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2 IPv6 Operations Working Group (v6ops) F. Gont
3 Internet-Draft SI6 Networks / UTN-FRH
4 Intended status: Informational N. Hilliard
5 Expires: January 2, 2016 INEX
6 G. Doering
7 SpaceNet AG
8 W. Liu
9 Huawei Technologies
10 W. Kumari
11 Google
12 July 1, 2015
14 Operational Implications of IPv6 Packets with Extension Headers
15 draft-gont-v6ops-ipv6-ehs-packet-drops-00
17 Abstract
19 This document summarizes the security and operational implications of
20 IPv6 extension headers, and attempts to analyze reasons why packets
21 with IPv6 extension headers may be dropped in the public Internet.
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 http://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 January 2, 2016.
40 Copyright Notice
42 Copyright (c) 2015 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 (http://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. Previous Work on IPv6 Extension Headers . . . . . . . . . . . 3
59 3. Security Implications . . . . . . . . . . . . . . . . . . . . 3
60 4. Operational Implications . . . . . . . . . . . . . . . . . . 5
61 4.1. Enforcing infrastructure ACLs . . . . . . . . . . . . . . 5
62 4.2. Route-Processor Protection . . . . . . . . . . . . . . . 5
63 4.3. DDoS Management and Customer Requests for Filtering . . . 5
64 4.4. ECMP and Hash-based Load-Sharing . . . . . . . . . . . . 6
65 4.5. Packet Forwarding Engine Constraints . . . . . . . . . . 6
66 5. A Possible Attack Vector . . . . . . . . . . . . . . . . . . 7
67 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
68 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
69 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
70 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
71 9.1. Normative References . . . . . . . . . . . . . . . . . . 9
72 9.2. Informative References . . . . . . . . . . . . . . . . . 10
73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
75 1. Introduction
77 IPv6 Extension Headers (EHs) allow for the extension of the IPv6
78 protocol, and provide support for core functionality such as IPv6
79 fragmentation. However, widespread implementation limitations
80 suggest that EHs present a challenge for IPv6 packet routing
81 equipment, and evidence exists to suggest that IPv6 with EHs may be
82 intentionally dropped on the public Internet in some network
83 deployments.
85 Discussions about the security and operational implications of IPv6
86 extension headers are a regular feature in IETF working groups and
87 other places. Often in these discussions, important security and
88 operational issues are overlooked.
90 This document tries to raise awareness about the security and
91 operational implications of IPv6 Extension Headers, and presents
92 reasons why some networks drop packets containing IPv6 Extension
93 Headers.
95 Section 2 of this document summarizes the work that has been done in
96 the area of IPv6 extension headers. Section 3 discusses the security
97 implications of IPv6 Extension Headers, while Section 4 discusses
98 their operational implications.
100 2. Previous Work on IPv6 Extension Headers
102 Some of the implications of IPv6 Extension Headers have been
103 discussed in IETF circles. For example, [I-D.taylor-v6ops-fragdrop]
104 discusses a rationale for which operators drop IPv6 fragments.
105 [I-D.wkumari-long-headers] discusses possible issues arising from
106 "long" IPv6 header chains. [RFC7045] clarifies how intermediate
107 nodes should deal with IPv6 extension headers. [RFC7112] discusses
108 the issues arising in a specific case where the IPv6 header chain is
109 fragmented into two or more fragments (and formally forbids such
110 case). [I-D.kampanakis-6man-ipv6-eh-parsing] describes how
111 inconsistencies in the way IPv6 packets with extension headers are
112 parsed by different implementations may result in evasion of security
113 controls, and presents guidelines for parsing IPv6 extension headers
114 with the goal of providing a common and consistent parsing
115 methodology for IPv6 implementations. [RFC6980] analyzes the
116 security implications of employing IPv6 fragmentation with Neighbor
117 Discovery for IPv6, and formally recommends against such usage.
118 Finally, [RFC7123] discusses how some popular RA-Guard
119 implementations are subject to evasion by means of IPv6 extension
120 headers.
