Talk:Network Time Protocol

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WikiProject Time (Rated B-class, Top-importance)
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WikiProject Time assessment rating comment[edit]

A basic B as far as WikiProject Time is concerned.

Want to help write or improve articles about Time? Join WikiProject Time or visit the Time Portal for a list of articles that need improving. -- Yamara 19:07, 17 January 2008 (UTC)

I have promoted to B-class. ~Kvng (talk) 14:47, 29 September 2016 (UTC)

What does this mran ?![edit]

"...the amount of time it takes a proton to pass an electron"

How can one use NTP in Javascript ??. —Preceding unsigned comment added by Mac (talkcontribs) 19:24, 10 February 2003

TCP/IP or not?[edit]

NTP is a purely UDP/IP protocol, not TCP/IP.
NTP is one of the oldest TCP/IP protocols still in use

Aren't those two lines contradicting? They are both in the article, so they should either be corrected, or explained —Preceding unsigned comment added by (talkcontribs) 11:12, 4 November 2004

That comes from 20040921 edit by I'm wondering if that's a gremlin. He changed "NTP program developed by the OpenBSD project" to "SNTP..." which seems wrong. Someone with better knowledge of protocols should see.--Chealer 14:57, 2004 Dec 3 (UTC)
NTP is a TCP/IP protocol (which doesn't mean it has anything to do with TCP). No such thing as UDP/IP exists.
Yes. the name "TCP/IP" is confusing. -- Naive cynic 13:00, 20 Jun 2005 (UTC)
Terminology was cleaned up at some point to indicate NTP is a UDP/IP protocol. ~KvnG 16:16, 27 May 2013 (UTC)

Link to list of publich ntp servers[edit]


I just came to this entry because I was searching for a list of public accesable time servers. Something like:

I don't know if it's legal to deeply link to it on the main article. —Preceding unsigned comment added by (talkcontribs) 18:41, 26 March 2005

32-bit fractional second part[edit]

So you multiply the fractional part by 2-32 then add it to the integer part to get the time in seconds? Ojw 14:43, 30 August 2005 (UTC)

Denial of Service[edit]

The University of Wisconsin Madison suffered a denial of service "attack" from flawed NetGear routers using NTP. Seems like something relevant to this article, though the relevance may be more tangental than anything. Perhaps a request for a new article is warranted? I've not done that before...

The history of the NTP DoS at the UW-Madison as told by the source is at —Preceding unsigned comment added by DavidDouthitt (talkcontribs) 19:03, 8 November 2005

I heard this story repeatedly from the horse's mouth. What happened was that Netgear outsourced the production of their routers to China, and the designs done there were subpar. They all targetted the same time server at UW Madison, and the reply packets were by default blocked by the firewall, causing a retransmission every second. Think about that - millions of routers hitting on the same time server once a second (whoa...). Eventually were pouring in excess of 50 megabits of traffic onto the UW network. Mills called netgear to tell them that they needed to stop production immediately and fix the problem; Netgear's response was that they saw no reason why they should. Mills then adviced UW to take netgear to court, but UW decided to work out a deal instead. →Raul654 00:56, 9 November 2005 (UTC)

This topic is covered in NTP server misuse and abuse. Jaho 02:52, 15 March 2007 (UTC)


I am surprised no one has mentioned the Law Suits that NTP has on RIM (& in consideration are MS and IBM) —Preceding unsigned comment added by (talkcontribs) 12:41, 24 November 2005

That's because this article is about the Network Time Protocol, not about NTP, Inc. RossPatterson 03:33, 3 April 2006 (UTC)

Significance of port #123?[edit]

Dunno if it's worth mentioning in the main article, but in the UK 123 is the phone number for the Speaking clock. Anyone know if there's any connection between the two? mh. 01:34, 18 December 2005 (UTC)

  • There's the fact that Greenwich is historically the world's time authority, so choosing port 123 would make a kind of sense. --Rfsmit (talk) 19:04, 7 December 2007 (UTC)

Chrony NTP daemon[edit]

Please mention Chrony as well as Ntp and Openntpd. The home page for the project is http://

No need to. This article is about the NTP protocol, ntpd and OpenNTPD are the major deamons implementing it. There are dozens NTP clients out there and chrony is just one of them. Jaho 20:01, 15 March 2007 (UTC)

Clarification needed?[edit]

In the "NTP Timestamps" section, there is the following quote:

"The 64 bit value for the fraction is enough to resolve the amount of time it takes a photon to pass an electron at the speed of light."

