NTP stands for Network Time Protocol, and it is an Internet protocol used to synchronize the clocks of computers to some time reference.

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Building NTP with OpenSSL

I am trying to build the latest version of NTP (4.2.8p3 released on 2015/06/29) with OpenSSL support. I can definitely build NTP but when I try to use ntp-keygen to create a new certificate it tells ...
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network namespaces and ntp

I have the same VM two times in my host and I´m using linux namespaces to access into the VM, the VMs are equals therefore their IPs are 192.168.0.1 I need the same machine to parallelize a lot of ...
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Trouble with NTP Sync between ntp servers and VMs

I have many VMs on production that run vmware, with vmtools running and the sync between ESXI and hosts is disabled. I run ntp client on all hosts, the OS of hosts is RHEL. The problem I have is that ...
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/proc/stat btime value change after boot

In a Linux server with the kernel 3.16, not virtualized, but with the ntp daemon active, the variable "btime" wich gives the time at which the system booted, change a few seconds before booting. For ...
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26 views

Dynamic timezone change for OpenWrt (Chaos Calmer), NTP

I have this idea for my routers running OpenWrt, since for them there is no way of knowing in what time zone they are by default. What if there was a list of lets say three time servers each per one ...
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31 views

How to solve XenServer Windows guest time driffting issue?

I do have two different Windows VM guests that seem to be drifting time seriously, reaching an offset of 10-15 seconds in less than a week. Both the Windows guests and the XenServer 6.5 host are ...
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40 views

NTP server acting weird

I have an NTP server on the network that is acting very weird. I have not changed any of the ntpd.conf settings. Its a debian box and I did a regular install. I have an NTP client on the network. If ...
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37 views

NTP service stopped in centos7.1 linux machine

In our 3 linux boxes centos 7.1, we saw below messages in the logs and then ntpd service got stopped since the offset is more than 1000s. systemd: Time has been changed ntpd[2626]: 0.0.0.0 0617 07 ...
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Windows Server internet time server reset after restart

I encountered an issue with Windows Server 2012 (running as a virtual machine), after an unplanned restart: the original internet time server - time-b.nist.gov - changed to time.windows.com. This set ...
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36 views

ntp.conf pool vs server directives

I came across an ntp.conf file that specifies pool directives: # Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board # on 2011-02-08 (LP: #104525). See ...
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153 views

Linux ntpd leap second preparation

There will be a leap second on June 30, 2015 at 23:59:60 UTC. I have a Linux based stratum 1 NTP server which uses GPS as a reference clock. The server is using the "default" ntp.org ntpd. How ...
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235 views

Time synchronization in an heterogeneous environment

In a mixed environment, where machines can be running under Windows (most), Linux (a few), sometimes Android ... what is the best solution to have time synchronization with an accuracy close to ...
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24 views

UDel ntpd - completely disable time server discovery

I configured UDel ntpd (version 4.2.6.p5) as a client to three servers operated by my organization, and (I thought) no one else. server xx.yy.zz.1 iburst server xx.yy.zz.2 iburst server xx.yy.zz.3 ...
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62 views

How to synchronize the time in Debian6 server? We have 30 min delay in our VMs

I can't have the correct time in our servers. We get always the same delay in the three of them (they are VM on the same server). We use ntp to have our date always synchronized· The main server ...
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56 views

Using public ntp servers for backup to local stratum 1 server

In my data centers, I have access to a stratum 1 server but I set up our servers to use ntp pool servers in addition to it. My main thinking was for backup in case our local server goes down but I am ...
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31 views

ntp synchronize time between peers

I am a newbie, so please bear with me. I have a network of around 10 computers for which I want to synchronize their time up to millisecond precision. The computers do not have Internet connection. ...
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1answer
305 views

ntpd: servers stuck on .INIT

I am trying to set up an NTP server for my local network, but ntpd refuses to sync with outer servers. # ntptrace localhost: stratum 16, offset 0.000000, synch distance 0.396285 # ntpq -pn ...
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349 views

NTP running, server time is wrong on VM

The server time was 7 hours off (instead of 10AM it was 3AM, even though date showed the correct timezone). The output for ntpq was: $ ntpq -p remote refid st t when poll reach ...
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273 views

Does NT5DS time synchronization have any place in a mixed Windows / Linux environment?

