Internet DRAFT - draft-iannone-pidloc-privacy
draft-iannone-pidloc-privacy
Network Working Group L. Iannone
Internet-Draft Telecom Paris
Intended status: Standards Track D. von Hugo
Expires: September 10, 2020 Deutsche Telekom
B. Sarikaya
Denpel Informatique
E. Nordmark
Zededa
March 9, 2020
Privacy issues in Identifier/Locator Separation Systems
draft-iannone-pidloc-privacy-01
Abstract
There exists several protocols and proposals that leverage on the
Identifier/Locator split paradigm, having some form of control plane
by which participating nodes can share their current Identifier-to-
Location information with their peers. This document explores some
of the privacy considerations for such a type of system.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Keywords and Terminology . . . . . . . . . . . . . . . . . . 4
3. Identifier Locator Separation and Privacy . . . . . . . . . . 4
4. Identifier Locator Split Protocols . . . . . . . . . . . . . 5
4.1. Locator/Identifier Separation Protocol (LISP) . . . . . . 5
4.2. Identifier/Locator Network Protocol (ILNP) . . . . . . . 5
4.3. Information Centric Networking (ICN) . . . . . . . . . . 5
4.4. Host Identity Protocol (HIP) . . . . . . . . . . . . . . 6
4.5. Virtual eXtensible Local Area Network (VXLAN) . . . . . . 6
4.6. Some Relevant Privacy-Critical Scenarios . . . . . . . . 6
5. Threats against Privacy . . . . . . . . . . . . . . . . . . . 7
5.1. Location Privacy . . . . . . . . . . . . . . . . . . . . 8
5.2. Movement Privacy . . . . . . . . . . . . . . . . . . . . 8
6. Not everybody all the time . . . . . . . . . . . . . . . . . 8
6.1. Optimized Routing . . . . . . . . . . . . . . . . . . . . 8
6.2. Family and Friends . . . . . . . . . . . . . . . . . . . 8
6.3. Business Assets . . . . . . . . . . . . . . . . . . . . . 9
7. Boundary between ID/locator part and rest of Internet . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
When the IP address is separated, one way or another, into an
identifier and a locator, there is typically the need to be able to
look up an identifier to find possible locators which can be used to
reach the identified endpoint. If such a system (think a distributed
database) was publicly available, then this would introduce
additional privacy considerations which do not exist in the absence
of the ID/locator split. Think for instance if identifiers are
assigned to devices such as mobile phones which have a strong binding
with an individual. Having the location of such identifier publicly
available implies make the individual whereabouts public.
Without an ID/locator split, a device is already providing its IP
address (in the form of a source address) to any network device along
the path, and also to the remote endpoint. That endpoint in
particular might use IP geolocation databases to get a pretty good
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idea of where its peer is located, for instance to offer information
and/or advertising relevant to that location.
However, in such scenario, when a device (e.g., a laptop or
smartphone connected over WiFi) moves (e.g., from home to a coffee
shop) the IP address changes. This makes it harder for network
devices along the paths to realize that the it is the same mobile
device. If the mobile device is not retaining cookies or logged into
websites, those remote peers would also have some difficulty
determining whether it is the same mobile device. Furthermore, a
mobile device which is using typical cellular network technologies
ends up with an IP address, at least as seen by remote peers outside
of the cellular network, which is associated with the cellular
operator but does not necessarily indicate a particular location of
the mobile device.
Note that even if the IP address isn't always useful to track a
mobile device today, there are several mechanisms higher in the stack
which can do this. For instance cookies or SSL sessions,
applications which share GPS location, or operators who offer
additional location information (for instance based on which cellular
base station a mobile device is using) to business partners.
Promising proposals leveraging on the Identifier Locator (Id-Loc)
separation paradigm are: Identifier-Locator Network Protocol (ILNP)
[RFC6740]; Locator/ID Separation Protocol (LISP)
[I-D.ietf-lisp-rfc6830bis] [I-D.ietf-lisp-rfc6833bis]; Virtual
eXtensible LAN [RFC7348]; Information-Centric Networking (ICN)
[RFC7927]; Host Identity Protocol (HIP) [RFC4423]. Note that ICN
does not leverage on IP addresses, however, the general architecture
for this paradgim is based on a clear separation between content
identifier and content location. Similarly, in HIP the identifier,
while identifying representing a communication end-point it is not an
IP address.
