Network Time Protocol Version 4 (NTPv4) Extension Fields
RFC 7822
Document | Type |
RFC - Proposed Standard
(March 2016; No errata)
Updates RFC 5905
|
|
---|---|---|---|
Authors | Tal Mizrahi , Danny Mayer | ||
Last updated | 2017-05-25 | ||
Replaces | draft-mizrahi-ntp-extension-field | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Karen O'Donoghue | ||
Shepherd write-up | Show (last changed 2015-08-13) | ||
IESG | IESG state | RFC 7822 (Proposed Standard) | |
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Brian Haberman | ||
Send notices to | (None) | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | No IANA Actions |
Internet Engineering Task Force (IETF) T. Mizrahi Request for Comments: 7822 Marvell Updates: 5905 D. Mayer Category: Standards Track Network Time Foundation ISSN: 2070-1721 March 2016 Network Time Protocol Version 4 (NTPv4) Extension Fields Abstract The Network Time Protocol version 4 (NTPv4) defines the optional usage of extension fields. An extension field, as defined in RFC 5905, is an optional field that resides at the end of the NTP header and that can be used to add optional capabilities or additional information that is not conveyed in the standard NTP header. This document updates RFC 5905 by clarifying some points regarding NTP extension fields and their usage with Message Authentication Codes (MACs). Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7822. Copyright Notice Copyright (c) 2016 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 (http://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. Mizrahi & Mayer Standards Track [Page 1] RFC 7822 NTP Extension Fields March 2016 Table of Contents 1. Introduction ....................................................2 2. Conventions Used in This Document ...............................3 2.1. Terminology ................................................3 2.2. Terms and Abbreviations ....................................3 3. NTP Extension Fields - RFC 5905 Update ..........................3 4. Security Considerations .........................................6 5. References ......................................................7 5.1. Normative References .......................................7 5.2. Informative References .....................................7 Acknowledgments ....................................................8 Authors' Addresses .................................................8 1. Introduction The NTP header format consists of a set of fixed fields that may be followed by some optional fields. Two types of optional fields are defined: Message Authentication Codes (MACs), and extension fields as defined in Section 7.5 of [NTPv4]. If a MAC is used, it resides at the end of the packet. This field can be either 24 octets long, 20 octets long, or a 4-octet crypto-NAK. NTP extension fields were defined in [NTPv4] as a generic mechanism that allows the addition of future extensions and features without modifying the NTP header format (Section 16 of [NTPv4]). The only currently defined extension fields are those fields used by the Autokey protocol [Autokey] and the Checksum Complement [RFC7821]. The Autokey extension field is always followed by a MAC, and Section 10 of [Autokey] specifies the parsing rules that allow a host to distinguish between an extension field and a MAC. However, a MAC is not mandatory after an extension field; an NTPv4 packet can include one or more extension fields without including a MAC. This behavior is specified in Section 7.5 of [NTPv4] and in [Err3627], and is further clarified in this document. This document updates [NTPv4] (RFC 5905) by clarifying some points regarding the usage of extension fields. These updates include changes to address errors found after the publication of [NTPv4] with respect to extension fields. Specifically, this document updates Section 7.5 of [NTPv4], clarifying the relationship between extension fields and MACs, and defining the behavior of a host that receives an unknown extension field. Mizrahi & Mayer Standards Track [Page 2] RFC 7822 NTP Extension Fields March 2016Show full document text