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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group W. Kumari 3 Internet-Draft Google 4 Obsoletes: 7710 (if approved) E. Kline 5 Updates: 3679 (if approved) Loon 6 Intended status: Standards Track July 1, 2020 7 Expires: January 2, 2021 9 Captive-Portal Identification in DHCP / RA 10 draft-ietf-capport-rfc7710bis-10 12 Abstract 14 In many environments offering short-term or temporary Internet access 15 (such as coffee shops), it is common to start new connections in a 16 captive portal mode. This highly restricts what the user can do 17 until the user has satisfied the captive portal conditions. 19 This document describes a DHCPv4 and DHCPv6 option and a Router 20 Advertisement (RA) option to inform clients that they are behind some 21 sort of captive portal enforcement device, and that they will need to 22 satify the Captive Portal conditions to get Internet access. It is 23 not a full solution to address all of the issues that clients may 24 have with captive portals; it is designed to be one component of a 25 standardized approach for hosts to interact with such portals. While 26 this document defines how the network operator may convey the captive 27 portal API endpoint to hosts, the specific methods of satisfying and 28 interacting with the captive portal are out of scope of this 29 document. 31 This document replaces [RFC7710]. [RFC7710] used DHCP code point 32 160. Due to a conflict, this document specifies 114. Consequently, 33 this document also updates [RFC3679]. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at https://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on January 2, 2021. 51 Copyright Notice 53 Copyright (c) 2020 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (https://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 69 1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 3 70 2. The Captive-Portal Option . . . . . . . . . . . . . . . . . . 3 71 2.1. IPv4 DHCP Option . . . . . . . . . . . . . . . . . . . . 4 72 2.2. IPv6 DHCP Option . . . . . . . . . . . . . . . . . . . . 5 73 2.3. The Captive-Portal IPv6 RA Option . . . . . . . . . . . . 5 74 3. Precedence of API URIs . . . . . . . . . . . . . . . . . . . 6 75 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 76 4.1. Captive Portal Unrestricted Identifier . . . . . . . . . 7 77 4.2. BOOTP Vendor Extensions and DHCP Options Code Change . . 7 78 4.3. Update DHCPv6 and IPv6 ND Options Registries . . . . . . 7 79 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 80 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 81 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 82 7.1. Normative References . . . . . . . . . . . . . . . . . . 9 83 7.2. Informative References . . . . . . . . . . . . . . . . . 10 84 Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 11 85 Appendix B. Changes from RFC 7710 . . . . . . . . . . . . . . . 12 86 Appendix C. Observations From IETF 106 Network Experiment . . . 12 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 89 1. Introduction 91 In many environments, users need to connect to a captive portal 92 device and agree to an Acceptable Use Policy (AUP) and / or provide 93 billing information before they can access the Internet. Regardless 94 of how that mechanism operates, this document provides functionality 95 to allow the client to know when it is behind a captive portal and 96 how to contact it. 98 In order to present users with the payment or AUP pages, presently a 99 captive portal enforcement device has to intercept the user's 100 connections and redirect the user to a captive portal server, using 101 methods that are very similar to man-in-the-middle (MITM) attacks. 102 As increasing focus is placed on security, and end nodes adopt a more 103 secure stance, these interception techniques will become less 104 effective and/or more intrusive. 106 This document describes a DHCPv4 [RFC2131] and DHCPv6 [RFC8415] 107 option (Captive-Portal) and an IPv6 Router Advertisement (RA) 108 [RFC4861] option that informs clients that they are behind a captive 109 portal enforcement device and the API endpoint that the host can 110 contact for more information. 112 This document replaces RFC 7710 [RFC7710]. 