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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 June 23, 2020 7 Expires: December 25, 2020 9 Captive-Portal Identification in DHCP / RA 10 draft-ietf-capport-rfc7710bis-08 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 satified 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 [ This document is being collaborated on in Github at: 36 https://github.com/capport-wg/7710bis. The most recent version of 37 the document, open issues, etc should all be available here. The 38 authors (gratefully) accept pull requests. Text in square brackets 39 will be removed before publication. ] 41 Status of This Memo 43 This Internet-Draft is submitted in full conformance with the 44 provisions of BCP 78 and BCP 79. 46 Internet-Drafts are working documents of the Internet Engineering 47 Task Force (IETF). Note that other groups may also distribute 48 working documents as Internet-Drafts. The list of current Internet- 49 Drafts is at https://datatracker.ietf.org/drafts/current/. 51 Internet-Drafts are draft documents valid for a maximum of six months 52 and may be updated, replaced, or obsoleted by other documents at any 53 time. It is inappropriate to use Internet-Drafts as reference 54 material or to cite them other than as "work in progress." 56 This Internet-Draft will expire on December 25, 2020. 58 Copyright Notice 60 Copyright (c) 2020 IETF Trust and the persons identified as the 61 document authors. All rights reserved. 63 This document is subject to BCP 78 and the IETF Trust's Legal 64 Provisions Relating to IETF Documents 65 (https://trustee.ietf.org/license-info) in effect on the date of 66 publication of this document. Please review these documents 67 carefully, as they describe your rights and restrictions with respect 68 to this document. Code Components extracted from this document must 69 include Simplified BSD License text as described in Section 4.e of 70 the Trust Legal Provisions and are provided without warranty as 71 described in the Simplified BSD License. 73 Table of Contents 75 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 76 1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 3 77 2. The Captive-Portal Option . . . . . . . . . . . . . . . . . . 3 78 2.1. IPv4 DHCP Option . . . . . . . . . . . . . . . . . . . . 4 79 2.2. IPv6 DHCP Option . . . . . . . . . . . . . . . . . . . . 5 80 2.3. The Captive-Portal IPv6 RA Option . . . . . . . . . . . . 6 81 3. Precedence of API URIs . . . . . . . . . . . . . . . . . . . 6 82 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 83 4.1. Captive Portal Unrestricted Identifier . . . . . . . . . 7 84 4.2. BOOTP Vendor Extensions and DHCP Options Code Change . . 7 85 4.3. Update DHCPv6 and IPv6 ND Options Registries . . . . . . 8 86 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 87 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 88 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 89 7.1. Normative References . . . . . . . . . . . . . . . . . . 9 90 7.2. Informative References . . . . . . . . . . . . . . . . . 11 91 Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 11 92 Appendix B. Changes from RFC 7710 . . . . . . . . . . . . . . . 12 93 Appendix C. Observations From IETF 106 Network Experiment . . . 12 94 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 96 1. Introduction 98 In many environments, users need to connect to a captive-portal 99 device and agree to an Acceptable Use Policy (AUP) and / or provide 100 billing information before they can access the Internet. Regardless 101 of how that mechanism operates, this document provides functionality 102 to allow the client to know when it is behind a captive portal and 103 how to contact it. 105 In order to present users with the payment or AUP pages, presently a 106 captive-portal enforcement device has to intercept the user's 107 connections and redirect the user to a captive portal server, using 108 methods that are very similar to man-in-the-middle (MITM) attacks. 109 As increasing focus is placed on security, and end nodes adopt a more 110 secure stance, these interception techniques will become less 111 effective and/or more intrusive. 113 This document describes a DHCPv4 [RFC2131] and DHCPv6 [RFC8415] 114 option (Captive-Portal) and an IPv6 Router Advertisement (RA) 115 [RFC4861] option that informs clients that they are behind a captive- 116 portal enforcement device and the API endpoint that the host can 117 contact for more information. 