while relieving the
application for low-level IPv6 addressing details. Such API might
also trigger the generation of new IPv6 addresses when the specified
properties would require so.
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7.3. Sub-optimal IPv6 Address Configuration
Most operating systems configure the same types of addresses
regardless of the current "operating mode" or "profile" of the device
(e.g., device connected to enterprise network vs roaming across
untrusted networks). For example, many operating systems configure
both stable [RFC8064] and temporary [RFC4941] addresses on all
network interfaces. However, this "one size fits all" approach tends
to be sub-optimal or inappropriate for some scenarios. For example,
enterprise networks typically prefer usage of only stable address,
thus meaning that a network administator needs to find the means for
disabling the generation of temporary addresses on all those systems
that would otherwise generate them. On the other hand, some mobile
devices configure both stable and temporary addresses, even when
their usage pattern (client-like operation, as opposed to offering
services to other nodes) would allow for the more privacy-sensible
option of configuring only temporary addresses.
The lack of better tuned address configuration policies has helped
the "one size fits all" approach that, as noted, may lead to
suboptimal results. Advice in this area might help achieve more
optional address generation policies such that IPv6 addressing
capabilities are fully leveraged.
NOTE:
One might envision a document that provides advice regarding the
address generation for different typical scenarios (e.g., when to
configure stable-only, temporary-only, or stable+temporary). In
the most simple analysis, one might expect nodes in a typical
enterprise network to employ only stable addresses. General-
purpose nodes in a home or "trusted" network may want to employ
both stable and temporary addresses. Finally, mobile nodes (e.g.
when roaming across non-trusted networks) may want to employ only
temporary addresses).
7.4. Sub-optimal IPv6 Address Usage
An application programmer, left with the question of which are the
most appropriate addresses for a given usage type and application,
typically resorts to the Default IPv6 Address Selection for IPv6 (see
Section 5) for outgoing communications, and to accepting incoming
communications on all available addresses for incoming
communications. As discussed throughout this document, this leads to
sub-optimal results. Besides, all applications on a node share the
same pool of configured addresses, and applications are also
prevented from triggering the generation of new addresses (e.g. to be
employed for a particular application or communcation instance).
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Guidance in this area is warranted such that applications and systems
fully-leverage IPv6 addressing.
NOTE:
Such guidance would elaborate, among other things, on the usage of
IPv6 addresses when offering network services and when performing
client-like communications. For example, for incomming
communications, hosts might want to employ only the smallest-scope
applicable addresses (if available) and, if stable addresses are
available, they might want to accept incoming connections only on
such addresses (but *not* on temporary addresses). For client-
like communications, hosts might prefer temporary addresses,
unless the coresponding communication instances are expected to be
long-lived (e.g., SSH sessions).
7.5. Operational Considerations
The desires of protecting individual privacy versus the desire to
effectively maintain and debug a network can conflict with each
other. Having clients e.g. use addresses that change over time will
make it more difficult to track down and isolate operational
problems. For example, when looking at packet traces, it could
become more difficult to determine whether one is seeing behavior
caused by a single errant machine, or by a number of them.
Network deployments are currently recommended to provide multiple
IPv6 addresses from each prefix to general-purpose hosts [RFC7934].
However, in some scenarios, use of a large number of IPv6 addresses
may have negative implications on network devices that need to
maintain entries for each IPv6 address in some data structures (e.g.,
[RFC7039]). Additionally, concurrent active use of multiple IPv6
addresses will increase neighbour discovery traffic if Neighbour
Caches in network devices are not large enough to store all addresses
on the link. This can impact performance and energy efficiency on
networks on which multicast is expensive (e.g.
[I-D.ietf-mboned-ieee802-mcast-problems]).
8. IANA Considerations
There are no IANA registries within this document. The RFC-Editor
can remove this section before publication of this document as an
RFC.
9. Security Considerations
The security and privacy implications associated with the
predictability and lifetime of IPv6 addresses has been analyzed in
[RFC7217] [RFC7721], and [RFC7707]. This document complements and
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extends the aforementioned analysis by considering other IPv6
properties such as the address scope and address usage type, and the
associated tradeoffs. Finally, it describes possible future
standards-track work to allow for greater flexibility in IPv6 address
usage.
10. Acknowledgements
The authors would like to thank (in alphabetical order) Francis
Dupont, Tatuya Jinmei, and Dave Thaler for providing valuable
comments on earlier versions of this document.
