Network Time Protocol Version 4 (NTPv4) Extension Fields
draft-stenn-ntp-extension-fields-07

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Last updated 2018-08-30
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Internet Engineering Task Force                                 H. Stenn
Internet-Draft                                                  D. Mills
Obsoletes: 7822 (if approved)                    Network Time Foundation
Intended status: Standards Track                         August 30, 2018
Expires: March 3, 2019

        Network Time Protocol Version 4 (NTPv4) Extension Fields
                  draft-stenn-ntp-extension-fields-07

Abstract

   Network Time Protocol version 4 (NTPv4) defines the optional usage of
   extension fields.  An extension field, as defined in RFC 5905
   [RFC5905] and RFC 5906 [RFC5906], resides after the end of the NTP
   header and supplies optional capabilities or information that cannot
   be conveyed in the basic NTP packet.  This document updates RFC 5905
   [RFC5905] by clarifying some points regarding NTP extension fields
   and their usage with legacy Message Authentication Codes (MACs), and
   removes wasteful requirements added by RCF 7822 [RFC7822].

   This proposal deprecates RFC 7822 [RFC7822].

Status of This Memo

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Copyright Notice

   Copyright (c) 2018 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

Stenn & Mills             Expires March 3, 2019                 [Page 1]
Internet-Draft           NTPv4 Extension Fields              August 2018

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     2.2.  Terms and Abbreviations . . . . . . . . . . . . . . . . .   3
   3.  NTP MAC - RFC 5906 Update . . . . . . . . . . . . . . . . . .   4
     3.1.  RFC5906 Section 4. - Autokey Cryptography . . . . . . . .   4
     3.2.  RFC5906 Section 10. - Autokey Protocol Messages . . . . .   4
     3.3.  RFC5906 Section 11.5. - Error Recovery  . . . . . . . . .   4
     3.4.  RFC5906 Section 13. - IANA Consideration  . . . . . . . .   4
   4.  NTP Extension Fields - RFC 5905 Update  . . . . . . . . . . .   5
     4.1.  OLD: 'RFC5905 7.5 - NTP Extension Field Format' . . . . .   5
     4.2.  NEW: 'RFC5905 Section 7.5 - NTP Extension Field Format' .   5
     4.3.  NEW: 'RFC5905 Section 7.5.1 - Extension Fields and MACs'    8
     4.4.  OLD: 'RFC5905 Section 9.2. - Peer Process Operations' . .   9
     4.5.  NEW: 'RFC5905 Section 9.2. - Peer Process Operations' . .   9
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   An NTP packet consists of a set of fixed fields that may be followed
   by optional fields.  Two types of optional fields are defined:
   extension fields (EFs) as defined in Section 7.5 of RFC 5905
   [RFC5905], and legacy Message Authentication Codes (legacy MACs).

   If a legacy MAC is used, it resides at the end of the packet.  This
   field can be either a 4-octet crypto-NAK or data that has
   traditionally been 16, 20 or 24 octets long.

   Additional information about the content of a MAC is specified in RFC
   5906 [RFC5906], but since that RFC is Informational an implementor
   that was not planning to provide Autokey would likely never read that
   document.  The result of this would be interoperability problems, at
   least.  To address this problem this proposal also copies and
   clarifies some of the content of RFC 5906, putting it into RFC 5905.
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