119 This document replaces RFC 7710 [RFC7710]. 121 1.1. Requirements Notation 123 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 124 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 125 "OPTIONAL" in this document are to be interpreted as described in BCP 126 14 [RFC2119] [RFC8174] when, and only when, they appear in all 127 capitals, as shown here. 129 2. The Captive-Portal Option 131 The Captive Portal DHCP / RA Option informs the client that it may be 132 behind a captive portal and provides the URI to access an API as 133 defined by [draft-ietf-capport-api]. This is primarily intended to 134 improve the user experience by showing the user the captive portal 135 information faster and more reliably. Note that, for the foreseeable 136 future, captive portals will still need to implement interception 137 techniques to serve legacy clients, and clients will need to perform 138 probing to detect captive portals. 140 Clients that support the Captive Portal DHCP option SHOULD include 141 the option in the Parameter Request List in DHCPREQUEST messages. 142 DHCP servers MAY send the Captive Portal option without any explicit 143 request. 145 In order to support multiple "classes" of clients (e.g. IPv4 only, 146 IPv6 only with DHCPv6 ([RFC8415]), and IPv6 only with RA) the captive 147 network can provision the client with the URI via multiple methods 148 (IPv4 DHCP, IPv6 DHCP, and IPv6 RA). The captive portal operator 149 SHOULD ensure that the URIs provisioned by each method are identical 150 to reduce the chance of operational problems. As the maximum length 151 of the URI that can be carried in IPv4 DHCP is 255 bytes, URIs longer 152 than this SHOULD NOT be provisioned by any of the IPv6 options 153 described in this document. In IPv6-only environments this 154 restriction can be relaxed. 156 In all variants of this option, the URI MUST be that of the captive 157 portal API endpoint [draft-ietf-capport-api]. 159 A captive portal MAY do content negotiation ([RFC7231] section 3.4) 160 and attempt to redirect clients querying without an explicit 161 indication of support for the captive portal API content type (i.e. 162 without application/capport+json listed explicitly anywhere within an 163 Accept header vis. [RFC7231] section 5.3). In so doing, the captive 164 portal SHOULD redirect the client to the value associated with the 165 "user-portal-url" API key. When performing such content negotiation 166 ([RFC7231] Section 3.4), implementors of captive portals need to keep 167 in mind that such responses might be cached, and therefore SHOULD 168 include an appropriate Vary header field ([RFC7231] Section 7.1.4) or 169 set the Cache-Control header field in any responses to "private", or 170 a more restrictive value such as "no-store" [RFC7234] 171 Section 5.2.2.3). 173 The URI SHOULD NOT contain an IP address literal. Exceptions to this 174 might include networks with only one operational IP address family 175 where DNS is either not available or not fully functional until the 176 captive portal has been satisfied. Use of iPAddress certificates 177 ([RFC3779]) adds considerations that are out of scope for this 178 document. 180 Networks with no captive portals may explicitly indicate this 181 condition by using this option with the IANA-assigned URI for this 182 purpose. Clients observing the URI value 183 "urn:ietf:params:capport:unrestricted" may forego time-consuming 184 forms of captive portal detection. 186 2.1. IPv4 DHCP Option 188 The format of the IPv4 Captive-Portal DHCP option is shown below. 190 0 1 2 3 191 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 1 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 | Code | Len | URI (variable length) ... | 194 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 195 . ...URI continued... . 196 | ... | 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 199 o Code: The Captive-Portal DHCPv4 Option (114) (one octet) 201 o Len: The length (one octet), in octets, of the URI. 203 o URI: The URI for the captive portal API endpoint to which the user 204 should connect (encoded following the rules in [RFC3986]). 206 See [RFC2132], Section 2 for more on the format of IPv4 DHCP options. 208 Note that the URI parameter is not null terminated. 210 2.2. IPv6 DHCP Option 212 The format of the IPv6 Captive-Portal DHCP option is shown below. 