122 Some preliminary measurements regarding the extent to which packet
123 containing IPv6 EHs are dropped in the public Internet have been
124 presented in [PMTUD-Blackholes], [Gont-IEPG88], [Gont-Chown-IEPG89],
125 and [Linkova-Gont-IEPG90]. [I-D.ietf-v6ops-ipv6-ehs-in-real-world]
126 presents more comprehensive results and documents the methodology for
127 obtaining the presented results.
129 3. Security Implications
131 The security implications of IPv6 Extension Headers generally fall
132 into one or more of these categories:
134 o Evasion of security controls
136 o DoS due to processing requirements
138 o DoS due to implementation errors
140 o Extension Header-specific issues
142 Unlike IPv4 packets where the upper-layer protocols can be trivially
143 found by means of the "IHL" ("Internet Header Length") IPv4 header
144 field, the structure of IPv6 packets is more flexible and complex.
146 Locating upper-layer protocol information requires that all IPv6
147 extension headers be examined. This has presented implementation
148 difficulties, and packet filtering mechanisms on several security
149 devices can be trivially evaded by inserting IPv6 Extension Headers
150 between the main IPv6 header and the upper layer protocol. [RFC7113]
151 describes this issue for the RA-Guard case, but the same techniques
152 can be employed to circumvent other IPv6 firewall and packet
153 filtering mechanisms. Additionally, implementation inconsistencies
154 in packet forwarding engines may result in evasion of security
155 controls [I-D.kampanakis-6man-ipv6-eh-parsing] [Atlasis2014]
156 [BH-EU-2014].
158 As noted in Section 4, packets that use IPv6 Extension Headers may
159 have a negative performance impact on the handling devices. Unless
160 appropriate mitigations are put in place (e.g., packet filtering and/
161 or rate-limiting), an attacker could simply send a large amount of
162 IPv6 traffic employing IPv6 Extension Headers with the purpose of
163 performing a Denial of Service (DoS) attack.
165 NOTE: In the most trivial case, a packet that includes a Hop-by-
166 Hop Options header will typically go through the slow forwarding
167 path, and be processed by the router's CPU. An implementation-
168 dependent case might be that in which a router that has been
169 configured to enforce an ACL based on upper-layer information
170 (e.g., upper layer protocol or TCP Destination Port), needs to
171 process the entire IPv6 header chain (in order to find the
172 required information) and this causes the packet to be processed
173 in the slow path [Cisco-EH-Cons]. We note that, for obvious
174 reasons, the aforementioned performance issues may also affect
175 other devices such as firewalls, Network Intrusion Detection
176 Systems (NIDS), etc. [Zack-FW-Benchmark]. The extent to which
177 these devices are affected will typically be implementation-
178 dependent.
180 IPv6 implementations, like all other software, tend to mature with
181 time and wide-scale deployment. While the IPv6 protocol itself has
182 existed for almost 20 years, serious bugs related to IPv6 Extension
183 Header processing continue to be discovered. Because there is
184 currently little operational reliance on IPv6 Extension headers, the
185 corresponding code paths are rarely exercised, and there is the
186 potential that bugs still remain to be discovered in some
187 implementations.
189 IPv6 Fragment Headers are employed to allow fragmentation of IPv6
190 packets. While many of the security implications of the
191 fragmentation / reassembly mechanism are known from the IPv4 world,
192 several related issues have crept into IPv6 implementations. These
193 range from denial of service attacks to information leakage, for
194 example [I-D.ietf-6man-predictable-fragment-id], [Bonica-NANOG58] and
195 [Atlasis2012]).
197 4. Operational Implications
199 Intermediate systems and middleboxes often need to process the entire
200 IPv6 extension header chain to find the layer-4 header. The
201 following subsections discuss some of reasons for which such layer-4
202 information may be needed by an intermediate systems or middlebox,
203 and why packets containing IPv6 extension headers may represent a
204 challenge in such scenarios.
