A Survey of Worldwide Censorship Techniques
draft-hall-censorship-tech-06
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Network Working Group J. Hall
Internet-Draft CDT
Intended status: Informational M. Aaron
Expires: April 25, 2019 CU Boulder
S. Adams
CDT
B. Jones
N. Feamster
Princeton
October 22, 2018
A Survey of Worldwide Censorship Techniques
draft-hall-censorship-tech-06
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 April 25, 2019.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
Hall, et al. Expires April 25, 2019 [Page 1]
Internet-Draft draft-hall-censorship-tech October 2018
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
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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
3.2.5. Server Name Indication . . . . . . . . . . . . . . . 9
3.3. Transport Layer . . . . . . . . . . . . . . . . . . . . . 10
3.3.1. 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 . . . . . . . . . . . . . . . . . . . 14
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
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