214 0 1 2 3 215 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 1 216 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 217 | option-code | option-len | 218 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 219 . URI (variable length) . 220 | ... | 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 223 o option-code: The Captive-Portal DHCPv6Option (103) (two octets) 225 o option-len: The unsigned 16-bit length, in octets, of the URI. 227 o URI: The URI for the captive portal API endpoint to which the user 228 should connect (encoded following the rules in [RFC3986]). 230 See [RFC7227], Section 5.7 for more examples of DHCP Options with 231 URIs. See [RFC8415], Section 21.1 for more on the format of IPv6 232 DHCP options. 234 Note that the URI parameter is not null terminated. 236 As the maximum length of the URI that can be carried in IPv4 DHCP is 237 255 bytes, URIs longer than this SHOULD NOT be provisioned via IPv6 238 DHCP options. 240 2.3. The Captive-Portal IPv6 RA Option 242 This section describes the Captive-Portal Router Advertisement 243 option. 245 0 1 2 3 246 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 1 247 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 248 | Type | Length | URI . 249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . 250 . . 251 . . 252 . . 253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 Figure 2: Captive-Portal RA Option Format 256 Type 37 258 Length 8-bit unsigned integer. The length of the option (including 259 the Type and Length fields) in units of 8 bytes. 261 URI The URI for the captive portal API endpoint to which the user 262 should connect. This MUST be padded with NUL (0x00) to make the 263 total option length (including the Type and Length fields) a 264 multiple of 8 bytes. 266 Note that the URI parameter is not guaranteed to be null terminated. 268 As the maximum length of the URI that can be carried in IPv4 DHCP is 269 255 bytes, URIs longer than this SHOULD NOT be provisioned via IPv6 270 RA options. 272 3. Precedence of API URIs 274 A device may learn about Captive Portal API URIs through more than 275 one of (or indeed all of) the above options. Implementations can 276 select their own precedence order (e.g., prefer one of the IPv6 277 options before the DHCPv4 option, or vice versa, et cetera). 279 If the URIs learned via more than one option described in Section 2 280 are not all identical, this condition should be logged for the device 281 owner or administrator; it is a network configuration error if the 282 learned URIs are not all identical. 284 4. IANA Considerations 286 This document requests one new IETF URN protocol parameter 287 ([RFC3553]) entry. This document also requests a reallocation of 288 DHCPv4 option codes (see Appendix C for background). 290 Thanks IANA! 292 4.1. Captive Portal Unrestricted Identifier 294 This document registers a new entry under the IETF URN Sub-namespace 295 for Registered Protocol Parameter Identifiers defined in [RFC3553]: 297 Registered Parameter Identifier: capport:unrestricted 299 Reference: RFC TBD (this document) 301 IANA Registry Reference: RFC TBD (this document) 303 Only one value is defined (see URN above). No hierarchy is defined 304 and therefore no sub-namespace registrations are possible. 306 4.2. BOOTP Vendor Extensions and DHCP Options Code Change 308 [ RFC Ed: Please remove before publication: RFC7710 uses DHCP Code 309 160 -- unfortunately, it was discovered that this option code is 310 already widely used by Polycom (see appendix). Option 114 (URL) is 311 currently assigned to Apple (RFC3679, Section 3.2.3 - Contact: Dieter 312 Siegmund, dieter@apple.com - Reason to recover: Never published in an 313 RFC) Tommy Pauly (Apple) and Dieter Siegmund confirm that this 314 codepoint hasn't been used, and Apple is willing to relinquish it for 315 use in CAPPORT. Please see thread: 316 https://mailarchive.ietf.org/arch/msg/captive-portals/ 317 TmqQz6Ma_fznD3XbhwkH9m2dB28 for more background. ] 319 The IANA is requested to update the "BOOTP Vendor Extensions and DHCP 320 Options" registry (https://www.iana.org/assignments/bootp-dhcp- 321 parameters/bootp-dhcp-parameters.xhtml) as follows. 323 Tag: 114 324 Name: DHCP Captive-Portal 325 Data Length: N 326 Meaning: DHCP Captive-Portal 327 Reference: [THIS-RFC] 329 Tag: 160 330 Name: Unassigned 331 Data Length: 332 Meaning: Previously assigned by RFC7710; known to also be used by Polycom. 333 Reference: [THIS-RFC][RFC7710] 335 4.3. Update DHCPv6 and IPv6 ND Options Registries 337 This document requests that the DHCPv6 and IPv6 ND options previously 338 registered in [RFC7710] be updated to reference this document. 