114 1.1. Requirements Notation 116 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 117 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 118 "OPTIONAL" in this document are to be interpreted as described in BCP 119 14 [RFC2119] [RFC8174] when, and only when, they appear in all 120 capitals, as shown here. 122 2. The Captive-Portal Option 124 The Captive-Portal DHCP / RA Option informs the client that it may be 125 behind a captive portal and provides the URI to access an API as 126 defined by [draft-ietf-capport-api]. This is primarily intended to 127 improve the user experience by showing the user the captive portal 128 information faster and more reliably. Note that, for the foreseeable 129 future, captive portals will still need to implement interception 130 techniques to serve legacy clients, and clients will need to perform 131 probing to detect captive portals"; nonetheless, the mechanism 132 provided by this document provides a more reliable and performant way 133 to do so, and is therefore the preferred mechanism for captive portal 134 detection. 136 Clients that support the Captive Portal DHCP option SHOULD include 137 the option in the Parameter Request List in DHCPREQUEST messages. 138 DHCP servers MAY send the Captive Portal option without any explicit 139 request. 141 In order to support multiple "classes" of clients (e.g. IPv4 only, 142 IPv6 only with DHCPv6 ([RFC8415]), and IPv6 only with RA) the captive 143 network can provision the client with the URI via multiple methods 144 (IPv4 DHCP, IPv6 DHCP, and IPv6 RA). The captive portal operator 145 SHOULD ensure that the URIs provisioned by each method are identical 146 to reduce the chance of operational problems. As the maximum length 147 of the URI that can be carried in IPv4 DHCP is 255 bytes, URIs longer 148 than this SHOULD NOT be provisioned by any of the IPv6 options 149 described in this document. In IPv6-only environments this 150 restriction can be relaxed. 152 In all variants of this option, the URI MUST be that of the captive 153 portal API endpoint [draft-ietf-capport-api]. 155 A captive portal MAY do content negotiation ([RFC7231] section 3.4) 156 and attempt to redirect clients querying without an explicit 157 indication of support for the captive portal API content type (i.e. 158 without application/capport+json listed explicitly anywhere within an 159 Accept header vis. [RFC7231] section 5.3). In so doing, the captive 160 portal SHOULD redirect the client to the value associated with the 161 "user-portal-url" API key. When performing such content negotiation 162 ([RFC7231] Section 3.4), implementors of captive portals need to keep 163 in mind that such responses might be cached, and therefore SHOULD 164 include an appropriate Vary header field ([RFC7231] Section 7.1.4) or 165 set the Cache-Control header field in any responses to "private", or 166 a more restrictive value such as "no-store" [RFC7234] 167 Section 5.2.2.3). 169 The URI SHOULD NOT contain an IP address literal. Exceptions to this 170 might include networks with only one operational IP address family 171 where DNS is either not available or not fully functional until the 172 captive portal has been satisfied. Use of iPAddress certificates 173 ([RFC3779]) adds considerations that are out of scope for this 174 document. 176 Networks with no captive portals may explicitly indicate this 177 condition by using this option with the IANA-assigned URI for this 178 purpose. Clients observing the URI value 179 "urn:ietf:params:capport:unrestricted" may forego time-consuming 180 forms of captive portal detection. 182 2.1. IPv4 DHCP Option 184 The format of the IPv4 Captive-Portal DHCP option is shown below. 186 0 1 2 3 187 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 188 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 189 | Code | Len | URI (variable length) ... | 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 . ...URI continued... . 192 | ... | 193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 195 o Code: The Captive-Portal DHCPv4 Option (114) (one octet) 197 o Len: The length (one octet), in octets, of the URI. 199 o URI: The URI for the captive portal API endpoint to which the user 200 should connect (encoded following the rules in [RFC3986]). 202 See [RFC2132], Section 2 for more on the format of IPv4 DHCP options. 204 Note that the URI parameter is not null terminated. 206 2.2. IPv6 DHCP Option 208 The format of the IPv6 Captive-Portal DHCP option is shown below. 210 0 1 2 3 211 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 212 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 213 | option-code | option-len | 214 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 215 . URI (variable length) . 