Network Time Protocol MAC/Last Extension Fields

Document Type Expired Internet-Draft (candidate for ntp WG)
Authors Harlan Stenn  , Danny Mayer 
Last updated 2019-09-26 (latest revision 2019-03-25)
Stream IETF
Intended RFC status (None)
Expired & archived
pdf htmlized (tools) htmlized bibtex
Stream WG state Call For Adoption By WG Issued
Document shepherd No shepherd assigned
IESG IESG state Expired
Consensus Boilerplate Unknown
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


NTP packets can be authenticated by a Message Authentication Code (MAC) if a MAC is present at the end of an NTP packet. The legacy format for this MAC is not formatted as an NTP Extension Field, and its presence may cause some implementations a parsing ambiguity. This proposal introduces two ways to resolve this problem. One is to provide a MAC Extension Field. The other is an extension field that unambiguously declares itself to be the last extension field in an NTP packet (so any additional data MUST be a legacy MAC). RFC EDITOR: PLEASE REMOVE THE FOLLOWING PARAGRAPH BEFORE PUBLISHING: The source code and issues list for this draft can be found in


Harlan Stenn (
Danny Mayer (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)