Architectures and protocols for these approaches are already
documented in detail and some are under continuous evolution in
different WGs or RGs. This document on the other hand attempts to
identify potential issues with respect to real-world deployment
scenarios, which may demand for implementations of the above-
mentionned Id-Loc systems. In particular, this document overviews
issues related to threats due to privacy violation of devices and
their users, as well as location detection and movement tracking,
where specific countermeasures may be needed.
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2. Keywords and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Identifier: An identifier is information allowing to unambiguously
identify an entity or an entity group within a given scope. An
identifier is the equivalent of an End-point IDentifier (EID) in The
Locator/ID Separation Protocol (LISP). It may or may not be visible
in communications.
Locator: A locator is a routable network address. It may be
associated with an identifier and used for communication on the
network layer according to identifier locator split principle. A
locator is the equivalent of a Routing Locator (RLOC) in LISP or an
IP address in other cases.
3. Identifier Locator Separation and Privacy
Identifier represents a communication end-point, a content, or any
identifiable entity and may not be a routable IP address, and in
general it is not an IP address at all. Locator may represent a
communication end-point, and in this case it usually is a routable
network address. Because entities identified by an Identifier can
move the association between Identifiers and Locators may be
ephemeral. A database called a mapping system needs to be used for
Identifier to Locator mapping. Identifiers are mapped to locators
for reachability purposes. A mapping system has to handle mobility
by updating the identifier to locator mappings in the database. Note
that different protocols/system may use a different terminology,
however, the principle remains the same: a form of (ephemeral)
binding between identifiers and locators.
To start the communication, a device needs to know the identifier of
the destination, hence it relies on a identifier lookup process to
obtain the associated locator(s). Note that both identifier and
locator may be carried in clear in packet headers, depending on the
specific technology used and the level of security/privacy enforced.
Usage of identifiers (and their locators) readily available for
public access raises privacy issues. For public entities, it may be
desirable to have their fully qualified domain names or host names
available for public lookups by the clients. For private entities,
usually the clients of the public ones, however, this is not the
case. For instance for individuals roaming in a mobile network may
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not want their locators publicly available, or may be onlyavailable
to the memebers of his/her family.
Privacy is an increasingly desirable and often necessary property for
Internet technologies.
4. Identifier Locator Split Protocols
Herefater a non-exhaustive overview of protocolc/system leveraging on
the Locator/Identifier seapration is provided.
4.1. Locator/Identifier Separation Protocol (LISP)
Locator/Id Separation Protocol (LISP) [I-D.ietf-lisp-rfc6830bis]
[I-D.ietf-lisp-rfc6833bis] is based on a map-and-encap approach,
which provides a level of indirection for routing and addressing
performed at specific ingress/egress routers at the LISP domain
boundaries. Such border routers performing LISP encapsulation at the
packet's source stub network are indicated as Ingress Tunnel Routers
(ITRs), while border routers at the packet's destination stub network
are called Egress Tunnel Routers (ETRs), all of them are indicated by
the general term xTRs. In order to obtain mappings used for
encapsulation operation, xTRs query the mapping system in order to
obtain all mappings related to a certain EID only when necessary
(usually, but not exclusively, at the beginning of a new flow
transmission). The LISP control plane protocol
[I-D.ietf-lisp-rfc6833bis] allows to support several different
mapping systems (e.g., LISP+ALT [RFC6836] and LISP-DDT [RFC8111]).
More than that, it can actually also be applied to various other data
plane protocols.
4.2. Identifier/Locator Network Protocol (ILNP)
Identifier-Locator Network Protocol (ILNP) [RFC6740] is a host-based
approach enabling mobility using mechanisms that are only deployed in
end-systems and do not require any router changes.
4.3. Information Centric Networking (ICN)
Information-Centric Networking (ICN) [RFC7927] is an approach to
evolve the Internet infrastructure to directly support information
distribution by introducing uniquely named data as a core Internet
principle. Data becomes independent from location, application,
storage, and means of transportation, enabling or enhancing a number
of desirable features, such as security, user mobility, multicast,
and in-network caching.
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4.4. Host Identity Protocol (HIP)
The Host Identity Protocol (HIP) [RFC4423] Architecture introduces a
new namespace, namely the Host Identity namespace, and a new
protocol. The HIP protocol aim at providing for limited forms of
trust between systems, enhance mobility, multi-homing, and dynamic IP
renumbering; aid in protocol translation/transition; and reduce
certain types of denial-of-service (DoS) attacks.