206 4.1. Enforcing infrastructure ACLs
208 Generally speaking, infrastructure ACLs drop unwanted packets
209 destined to parts of a provider's infrastructure, because they are
210 not operationally needed and can be used for attacks of different
211 sorts against the router's control plane. Some traffic needs to be
212 differentiated depending on layer-3 or layer-4 criteria to achieve a
213 useful balance of protection and functionality, for example:
215 o Permit some amount of ICMP echo (ping) traffic towards the
216 router's addresses for troubleshooting.
218 o Permit BGP sessions on the shared network of an exchange point
219 (potentially differentiating between the amount of packets/seconds
220 permitted for established sessions and connection establishment),
221 but do not permit other traffic from the same peer IP addresses.
223 4.2. Route-Processor Protection
225 Most modern routers have a fast hardware-assisted forwarding plane
226 and a loosely coupled control plane, connected together with a link
227 that has much less capacity than the forwarding plane could handle.
228 Traffic differentiation cannot be done by the control plane side,
229 because this would overload the internal link connecting the
230 forwarding plane to the control plane.
232 4.3. DDoS Management and Customer Requests for Filtering
234 The case of customer DDoS protection and edge-to-core customer
235 protection filters is similar in nature to the infrastructure ACL
236 protection. Similar to iACL protection, layer-4 ACLs generally need
237 to be applied as close to the edge of the network as possible, even
238 though the intent is to protect the customer edge rather than the
239 provider core. Application of layer-4 DDoS protection to a network
240 edge is often automated using Flowspec [RFC5575].
242 For example, a web site which normally only handled traffic on TCP
243 ports 80 and 443 could be subject to a volumetric DDoS attack using
244 NTP and DNS packets with randomised source IP address, thereby
245 rendering useless traditional [RFC5635] source-based real-time black
246 hole mechanisms. In this situation, DDoS protection ACLs could be
247 configured to block all UDP traffic at the network edge without
248 impairing the web server functionality in any way. Thus, being able
249 to filter out arbitrary protocols at the network edge can avoid DDoS-
250 related problems both in the provider network and on the customer
251 edge link.
253 4.4. ECMP and Hash-based Load-Sharing
255 In the case of ECMP (equal cost multi path) load sharing, the router
256 on the sending side of the link needs to make a decision regarding
257 which of the links to use for a given packet. Since round-robin
258 usage of the links is usually avoided in order to prevent packet
259 reordering, forwarding engines need to use a mechanism which will
260 consistently forward the same data streams down the same forwarding
261 paths. Most forwarding engines achieve this by calculating a simple
262 hash using an n-tuple gleaned from a combination of layer-2 through
263 to layer-4 packet header information. This n-tuple will typically
264 use the src/dst MAC address, src/dst IP address, and if possible
265 further layer-4 src/dst port information. As layer-4 port
266 information increases the entropy of the hash, it is highly desirable
267 to use it where possible.
269 4.5. Packet Forwarding Engine Constraints
271 Most modern routers use dedicated hardware (e.g. ASICs or NPUs) to
272 determine how to forward packets across their internal fabrics. One
273 of the common methods of handling next-hop lookup is to send a small
274 portion of the ingress packet to a lookup engine with specialised
275 hardware (e.g. Tertiary CAM or RLDRAM) to determine the packet's
276 next-hop. Technical constraints mean that there is a trade-off
277 between the amount of data sent to the lookup engine and the overall
278 performance of the lookup engine. If more data is sent, the lookup
279 engine can inspect further into the packet, but the overall
280 performance of the system will be reduced. If less data is sent, the
281 overall performance of the router will be increased but the packet
282 lookup engine may not be able to inspect far enough into a packet to
283 determine how it should be handled.