Unless I'm misunderstanding something, isn't there something missing here? What is the initial distance between these two particles (or whatever they are)? If they're billions and billions of light years apart, for example, then I could probably "resolve the amount of time" for one to pass the other using my kitchen clock. Is this an incomplete quote or am I just confused? (talk) 21:20, 28 November 2007 (UTC)

I think he's trying to refer to the amount of time that a photon would take to travel the diameter of an electron. I'm not sure the quote is clear and even if it is I'm not sure anyone really knows how wide an electron is? There is a classic radius O(10^-15)m, perhaps that is what is being referred to? (talk) 06:13, 5 June 2008 (UTC)

(The point seems to be that 64+64 bits is sufficient for any possible timekeeping needs in our universe, in a stronger sense than the prediction that ["nobody will ever need more than X kilobytes of memory"]. (talk) 01:17, 16 February 2009 (UTC)

Another clarification needed[edit]

The section also says

"Implementations should disambiguate NTP time using a knowledge of the approximate time from other sources. Since this only requires time accurate to a few decades, this is unlikely to ever be a problem in general use."

I think I see what this means, but I'm not sure. Maybe an example and an explanation of the assumptions would clarify it, as in:

"For example, an operating system version that was released in the early 21st century can safely assume that the system clock should never be set to a time in the 20th century, and can probably assume that it will not still be in use in the 22nd century. In this case, a time built into the operating system would be the other source."

But it could equally well be talking about the DAYTIME protocol, file timestamps, or the computer's hardware clock. Someone who is confident of what is intended should disambiguate it.

-- (talk) 01:17, 16 February 2009 (UTC)

How is this used with routers[edit]

A lot of notes and discussions on the internet about routers and NTP. I can't find any other subject that "NTP" might stand for, so I assume they are referring to this. But how is this protocol significant to router operation?\\

Routers only get their timing information from an accurate time source. NTP is the means to transmit that time reference information.-- (talk) 04:45, 19 November 2011 (UTC)

Illustration misleading[edit]

Under Network_Time_Protocol#Clock_strata, the illustration has arrows indication traffic pointing down. This implies that the higher strata servers push time sync data to the lower strata, when in fact it is a pull operation. —Preceding unsigned comment added by Rfsmit (talkcontribs) 18:56, 7 December 2007 (UTC) (edit: Sorry -- adding sig) --Rfsmit (talk) 18:58, 7 December 2007 (UTC)

Am I the only person that thinks those arrows are YELLOW? I was looking at the diagram for a few seconds thinking to myself "what green arrows?" until I realised it must mean the yellow ones. --Lytel (talk) 17:33, 2 June 2009 (UTC)
I looked at the history of the image, turns out it was change to be colour-blind-friendly. I've updated the description on the page... hope that's OK. --Lytel (talk) 17:34, 2 June 2009 (UTC)

Security Concerns[edit]

Several security experts have voiced their concern about the inherent security of NTP. After attacks targeting highly secured servers in 2009 were revealed to have been broken into via an NTP client vulnerability. Numerous figures in the security community have voiced their concerns about the security of the code base and have called for comprehensive review of the protocol and several wide-spread clients. —Preceding unsigned comment added by SteveKostecke (talkcontribs) 23:01, 12 June 2009 (UTC)

This unverifiable clains have been replaced with properly cited text. SteveKostecke (talk) 22:18, 17 June 2009 (UTC)

Number of strata[edit]

The article doesn't explain why "It is hoped that in NTP 5, a protocol still in development, only 8 strata will be permitted." —Preceding unsigned comment added by (talk) 15:56, 11 October 2009 (UTC)

Sentence is no longer in the article. ~Kvng (talk) 14:37, 29 September 2016 (UTC)


I don't know where are NTP servers times comes from? Does it comes from computer's clock? Or what?-- (talk) 19:17, 26 October 2010 (UTC)

If I understand it right, the original time source is the U.S. National Institute of Standards (NIST). However, transmission latency can cause some minor errors in accuracy.-- (talk) 04:43, 19 November 2011 (UTC)
NTP is based on Coordinated Universal Time. Several atomic clocks and other stratum 0 devices are synchronized on UTC, but how this is done is outside the scope of NTP.Calimo (talk) 14:58, 21 November 2011 (UTC)

Requesting community opinion on archiving older parts of this talk page[edit]

I would like to archive (and/or hava a bot archive) older parts of this talk page. A lot of the sections have not had any discussion for some time now. Many of these are support requests and I think that removing them might help to limit people to resist adding further ntpd support requests. I am not sure how exactly to establish community consent, please indicate if you have any objections.