4.5. Virtual eXtensible Local Area Network (VXLAN)
Virtual Extensible LAN (VXLAN) [RFC7348] is a network virtualization
technology that attempts to address the scalability problems
associated with large cloud computing deployments. It uses a VLAN-
like encapsulation technique to encapsulate layer 2 Ethernet frames
within layer 4 UDP datagrams, using 4789 as the default IANA-assigned
destination UDP port number. VXLAN endpoints, which terminate VXLAN
tunnels and may be either virtual or physical switch ports, are known
as VXLAN tunnel endpoints (VTEPs) and can be considered the locators
of the devices in the extended VLAN.
4.6. Some Relevant Privacy-Critical Scenarios
The collection of scenarios shall serve as an overview of possible
Loc/ID separation application and help in identifying different
issues in privacy and security in generic Identifier Locator Split
approaches.
4.6.1. Industrial IoT
Sensors and other connected things in the industry are usually not
personal items (e.g. wearables) potentially revealing an individuals
sensitive information. Yet, industrial connected objects are
business assets whose information (e.g. location) should be available
only to authorised intra-company entities. Hence, there is an
interest in not shaing the ID/Locator binding with third parties, to
retain the privacy. This can be achieved in a number of ways such
as: using an ID/locator system but using some fixed anchor point as a
locator; injecting routing prefixes for the ID prefixes into the
normal routing system and use proxy indirection; providing limited
ID/Locator exposure. These are just examples, more approaches should
be explored in order to find which one is the most suitable in the
context of industrial IoT.
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4.6.2. 5G
Upcoming new truly universal communication via so-called 5G systems
will demand for much more than (just) higher bandwidth and lower
latency. Integration of heterogeneous multiple access technologies
(both wireless and wireline) controlled by a common converged core
network and the evolution to service-based flexile functionalities
instead of hard-coded network functions calls for new protocols both
on control and user (data) plane. While Id-Loc approach would serve
well here, the challenge to provide a unique level of security and
privacy even for a lightweight routing and forwarding mechanism -
allowing for ease of deployment and migration from existing
operational network architecture - remains to be solved.
4.6.3. Cloud
The cloud, i.e. a set of distributed data centers for processing and
storage connected via high-speed transmission paths, is seen as
logical location for content and also for virtualized network
function instances and shall provide measures for easy re-location
and migration of these instances deployed as e.g. containers or
virtual machines. Id-Loc split routing protocols are proposed for
usage here as in VXLAN [RFC7348] and LISP [I-D.ietf-lisp-rfc6830bis]
[I-D.ietf-lisp-rfc6833bis] while the topology of the cloud components
and logical correlations shall be invisible from outside.
In a cloud, an upstream IP address does not necessarily belong to the
actual service location, but a gateway or load balancer. So, the
locator or also ID reveal the location with the accuracy of a data
center, not the function taking a service request. This issue also
manifests itself in today's LTE as PGWs are in a data center binding
UEs' IP addresses which are from the network of the data center.
5. Threats against Privacy
There seems to be at least two different privacy threats relating to
ID/locator mapping systems:
1. Location Privacy
2. Movement Privacy
Note that these threats appear in the hypothesys that the ID does not
change. Nevertheless, even in the case of mutable IDs, there are
other forms of information correlation that may allow to identify
network entities.
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5.1. Location Privacy
If a third party can at any time determine the IP location of some
identifier, then the device can at one point be IP geolocated at
home, and later a coffee shop.
5.2. Movement Privacy
If a third party can determine that an identifier has changed
locator(s) at time T, then even without knowing the particular
locators before and after, it can correlate this movement event with
other information (e.g., security cameras) to create a binding
between the identifier and a person.
6. Not everybody all the time
In order to see the benefits about but minimizing the privacy
implication one can explore limiting to which peers and when the ID/
locator binding are exposed.
A few initial examples help illustrate this.
6.1. Optimized Routing
If some operator of a network where there is a large amount of
mobility wants to ensure efficient routing, then a ID/locator split
approach might make sense. Such a system can potentially be limited
to the set of devices (routers etc) which are under the operators
control. If this is the case, then the ID/locator mapping system can
provide access control so that only those trusted devices can access
the mappings.
