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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Set NTP not to receive time from peers on Ubuntu

In my /etc/ntp.conf, it says By default, exchange time with everybody, but don't allow configuration. restrict -4 default kod notrap nomodify nopeer noquery restrict -6 default kod notrap nomodify ...
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29 views

ntpd -gq do not working on CentOS 6.4

when I'm running 'ntpd -gq' from CentOS 5.10 (i686) the time is synced, but in CentOS 6.4 (x86_64) the command gets stuck (I need to stop it using ctl+c). Any idea hoe to fix it? EDIT: iptables ...
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27 views

ntpd default rate limiting?

I've got about 70 linux instances running on an OpenStack cluster that currently consists of two compute nodes and one controller. Also, these machines live in a RackSpace DC as part of their 'Private ...
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1answer
35 views

Easiest Way to Keep Time Synced on VMware Cluster

I have a three host VMware cluster (5.1) running mainly windows 2008r2 servers with a single DC. I'm having allot of problems with time drift across the servers and while I've found several articles ...
3
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1answer
27 views

Synchronizing RODCs to NTP servers?

I've read this nice article from Gareth Hooper regarding Domain Controller syncing to external time sources. In essence, he wrote that although Microsoft don't actually condone the practice, it's a ...
4
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2answers
224 views

Active Directory Time Synchronisation - Time-Service Event ID 50

I have an Active Directory domain with two DCs. The first DC in the forest/domain is Server 2012, the second is 2008 R2. The first DC holds the PDC Emulator role. I sporadically receive a warning ...
2
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2answers
57 views

Why does ntpd need to bind external interfaces to sync the local clock?

I wanted to tighten my security so I don't want to open any ports that are not really needed. I have no intentions of running an ntp server for other people to use, I only run the ntp daemon to keep ...
2
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0answers
51 views

Server 2008 will not sync with NTP [closed]

I recently got given a server 2008 r1 machine and thought I would set it up to help maintain my small work network of 10 PCs better. The issue I am having is that I cannot get it to sync with an ...
2
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2answers
31 views

How to configure NTP has a TAI or GPS time reference?

For our project, we would like to have all servers and systems synchronised to a linear time reference (without leap second). Therefore, we would discard UTC but are very interested in advertising ...
3
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1answer
44 views

The wisdom of 'server 127.127.1.0' in ntp.conf for virtual servers

Considering the 'undisciplined local clock' on VMs is not what you'd call accurate in most cases, how wise is it to include lines such as these in your NTP configuration? # Undisciplined Local Clock. ...
2
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3answers
208 views

Why should I need a tweak to force VMware ESXi 5 to sync time with Windows NTP server

I'm plagued by a seemingly simple but actually troublesome problem, so I ask for help here. Symptom I installed an instance of VMware ESXi 5.1 inside VMware Workstation to learn about various ESXi ...
2
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1answer
455 views

Disable NTP on Juniper SRX-240

I'm trying to shutdown/disable the ntp daemon running on a Juniper SRX-240 (junos 11.4), but the obvious solution is apparently not valid for this hardware/software combination.
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5answers
1k views

How can I defend against a DRDoS exploiting NTP server on an ESXi host?

Recently, we had some problems with one of our ESXi servers, caused by the NTP Server DRDoS Amplification Attack using ntpdc. How do I configure the NTP server on ESXi to not be exposed to this DDoS ...
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0answers
91 views

Ubuntu 12.04 LTS ntp not working

I'm having major woes trying to get ntp working on several ubuntu 12.04 servers. Note this is NTP to keep the time set on those servers. Not to distribute the time! I've installed several of those ...
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2answers
142 views

Why does NTP daemon keep listening on UDP6?