285 Note: For example, current high-end routers at the time of
286 authorship of this document can use up to 192 bytes of header
287 (Cisco ASR9000 Typhoon) or 384 bytes of header (Juniper MX Trio)
289 If a hardware forwarding engine on a modern router cannot make a
290 forwarding decision about a packet because critical information is
291 not sent to the look-up engine, then the router will normally drop
292 the packet. Historically, some packet forwarding engines punted
293 packets of this form to the control plane for more in-depth analysis,
294 but this is unfeasible on most current router architectures as a
295 result of the vast difference between the hardware forwarding
296 capacity of the router and the size of the management link which
297 connects the control plane to the forwarding plane.
299 If an IPv6 header chain is sufficiently long that its header exceeds
300 the packet look-up capacity of the router, then it may be dropped due
301 to hardware inability to determine how it should be handled.
303 5. A Possible Attack Vector
305 The widespread drop of IPv6 packets employing IPv6 Extension Headers
306 can, in some scenarios, be exploited for malicious purposes: if
307 packets employing IPv6 EHs are known to be dropped on the path from
308 system A to system B, an attacker could cause packets sent from A to
309 B to be dropped by sending a forged ICMPv6 Packet Too Big (PTB)
310 [RFC4443] error message to A (advertising an MTU smaller than 1280),
311 such that subsequent packets from A to B include a fragment header
312 (i.e., they result in atomic fragments [RFC6946]).
314 Possible scenarios where this attack vector could be exploited
315 include (but are not limited to):
317 o Communication between any two systems through to public network
318 (e.g., client from/to server or server from/to server), where
319 packets with IPv6 extension headers are dropped by some
320 intermediate router
322 o Communication between two BGP peers employing IPv6 transport,
323 where these BGP peers implement ACLs to drop IPv6 fragments (to
324 avoid control-plane attacks)
326 The aforementioned attack vector is exacerbated by the following
327 factors:
329 o The attacker does not need to forge the IPv6 Source Address of his
330 attack packets. Hence, deployment of simple BCP38 filters will
331 not help as a counter-measure.
333 o Only the IPv6 addresses of the IPv6 packet embedded in the ICMPv6
334 payload need to be forged. While one could envision filtering
335 devices enforcing BCP38-style filters on the ICMPv6 payload, the
336 use of extension headers (by the attacker) could make this
337 difficult, if not impossible.
339 o Many implementations fail to perform validation checks on the
340 received ICMPv6 error messages, as recommended in Section 5.2 of
341 [RFC4443] and documented in [RFC5927]. It should be noted that in
342 some cases, such as when an ICMPv6 error message has (supposedly)
343 been elicited by a connection-less transport protocol (or some
344 other connection-less protocol being encapsulated in IPv6), it may
345 be virtually impossible to perform validation checks on the
346 received ICMPv6 error messages. And, because of IPv6 extension
347 headers, the ICMPv6 payload might not even contain any useful
348 information on which to perform validation checks.
350 o Upon receipt of one of the aforementioned ICMPv6 "Packet Too Big"
351 error messages, the Destination Cache [RFC4861] is usually updated
352 to reflect that any subsequent packets to such destination should
353 include a Fragment Header. This means that a single ICMPv6
354 "Packet Too Big" error message might affect multiple communication
355 instances (e.g. TCP connections) with such destination.
357 o A router or other middlebox cannot simply drop all incoming ICMPv6
358 Packet Too Big error messages, as this would create a PMTUD
359 blackhole.
361 Possible mitigations for this issue include:
363 o Filtering incoming ICMPv6 Packet Too Big error messages that
364 advertise a Next-Hop MTU smaller than 1280 bytes.
366 o Artificially reducing the MTU to 1280 bytes and filter incoming
367 ICMPv6 PTB error messages.
369 Both of these mitigations come at the expense of possibly preventing
370 communication through SIIT [RFC6145] that rely on IPv6 atomic
371 fragments (see [I-D.ietf-6man-deprecate-atomfrag-generation]), and
372 also implies that the filtering device has the ability to filter ICMP
373 PTB messages based on the contents of the MTU field.
375 [I-D.ietf-6man-deprecate-atomfrag-generation] has recently proposed
376 to deprecate the generation of IPv6 atomic fragments, and update SIIT
377 [RFC6145] such that it does not rely on ICMPv6 atomic fragments.
