Using NTP Extension Fields without Authentication

Document Type Expired Internet-Draft (ntp WG)
Authors Tal Mizrahi  , Danny Mayer 
Last updated 2014-07-21 (latest revision 2014-01-02)
Replaced by RFC 7822
Stream Internet Engineering Task Force (IETF)
Expired & archived
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This Internet-Draft is no longer active.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 the optional usage of extension fields. An extension field is an optional field that resides at the end of the NTP header, and can be used to add optional capabilities or additional information that is not conveyed in the standard NTP header. The current definition of extension fields in NTPv4 is somewhat ambiguous regarding the connection between extension fields and the presence of a Message Authentication Code (MAC). This draft clarifies the usage of extension fields in the presence and in the absence of a MAC, while maintaining interoperability with existing implementations.


Tal Mizrahi (
Danny Mayer (

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