I have a clean Debian 7 installation, and I manually entered the following lines in /etc/ntp.conf: interface ignore wildcard interface listen <local_nic_ip> Hoping that NTP will no longer ...
1
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1answer
68 views

ESXi host time not syncing with NTP servers

I have 2 NTP servers (AD 2003 machines) and some ESXi hosts, which are configured to sync time from these 2 servers. I found the time is not in sync between these hosts and servers. And time in each ...
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1answer
64 views

Godaddy fails to properly configure NTP on their node server hosting my VPS

I have a few VPS servers with Godaddy and with every new server I contracted I had to ask them to set up NTP on the node hosting my container. They always did until now. It seems like their ...
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24 views

ntp.conf function and format for server keyword

I have 4 redhat boxes that are each sync'ed by their own arbiter gps clock. These are acting as time sources for the rest of my network. Can I include all four boxes in the peer statements in ...
4
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3answers
248 views

Usefulness of a new stratum-1 NTP server

A physicist I know that works in a government institution recently commented that they have a cesium clock, and they were considering the possibility of setting up a public stratum 1 NTP server ...
2
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1answer
283 views

ntpdate failing “Name or service not known”

I've got a NAS that is Linux-based (Linux version 2.6.32.11-svn70860) and it is not able to set its time using ntp. The previous SysAdmin is long gone so I have no idea whether this problem just ...
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156 views

Linux - NTP stopped working after recent update

A few days ago I had ntp setup on my network, and everything was running fine. One node was set to sync with upstream servers, and the rest of the nodes from the one set to sync upstream. Yesterday I ...
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3answers
133 views

hyper-v server time sync source - PDC / external NTP?

The environement: 10 Hyper-V hosts, all AD joined a lot of VMs AD joined and some not some AD DCs including PDC as Guests What You think is the best approach to time sync a hyper-v farm with AD ...
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3answers
1k views

DDOS using ntp server

I've heard about new kind of DDOS where ntp is used for reflection . My questions are really simple : Can you please give details on how they work and clarify? Since ntp is ran over UDP, I suppose ...
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2answers
110 views

ntp server that syncs with other ntp servers but supplies a modified utc

Question We need to create an ntp server that syncs against other ntp servers but gives its client a modified utc. For example, it will receive utc 5:17 pm but it's clients will receive utc 7:17pm. ...
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3answers
100 views

Time synchronization in Active directory

I've got issues with time synchronization in a domain. I have DCs that spans time zones, however the PDC is located in a time zone where daylight savings is active, this caused all the additional DCs ...
10
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2answers
148 views

why doesn't ntp recover after an Internet-less startup?

I have a few Linux devices (without TOY chips, so they completely rely on ntp) which may boot without access to Internet (the link to the switch is up). The ntp service will start but obviously no ...
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1answer
672 views

NTP local query always times out

I have a CentOS 6.4 server, it does not have any iptable rules, it runs NTP daemon as service using the following configuration: driftfile /var/lib/ntp/drift server 0.pool.ntp.org server ...
10
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2answers
210 views

Linux kernel detecting wrong processor frequency

After a cold boot of a 6.0.8 Debian server (HP ProLiant), ntpd played havoc with system time: offset and jitter with respect to the usual and reliable reference time servers growing without limit. ...
0
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1answer
61 views

Gentoo server time issue, can't manually set time, NTPD won't correct, too big of a time difference

So, my server is living in the future, unfortunately I can't get lottery numbers, or stock picks out of it. It thinks this is the time: Thu Nov 7 04:07:18 EST 2013 Not correct, I tried to set the ...
3
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2answers
83 views

Setup NTP on Debian

I installed ntp on my debian system: apt-get install ntp ntpdate ntp-server. My questions: How often is the time synchronized - is there a schedule? Is there a log that says when the time was ...
2
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1answer
134 views

Which NTP source should I use in ESXi virtual machines?

I have a ESXi host running ~20 virtual machines (mostly EL6, but also one or two Windows Server 2008 R2). What is the best practice for timekeeping on virtual machines? I'm thinking about 3 ...
2
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3answers
168 views

Allow NTP to update by large amounts automatically?

Here is my scenario: I run multiple VMs on my workstation to simulate the production environment. At the end of the day I sleep my workstation (with my VMs running in the background) at 6PM. When I ...
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1answer
121 views

Ubuntu 12.04 LTS regularly loses sync with NTP server

I have a Ubuntu 12.04 LTS VM running inside VirtualBox. It is fine except the clock winds up being exactly 25 minutes behind every other machine on the network. My normal procedure is to setup NTP, ...
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1answer
101 views

NTP synchronisation not visible in syslog

I am trying to set up a local NTP server for our LAN. I am able run ntpdate server_ip to manually update the time. However, ntp daemon does not seem to be logging anything into syslog, and so I can't ...
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1answer
531 views

What are the disadvantages of disabling tinker panic 0 in NTP?

