A Survey of Worldwide Censorship Techniques
draft-irtf-pearg-censorship-00

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Last updated 2019-08-23
Replaces draft-hall-censorship-tech
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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
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   Internet-Drafts are draft documents valid for a maximum of six months
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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 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
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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
     3.3.  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
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