Technical Considerations for Internet Service Blocking and Filtering
draft-iab-filtering-considerations-08

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Last updated 2015-10-19
Replaces draft-barnes-blocking-considerations
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Internet Architecture Board                                    R. Barnes
Internet-Draft                                                   Mozilla
Intended status: Informational                                 A. Cooper
Expires: April 21, 2016                                            Cisco
                                                              O. Kolkman
                                                              NLnet Labs
                                                               D. Thaler
                                                               Microsoft
                                                        October 19, 2015

  Technical Considerations for Internet Service Blocking and Filtering
               draft-iab-filtering-considerations-08.txt

Abstract

   The Internet is structured to be an open communications medium.  This
   openness is one of the key underpinnings of Internet innovation, but
   it can also allow communications that may be viewed as undesirable by
   certain parties.  Thus, as the Internet has grown, so have mechanisms
   to limit the extent and impact of abusive or objectionable
   communications.  Recently, there has been an increasing emphasis on
   "blocking" and "filtering," the active prevention of such
   communications.  This document examines several technical approaches
   to Internet blocking and filtering in terms of their alignment with
   the overall Internet architecture.  When it is possible to do so, the
   approach to blocking and filtering that is most coherent with the
   Internet architecture is to inform endpoints about potentially
   undesirable services, so that the communicants can avoid engaging in
   abusive or objectionable communications.  We observe that certain
   filtering and blocking approaches can cause unintended consequences
   to third parties, and we discuss the limits of efficacy of various
   approaches.

Status of this Memo

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Barnes, et al.           Expires April 21, 2016                 [Page 1]
Internet-Draft          Filtering Considerations            October 2015

   This Internet-Draft will expire on April 21, 2016.

Copyright Notice

   Copyright (c) 2015 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
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   described in the Simplified BSD License.

Barnes, et al.           Expires April 21, 2016                 [Page 2]
Internet-Draft          Filtering Considerations            October 2015

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Filtering Examples . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Characteristics of Blocking Systems  . . . . . . . . . . . . .  7
     3.1.  The party who sets blocking policies . . . . . . . . . . .  8
     3.2.  Purposes of blocking . . . . . . . . . . . . . . . . . . .  8
       3.2.1.  Blacklist vs. Whitelist Model  . . . . . . . . . . . .  9
     3.3.  Intended targets of blocking . . . . . . . . . . . . . . .  9
     3.4.  Components used for blocking . . . . . . . . . . . . . . .  9
   4.  Evaluation of Blocking Design Patterns . . . . . . . . . . . . 11
     4.1.  Criteria for evaluation  . . . . . . . . . . . . . . . . . 11
       4.1.1.  Scope: What set of hosts and users are affected? . . . 11
       4.1.2.  Granularity: How specific is the blocking?  Will
               blocking one service also block others?  . . . . . . . 12
       4.1.3.  Efficacy: How easy is it for a resource or service
               to avoid being blocked?  . . . . . . . . . . . . . . . 13
       4.1.4.  Security: How does the blocking impact existing
               trust infrastructures? . . . . . . . . . . . . . . . . 14
     4.2.  Network-Based Blocking . . . . . . . . . . . . . . . . . . 15
       4.2.1.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . 16
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