We sometimes have the problem that new servers have the wrong time in the bios, so there time can be off by a month. When you suspend a VM in VMware and then unsuspend it, the time will be off too. ...
6
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3answers
104 views

How to make NTP work despite a high offset?

Recently I have kickstarted some servers that had their time off by a month in the bios. The time in the bios said it was a random time/date in May, while it was June. This caused NTP not to work, ...
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2answers
151 views

Set up an NTP server to allow local machines to be syncronised for Linux

I am trying to set up a machine to act as an ntp server to which the other local machines will syncronise their times to. This needs to happen regardless of whether the ntp server machine is connected ...
9
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2answers
469 views

What is the strategy for detecting time drift in a linux based data centre?

What is the strategy for detecting time drift in all linux based data centre? This is a more difficult problem than it seems at first. Time drift can cause serious problems for certain applications ...
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2answers
119 views

Clock skew on my VPS server

I am having a problem with the time on my VPS hosted at Rackspace. Its running Red Hat Enterprise Linux 5.4. Date commands gives a time which is 11 minutes ahead of the actual time. I am running ntpd ...
0
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1answer
54 views

Debian Server System time and time used by processes are different

I have a dedicated server running debian 7, the system time shows "Wed Aug 7 04:28:26 EAT 2013" I have restarted the server several times but processes like deluge and apache return http headers ...
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2answers
490 views

enable/disable ntp service on ubuntu 12.04

Our application runs on Ubuntu 12.04 Precise. On this server, we have both ntpdate and ntp. How to enable and disable the NTP service on-demand? I tried # sudo update-rc.d -f ntp remove/default ...
2
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0answers
48 views

Pinpointing source of clock inaccuracy

I am having a huge problem with the clock on a Windows XP machine. Whether getting its time from the domain controller using w32time and an ntp server (PDC) / client, from a GPS clock directly using ...
9
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3answers
801 views

Why not use vmware tools for time synchronisation?

We have two VMWare environments running a bunch of (mainly) Redhat 5.9 and 6.4 guests. We are having issues with time drift (minutes ahead per week). We use ntp, syncing to the local domain ...
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72 views

ntp.conf being rewritten in Fedora

Something rewrites my ntp.conf on reboot. It's easy to google that DHCP client may do it, and there is a simple solution for that. Just including -N option into dhcpcd_eth in /etc/conf.d/net should be ...
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90 views

Meinberg NTP Client large wandering

All, One of the computers on my network runs Windows Embedded Standard and is running the meinberg NTP client and gets its time directly from a GPS clock. The service is set to run automatically and ...
0
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1answer
160 views

Failed to install ntp via apt-get in Debian

When trying to install ntp (because my server clock is wrong), it just pukes this massive error. Any idea how to fix this? root@pan-prodweb01:~# apt-get install ntp Reading package lists... Done ...
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2answers
123 views

compile ntp without ssl

I need to deploy ntp to a very space-critical pxe-imaging-system. (Yes, each KB matters.) Footprint needs to be as small as possible, so I want to compile ntp without linking openssl. According to the ...
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2answers
236 views

Discovering NTP servers providing time service on network

As a linux (Debian-based) host on a network, how can I discover whether an NTP service exists somewhere locally on the network? Thanks.
0
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2answers
170 views

How to clear/flush ntp server peer in Centos

We were using centos.pool.ntp.org for our clock sync among servers. Now we do ave a local NTP server, but the problem is servers are using the old ntp. From centos.pool.ntp.org we can see, ...
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1answer
2k views

Wrong time on my Ubuntu Amazon EC2 instances

I have three Ubuntu EC2 instances on Amazon AWS (EU/Ireland), all set up as web server. I noticed the system date/time is incorrect in two of them (timezone is always set to UTC for my choice). Here ...