216 | ... | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 219 o option-code: The Captive-Portal DHCPv6Option (103) (two octets) 221 o option-len: The unsigned 16-bit length, in octets, of the URI. 223 o URI: The URI for the captive portal API endpoint to which the user 224 should connect (encoded following the rules in [RFC3986]). 226 See [RFC7227], Section 5.7 for more examples of DHCP Options with 227 URIs. See [RFC8415], Section 21.1 for more on the format of IPv6 228 DHCP options. 230 Note that the URI parameter is not null terminated. 232 As the maximum length of the URI that can be carried in IPv4 DHCP is 233 255 bytes, URIs longer than this SHOULD NOT be provisioned via IPv6 234 DHCP options. 236 2.3. The Captive-Portal IPv6 RA Option 238 This section describes the Captive-Portal Router Advertisement 239 option. 241 0 1 2 3 242 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 244 | Type | Length | URI . 245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . 246 . . 247 . . 248 . . 249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 250 Figure 2: Captive-Portal RA Option Format 252 Type 37 254 Length 8-bit unsigned integer. The length of the option (including 255 the Type and Length fields) in units of 8 bytes. 257 URI The URI for the captive portal API endpoint to which the user 258 should connect. This MUST be padded with NUL (0x00) to make the 259 total option length (including the Type and Length fields) a 260 multiple of 8 bytes. 262 Note that the URI parameter is not guaranteed to be null terminated. 264 As the maximum length of the URI that can be carried in IPv4 DHCP is 265 255 bytes, URIs longer than this SHOULD NOT be provisioned via IPv6 266 RA options. 268 3. Precedence of API URIs 270 A device may learn about Captive Portal API URIs through more than 271 one of (or indeed all of) the above options. Implementations can 272 select their own precedence order (e.g., prefer one of the IPv6 273 options before the DHCPv4 option, or vice versa, et cetera). 275 If the URIs learned via more than one option described in Section 2 276 are not all identical, this condition should be logged for the device 277 owner or administrator; it is a network configuration error if the 278 learned URIs are not all identical. 280 4. IANA Considerations 282 This document requests one new IETF URN protocol parameter 283 ([RFC3553]) entry. This document also requests a reallocation of 284 DHCPv4 option codes (see Appendix C for background). 286 Thanks IANA! 288 4.1. Captive Portal Unrestricted Identifier 290 This document registers a new entry under the IETF URN Sub-namespace 291 for Registered Protocol Parameter Identifiers defined in [RFC3553]: 293 Registered Parameter Identifier: capport:unrestricted 295 Reference: RFC TBD (this document) 297 IANA Registry Reference: [RFC3553] 299 Only one value is defined (see URN above). No hierarchy is defined 300 and therefore no sub-namespace registrations are possible. 302 4.2. BOOTP Vendor Extensions and DHCP Options Code Change 304 [ RFC Ed: Please remove before publication: RFC7710 uses DHCP Code 305 160 -- unfortunately, it was discovered that this option code is 306 already widely used by Polycom (see appendix). Option 114 (URL) is 307 currently assigned to Apple (RFC3679, Section 3.2.3 - Contact: Dieter 308 Siegmund, dieter@apple.com - Reason to recover: Never published in an 309 RFC) Tommy Pauly (Apple) and Dieter Siegmund confirm that this 310 codepoint hasn't been used, and Apple is willing to relinquish it for 311 use in CAPPORT. Please see thread: 312 https://mailarchive.ietf.org/arch/msg/captive-portals/ 313 TmqQz6Ma_fznD3XbhwkH9m2dB28 for more background. ] 315 The IANA is requested to update the "BOOTP Vendor Extensions and DHCP 316 Options" registry (https://www.iana.org/assignments/bootp-dhcp- 317 parameters/bootp-dhcp-parameters.xhtml) as follows. 319 Tag: 114 320 Name: DHCP Captive-Portal 321 Data Length: N 322 Meaning: DHCP Captive-Portal 323 Reference: [THIS-RFC] 325 Tag: 160 326 Name: Unassigned 327 Data Length: 328 Meaning: Previously assigned by RFC7710; known to also be used by Polycom. 329 Reference: [THIS-RFC][RFC7710] 331 4.3. Update DHCPv6 and IPv6 ND Options Registries 333 This document requests that the DHCPv6 and IPv6 ND options previously 334 registered in [RFC7710] be updated to reference this document. 