Note that from a privacy perspective this isn't any different than
the same operator using a link-state routing protocol to share host
routes for all the mobile devices. In that case all participants in
the link-state protocol can determine the location (attached to which
router) and notice any mobility events. Of course, there are
significant non-privacy differences between those two approaches.
Exposing the ID/locator mapping to attached devices (e.g., any mobile
devices which wouldn't be trusted to participate in the link-state
routing counterpart approach), will change the privacy implications.
6.2. Family and Friends
There are cases where it is quite reasonable to share location
information with other family members or friends. For instance,
young children might run applications which enable their parents to
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track them on their way to/from school. And I might share my
location with friends so we can more easily find each other while out
on town.
Today such location sharing happens at an application layer using GPS
coordinates. But while such sharing is in effect, it wouldn't be
unreasonable to also consider sharing IP locators to make it more
efficient or more robust to e.g., route a video feed from one device
to another.
6.3. Business Assets
In the area of Industrial IoT there are cases where an asset owner
might want to ensure that their assets can communicate efficiently
and robustly. In many cases those assets might be decoupled from any
persons, but there can still be strong reasons to not share the ID/
locator binding with third parties, such as enabling competitors to
determine the number of deployed devices in a particular IP prefix.
7. Boundary between ID/locator part and rest of Internet
If the access to the ID/locator mapping are restricted as suggested
above, then most of the potential peer devices would not have access
to the ID/locator mappings. This means that there has to be a
demarcation point between the part of the network which can access
the ID/locator mappings for a particular identifier and the one which
can not. There might be several choices how to handle this such as
still using an ID/locator system but pointing a locator for some
fixed anchor point, or injecting routing prefixes for the ID prefixes
into the normal routing system, or not providing any stable locators
across this boundary; only allow ephemeral IP addresses per session
or otherwise limited exposure.
8. Security Considerations
This document discusses privacy considerations, but does not explore
any security considerations.
9. IANA Considerations
There are no IANA actions needed for this document.
10. References
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[I-D.ietf-lisp-rfc6830bis]
Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.
Cabellos-Aparicio, "The Locator/ID Separation Protocol
(LISP)", draft-ietf-lisp-rfc6830bis-32 (work in progress),
March 2020.
[I-D.ietf-lisp-rfc6833bis]
Farinacci, D., Maino, F., Fuller, V., and A. Cabellos-
Aparicio, "Locator/ID Separation Protocol (LISP) Control-
Plane", draft-ietf-lisp-rfc6833bis-27 (work in progress),
January 2020.
[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>.
[RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol
(HIP) Architecture", RFC 4423, DOI 10.17487/RFC4423, May
2006, <https://www.rfc-editor.org/info/rfc4423>.
[RFC6740] Atkinson, RJ. and SN. Bhatti, "Identifier-Locator Network
Protocol (ILNP) Architectural Description", RFC 6740,
DOI 10.17487/RFC6740, November 2012,
<https://www.rfc-editor.org/info/rfc6740>.
[RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol Alternative Logical
Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836,
January 2013, <https://www.rfc-editor.org/info/rfc6836>.
[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<https://www.rfc-editor.org/info/rfc7348>.
[RFC7927] Kutscher, D., Ed., Eum, S., Pentikousis, K., Psaras, I.,
Corujo, D., Saucez, D., Schmidt, T., and M. Waehlisch,
"Information-Centric Networking (ICN) Research
Challenges", RFC 7927, DOI 10.17487/RFC7927, July 2016,
<https://www.rfc-editor.org/info/rfc7927>.
[RFC8111] Fuller, V., Lewis, D., Ermagan, V., Jain, A., and A.
Smirnov, "Locator/ID Separation Protocol Delegated
Database Tree (LISP-DDT)", RFC 8111, DOI 10.17487/RFC8111,
May 2017, <https://www.rfc-editor.org/info/rfc8111>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Authors' Addresses
Luigi Iannone
Telecom Paris
Email: ggx@gigix.net
Dirk von Hugo
Deutsche Telekom
Deutsche-Telekom-Allee 7
D-64295 Darmstadt
Germany
Email: Dirk.von-Hugo@telekom.de
Behcet Sarikaya
Denpel Informatique
Email: sarikaya@ieee.org
Erik Nordmark
Zededa
Santa Clara, CA
USA
Email: nordmark@sonic.net
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