A Survey of Worldwide Censorship Techniques
draft-irtf-pearg-censorship-04

Document Type Active Internet-Draft (pearg RG)
Authors Joseph Hall  , Michael Aaron  , Stan Adams  , Amelia Andersdotter  , Ben Jones  , Nick Feamster 
Last updated 2020-07-13
Replaces draft-hall-censorship-tech
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pearg                                                            J. Hall
Internet-Draft                                          Internet Society
Intended status: Informational                                  M. Aaron
Expires: January 14, 2021                                     CU Boulder
                                                                S. Adams
                                                                     CDT
                                                         A. Andersdotter

                                                                B. Jones
                                                               Princeton
                                                             N. Feamster
                                                               U Chicago
                                                           July 13, 2020

              A Survey of Worldwide Censorship Techniques
                     draft-irtf-pearg-censorship-04

Abstract

   This document describes technical mechanisms censorship regimes
   around the world use for blocking or impairing Internet traffic.  It
   aims to make designers, implementers, and users of Internet protocols
   aware of the properties exploited and mechanisms used for censoring
   end-user access to information.  This document makes no suggestions
   on individual protocol considerations, and is purely informational,
   intended as 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 January 14, 2021.

Hall, et al.            Expires January 14, 2021                [Page 1]
Internet-Draft         draft-irtf-pearg-censorship             July 2020

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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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   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Technical Prescription  . . . . . . . . . . . . . . . . . . .   3
   4.  Technical Identification  . . . . . . . . . . . . . . . . . .   4
     4.1.  Points of Control . . . . . . . . . . . . . . . . . . . .   4
     4.2.  Application Layer . . . . . . . . . . . . . . . . . . . .   6
       4.2.1.  HTTP Request Header Identification  . . . . . . . . .   6
       4.2.2.  HTTP Response Header Identification . . . . . . . . .   7
       4.2.3.  Instrumenting Content Distributors  . . . . . . . . .   8
       4.2.4.  Deep Packet Inspection (DPI) Identification . . . . .   9
     4.3.  Transport Layer . . . . . . . . . . . . . . . . . . . . .  12
       4.3.1.  Shallow Packet Inspection and Transport Header
               Identification  . . . . . . . . . . . . . . . . . . .  12
       4.3.2.  Protocol Identification . . . . . . . . . . . . . . .  13
   5.  Technical Interference  . . . . . . . . . . . . . . . . . . .  14
     5.1.  Application Layer . . . . . . . . . . . . . . . . . . . .  14
       5.1.1.  DNS Interference  . . . . . . . . . . . . . . . . . .  14
     5.2.  Transport Layer . . . . . . . . . . . . . . . . . . . . .  17
       5.2.1.  Performance Degradation . . . . . . . . . . . . . . .  17
       5.2.2.  Packet Dropping . . . . . . . . . . . . . . . . . . .  17
       5.2.3.  RST Packet Injection  . . . . . . . . . . . . . . . .  18
     5.3.  Multi-layer and Non-layer . . . . . . . . . . . . . . . .  19
       5.3.1.  Distributed Denial of Service (DDoS)  . . . . . . . .  19
       5.3.2.  Network Disconnection or Adversarial Route
               Announcement  . . . . . . . . . . . . . . . . . . . .  20
   6.  Non-Technical Interference  . . . . . . . . . . . . . . . . .  21
     6.1.  Manual Filtering  . . . . . . . . . . . . . . . . . . . .  21
     6.2.  Self-Censorship . . . . . . . . . . . . . . . . . . . . .  21
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