336 5. Security Considerations 338 By removing or reducing the need for captive portals to perform MITM 339 hijacking, this mechanism improves security by making the portal and 340 its actions visible, rather than hidden, and reduces the likelihood 341 that users will disable useful security safeguards like DNSSEC 342 validation, VPNs, etc in order to interact with the captive portal. 343 In addition, because the system knows that it is behind a captive 344 portal, it can know not to send cookies, credentials, etc. By 345 handing out a URI which is protected with TLS, the captive portal 346 operator can attempt to reassure the user that the captive portal is 347 not malicious. 349 Clients processing these options SHOULD validate that the option's 350 contents conform to the validation requirements for URIs, including 351 [RFC3986]. 353 Each of the options described in this document is presented to a node 354 using the same protocols used to provision other information critical 355 to the node's successful configuration on a network. The security 356 considerations applicable to each of these provisioning mechanisms 357 also apply when the node is attempting to learn the information 358 conveyed in these options. In the absence of security measures like 359 RA Guard ([RFC6105], [RFC7113]) or DHCP Shield [RFC7610], an attacker 360 could inject, modify, or block DHCP messages or RAs. 362 An attacker with the ability to inject DHCP messages or RAs could 363 include an option from this document to force users to contact an 364 address of his choosing. As an attacker with this capability could 365 simply list themselves as the default gateway (and so intercept all 366 the victim's traffic); this does not provide them with significantly 367 more capabilities, but because this document removes the need for 368 interception, the attacker may have an easier time performing the 369 attack. 371 However, as the operating systems and application(s) that make use of 372 this information know that they are connecting to a captive portal 373 device (as opposed to intercepted connections where the OS/ 374 application may not know that they are connecting to a captive portal 375 or hostile device) they can render the page in a sandboxed 376 environment and take other precautions, such as clearly labeling the 377 page as untrusted. The means of sandboxing and user interface 378 presenting this information is not covered in this document - by its 379 nature it is implementation specific and best left to the application 380 and user interface designers. 382 Devices and systems that automatically connect to an open network 383 could potentially be tracked using the techniques described in this 384 document (forcing the user to continually re-satisfy the Captive 385 Portal conditions, or exposing their browser fingerprint). However, 386 similar tracking can already be performed with the presently common 387 captive portal mechanisms, so this technique does not give the 388 attackers more capabilities. 390 Captive portals are increasingly hijacking TLS connections to force 391 browsers to talk to the portal. Providing the portal's URI via a 392 DHCP or RA option is a cleaner technique, and reduces user 393 expectations of being hijacked - this may improve security by making 394 users more reluctant to accept TLS hijacking, which can be performed 395 from beyond the network associated with the captive portal. 397 6. Acknowledgements 399 This document is a -bis of RFC7710. Thanks to all of the original 400 authors (Warren Kumari, Olafur Gudmundsson, Paul Ebersman, Steve 401 Sheng), and original contributors. 403 Also thanks to the CAPPORT WG for all of the discussion and 404 improvements including contributions and review from Joe Clarke, 405 Lorenzo Colitti, Dave Dolson, Hans Kuhn, Kyle Larose, Clemens 406 Schimpe, Martin Thomson, Michael Richardson, Remi Nguyen Van, Subash 407 Tirupachur Comerica, Bernie Volz, and Tommy Pauly. 409 7. References 411 7.1. Normative References 413 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 414 Requirement Levels", BCP 14, RFC 2119, 415 DOI 10.17487/RFC2119, March 1997, 416 . 418 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 419 RFC 2131, DOI 10.17487/RFC2131, March 1997, 420 . 422 [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor 423 Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997, 424 . 