NTP Client Data Minimization
draft-dfranke-ntp-data-minimization-02

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Last updated 2017-03-27
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Network Working Group                                          D. Franke
Internet-Draft                                                    Akamai
Updates: 5905 (if approved)                                  A. Malhotra
Intended status: Standards Track                       Boston University
Expires: September 28, 2017                               March 27, 2017

                      NTP Client Data Minimization
                 draft-dfranke-ntp-data-minimization-02

Abstract

   This memo proposes backward-compatible updates to the Network Time
   Protocol to strip unnecessary identifying information from client
   requests and to improve resilience against blind spoofing of
   unauthenticated server responses.

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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   This Internet-Draft will expire on September 28, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Franke & Malhotra      Expires September 28, 2017               [Page 1]
Internet-Draft        NTP Client Data Minimization            March 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  Client Packet Format  . . . . . . . . . . . . . . . . . . . .   2
   4.  Security and Privacy Considerations . . . . . . . . . . . . .   3
     4.1.  Data Minimization . . . . . . . . . . . . . . . . . . . .   3
     4.2.  Transmit Timestamp Randomization  . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Network Time Protocol (NTP) packets, as specified by RFC 5905
   [RFC5905], carry a great deal of information about the state of the
   NTP daemon which transmitted them.  In the case of mode 4 packets
   (responses sent from server to client), as well as in broadcast (mode
   5) and symmetric peering modes (mode 1/2), most of this information
   is essential for accurate and reliable time synchronizaton.  However,
   in mode 3 packets (requests sent from client to server), most of
   these fields serve no purpose.  Server implementations never need to
   inspect them, and they can achieve nothing by doing so.  Populating
   these fields with accurate information is harmful to privacy of
   clients because it allows a passive observer to fingerprint clients
   and track them as they move across networks.

   This memo updates RFC 5905 to redact unnecessary data from mode 3
   packets.  This is a fully backwards-compatible proposal.  It calls
   for no changes on the server side, and clients which implement these
   updates will remain fully interoperable with existing servers.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

3.  Client Packet Format

   In every client-mode packet sent by a Network Time Protocol [RFC5905]
   implementation:
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