Network Time Protocol Suggest REFID Extension Field
draft-stenn-ntp-suggest-refid-01

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Last updated 2016-10-24
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Internet Engineering Task Force                                 H. Stenn
Internet-Draft                                   Network Time Foundation
Intended status: Standards Track                        October 24, 2016
Expires: April 27, 2017

          Network Time Protocol Suggest REFID Extension Field
                    draft-stenn-ntp-suggest-refid-01

Abstract

   NTP has been widely used through several revisions, with the latest
   being RFC 5905 [RFC5905].  A core component of the protocol and the
   algoritms is the Reference ID, or REFID, which is used to identify
   the source of time used for synchronization.  Traditionally, when the
   source of time was another system the REFID was the IPv4 address of
   that other system.  The purpose of the REFID is to prevent a one-
   degree timing loop, where if A has several timing sources that
   include B, if B decides to get its time from A we don't want A then
   deciding to get its time from B.  The REFID is considered to be
   "public data" and is a vital core-component of the base NTP packet.
   If a system's REFID is the IPv4 address of its system peer, an
   attacker can try to use that information to send spoofed time packets
   to either or both the target or the target's server, attempting to
   cause a disruption in time service.  This proposal is a backward-
   compatible way for a time source to tell its peers or clients "If you
   use me as your system peer, use this nonce as your REFID."  This
   nonce SHOULD not be traceable to the original system, and if it is
   used as the REFID this type of attack is prevented.

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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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 27, 2017.

Stenn                    Expires April 27, 2017                 [Page 1]
Internet-Draft     Network Time Protocol Suggest REFID      October 2016

Copyright Notice

   Copyright (c) 2016 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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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  The REFID . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  The Suggested REFID Extension Field . . . . . . . . . . . . .   3
   4.  Generating and Sending the Suggested REFID Extension Field  .   4
   5.  Receiving a Suggested REFID Extension Field . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   NTP has been widely used through several revisions, with the latest
   being RFC 5905 [RFC5905].  A core component of the protocol and the
   algoritms is the Reference ID, or REFID, which is used to identify
   the source of time used for synchronization.  Traditionally, when the
   source of time was another system, the REFID was the IPv4 address of
   that other system.  If the remote system was using IPv6 for its
   connection, a 4 octet digest value of the IPv6 address was used.  The
   purpose of the REFID is to prevent a one-degree timing loop, where if
   A has several timing sources that include B, if B decides to get its
   time from A we don't want A then deciding to get its time from B.
   The REFID is considered to be "public data" and is a vital core-
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