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
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   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
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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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