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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group L. Iannone 3 Internet-Draft Telecom Paris 4 Intended status: Standards Track D. von Hugo 5 Expires: September 10, 2020 Deutsche Telekom 6 B. Sarikaya 7 Denpel Informatique 8 E. Nordmark 9 Zededa 10 March 9, 2020 12 Privacy issues in Identifier/Locator Separation Systems 13 draft-iannone-pidloc-privacy-01 15 Abstract 17 There exists several protocols and proposals that leverage on the 18 Identifier/Locator split paradigm, having some form of control plane 19 by which participating nodes can share their current Identifier-to- 20 Location information with their peers. This document explores some 21 of the privacy considerations for such a type of system. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on September 10, 2020. 40 Copyright Notice 42 Copyright (c) 2020 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Keywords and Terminology . . . . . . . . . . . . . . . . . . 4 59 3. Identifier Locator Separation and Privacy . . . . . . . . . . 4 60 4. Identifier Locator Split Protocols . . . . . . . . . . . . . 5 61 4.1. Locator/Identifier Separation Protocol (LISP) . . . . . . 5 62 4.2. Identifier/Locator Network Protocol (ILNP) . . . . . . . 5 63 4.3. Information Centric Networking (ICN) . . . . . . . . . . 5 64 4.4. Host Identity Protocol (HIP) . . . . . . . . . . . . . . 6 65 4.5. Virtual eXtensible Local Area Network (VXLAN) . . . . . . 6 66 4.6. Some Relevant Privacy-Critical Scenarios . . . . . . . . 6 67 5. Threats against Privacy . . . . . . . . . . . . . . . . . . . 7 68 5.1. Location Privacy . . . . . . . . . . . . . . . . . . . . 8 69 5.2. Movement Privacy . . . . . . . . . . . . . . . . . . . . 8 70 6. Not everybody all the time . . . . . . . . . . . . . . . . . 8 71 6.1. Optimized Routing . . . . . . . . . . . . . . . . . . . . 8 72 6.2. Family and Friends . . . . . . . . . . . . . . . . . . . 8 73 6.3. Business Assets . . . . . . . . . . . . . . . . . . . . . 9 74 7. Boundary between ID/locator part and rest of Internet . . . . 9 75 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 76 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 77 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 80 1. Introduction 82 When the IP address is separated, one way or another, into an 83 identifier and a locator, there is typically the need to be able to 84 look up an identifier to find possible locators which can be used to 85 reach the identified endpoint. If such a system (think a distributed 86 database) was publicly available, then this would introduce 87 additional privacy considerations which do not exist in the absence 88 of the ID/locator split. Think for instance if identifiers are 89 assigned to devices such as mobile phones which have a strong binding 90 with an individual. Having the location of such identifier publicly 91 available implies make the individual whereabouts public. 93 Without an ID/locator split, a device is already providing its IP 94 address (in the form of a source address) to any network device along 95 the path, and also to the remote endpoint. That endpoint in 96 particular might use IP geolocation databases to get a pretty good 97 idea of where its peer is located, for instance to offer information 98 and/or advertising relevant to that location. 100 However, in such scenario, when a device (e.g., a laptop or 101 smartphone connected over WiFi) moves (e.g., from home to a coffee 102 shop) the IP address changes. This makes it harder for network 103 devices along the paths to realize that the it is the same mobile 104 device. If the mobile device is not retaining cookies or logged into 105 websites, those remote peers would also have some difficulty 106 determining whether it is the same mobile device. Furthermore, a 107 mobile device which is using typical cellular network technologies 108 ends up with an IP address, at least as seen by remote peers outside 109 of the cellular network, which is associated with the cellular 110 operator but does not necessarily indicate a particular location of 111 the mobile device. 113 Note that even if the IP address isn't always useful to track a 114 mobile device today, there are several mechanisms higher in the stack 115 which can do this. For instance cookies or SSL sessions, 116 applications which share GPS location, or operators who offer 117 additional location information (for instance based on which cellular 118 base station a mobile device is using) to business partners. 