A Survey of Worldwide Censorship Techniques
draft-irtf-pearg-censorship-00
Network Working Group J. Hall
Internet-Draft CDT
Intended status: Informational M. Aaron
Expires: February 24, 2020 CU Boulder
S. Adams
CDT
B. Jones
N. Feamster
Princeton
August 23, 2019
A Survey of Worldwide Censorship Techniques
draft-irtf-pearg-censorship-00
Abstract
This document describes the technical mechanisms used by censorship
regimes around the world to block or impair Internet traffic. It
aims to make designers, implementers, and users of Internet protocols
aware of the properties being exploited and mechanisms used to censor
end-user access to information. This document makes no suggestions
on individual protocol considerations, and is purely informational,
intended to be a reference.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 24, 2020.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
Hall, et al. Expires February 24, 2020 [Page 1]
Internet-Draft draft-irtf-pearg-censorship August 2019
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 . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Technical Prescription . . . . . . . . . . . . . . . . . . . 3
3. Technical Identification . . . . . . . . . . . . . . . . . . 4
3.1. Points of Control . . . . . . . . . . . . . . . . . . . . 4
3.2. Application Layer . . . . . . . . . . . . . . . . . . . . 5
3.2.1. HTTP Request Header Identification . . . . . . . . . 5
3.2.2. HTTP Response Header Identification . . . . . . . . . 6
3.2.3. Instrumenting Content Providers . . . . . . . . . . . 7
3.2.4. Deep Packet Inspection (DPI) Identification . . . . . 8
3.3. Transport Layer . . . . . . . . . . . . . . . . . . . . . 10
3.3.1. Shallow Packet Inspection and TCP/IP Header
Identification . . . . . . . . . . . . . . . . . . . 10
3.3.2. Protocol Identification . . . . . . . . . . . . . . . 11
4. Technical Interference . . . . . . . . . . . . . . . . . . . 12
4.1. Application Layer . . . . . . . . . . . . . . . . . . . . 12
4.1.1. DNS Interference . . . . . . . . . . . . . . . . . . 12
4.2. Transport Layer . . . . . . . . . . . . . . . . . . . . . 14
4.2.1. Performance Degradation . . . . . . . . . . . . . . . 14
4.2.2. Packet Dropping . . . . . . . . . . . . . . . . . . . 15
4.2.3. RST Packet Injection . . . . . . . . . . . . . . . . 15
4.3. Multi-layer and Non-layer . . . . . . . . . . . . . . . . 16
4.3.1. Distributed Denial of Service (DDoS) . . . . . . . . 16
4.3.2. Network Disconnection or Adversarial Route
Announcement . . . . . . . . . . . . . . . . . . . . 17
5. Non-Technical Prescription . . . . . . . . . . . . . . . . . 18
6. Non-Technical Interference . . . . . . . . . . . . . . . . . 18
6.1. Self-Censorship . . . . . . . . . . . . . . . . . . . . . 18
6.2. Domain Name Reallocation . . . . . . . . . . . . . . . . 19
6.3. Server Takedown . . . . . . . . . . . . . . . . . . . . . 19
6.4. Notice and Takedown . . . . . . . . . . . . . . . . . . . 19
Show full document text