I am working on a plan towards overhauling how time synchronization is handled on our network. Currently our network is predominantly Windows-based, in a fairly standard AD domain broken up into ...
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83 views

Tracing chain of NTP servers

For educational purposes I wanted to trace a chain of NTP servers, e.g. 0.de.pool.ntp.org back to a stratum 1 NTP server. How can I do this? I found ntptrace, but it doesn't work: /home/xyzdragon# ...
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Linux-NTP: What could cause high offset in some servers while all of them reside on the same network sigment and are configured the same?

I've installed a new NTP server and configured all Hadoop clients to use it. I've been told by the Hadoop Engineers that an offset of maximum 3 seconds is mandatory for the cluster to work properly. ...
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366 views

DST Morocco, a way to trick NTP server

From several years Morocco have been using GMT without DST, in the past years, our government reactivated the use of DST. In the first years, the DST was a mess, different periods, starts, ends, so ...
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86 views

NTP can't synchronise

Okay so I tried syncing a windows clients clock to the ubuntu ntp server i just set up, but it gets a time out, when trying. So I went on the ubuntu server and looked at syslog: Apr 10 13:15:01 ...
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114 views

Best practices for time syncing a WS2012R2 domain controller that is a Hyper-V virtual machine?

What are generally the best practices for keeping time in a WS2012R2 domain controller? Right now I have left it as installation and honestly, there is no problem ("If it aint broke, don't fix it") ...
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93 views

Time Zone keeps changing after sync with PDC in different site

Background: I have a single domain, running in 2 sites that is connected using Site-to-Site VPN. Site A is running in time zone 2:00+ UTC Site B is running in time zone 4:00+ UTC DCs are correctly ...
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75 views

how to get a subset of NTP servers from *.pool.ntp.org?

I am doing some reliability tests and needed a list of NTP servers from fr.pool.ntp.org (or any other geographic or national pool). I queried the pool 100 times but only got 13 unique servers (out of ...
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841 views

Where do computers/servers in a Windows Domain get their time settings from? [duplicate]

I have 5 Windows Server 2012 servers and around 100 computers in our domain. Recently I noticed that the time on the servers and computers is around 30 seconds fast. Where do servers and computers ...
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231 views

“NTP socket is in use” messages from ntpdate in syslog

In cron.log I can see that ntpdate is being triggered from a cron job which is running daily at 23:15 Mar 10 23:15:01 seitan /USR/SBIN/CRON[22407]: (root) CMD (/etc/network/if-up.d/ntpdate) But ...
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82 views

Can I configure a server to use a user port(>1023) for NTP?

Can a linux server be configured to use a high source port(above 1023) for NTP synchronization with a Stratum 1/2 server? Are there any disadvantages to doing this?
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Risk of starting NTP on database server?

I've heard rumors of bad things happening to database and mail servers if you change the system time while they are running. However, I'm having a hard time finding any concrete information on actual ...
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ntpd logging debug to ntpd.log

using ntpd 4.2.6p5 on redhat 6.5 How do I configure /etc/ntp.conf to generate debug messages to logfile? in /etc/ntp.conf I have logfile /var/log/ntpd.log but that only does very basic entries. ...
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176 views

date and sleep during leap second [closed]

Did you ever watch what happens with a sleep during a leap second or what date will show us? Most UNIX systems can handle a sleep with a fraction of a second and the date command can display ...
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79 views

NTP offset warning when no NTP server is defined and NTP not running?

