The Network Time Protocol Version 4 (NTPv4) MAC Extension Field

Document Type Expired Internet-Draft (ntp WG)
Authors Danny Mayer  , Harlan Stenn 
Last updated 2016-09-15 (latest revision 2016-03-14)
Stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Expired & archived
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Stream WG state Candidate for WG Adoption
Document shepherd No shepherd assigned
IESG IESG state Expired
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


The Network Time Protocol Version 4 (NTPv4) defines in RFC5905 the optional usage of Message Authentication Code (MAC). The MAC is an optional component of the NTP packet at the end of the packet. There can only be one MAC segment in the packet but there is no way of knowing if the last data segment at the end of an NTP packet is a MAC or an extension field, which is also defined in RFC5905. This draft defines a MAC extension field which will allow the existing MAC segment to be moved into an extension field and have a known length and deprecates the existing MAC.


Danny Mayer (
Harlan Stenn (

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