378 Thus, any of the above mitigations would eliminate the attack vector
379 without any interoperability implications.
381 6. IANA Considerations
383 There are no IANA registries within this document. The RFC-Editor
384 can remove this section before publication of this document as an
385 RFC.
387 7. Security Considerations
389 The security implications of IPv6 extension headers are discussed in
390 Section 3. A specific attack vector that could leverage the
391 widespread filtering of packets with IPv6 EHs (along with possible
392 countermeasures) is discussed in Section 5. This document does not
393 introduce any new security issues.
395 8. Acknowledgements
397 The authors would like to thank (in alphabetical order) [TBD] for
398 providing valuable comments on earlier versions of this document.
399 Additionally, the authors would like to thank participants of the
400 v6ops working group for their valuable input on the topics that led
401 to the publication of this document.
403 Fernando Gont would like to thank Fernando Gont would like to thank
404 Jan Zorz / Go6 Lab , and Jared Mauch / NTT
405 America, for providing access to systems and networks that were
406 employed to perform experiments and measurements involving packets
407 with IPv6 Extension Headers. Additionally, he would like to thank
408 SixXS for providing IPv6 connectivity.
410 9. References
412 9.1. Normative References
414 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
415 (IPv6) Specification", RFC 2460, December 1998.
417 [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control
418 Message Protocol (ICMPv6) for the Internet Protocol
419 Version 6 (IPv6) Specification", RFC 4443, March 2006.
421 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
422 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
423 September 2007.
425 [RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
426 Algorithm", RFC 6145, April 2011.
428 [RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments", RFC
429 6946, May 2013.
431 9.2. Informative References
433 [Atlasis2012]
434 Atlasis, A., "Attacking IPv6 Implementation Using
435 Fragmentation", BlackHat Europe 2012. Amsterdam,
436 Netherlands. March 14-16, 2012,
437 .
440 [Atlasis2014]
441 Atlasis, A., "A Novel Way of Abusing IPv6 Extension
442 Headers to Evade IPv6 Security Devices", May 2014,
443 .
446 [BH-EU-2014]
447 Atlasis, A., Rey, E., and R. Schaefer, "Evasion of High-
448 End IDPS Devices at the IPv6 Era", BlackHat Europe 2014,
449 2014, .
452 [Bonica-NANOG58]
453 Bonica, R., "IPv6 Extension Headers in the Real World
454 v2.0", NANOG 58. New Orleans, Louisiana, USA. June 3-5,
455 2013, .
458 [Cisco-EH-Cons]
459 Cisco, , "IPv6 Extension Headers Review and
460 Considerations", October 2006,
461 .
464 [Gont-Chown-IEPG89]
465 Gont, F. and T. Chown, "A Small Update on the Use of IPv6
466 Extension Headers", IEPG 89. London, UK. March 2, 2014,
467 .
470 [Gont-IEPG88]
471 Gont, F., "Fragmentation and Extension header Support in
472 the IPv6 Internet", IEPG 88. Vancouver, BC, Canada.
473 November 13, 2013, .
476 [I-D.ietf-6man-deprecate-atomfrag-generation]
477 Gont, F., LIU, S., and T. Anderson, "Deprecating the
478 Generation of IPv6 Atomic Fragments", draft-ietf-6man-
479 deprecate-atomfrag-generation-01 (work in progress), April
480 2015.
482 [I-D.ietf-6man-predictable-fragment-id]
483 Gont, F., "Security Implications of Predictable Fragment
484 Identification Values", draft-ietf-6man-predictable-
485 fragment-id-08 (work in progress), June 2015.