I just want to preface by saying that I am still learning linux and don't have too much experience with it. My job requires me to monitor an alert system for our clients hosts that are running our ...
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332 views

Cisco SG300 SNTP servers always down

I'm trying to setup the SNTP of a new Cisco SG300-48 Switch in L3 mode. So far I have enabled the Main Clock Source (SNTP Servers) option (Administration -> Time Settings), set my time zone and ...
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What causes ntpq refid CRYP when authentication is successful?

I have five servers that I'm configuring for production use based on a configuration we've recently tested. The servers are RHEL6 with NTP version 4.2.4p8@1.1612-o. Right now, though, I'm trying to ...
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521 views

What happens when DC cannot reach external time server?

We have a small Windows 2012 R2 domain with a single DC. The DC is advertising as a time server, and the clients are syncing just fine. The DC is getting its time from an external time server, and ...
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134 views

Why my server on Digital Ocean woke up with a wrong time?

Today one of my servers hosted on Digital Ocean (the only one hosted there) is reporting wrong time. It's two hours late. sudo dpkg-reconfigure tzdata # then I set up the timezone to Europe/Rome ...
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Using RTC to synchronize ntpd when offline

I need a stable configuration, presumably using ntpd, to keep system clock as precise as possible. Background: I have several embedded devices (arm9) running linux (currently: 3.16.1 / debian 7.2) ...
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Server Migration 03 -> 12

I have run into a wall and out of ideas. Here's the situation. I have a client that has a old '03 DC with a 12 replicating the '03 server. It is out dated and has to many group policies and stuff it ...
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177 views

chronyd peer not syncing

I would like to configure two my servers as chronyd ntp peers. Both servers run on amazon ec2, one on centos 7, one on rhel 7 -what is minimal chrony peer configuration ? I cant use my other server ...
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117 views

Resync windows time after a long power outage

I'm facing the following situation: We have a computer with Windows 8 Standard Embedded. The machine is an industrial computer that doesn't have a CMOS Battery but a capacitor (a Gold Cap acting as a ...
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Ubuntu server is randomly having large time sync issues

It seems that randomly the time on my server will jump forward several hours. This happens randomly and the only way I've found to fix it is to manually force an NTP call. I don't see anything out of ...
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What does this shell script mean? [closed]

#!/bin/bash /usr/sbin/ntpdate ntp.jst.mfeed.ad.jp I found such a script file,maybe it is used to confirm the time, can you explain it in detail?
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1answer
131 views

ntpd keeps adding local servers while being told not to

I'm configuring ntp inside a corporate network. I've done restrict default ignore restrict -6 default ignore and listed servers explicitly (I'm using public servers from pool.ntp.org). I also ...
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ntp authentication - MD5 - freeBSD

NTP claims to support md5 authentication. The docs I've found aren't clear enough for my level of luserhood. How would I go about using it, with a collection of freebsd clients, and a couple of ...
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343 views

How to have ntpd serve only my local subnet

I have a few servers with public Internet IP addresses like A.B.C.x. One of my hosts (A.B.C.10) runs ntpd and I have it syncing it's time from europe.pool.ntp.org. Now I only want to allow hosts ...
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Proper NTP configuration for a few servers

I have about 20 Linux servers in a small network and I need their clocks decently close to each other (e.g. within 20msec). I've started with every one of them synced to europe.pool.ntp.org and the ...
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1answer
234 views

NTP Version Check

How can I check other NTP server's NTP version without query the server? NTPv3 and NTPv4 network packet is different, and I know I can just catch the packet and analysis it when ntpd is doing sync. ...
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294 views

NTP not sync the time continuously, Have to restart the service of NTP then it SYNC in Ubuntu

I am facing one problem. NTP server not sync the time automatically. If I change the the time of system then NTP server not able to correct it. After reboot the service of NTP it sync the time ...
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159 views

How to update NTP-deamon on a Debian Squeeze (Proxmox 2.x)?

Because of security issue in NTP (CVE-2014-9295) I need to update NTP-deamon on a Debian Squeeze (it is the Proxmox 2.x installation). The problem is that it is a productional system and I can not ...