Section 7.5 borrows text from [I-D.ietf-6man-rfc4941bis] co-authored
by Fernando Gont, Suresh Krishnan, Thomas Narten, and Richard Draves.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,
<https://www.rfc-editor.org/info/rfc4193>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<https://www.rfc-editor.org/info/rfc4941>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<https://www.rfc-editor.org/info/rfc5905>.
[RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012,
<https://www.rfc-editor.org/info/rfc6724>.
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[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<https://www.rfc-editor.org/info/rfc6763>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014,
<https://www.rfc-editor.org/info/rfc7217>.
[RFC7934] Colitti, L., Cerf, V., Cheshire, S., and D. Schinazi,
"Host Address Availability Recommendations", BCP 204,
RFC 7934, DOI 10.17487/RFC7934, July 2016,
<https://www.rfc-editor.org/info/rfc7934>.
[RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu,
"Recommendation on Stable IPv6 Interface Identifiers",
RFC 8064, DOI 10.17487/RFC8064, February 2017,
<https://www.rfc-editor.org/info/rfc8064>.
11.2. Informative References
[Barnes2012]
Barnes, R., Altmann, R., and D. Kerr, "Mapping the Great
Void Smarter scanning for IPv6", ISMA 2012 AIMS-4 -
Workshop on Active Internet Measurements, February 2012,
<https://www.caida.org/workshops/isma/1202/slides/
aims1202_rbarnes.pdf>.
[Hein] Hein, B., "The Rising Sophistication of Network
Scanning", January 2016,
<http://netpatterns.blogspot.be/2016/01/the-rising-
sophistication-of-network.html>.
[I-D.gont-6man-non-stable-iids]
Gont, F., Huitema, C., Krishnan, S., Gont, G., and M.
Corbo, "Recommendation on Temporary IPv6 Interface
Identifiers", draft-gont-6man-non-stable-iids-04 (work in
progress), March 2018.
[I-D.gont-opsawg-firewalls-analysis]
Gont, F. and F. Baker, "On Firewalls in Network Security",
draft-gont-opsawg-firewalls-analysis-02 (work in
progress), February 2016.
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[I-D.ietf-6man-rfc4941bis]
Gont, F., Krishnan, S., Narten, T., and R. Draves,
"Privacy Extensions for Stateless Address
Autoconfiguration in IPv6", draft-ietf-6man-rfc4941bis-07
(work in progress), February 2020.
[I-D.ietf-mboned-ieee802-mcast-problems]
Perkins, C., McBride, M., Stanley, D., Kumari, W., and J.
Zuniga, "Multicast Considerations over IEEE 802 Wireless
Media", draft-ietf-mboned-ieee802-mcast-problems-11 (work
in progress), December 2019.
[I-D.ietf-v6ops-ula-usage-considerations]
Liu, B. and S. Jiang, "Considerations For Using Unique
Local Addresses", draft-ietf-v6ops-ula-usage-
considerations-02 (work in progress), March 2017.
[RFC7039] Wu, J., Bi, J., Bagnulo, M., Baker, F., and C. Vogt, Ed.,
"Source Address Validation Improvement (SAVI) Framework",
RFC 7039, DOI 10.17487/RFC7039, October 2013,
<https://www.rfc-editor.org/info/rfc7039>.
[RFC7707] Gont, F. and T. Chown, "Network Reconnaissance in IPv6
Networks", RFC 7707, DOI 10.17487/RFC7707, March 2016,
<https://www.rfc-editor.org/info/rfc7707>.
[RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
Considerations for IPv6 Address Generation Mechanisms",
RFC 7721, DOI 10.17487/RFC7721, March 2016,
<https://www.rfc-editor.org/info/rfc7721>.
Authors' Addresses
Fernando Gont
SI6 Networks / UTN-FRH
Evaristo Carriego 2644
Haedo, Provincia de Buenos Aires 1706
Argentina
Phone: +54 11 4650 8472
Email: fgont@si6networks.com
URI: http://www.si6networks.com
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Guillermo Gont
SI6 Networks
Evaristo Carriego 2644
Haedo, Provincia de Buenos Aires 1706
Argentina
Phone: +54 11 4650 8472
Email: ggont@si6networks.com
URI: https://www.si6networks.com
Christian Huitema
Private Octopus Inc.
Friday Harbor, WA 98250
U.S.A.
Email: huitema@huitema.net
URI: http://privateoctopus.com
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