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 ...
7
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1answer
4k 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, ...
6
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1answer
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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) ...
5
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2answers
183 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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2answers
668 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 ...
5
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1answer
756 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 ...
4
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1answer
3k 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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1answer
210 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 ...
4
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3answers
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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 ...
4
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1answer
2k 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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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 ...
4
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1answer
63 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
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2answers
82 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
373 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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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 ...
3
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2answers
164 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 ...
3
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1answer
73 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
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2answers
355 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
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1answer
44 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 ...
3
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1answer
373 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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1answer
202 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
559 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
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2answers
76 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
7k 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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2answers
302 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
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2answers
2k 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
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2answers
1k 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
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2answers
142 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 ...
2
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2answers
507 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 ...
2
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1answer
51 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 ...
2
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1answer
369 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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0answers
205 views

ntp not syncing

Since my hardware (Rasberry Pi) does not have a hardware-clock, each bootup warps us back to the 1970's, so I use NTP. The gateway in the wifi I am in provides an NTP-Server-service. my /etc/ntp.conf ...
2
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1answer
241 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 ...
1
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1answer
114 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
908 views

Finding log file of ntp daemon in Ubuntu 10.04 LTS

My Ubuntu is set to run ntp before dovecot at startup. (See my earlier question: The rc0.d,rc1.d,... directories in /etc in Ubuntu 10.04 LTS) However, I suspect that dovecot may have finished ...
1
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2answers
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ntpd installed to local directory, now have two versions

I got the latest version of ntpd because the binary releases have vulnerabilities. Unfortunately, after I built it and ran make install, it was installed to /usr/local/sbin, but the system is running ...
1
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1answer
721 views

last reboot/uptime/… strange behaviour

I know this has been more or less asked before but I still don't have any answer. I started to investigate why on my system (it is a remote machine) who -b and uptime gave different results (~3 days ...
1
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1answer
1k 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 ntp service on-demand? I tried sudo update-rc.d -f ntp remove/default and ...
1
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1answer
3k views

NTP not syncing in a VM

I'm managing some VirtualBox developer environments. The time drifts out of sync when the box is suspended, so I want to use NTP to keep it in sync. NTP doesn't seem to be doing its job, though - the ...
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30 views

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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0answers
33 views

NTP authentication failing with opcode 108

I'm trying to get NTP authentication working on a cluster of test servers and a couple clients. I've followed the instructions at ntp.org. To be honest, though, I'm not sure they are entirely clear ...
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0answers
113 views

NTP compilation failed - without ssl

I am trying to cross compile NTP ver 4.2.8 without SSL support. I gave --without-crypto while configuring, but still it was throwing following error: ../libntp/libntp.a(ntp_crypto_rnd.o): In function ...
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709 views

NTP Problems - sntp: too many bad or lost packets

I need some help from you guys regarding NTP on Suse. I have a server, whose IP is 192.168.100.52, which is based on Suse Linux and here is my NTP conf file: server 192.168.100.11 iburst restrict ...
0
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3answers
1k views

How to send ntp request?

I would like to get local time of server. Is there command/way to get time of server. Operating system is solaris
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1answer
4k 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 ...
0
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1answer
19 views

Do I need nomodify set on NTP servers which are not publicly accessible?

I am configuring five new RHEL6 NTP servers. Each uses a list of five USNO servers as their source with at least one unique server one each one. Each of the five servers also peers to the others. None ...
0
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1answer
254 views

How can I make a Puppet module that fixes time? [duplicate]

I have written a Puppet module that corrects the time via NTP, but this only works on server with a small NTP offset. There are sometimes server with a time offset higher than 10 minutes for various ...
0
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1answer
304 views

Allowing a domain name in my IP Tables

I have a Linux server that gets a time offset for some strange reason. I set up cron job to run and update the time using the following command: /usr/sbin/ntpdate pool.ntp.org The problem is the ...
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NTP setup on a Java application Linux server

In a farm of time sensitive Java application Linux servers, how should one configure NTP in the ntp.conf file? Would it be okay to point the server to four stratum 3 NTP servers (switches) that are ...