The Network Time Protocol, is used to synchronize system clocks to precision time servers on the internet or locally connected devices such as a GPS.

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What is the recommended way to synchronize time using NTP?

This question has come up a number of times in a localized way, this question is meant to provide the preferred/best method for synchronizing a system's clock using NTP. The solution should handle ...
11
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1answer
15k views

ntpdate -d seems successful, but ntpdate returns no server suitable

I've got a system that is not running ntpd on which I'm attempting to update the clock using ntpdate. The system is an appliance that appears to be CentOS 6 based. When I run ntpdate 0.pool.ntp.org, ...
8
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4answers
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timed out, nothing received

I tried all and googled a lot! But I can't make work NTP on my server. This post is last hope! I have installed ntp on debian server with this configuration (/etc/ntp.conf): driftfile ...
7
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1answer
190 views

NTP and NTPD Nanokernel

I had a couple of questions about the NTP Nanokernel as explained here: http://www.eecis.udel.edu/~mills/database/brief/nano/nano.pdf The big question is how does this Nanokernel manage to deliver an ...
6
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1answer
8k views

Arch ntpd/ntpdate not synchronizng clock

My raspi running Arch isnt updating time with NTPD. Im running [root@fatpi ~]# cat /proc/version Linux version 3.10.28-1-ARCH (nobody@root-armv6-copy) (gcc version 4.8.2 20131219 (prerelease) ...
6
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1answer
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Error when running ntpd on openVZ host: cap_set_proc() failed to drop root privileges:

CentOS 6.x | OpenVZ I want to run a NTP server on a vps host of mine. Is this possible? When I try to start ntpd, it fails immediately and gives the following error: Mar 14 22:47:44 ev1 ...
6
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1answer
1k views

Why doesn't NTP increase polling interval when using a GPS/PPS receiver and internet servers?

I have a Debian system that is used as an NTP server. It queries several servers on the internet and also has a GPS receiver with PPS output for precision timekeeping. If I don't use the GPS ...
5
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5answers
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How to get system time with microsecond Resolution

I want to know current system time with microsecond Resolution. date +%s returns Time in seconds since epoch(1-1-1970). How can I get time in microseconds Resolution. How much delay is in querying ...
5
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2answers
222 views

NTP tool for showing deviance to a certain server

I am searching for a command-line that allows me to check the system time deviance to a NTP server specified on the command-line. I don't want to change/adapt the system time - only displays the ...
5
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1answer
341 views

Arch Linux RPI: How accurate is the time on the RPi in Linux?

Currently I'm working on a application on my RPi which will be monitoring a set of GPIOs in real-time where the exact time when the GPIO turns HIGH is crucial for my application. And I need to know ...
5
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2answers
1k views

Time synchronization of machines on LAN to GPS NTP server on the LAN

I have 4 computers on a LAN that need to have their system clocks closely synchronized within a ms or so if possible. I have just installed a GPS based time server (ESE-104A) on the LAN. At this ...
4
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2answers
112 views

Failure of ntpdate if the system is set to a date beyond 2038

The correct current date is .Fri Mar 25 12:11:07 CST 2016. When I change the date to "2018/01/01", ntpdate works properly. When I change the date to "2099/01/01", ntpdate does not work properly. ...
4
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2answers
978 views

Use local NTP service

I'm trying to get a system with no outside internet access (A) to get the time from another system on the LAN that does (B). In A's ntp.conf (the whole thing is at bottom), I've added: server ...
4
votes
2answers
94 views

Force time to stay put

The time on my Linux machine will not stay put. I need to test an issue with our server that only occurs on Saturdays. CentOS 6.5 64-bit I have NTPD off. (service ntpd stop and chkconfig ntpd off) ...
4
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1answer
5k views

Why am I getting apparmor error messages in the syslog about NTP and LDAP?

On my newly installed Ubuntu 12.04 machine, with ntp and slapd installed, the following messages appear in /var/log/syslog at regular intervals: Feb 23 18:54:07 my-host kernel: [ 24.610703] ...
4
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2answers
4k views

ntp.conf peer vs server

I'm setting up an NTP server (one of what will be five in a cluster). My config file: restrict default kod nomodify notrap driftfile /var/lib/ntp/drift server tick.usno.navy.mil server ntp.colby.edu ...
4
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1answer
4k views

What are possible reasons for erratic NTP synchronistation?