120 Promising proposals leveraging on the Identifier Locator (Id-Loc) 121 separation paradigm are: Identifier-Locator Network Protocol (ILNP) 122 [RFC6740]; Locator/ID Separation Protocol (LISP) 123 [I-D.ietf-lisp-rfc6830bis] [I-D.ietf-lisp-rfc6833bis]; Virtual 124 eXtensible LAN [RFC7348]; Information-Centric Networking (ICN) 125 [RFC7927]; Host Identity Protocol (HIP) [RFC4423]. Note that ICN 126 does not leverage on IP addresses, however, the general architecture 127 for this paradgim is based on a clear separation between content 128 identifier and content location. Similarly, in HIP the identifier, 129 while identifying representing a communication end-point it is not an 130 IP address. 132 Architectures and protocols for these approaches are already 133 documented in detail and some are under continuous evolution in 134 different WGs or RGs. This document on the other hand attempts to 135 identify potential issues with respect to real-world deployment 136 scenarios, which may demand for implementations of the above- 137 mentionned Id-Loc systems. In particular, this document overviews 138 issues related to threats due to privacy violation of devices and 139 their users, as well as location detection and movement tracking, 140 where specific countermeasures may be needed. 142 2. Keywords and Terminology 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 146 "OPTIONAL" in this document are to be interpreted as described in BCP 147 14 [RFC2119] [RFC8174] when, and only when, they appear in all 148 capitals, as shown here. 150 Identifier: An identifier is information allowing to unambiguously 151 identify an entity or an entity group within a given scope. An 152 identifier is the equivalent of an End-point IDentifier (EID) in The 153 Locator/ID Separation Protocol (LISP). It may or may not be visible 154 in communications. 156 Locator: A locator is a routable network address. It may be 157 associated with an identifier and used for communication on the 158 network layer according to identifier locator split principle. A 159 locator is the equivalent of a Routing Locator (RLOC) in LISP or an 160 IP address in other cases. 162 3. Identifier Locator Separation and Privacy 164 Identifier represents a communication end-point, a content, or any 165 identifiable entity and may not be a routable IP address, and in 166 general it is not an IP address at all. Locator may represent a 167 communication end-point, and in this case it usually is a routable 168 network address. Because entities identified by an Identifier can 169 move the association between Identifiers and Locators may be 170 ephemeral. A database called a mapping system needs to be used for 171 Identifier to Locator mapping. Identifiers are mapped to locators 172 for reachability purposes. A mapping system has to handle mobility 173 by updating the identifier to locator mappings in the database. Note 174 that different protocols/system may use a different terminology, 175 however, the principle remains the same: a form of (ephemeral) 176 binding between identifiers and locators. 178 To start the communication, a device needs to know the identifier of 179 the destination, hence it relies on a identifier lookup process to 180 obtain the associated locator(s). Note that both identifier and 181 locator may be carried in clear in packet headers, depending on the 182 specific technology used and the level of security/privacy enforced. 184 Usage of identifiers (and their locators) readily available for 185 public access raises privacy issues. For public entities, it may be 186 desirable to have their fully qualified domain names or host names 187 available for public lookups by the clients. For private entities, 188 usually the clients of the public ones, however, this is not the 189 case. For instance for individuals roaming in a mobile network may 190 not want their locators publicly available, or may be onlyavailable 191 to the memebers of his/her family. 193 Privacy is an increasingly desirable and often necessary property for 194 Internet technologies. 