DouglasCalvert (talk) 06:40, 24 May 2013 (UTC)

Why not just remove the inappropriate comments per wp:notaforum? In fact, I am going to have a go at some of them now. The talk page doesn't seem busy or large enough to justify archiving yet. TwoTwoHello (talk) 09:18, 24 May 2013 (UTC)

Indefinite article[edit]

See Wikipedia:Administrators' noticeboard/Incidents#User: 109.77.xx.xx and the indefinite article and Talk:XMPP#Please discuss changes to the indefinite article. Andrewa (talk) 15:16, 24 May 2013 (UTC)


There is no history discussion in this article. Here are a few sources that can be used to write such a section [1], [2], [3]. ~KvnG 19:30, 6 October 2014 (UTC)

Network Time Foundation[edit]

Glrx has removed mention of Network Time Foundation. Regardless of whether Network Time Foundation is independently notable, that they're responsible for ongoing NTP development is a notable fact concerning NTP. I would like to restore this to the lead. ~KvnG 18:33, 10 November 2014 (UTC)

I've added this to the History section now that sources have arrived. It looks like the Foundation may lose its funding this month. TwoTwoHello (talk) 19:25, 4 April 2015 (UTC)
The refs are not saying that NTF is an effective organization; one suggests the opposite. If the NTF loses its funding, then why should it be mentioned in this article? I do not get a good impression of NTF when I read its IRS Form 990. Glrx (talk) 02:01, 7 April 2015 (UTC)
I think I misread "Linux Foundation's $7,000-a-month contribution to NTP" as contribution to NTF. Re-reading the sources, I see the funding is going directly to Harlan Stenn. I agree mentioning the NTF is still not justified (although mentioning Stenn surely is) and unless I can find other sources, I propose to remove "and his Network Time Foundation" from the article. TwoTwoHello (talk) 10:03, 7 April 2015 (UTC)

leap second handling[edit]

I believe these sentences are wrong, in general:

Because of the requirement that time must appear to be monotonically increasing, a leap second is inserted with the sequence 23:59:59, 23:59:60, 00:00:00. Although the clock is actually halted during the event, any processes that query the system time cause it to increase by a tiny amount, preserving the order of events.[1]

These statements are only partially supported by the cited reference. Showing an inserted leap second as 23:59:60 is what a system honoring UTC is supposed to do, but as far as I know most systems do not. Most systems do not actually have a consistent way of representing the time 23:59:60, so they must use various imperfect workarounds, such as jumping time backwards for a second so that the last second (23:59:59) is repeated, or slowing time down so that the last second takes two seconds. (That is, many systems do not manage to achieve the requirement that time be monotonically increasing across a leap second.)

I believe a correct statement would be

Once NTP has determined that a leap second is upcoming, it depends on the operating system in use how the leap second will be represented and displayed. Some systems jump time backwards for a second so that the last second of the day is repeated, others slow time down or stop it so that the last second takes two seconds. Various additional steps may be taken in an attempt to preserve the necessary appearance that time is monotonically increasing.[2]

and after polishing it a little more, that's the edit I intend to submit. —Steve Summit (talk) 03:40, 17 November 2015 (UTC)

I agree that there is no 23:59:60 in NTP. It is also difficult in practice to separate NTP behavior from OS behavior (e.g. Unix time). I think it is still valuable to document NTP time behavior through a leap second. RFC 7164 section 3.4 is an additional reference for this. ~Kvng (talk) 14:29, 20 November 2015 (UTC)
Thanks. That's very useful. —Steve Summit (talk) 12:27, 21 November 2015 (UTC)
Section now edited along the lines suggested. —Steve Summit (talk) 15:03, 21 November 2015 (UTC)
I have reverted your changes. You have deleted the description of NTP time behavior. The reference for the section describes NTP time behavior. If we want to also describe OS time behavior, we need another reference (e.g. RFC 7164). ~Kvng (talk) 14:42, 26 November 2015 (UTC)


NTPsec new implementation of NTP[edit]

NTPsec is a secure version of NTP and a project fork of the reference implementation. They should probably be included in the page. You can find information on them here. TMLutas (talk) 21:32, 31 January 2016 (UTC)

Here is some coverage. Already mentioned at ntpd. Seems like it is worthy of inclusion here too. ~Kvng (talk) 14:42, 29 September 2016 (UTC)