Network Time Protocol Version 4 (NTPv4) Extension Fields
draft-stenn-ntp-extension-fields-04

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Internet Engineering Task Force                                 H. Stenn
Internet-Draft                                   Network Time Foundation
Obsoletes: 7822 (if approved)                           December 4, 2017
Intended status: Standards Track
Expires: June 7, 2018

        Network Time Protocol Version 4 (NTPv4) Extension Fields
                  draft-stenn-ntp-extension-fields-04

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 is not
   conveyed in the standard NTP header.  This document updates RFC 5905
   [RFC5905] by clarifying some points regarding NTP extension fields
   and their usage with legacy Message Authentication Codes (MACs).

   This proposal obsoletes RFC 7822 [RFC7822].

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
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   This Internet-Draft will expire on June 7, 2018.

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   Copyright (c) 2017 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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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

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Internet-Draft           NTPv4 Extension Fields            December 2017

   carefully, as they describe your rights and restrictions with respect
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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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   4
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     2.2.  Terms and Abbreviations . . . . . . . . . . . . . . . . .   4
   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  . . . . . . . . .   5
     3.4.  RFC5906 Section 13. - IANA Consideration  . . . . . . . .   5
   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 . .   6
     4.3.  NEW: RFC5905 Section 7.5.1 - Extension Fields and MACs  .   8
       4.3.1.  Legacy MAC/EF Parsing Pseudocode  . . . . . . . . . .  10
     4.4.  OLD: RFC5905 Section 9.2. - Peer Process Operations . . .  14
     4.5.  NEW: RFC5905 Section 9.2. - Peer Process Operations . . .  14
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .  16
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   The NTP header format 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 is usually 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 includes copying
   and clarifying some of the content of RFC 5906 and putting it into

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