196 4. Identifier Locator Split Protocols 198 Herefater a non-exhaustive overview of protocolc/system leveraging on 199 the Locator/Identifier seapration is provided. 201 4.1. Locator/Identifier Separation Protocol (LISP) 203 Locator/Id Separation Protocol (LISP) [I-D.ietf-lisp-rfc6830bis] 204 [I-D.ietf-lisp-rfc6833bis] is based on a map-and-encap approach, 205 which provides a level of indirection for routing and addressing 206 performed at specific ingress/egress routers at the LISP domain 207 boundaries. Such border routers performing LISP encapsulation at the 208 packet's source stub network are indicated as Ingress Tunnel Routers 209 (ITRs), while border routers at the packet's destination stub network 210 are called Egress Tunnel Routers (ETRs), all of them are indicated by 211 the general term xTRs. In order to obtain mappings used for 212 encapsulation operation, xTRs query the mapping system in order to 213 obtain all mappings related to a certain EID only when necessary 214 (usually, but not exclusively, at the beginning of a new flow 215 transmission). The LISP control plane protocol 216 [I-D.ietf-lisp-rfc6833bis] allows to support several different 217 mapping systems (e.g., LISP+ALT [RFC6836] and LISP-DDT [RFC8111]). 218 More than that, it can actually also be applied to various other data 219 plane protocols. 221 4.2. Identifier/Locator Network Protocol (ILNP) 223 Identifier-Locator Network Protocol (ILNP) [RFC6740] is a host-based 224 approach enabling mobility using mechanisms that are only deployed in 225 end-systems and do not require any router changes. 227 4.3. Information Centric Networking (ICN) 229 Information-Centric Networking (ICN) [RFC7927] is an approach to 230 evolve the Internet infrastructure to directly support information 231 distribution by introducing uniquely named data as a core Internet 232 principle. Data becomes independent from location, application, 233 storage, and means of transportation, enabling or enhancing a number 234 of desirable features, such as security, user mobility, multicast, 235 and in-network caching. 237 4.4. Host Identity Protocol (HIP) 239 The Host Identity Protocol (HIP) [RFC4423] Architecture introduces a 240 new namespace, namely the Host Identity namespace, and a new 241 protocol. The HIP protocol aim at providing for limited forms of 242 trust between systems, enhance mobility, multi-homing, and dynamic IP 243 renumbering; aid in protocol translation/transition; and reduce 244 certain types of denial-of-service (DoS) attacks. 246 4.5. Virtual eXtensible Local Area Network (VXLAN) 248 Virtual Extensible LAN (VXLAN) [RFC7348] is a network virtualization 249 technology that attempts to address the scalability problems 250 associated with large cloud computing deployments. It uses a VLAN- 251 like encapsulation technique to encapsulate layer 2 Ethernet frames 252 within layer 4 UDP datagrams, using 4789 as the default IANA-assigned 253 destination UDP port number. VXLAN endpoints, which terminate VXLAN 254 tunnels and may be either virtual or physical switch ports, are known 255 as VXLAN tunnel endpoints (VTEPs) and can be considered the locators 256 of the devices in the extended VLAN. 258 4.6. Some Relevant Privacy-Critical Scenarios 260 The collection of scenarios shall serve as an overview of possible 261 Loc/ID separation application and help in identifying different 262 issues in privacy and security in generic Identifier Locator Split 263 approaches. 265 4.6.1. Industrial IoT 267 Sensors and other connected things in the industry are usually not 268 personal items (e.g. wearables) potentially revealing an individuals 269 sensitive information. Yet, industrial connected objects are 270 business assets whose information (e.g. location) should be available 271 only to authorised intra-company entities. Hence, there is an 272 interest in not shaing the ID/Locator binding with third parties, to 273 retain the privacy. This can be achieved in a number of ways such 274 as: using an ID/locator system but using some fixed anchor point as a 275 locator; injecting routing prefixes for the ID prefixes into the 276 normal routing system and use proxy indirection; providing limited 277 ID/Locator exposure. These are just examples, more approaches should 278 be explored in order to find which one is the most suitable in the 279 context of industrial IoT. 281 4.6.2. 