340 5. Security Considerations 342 By removing or reducing the need for captive portals to perform MITM 343 hijacking, this mechanism improves security by making the portal and 344 its actions visible, rather than hidden, and reduces the likelihood 345 that users will disable useful security safeguards like DNSSEC 346 validation, VPNs, etc in order to interact with the captive portal. 347 In addition, because the system knows that it is behind a captive 348 portal, it can know not to send cookies, credentials, etc. By 349 handing out a URI which is protected with TLS, the captive portal 350 operator can attempt to reassure the user that the captive portal is 351 not malicious. 353 Clients processing these options SHOULD validate that the option's 354 contents conform to the validation requirements for URIs, including 355 [RFC3986]. 357 Each of the options described in this document is presented to a node 358 using the same protocols used to provision other information critical 359 to the node's successful configuration on a network. The security 360 considerations applicable to each of these provisioning mechanisms 361 also apply when the node is attempting to learn the information 362 conveyed in these options. In the absence of security measures like 363 RA Guard ([RFC6105], [RFC7113]) or DHCP Shield [RFC7610], an attacker 364 could inject, modify, or block DHCP messages or RAs. 366 An attacker with the ability to inject DHCP messages or RAs could 367 include an option from this document to force users to contact an 368 address of his choosing. As an attacker with this capability could 369 simply list themselves as the default gateway (and so intercept all 370 the victim's traffic); this does not provide them with significantly 371 more capabilities, but because this document removes the need for 372 interception, the attacker may have an easier time performing the 373 attack. 375 However, as the operating systems and application(s) that make use of 376 this information know that they are connecting to a captive-portal 377 device (as opposed to intercepted connections where the OS/ 378 application may not know that they are connecting to a captive portal 379 or hostile device) they can render the page in a sandboxed 380 environment and take other precautions, such as clearly labeling the 381 page as untrusted. The means of sandboxing and user interface 382 presenting this information is not covered in this document - by its 383 nature it is implementation specific and best left to the application 384 and user interface designers. 386 Devices and systems that automatically connect to an open network 387 could potentially be tracked using the techniques described in this 388 document (forcing the user to continually re-satisfy the Captive 389 Portal conditions, or exposing their browser fingerprint). However, 390 similar tracking can already be performed with the presently common 391 captive portal mechanisms, so this technique does not give the 392 attackers more capabilities. 394 Captive portals are increasingly hijacking TLS connections to force 395 browsers to talk to the portal. Providing the portal's URI via a 396 DHCP or RA option is a cleaner technique, and reduces user 397 expectations of being hijacked - this may improve security by making 398 users more reluctant to accept TLS hijacking, which can be performed 399 from beyond the network associated with the captive portal. 401 6. Acknowledgements 403 This document is a -bis of RFC7710. Thanks to all of the original 404 authors (Warren Kumari, Olafur Gudmundsson, Paul Ebersman, Steve 405 Sheng), and original contributors. 407 Also thanks to the CAPPORT WG for all of the discussion and 408 improvements including contributions and review from Joe Clarke, 409 Lorenzo Colitti, Dave Dolson, Hans Kuhn, Kyle Larose, Clemens 410 Schimpe, Martin Thomson, Michael Richardson, Remi Nguyen Van, Subash 411 Tirupachur Comerica, Bernie Volz, and Tommy Pauly. 413 7. References 415 7.1. Normative References 417 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 418 Requirement Levels", BCP 14, RFC 2119, 419 DOI 10.17487/RFC2119, March 1997, 420 . 422 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 423 RFC 2131, DOI 10.17487/RFC2131, March 1997, 424 . 426 [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor 427 Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997, 428 . 