Internet DRAFT - draft-451-new-protocol-elements
draft-451-new-protocol-elements
HTTP Working Group S. Sahib
Internet-Draft October 27, 2017
Intended status: Informational
Expires: April 30, 2018
New protocol elements for HTTP Status Code 451
draft-451-new-protocol-elements-01
Abstract
This draft recommends protocol updates to Hypertext Transfer Protocol
(HTTP) status code 451 (defined by RFC7725) based on an examination
of how the new status code is being used by parties involved in
denial of Internet resources because of legal demands.
Discussion of this draft is at https://www.irtf.org/mailman/listinfo/
hrpc and https://lists.ghserv.net/mailman/listinfo/statuscode451.
Status of This Memo
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This Internet-Draft will expire on April 30, 2018.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Existing Protocol Elements . . . . . . . . . . . . . . . . . 2
4. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
7. Normative References . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
[RFC7725] was standardized by the IETF in February 2016. It defined
HTTP status code 451 - to be used when a "a server operator has
received a legal demand to deny access to a resource or to a set of
resources that includes the requested resource". The intention was
to provide a uniform mechanism to indicate online censorship.
Subsequently, an effort was made to investigate usage of 451 status
code and evaluate if it fulfills its mandate of providing
"transparency in circumstances where issues of law or public policy
affect server operations" [IMPL_REPORT_DRAFT]. This draft attempts
to explicate the protocol recommendations arising out of that
investigation.
2. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Existing Protocol Elements
The status code as standardized by the IETF specifies the following
elements [RFC7725] -
- A server can return status code 451 to indicate that it is denying
access to a resource or multiple resources on account of a legal
demand.
- Responses using the status code SHOULD include an explanation in
the response body of the details of the legal demand.
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- Responses SHOULD include a "Link" HTTP header field [RFC8288]
whose value is a URI reference [RFC3986] identifying itself. The
"Link" header field MUST have a "rel" parameter whose value is
"blocked-by". The intent is that the header be used to identify
the entity actually implementing blockage, not any other entity
mandating it.
4. Recommendations
- In addition to the "blocked-by" header, an HTTP response with
status code 451 SHOULD include another "Link" HTTP header field
which has a "rel" parameter whose value is "blocking-authority".
It's important to distinguish between the implementer of the
block, and the authority that mandated the block in the first
place. This is because these two organizations might not be the
same - a government (the blocking authority) could force an
Internet Service Provider (the implementer of the block) to deny
access to a certain resource.
- HTTP status code 451 is increasingly being used to deny access to
resources based on geographical IP. The scope of this denial is
sometimes as finely scoped as a city or a province. The response
SHOULD contain a provisional header with geographical scope of
block.
5. Security Considerations
This document does not add additional security considerations to
[RFC7725].
6. IANA Considerations
The Link Relation Type Registry should be updated with the following
entry [TBD]:
- Relation Name: blocking-authority
- Description: Identifies the authority that has issued the block.
- Reference: This document
In addition, IANA should be updated with the following provisional
header [TBD]:
- Header field name: geo-scope-block
- Applicable protocol: http
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- Status: provisional
- Specification document(s): this document
7. Normative References
[IMPL_REPORT_DRAFT]
Abraham, S., Canales, MP., Hall, J., Khrustaleva, O., ten
Oever, N., Runnegar, C., and S. Sahib, "Implementation
Report for HTTP Status Code 451", 2017,
<https://tools.ietf.org/html/draft-451-imp-report-00>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC7725] Bray, T., "An HTTP Status Code to Report Legal Obstacles",
RFC 7725, DOI 10.17487/RFC7725, February 2016,
<https://www.rfc-editor.org/info/rfc7725>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017, <https://www.rfc-
editor.org/info/rfc8288>.
Author's Address
Shivan Kaul Sahib
EMail: shivankaulsahib@gmail.com
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