5G 283 Upcoming new truly universal communication via so-called 5G systems 284 will demand for much more than (just) higher bandwidth and lower 285 latency. Integration of heterogeneous multiple access technologies 286 (both wireless and wireline) controlled by a common converged core 287 network and the evolution to service-based flexile functionalities 288 instead of hard-coded network functions calls for new protocols both 289 on control and user (data) plane. While Id-Loc approach would serve 290 well here, the challenge to provide a unique level of security and 291 privacy even for a lightweight routing and forwarding mechanism - 292 allowing for ease of deployment and migration from existing 293 operational network architecture - remains to be solved. 295 4.6.3. Cloud 297 The cloud, i.e. a set of distributed data centers for processing and 298 storage connected via high-speed transmission paths, is seen as 299 logical location for content and also for virtualized network 300 function instances and shall provide measures for easy re-location 301 and migration of these instances deployed as e.g. containers or 302 virtual machines. Id-Loc split routing protocols are proposed for 303 usage here as in VXLAN [RFC7348] and LISP [I-D.ietf-lisp-rfc6830bis] 304 [I-D.ietf-lisp-rfc6833bis] while the topology of the cloud components 305 and logical correlations shall be invisible from outside. 307 In a cloud, an upstream IP address does not necessarily belong to the 308 actual service location, but a gateway or load balancer. So, the 309 locator or also ID reveal the location with the accuracy of a data 310 center, not the function taking a service request. This issue also 311 manifests itself in today's LTE as PGWs are in a data center binding 312 UEs' IP addresses which are from the network of the data center. 314 5. Threats against Privacy 316 There seems to be at least two different privacy threats relating to 317 ID/locator mapping systems: 319 1. Location Privacy 320 2. Movement Privacy 322 Note that these threats appear in the hypothesys that the ID does not 323 change. Nevertheless, even in the case of mutable IDs, there are 324 other forms of information correlation that may allow to identify 325 network entities. 327 5.1. Location Privacy 329 If a third party can at any time determine the IP location of some 330 identifier, then the device can at one point be IP geolocated at 331 home, and later a coffee shop. 333 5.2. Movement Privacy 335 If a third party can determine that an identifier has changed 336 locator(s) at time T, then even without knowing the particular 337 locators before and after, it can correlate this movement event with 338 other information (e.g., security cameras) to create a binding 339 between the identifier and a person. 341 6. Not everybody all the time 343 In order to see the benefits about but minimizing the privacy 344 implication one can explore limiting to which peers and when the ID/ 345 locator binding are exposed. 347 A few initial examples help illustrate this. 349 6.1. Optimized Routing 351 If some operator of a network where there is a large amount of 352 mobility wants to ensure efficient routing, then a ID/locator split 353 approach might make sense. Such a system can potentially be limited 354 to the set of devices (routers etc) which are under the operators 355 control. If this is the case, then the ID/locator mapping system can 356 provide access control so that only those trusted devices can access 357 the mappings. 359 Note that from a privacy perspective this isn't any different than 360 the same operator using a link-state routing protocol to share host 361 routes for all the mobile devices. In that case all participants in 362 the link-state protocol can determine the location (attached to which 363 router) and notice any mobility events. Of course, there are 364 significant non-privacy differences between those two approaches. 366 Exposing the ID/locator mapping to attached devices (e.g., any mobile 367 devices which wouldn't be trusted to participate in the link-state 368 routing counterpart approach), will change the privacy implications. 