Network Working Group T. Pauly, Ed.
Internet-Draft Apple Inc.
Intended status: Standards Track D. Thakore, Ed.
Expires: August 7, 2018 CableLabs
February 03, 2018
Captive Portal API
draft-ietf-capport-api-00
Abstract
This document describes an HTTP API that allows hosts to interact
with a Captive Portal system.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 7, 2018.
Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. API Details . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. URI of Captive Portal API endpoint . . . . . . . . . . . 3
3.2. JSON Keys . . . . . . . . . . . . . . . . . . . . . . . . 3
3.3. Example Exchange . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
4.1. Privacy Considerations . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
This document describes a HyperText Transfer Protocol (HTTP)
Application Program Interface (API) that allows hosts to interact
with a Captive Portal system. The API defined in this document has
been designed to meet the requirements in the Captive Portal
Architecture [I-D.ietf-capport-architecture]. Specifically, the API
provides:
o The state of captivity (whether or not the host has access to the
Internet)
o A URI that a host's browser can present to a user to get out of
captivity
o An encrypted connection (TLS for both the API and portal URI)
2. Workflow
The Captive Portal Architecture defines three steps of interaction
between hosts and a Captive Portal service:
1. Provisioning, in which a host discovers that a network has a
captive portal, and learns the URI of the API server
2. API Server interaction, in which a host queries the state of the
captive portal and retrieves the necessary information to get out
of captivity
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3. Enforcement, in which the enforcement device in the network
blocks disallowed traffic, and sends ICMP messages to let hosts
know they are blocked by the captive portal
This document is focused on the second step. It is assumed that the
location of the Captive Portal API server has been discovered by the
host as part of the first step. The mechanism for discovering the
API Server endpoint is not covered by this document.
3. API Details
3.1. URI of Captive Portal API endpoint
The URI of the API endpoint MUST be accessed using HTTP over TLS
(HTTPS) and SHOULD be served on port 443 [RFC2818]. The host SHOULD
NOT assume that the URI for a given network attachment will stay the
same, and SHOULD rely on the discovery or provisioning process each
time it joins the network. Depending on how the Captive Portal
system is configured, the URI may be unique for each host and between
sessions for the same host.
For example, if the Captive Portal API server is hosted at
example.org, the URI's of the API could be:
o "https://example.org/captive-portal/api"
o "https://example.org/captive-portal/api/X54PD"
3.2. JSON Keys
The Captive Portal API data structures are specified in JavaScript
Object Notation (JSON) [RFC7159].
The following keys are defined at the top-level of the JSON structure
returned by the API server:
o "permitted" (required, boolean): indicates whether or not the
Captive Portal is open to the requesting host
o "hmac-key" (required, string): provides a per-host key that can be
used to authenticate messages from the Captive Portal enforcement
server
o "user-portal-url" (required, string): provides the URL of a web
portal that can be presented to a user to interact with
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o "expire-date" (optional, string formatted as [RFC3339] datetime):
indicates the date and time after which the host will be in a
captive state
o "bytes-remaining" (optional, integer): indicates the number of
bytes left, after which the host will be in a captive state
Note that the use of the hmac-key is not defined in this document,
but is intended for use in the enforcement step of the Captive Portal
Architecture.
3.3. Example Exchange
To request the Captive Portal JSON content, a host sends an HTTP GET
request:
GET /captive-portal/api/X54PD
Host: example.org
Accept: application/json
The server then responds with the JSON content for that client:
HTTP/1.1 200 OK
Cache-Control: private
Date: Mon, 04 Dec 2013 05:07:35 GMT
Content-Type: application/json
{
"permitted": false,
"hmac-key": "7cec81acce3176b262a46363666a01881b0e3bf60d97a98b5409b71cc60a1ac0"
"user-portal-url": "https://example.org/portal.html"
"expire-date": "2014-01-01T23:28:56.782Z"
}
4. Security Considerations
TBD: Provide complete security requirements and analysis.
4.1. Privacy Considerations
Information passed in this protocol may include a user's personal
information, such as a full name and credit card details. Therefore,
it is important that Captive Portal API Servers do not allow access
to the Captive Portal API over unecrypted sessions.
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5. IANA Considerations
TBD: None
6. Acknowledgments
This work in this document was started by Mark Donnelly and Margaret
Cullen. Thanks to everyone in the CAPPORT Working Group who has
given input.
7. References
7.1. Normative References
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000,
<https://www.rfc-editor.org/info/rfc2818>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known
Uniform Resource Identifiers (URIs)", RFC 5785,
DOI 10.17487/RFC5785, April 2010,
<https://www.rfc-editor.org/info/rfc5785>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>.
7.2. Informative References
[I-D.ietf-capport-architecture]
Larose, K. and D. Dolson, "CAPPORT Architecture", draft-
ietf-capport-architecture-00 (work in progress), September
2017.
Authors' Addresses
Tommy Pauly (editor)
Apple Inc.
1 Infinite Loop
Cupertino, California 95014
United States of America
Email: tpauly@apple.com
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Darshak Thakore (editor)
CableLabs
858 Coal Creek Circle
Louisville, CO 80027
United States of America
Email: d.thakore@cablelabs.com
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