On a Ubuntu 10.04 system I noticed following strange NTP sync events: Jul 3 02:19:51 hst ntpd[1432]: no servers reachable Jul 3 02:36:55 hst ntpd[1432]: synchronized to 91.189.94.4, stratum 2 Jul ...
4
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2answers
398 views

RTC time synchronization not working (CONFIG_RTC_SYSTOHC)

I have the option CONFIG_RTC_SYSTOHC enabled in my kernel: Device Drivers ---> [*] Real Time Clock ---> [*] Set the RTC time based on NTP synchronization The help says: ...
4
votes
1answer
737 views

Does ntpd default allow query requests through?

I am confused as to what is the default access policy of an ntp server. According to the ntp_acc man page, access can only be denied if specifically blacklisted. Clients can be denied service ...
4
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1answer
420 views

How to run ntp commands as non-root?

NTP commands such as ntpd and ntpdate are privileged and belongs to the root group. What is the best way to run these commands as non-root ? Linux capabilities, ownership, any method ? I have openSUSE ...
4
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2answers
682 views

How long will NTP take to adjust the clock if it doesn't immediately set it?

I'm using SNTP to sync my Debian based system. SNTP has two ways to set the clock: -s, --settod Set (step) the time with settimeofday(). -j, --adjtime Set (slew) the time with adjtime(). The ...
4
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1answer
686 views

Properly configuring symmetric active NTP?

I'm trying to configure two NTP servers to be peers to each other but I have no idea how to tell if it is working or not or whether my NTP configuration is even correct. I've put a simplified view of ...
3
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2answers
99 views

NTP works but clock is not the same

I'm trying to sync multiple machines (9 machines that are cloned from one machine so they have exactly same config) on a LAN using NTP. All machines are running FreeBSD 10.2 on VirtualBox with Ubuntu ...
3
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1answer
108 views

NTP with networks isolated

I have a computer (CentOS) with 2 network cards. I want to use one network card (A) to retrieve time from NTP server (internet). This would then set [this] local computer's time. I then want to ...
3
votes
1answer
916 views

Automatically update hwclock at boot

We're having a small issue with our Beagle Bone Blacks. Since they do not come with a RTC battery, when they lose power, the hardware clock gets messed up. I need a simple and clean way of syncing the ...
3
votes
2answers
926 views

Strip specific option from a response in dhclient

I aim to prohibit dhclient from updating my NTP config with servers received via DHCP, as it is the default on Debian/Ubuntu. However, my DHCP server ignores the list of requested options (from the ...
3
votes
2answers
765 views

ntpd takes 9 hours to sync

I had a situation lately with a host that need up to date ntp servers. We had during the weekend a crash of our internet router. When everything came back to hte normal our application was still ...
3
votes
2answers
122 views

sntp replacement for -P (prompt) argument

I'm maintaining some cronjobs on machines that are set to be patched to the service pack of SLES11sp4, it appears that the service pack is upgrading sntp from version 4.2.4p8 to 4.2.8p2 and somewhere ...
3
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1answer
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Chrony 506 Cannot talk to daemon

I'm having trouble configuring chrony to sync the time between my raspberry pi and a desktop computer in an isolated network. My raspberry pi's chrony.config file looks like this: server master ...
3
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0answers
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Linux Mint system clock is days ahead after an overnight laptop suspend

I'm a long-time Ubuntu user, who recently started trying out Linux Mint on a laptop. This is not a dual-boot setup, Mint is the only OS on the machine. When I suspend the laptop (i.e. close the ...
3
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1answer
302 views

NTP symmetric mode

I'm configuring NTP symmetric modes. Say I have Peer A (192.168.101.1) and Peer B(192.168.101.2) and configure their ntp.conf as follows: # Peer A peer 192.168.101.2 server 127.127.1.0 fudge ...
2
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1answer
1k views

NTP is synced properly but still doesn't update the time?

I wanted to test if ntp was working on my machine, so I set the time back 5 minutes and restarted ntp $ sudo service ntp stop $ sudo date -s "9:40 AM" # This time was 5 minutes ago $ sudo service ntp ...
2
votes
1answer
13k views

Daylight saving option on Linux servers

My CentOS server is not updating showing correct time. I have set $ ln -sf /usr/share/zoneinfo/Europe/London /etc/localtime Still I am on GMT. I do see the following entries in ...
2
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1answer
79 views

Time synchronization, use NTP or just socket?