430 [RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An 431 IETF URN Sub-namespace for Registered Protocol 432 Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June 433 2003, . 435 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 436 Resource Identifier (URI): Generic Syntax", STD 66, 437 RFC 3986, DOI 10.17487/RFC3986, January 2005, 438 . 440 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 441 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 442 DOI 10.17487/RFC4861, September 2007, 443 . 445 [RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and 446 S. Krishnan, "Guidelines for Creating New DHCPv6 Options", 447 BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014, 448 . 450 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 451 Protocol (HTTP/1.1): Semantics and Content", RFC 7231, 452 DOI 10.17487/RFC7231, June 2014, 453 . 455 [RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, 456 Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", 457 RFC 7234, DOI 10.17487/RFC7234, June 2014, 458 . 460 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 461 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 462 May 2017, . 464 [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., 465 Richardson, M., Jiang, S., Lemon, T., and T. Winters, 466 "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", 467 RFC 8415, DOI 10.17487/RFC8415, November 2018, 468 . 470 7.2. Informative References 472 [RFC3679] Droms, R., "Unused Dynamic Host Configuration Protocol 473 (DHCP) Option Codes", RFC 3679, DOI 10.17487/RFC3679, 474 January 2004, . 476 [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP 477 Addresses and AS Identifiers", RFC 3779, 478 DOI 10.17487/RFC3779, June 2004, 479 . 481 [RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J. 482 Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105, 483 DOI 10.17487/RFC6105, February 2011, 484 . 486 [RFC7113] Gont, F., "Implementation Advice for IPv6 Router 487 Advertisement Guard (RA-Guard)", RFC 7113, 488 DOI 10.17487/RFC7113, February 2014, 489 . 491 [RFC7610] Gont, F., Liu, W., and G. Van de Velde, "DHCPv6-Shield: 492 Protecting against Rogue DHCPv6 Servers", BCP 199, 493 RFC 7610, DOI 10.17487/RFC7610, August 2015, 494 . 496 [RFC7710] Kumari, W., Gudmundsson, O., Ebersman, P., and S. Sheng, 497 "Captive-Portal Identification Using DHCP or Router 498 Advertisements (RAs)", RFC 7710, DOI 10.17487/RFC7710, 499 December 2015, . 501 7.3. URIs 503 [1] https://tickets.meeting.ietf.org/wiki/IETF106network#Experiments 505 [2] https://tickets.meeting.ietf.org/wiki/CAPPORT 507 [3] https://community.polycom.com/t5/VoIP-SIP-Phones/DHCP- 508 Standardization-160-vs-66/td-p/72577 510 Appendix A. Changes / Author Notes. 512 [RFC Editor: Please remove this section before publication ] 514 From initial to -00. 516 o Import of RFC7710. 518 From -00 to -01. 520 o Remove link-relation text. 522 o Clarify option should be in DHCPREQUEST parameter list. 524 o Uppercase some SHOULDs. 526 Appendix B. Changes from RFC 7710 528 This document incorporates the following changes from [RFC7710]. 530 1. Clarify that IP string literals are NOT RECOMMENDED. 532 2. Clarify that the option URI MUST be that of the captive portal 533 API endpoint. 535 3. Clarify that captive portals MAY do content negotiation. 537 4. Added text about Captive Portal API URI precedence in the event 538 of a network configuration error. 540 5. Added urn:ietf:params:capport:unrestricted URN. 542 6. Notes that the DHCPv4 Option Code changed from 160 to 114. 544 Appendix C. Observations From IETF 106 Network Experiment 546 During IETF 106 in Singapore an experiment [1] enabling Captive 547 Portal API compatible clients to discover a venue-info-url (see 548 experiment description [2] for more detail) revealed that some 549 Polycom devices on the same network made use of DHCPv4 option code 550 160 for other purposes [3]. 552 The presence of DHCPv4 Option code 160 holding a value indicating the 553 Captive Portal API URL caused these devices to not function as 554 desired. For this reason, this document requests IANA deprecate 555 option code 160 and reallocate different value to be used for the 556 Captive Portal API URL. 558 Authors' Addresses 559 Warren Kumari 560 Google 561 1600 Amphitheatre Parkway 562 Mountain View, CA 94043 563 US 565 Email: warren@kumari.net 567 Erik Kline 568 Loon 569 1600 Amphitheatre Parkway 570 Mountain View, CA 94043 571 US 573 Email: ek@loon.com