Captive-Portal Identification Using DHCP or Router Advertisements (RAs)
RFC 7710

Document Type RFC - Proposed Standard (December 2015; No errata)
Was draft-wkumari-dhc-capport (individual)
Last updated 2015-12-07
Stream IETF
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Stream WG state Submitted to IESG for Publication
Document shepherd Ted Lemon
Shepherd write-up Show (last changed 2015-03-25)
IESG IESG state RFC 7710 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Joel Jaeggli
Send notices to (None)
IANA IANA review state IANA - Not OK
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                         W. Kumari
Request for Comments: 7710                                        Google
Category: Standards Track                                 O. Gudmundsson
ISSN: 2070-1721                                               CloudFlare
                                                             P. Ebersman
                                                                 Comcast
                                                                S. Sheng
                                                                   ICANN
                                                           December 2015

Captive-Portal Identification Using DHCP or 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 customer can do
   until the customer has authenticated.

   This document describes a DHCP option (and a Router Advertisement
   (RA) extension) to inform clients that they are behind some sort of
   captive-portal device and that they will need to authenticate 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 used in larger solutions.  The method of authenticating to and
   interacting with the captive portal is out of scope for this
   document.

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 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7710.

Kumari, et al.               Standards Track                    [Page 1]
RFC 7710                   DHCP Captive-Portal             December 2015

Copyright Notice

   Copyright (c) 2015 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
   (http://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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements notation . . . . . . . . . . . . . . . . . .   3
   2.  The Captive-Portal Option . . . . . . . . . . . . . . . . . .   3
     2.1.  IPv4 DHCP Option  . . . . . . . . . . . . . . . . . . . .   3
     2.2.  IPv6 DHCP Option  . . . . . . . . . . . . . . . . . . . .   4
     2.3.  The Captive-Portal IPv6 RA Option . . . . . . . . . . . .   4
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   6.  Informative References  . . . . . . . . . . . . . . . . . . .   7
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

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.  It is
   anticipated that the IETF will work on a more fully featured protocol
   at some point, to ease interaction with captive portals.  Regardless
   of how that protocol operates, it is expected that this document will
   provide needed functionality because the client will need 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, the captive-
   portal device has to intercept the user's connections and redirect
   the user to the captive portal, 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.
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