370 6.2. Family and Friends 372 There are cases where it is quite reasonable to share location 373 information with other family members or friends. For instance, 374 young children might run applications which enable their parents to 375 track them on their way to/from school. And I might share my 376 location with friends so we can more easily find each other while out 377 on town. 379 Today such location sharing happens at an application layer using GPS 380 coordinates. But while such sharing is in effect, it wouldn't be 381 unreasonable to also consider sharing IP locators to make it more 382 efficient or more robust to e.g., route a video feed from one device 383 to another. 385 6.3. Business Assets 387 In the area of Industrial IoT there are cases where an asset owner 388 might want to ensure that their assets can communicate efficiently 389 and robustly. In many cases those assets might be decoupled from any 390 persons, but there can still be strong reasons to not share the ID/ 391 locator binding with third parties, such as enabling competitors to 392 determine the number of deployed devices in a particular IP prefix. 394 7. Boundary between ID/locator part and rest of Internet 396 If the access to the ID/locator mapping are restricted as suggested 397 above, then most of the potential peer devices would not have access 398 to the ID/locator mappings. This means that there has to be a 399 demarcation point between the part of the network which can access 400 the ID/locator mappings for a particular identifier and the one which 401 can not. There might be several choices how to handle this such as 402 still using an ID/locator system but pointing a locator for some 403 fixed anchor point, or injecting routing prefixes for the ID prefixes 404 into the normal routing system, or not providing any stable locators 405 across this boundary; only allow ephemeral IP addresses per session 406 or otherwise limited exposure. 408 8. Security Considerations 410 This document discusses privacy considerations, but does not explore 411 any security considerations. 413 9. IANA Considerations 415 There are no IANA actions needed for this document. 417 10. References 419 [I-D.ietf-lisp-rfc6830bis] 420 Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. 421 Cabellos-Aparicio, "The Locator/ID Separation Protocol 422 (LISP)", draft-ietf-lisp-rfc6830bis-32 (work in progress), 423 March 2020. 425 [I-D.ietf-lisp-rfc6833bis] 426 Farinacci, D., Maino, F., Fuller, V., and A. Cabellos- 427 Aparicio, "Locator/ID Separation Protocol (LISP) Control- 428 Plane", draft-ietf-lisp-rfc6833bis-27 (work in progress), 429 January 2020. 431 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 432 Requirement Levels", BCP 14, RFC 2119, 433 DOI 10.17487/RFC2119, March 1997, 434 . 436 [RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol 437 (HIP) Architecture", RFC 4423, DOI 10.17487/RFC4423, May 438 2006, . 440 [RFC6740] Atkinson, RJ. and SN. Bhatti, "Identifier-Locator Network 441 Protocol (ILNP) Architectural Description", RFC 6740, 442 DOI 10.17487/RFC6740, November 2012, 443 . 445 [RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, 446 "Locator/ID Separation Protocol Alternative Logical 447 Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836, 448 January 2013, . 450 [RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger, 451 L., Sridhar, T., Bursell, M., and C. Wright, "Virtual 452 eXtensible Local Area Network (VXLAN): A Framework for 453 Overlaying Virtualized Layer 2 Networks over Layer 3 454 Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014, 455 . 457 [RFC7927] Kutscher, D., Ed., Eum, S., Pentikousis, K., Psaras, I., 458 Corujo, D., Saucez, D., Schmidt, T., and M. Waehlisch, 459 "Information-Centric Networking (ICN) Research 460 Challenges", RFC 7927, DOI 10.17487/RFC7927, July 2016, 461 . 463 [RFC8111] Fuller, V., Lewis, D., Ermagan, V., Jain, A., and A. 464 Smirnov, "Locator/ID Separation Protocol Delegated 465 Database Tree (LISP-DDT)", RFC 8111, DOI 10.17487/RFC8111, 466 May 2017, . 468 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 469 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 470 May 2017, . 472 Authors' Addresses 474 Luigi Iannone 475 Telecom Paris 477 Email: ggx@gigix.net 479 Dirk von Hugo 480 Deutsche Telekom 481 Deutsche-Telekom-Allee 7 482 D-64295 Darmstadt 483 Germany 485 Email: Dirk.von-Hugo@telekom.de 487 Behcet Sarikaya 488 Denpel Informatique 490 Email: sarikaya@ieee.org 492 Erik Nordmark 493 Zededa 494 Santa Clara, CA 495 USA 497 Email: nordmark@sonic.net