Network Time Protocol Version 4 (NTPv4) Extension Fields
draft-stenn-ntp-extension-fields-02

Document Type Active Internet-Draft (individual)
Last updated 2017-09-29
Stream (None)
Intended RFC status (None)
Formats plain text xml pdf html bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
Internet Engineering Task Force                               T. Mizrahi
Internet-Draft                                                   Marvell
Intended status: Standards Track                                D. Mayer
Expires: April 1, 2018                                          H. Stenn
                                                 Network Time Foundation
                                                      September 28, 2017

        Network Time Protocol Version 4 (NTPv4) Extension Fields
                  draft-stenn-ntp-extension-fields-02

Abstract

   Network Time Protocol version 4 (NTPv4) defines the optional usage of
   extension fields.  An extension field, as defined in RFC 5905
   [RFC5905], 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).

   With the adoption of this update, the authors recommend rescinding
   [Err3627].

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 1, 2018.

Copyright Notice

   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
   Provisions Relating to IETF Documents

Mizrahi, et al.           Expires April 1, 2018                 [Page 1]
Internet-Draft           NTPv4 Extension Fields           September 2017

   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   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 . . . . . . . . . . . . . .   3
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     2.2.  Terms and Abbreviations . . . . . . . . . . . . . . . . .   3
   3.  NTP MAC - RFC 5906 Update . . . . . . . . . . . . . . . . . .   3
     3.1.  4. Autokey Cryptography . . . . . . . . . . . . . . . . .   4
     3.2.  10. Autokey Protocol Messages . . . . . . . . . . . . . .   4
     3.3.  11.5. Error Recovery  . . . . . . . . . . . . . . . . . .   4
     3.4.  13. IANA Consideration  . . . . . . . . . . . . . . . . .   4
   4.  NTP Extension Fields - RFC 5905 Update  . . . . . . . . . . .   4
     4.1.  OLD: 7.5 NTP Extension Field Format . . . . . . . . . . .   4
     4.2.  NEW: 7.5 NTP Extension Field Format . . . . . . . . . . .   5
     4.3.  NEW: 7.5.1 Extension Fields and MACs  . . . . . . . . . .   7
       4.3.1.  Legacy MAC/EF Parsing Pseudocode  . . . . . . . . . .   9
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

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 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 specifieded 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
Show full document text