I am using a PC and a raspberry pi(both run Linux) to gather sensor data, raspberry pi gathers laser scan data, PC gathers image captured by camera. I must synchronize time for these two machines. I ...
2
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2answers
126 views

Time requires to synch. UNIX server with NTP server; after manually chaging te UNIX server's time

I have a GPS server with NTP output. I want to synchronize the clock on the UNIX server using the NTP output of the GPS. After changing the UNIX server time manually, UNIX server takes a long time to ...
2
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1answer
21k views

How to keep Debian internal clock synchronized (with NTP servers)?

I have a home server which runs an up to date Debian 7.5 (wheezy) installation. I just discovered that the server has its internal clock set to ± 3 minutes in the future. I knew that I can use NTP ...
2
votes
2answers
931 views

How do you deal with unreliable NTP peers?

I ran lynis 1.5.6 and got the following log message. Performing test ID TIME-3120 (Check unreliable NTP peers) Test: Checking unreliable ntp peers Result: Found one or more unreliable peers (marked ...
2
votes
2answers
3k views

Setup ntp client with embedded device

I need to run an NTP client on a very limited embedded device. ntpd is available but I do not see anything like rc.conf, or ntp.conf, or xntp.conf? Can someone advise on how to setup NTP? I ran ...
2
votes
2answers
2k views

NTPDate runs three times at boot resulting in incorrect date

I am running Voyage Linux (a Debian-based distribution) and am having trouble getting the correct date. When I look in /var/log/daemon.log I see the following: Nov 18 11:04:07 voyage ntpdate[1676]: ...
2
votes
3answers
99 views

Where to check ntp related logs on Sun Solaris?

Can you please guide, where on solaris i can check NTP related logs? If there is any issue related to NTP on solaris, which is the right place to check for the root cause? Thanks
2
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2answers
243 views

Use default gateway as ntp server

I have a lot of servers running debian and they all must synchronize clock to NTP server running on their respective default gateway. Since there is many servers on many different network segments, I ...
2
votes
1answer
98 views

Which NTP server should I use?

I want to set up the NTP server in my servers that are located in Frankfurt, using UTC as timezone. But I don't know which NTP server should I use. This is the result from the ubuntu ntp server: ...
2
votes
1answer
313 views

NTPd Not Syncing on RaspberryPi

Since my hardware (RasberryPi) does not have a hardware-clock, each bootup warps us back to the 1970's, so I use NTP. The gateway on the network I am on provides an NTP-Server service. my ...
2
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1answer
645 views

Why is ntpd listening on most of 192.168.1.X/192.168.2.X

I'm using the ntp package in debian squeeze and the ntpd process is listening on hundreds of rfc1918 addresses that are not configured on the server. Check this out: Mar 26 10:07:24 server ...
2
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1answer
383 views

NTP synchroinzation waiting for a while after booting

According to the recommendation on Arch Wiki, I set my hardware clock to UTC. And here is the result of timedatectl status on my machine when just booted: Local time: Tue 2013-07-02 15:38:03 ...
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3answers
111 views

NTP synchronization in CentOS 7

I configured an NTP server on a CentOS 7 machine (a virtual one) and also configured the ntp.conf file of the clients (which also are virtual and run CentOS 7). The NTP synchronization works perfectly ...
1
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1answer
560 views

How to know my server's time offset? [duplicate]

I have a few guest machines on VMware. Up until now I was keeping my time sync with ntpd inside guests. Now our VMware admins decided to setup VM hosts to keep time, so VMs don't have to. I disabled ...
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1answer
1k views

How to set tz and date without restart in Debian Squeeze?

I've tried tzselect and all it appears to do is tell me what region I want to pick. I'm trying to change tz without a restart and for all users, then sync the time accordingly.
1
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1answer
42 views

Get the process start time irrespective of NTP updates

I'm trying to record the start time of a process kicked off by an @reboot cronjob. I'm using ps -p $$ -o ltime= presently, but I've run into a catch. My machine (a Raspberry Pi) connects to the ...
1
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1answer
77 views

Script to check ntp status and system time sync

Looking for a script to (1) check status of ntp and (2) if it is within +/- 1 second of a given time server (eg 123.456.789.10). (3) In addition, system time should be checked to see if the timezone ...