426 [RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An 427 IETF URN Sub-namespace for Registered Protocol 428 Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June 429 2003, . 431 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 432 Resource Identifier (URI): Generic Syntax", STD 66, 433 RFC 3986, DOI 10.17487/RFC3986, January 2005, 434 . 436 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 437 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 438 DOI 10.17487/RFC4861, September 2007, 439 . 441 [RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and 442 S. Krishnan, "Guidelines for Creating New DHCPv6 Options", 443 BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014, 444 . 446 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 447 Protocol (HTTP/1.1): Semantics and Content", RFC 7231, 448 DOI 10.17487/RFC7231, June 2014, 449 . 451 [RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, 452 Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", 453 RFC 7234, DOI 10.17487/RFC7234, June 2014, 454 . 456 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 457 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 458 May 2017, . 460 [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., 461 Richardson, M., Jiang, S., Lemon, T., and T. Winters, 462 "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", 463 RFC 8415, DOI 10.17487/RFC8415, November 2018, 464 . 466 7.2. Informative References 468 [RFC3679] Droms, R., "Unused Dynamic Host Configuration Protocol 469 (DHCP) Option Codes", RFC 3679, DOI 10.17487/RFC3679, 470 January 2004, . 472 [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP 473 Addresses and AS Identifiers", RFC 3779, 474 DOI 10.17487/RFC3779, June 2004, 475 . 477 [RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J. 478 Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105, 479 DOI 10.17487/RFC6105, February 2011, 480 . 482 [RFC7113] Gont, F., "Implementation Advice for IPv6 Router 483 Advertisement Guard (RA-Guard)", RFC 7113, 484 DOI 10.17487/RFC7113, February 2014, 485 . 487 [RFC7610] Gont, F., Liu, W., and G. Van de Velde, "DHCPv6-Shield: 488 Protecting against Rogue DHCPv6 Servers", BCP 199, 489 RFC 7610, DOI 10.17487/RFC7610, August 2015, 490 . 492 [RFC7710] Kumari, W., Gudmundsson, O., Ebersman, P., and S. Sheng, 493 "Captive-Portal Identification Using DHCP or Router 494 Advertisements (RAs)", RFC 7710, DOI 10.17487/RFC7710, 495 December 2015, . 497 7.3. URIs 499 [1] https://tickets.meeting.ietf.org/wiki/IETF106network#Experiments 501 [2] https://tickets.meeting.ietf.org/wiki/CAPPORT 503 [3] https://community.polycom.com/t5/VoIP-SIP-Phones/DHCP- 504 Standardization-160-vs-66/td-p/72577 506 Appendix A. Changes / Author Notes. 508 [RFC Editor: Please remove this section before publication ] 510 From initial to -00. 512 o Import of RFC7710. 514 From -00 to -01. 516 o Remove link-relation text. 518 o Clarify option should be in DHCPREQUEST parameter list. 520 o Uppercase some SHOULDs. 522 Appendix B. Changes from RFC 7710 524 This document incorporates the following changes from [RFC7710]. 526 1. Clarify that IP string literals are NOT RECOMMENDED. 528 2. Clarify that the option URI MUST be that of the captive portal 529 API endpoint. 531 3. Clarify that captive portals MAY do content negotiation. 533 4. Added text about Captive Portal API URI precedence in the event 534 of a network configuration error. 536 5. Added urn:ietf:params:capport:unrestricted URN. 538 6. Notes that the DHCPv4 Option Code changed from 160 to 114. 540 Appendix C. Observations From IETF 106 Network Experiment 542 During IETF 106 in Singapore an experiment [1] enabling Captive 543 Portal API compatible clients to discover a venue-info-url (see 544 experiment description [2] for more detail) revealed that some 545 Polycom devices on the same network made use of DHCPv4 option code 546 160 for other purposes [3]. 548 The presence of DHCPv4 Option code 160 holding a value indicating the 549 Captive Portal API URL caused these devices to not function as 550 desired. For this reason, this document requests IANA deprecate 551 option code 160 and reallocate different value to be used for the 552 Captive Portal API URL. 554 Authors' Addresses 556 Warren Kumari 557 Google 558 1600 Amphitheatre Parkway 559 Mountain View, CA 94043 560 US 562 Email: warren@kumari.net 563 Erik Kline 564 Loon 565 1600 Amphitheatre Parkway 566 Mountain View, CA 94043 567 US 569 Email: ek@loon.com