487 [I-D.ietf-v6ops-ipv6-ehs-in-real-world]
488 Gont, F., Linkova, J., Chown, T., and S. LIU,
489 "Observations on IPv6 EH Filtering in the Real World",
490 draft-ietf-v6ops-ipv6-ehs-in-real-world-00 (work in
491 progress), April 2015.
493 [I-D.kampanakis-6man-ipv6-eh-parsing]
494 Kampanakis, P., "Implementation Guidelines for parsing
495 IPv6 Extension Headers", draft-kampanakis-6man-ipv6-eh-
496 parsing-01 (work in progress), August 2014.
498 [I-D.taylor-v6ops-fragdrop]
499 Jaeggli, J., Colitti, L., Kumari, W., Vyncke, E., Kaeo,
500 M., and T. Taylor, "Why Operators Filter Fragments and
501 What It Implies", draft-taylor-v6ops-fragdrop-02 (work in
502 progress), December 2013.
504 [I-D.wkumari-long-headers]
505 Kumari, W., Jaeggli, J., Bonica, R., and J. Linkova,
506 "Operational Issues Associated With Long IPv6 Header
507 Chains", draft-wkumari-long-headers-03 (work in progress),
508 June 2015.
510 [Linkova-Gont-IEPG90]
511 Linkova, J. and F. Gont, "IPv6 Extension Headers in the
512 Real World v2.0", IEPG 90. Toronto, ON, Canada. July 20,
513 2014, .
516 [PMTUD-Blackholes]
517 De Boer, M. and J. Bosma, "Discovering Path MTU black
518 holes on the Internet using RIPE Atlas", July 2012,
519 .
522 [RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
523 and D. McPherson, "Dissemination of Flow Specification
524 Rules", RFC 5575, August 2009.
526 [RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole
527 Filtering with Unicast Reverse Path Forwarding (uRPF)",
528 RFC 5635, August 2009.
530 [RFC5927] Gont, F., "ICMP Attacks against TCP", RFC 5927, July 2010.
532 [RFC6980] Gont, F., "Security Implications of IPv6 Fragmentation
533 with IPv6 Neighbor Discovery", RFC 6980, August 2013.
535 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing
536 of IPv6 Extension Headers", RFC 7045, December 2013.
538 [RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of
539 Oversized IPv6 Header Chains", RFC 7112, January 2014.
541 [RFC7113] Gont, F., "Implementation Advice for IPv6 Router
542 Advertisement Guard (RA-Guard)", RFC 7113, February 2014.
544 [RFC7123] Gont, F. and W. Liu, "Security Implications of IPv6 on
545 IPv4 Networks", RFC 7123, February 2014.
547 [RIPE-Atlas]
548 RIPE, , "RIPE Atlas", .
550 [Zack-FW-Benchmark]
551 Zack, E., "Firewall Security Assessment and Benchmarking
552 IPv6 Firewall Load Tests", IPv6 Hackers Meeting #1,
553 Berlin, Germany. June 30, 2013,
554 .
558 Authors' Addresses
560 Fernando Gont
561 SI6 Networks / UTN-FRH
562 Evaristo Carriego 2644
563 Haedo, Provincia de Buenos Aires 1706
564 Argentina
566 Phone: +54 11 4650 8472
567 Email: fgont@si6networks.com
568 URI: http://www.si6networks.com
569 Nick Hilliard
570 INEX
571 4027 Kingswood Road
572 Dublin 24
573 IE
575 Email: nick@inex.ie
577 Gert Doering
578 SpaceNet AG
579 Joseph-Dollinger-Bogen 14
580 Muenchen D-80807
581 Germany
583 Email: gert@space.net
585 Will (Shucheng) Liu
586 Huawei Technologies
587 Bantian, Longgang District
588 Shenzhen 518129
589 P.R. China
591 Email: liushucheng@huawei.com
593 Warren Kumari
594 Google
595 1600 Amphitheatre Parkway
596 Mountain View, CA 94043
597 US
599 Email: warren@kumari.net