Captive-Portal Identification in DHCP and Router Advertisements (RAs)
RFC 8910
Document | Type |
RFC - Proposed Standard
(September 2020; No errata)
Obsoletes RFC 7710
Updates RFC 3679
|
|
---|---|---|---|
Authors | Warren Kumari , Erik Kline | ||
Last updated | 2020-09-21 | ||
Replaces | draft-ekwk-capport-rfc7710bis | ||
Stream | IETF | ||
Formats | plain text html xml pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Martin Thomson | ||
Shepherd write-up | Show (last changed 2020-04-20) | ||
IESG | IESG state | RFC 8910 (Proposed Standard) | |
Action Holders |
(None)
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||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Barry Leiba | ||
Send notices to | Martin Thomson <mt@lowentropy.net> | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | RFC-Ed-Ack |
Internet Engineering Task Force (IETF) W. Kumari Request for Comments: 8910 Google Obsoletes: 7710 E. Kline Updates: 3679 Loon Category: Standards Track September 2020 ISSN: 2070-1721 Captive-Portal Identification in DHCP and Router Advertisements (RAs) Abstract In many environments offering short-term or temporary Internet access (such as coffee shops), it is common to start new connections in a captive portal mode. This highly restricts what the user can do until the user has satisfied the captive portal conditions. This document describes a DHCPv4 and DHCPv6 option and a Router Advertisement (RA) option to inform clients that they are behind some sort of captive portal enforcement device, and that they will need to satisfy the Captive Portal conditions to get Internet access. It is not a full solution to address all of the issues that clients may have with captive portals; it is designed to be one component of a standardized approach for hosts to interact with such portals. While this document defines how the network operator may convey the captive portal API endpoint to hosts, the specific methods of satisfying and interacting with the captive portal are out of scope of this document. This document replaces RFC 7710, which used DHCP code point 160. Due to a conflict, this document specifies 114. Consequently, this document also updates RFC 3679. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8910. Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction 1.1. Requirements Notation 2. The Captive-Portal Option 2.1. IPv4 DHCP Option 2.2. IPv6 DHCP Option 2.3. The Captive-Portal IPv6 RA Option 3. Precedence of API URIs 4. IANA Considerations 4.1. Captive Portal Unrestricted Identifier 4.2. BOOTP Vendor Extensions and DHCP Options Code Change 4.3. Update DHCPv6 and IPv6 ND Options Registries 5. Security Considerations 6. References 6.1. Normative References 6.2. Informative References Appendix A. Changes from RFC 7710 Appendix B. Observations from IETF 106 Network Experiment Acknowledgements Authors' Addresses 1. Introduction In many environments, users need to connect to a captive portal device and agree to an Acceptable Use Policy (AUP) and/or provide billing information before they can access the Internet. Regardless of how that mechanism operates, this document provides functionality to allow the client to know when it is behind a captive portal and how to contact it. In order to present users with the payment or AUP pages, a captive portal enforcement device presently has to intercept the user's connections and redirect the user to a captive portal server, using methods that are very similar to man-in-the-middle (MITM) attacks. As increasing focus is placed on security, and end nodes adopt a more secure stance, these interception techniques will become less effective and/or more intrusive. This document describes a DHCPv4 [RFC2131] and DHCPv6 [RFC8415] option (Captive-Portal) and an IPv6 Router Advertisement (RA) [RFC4861] option that informs clients that they are behind a captive portal enforcement device and the API endpoint that the host can contact for more information. This document replaces RFC 7710 [RFC7710], which used DHCP code point 160. Due to a conflict, this document specifies 114. Consequently, this document also updates [RFC3679]. 1.1. Requirements Notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",Show full document text