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Questions tagged [ntpd]

The Network Time Protocol daemon (NTPd) is a daemon program that synchronizes the system time with time servers using the Network Time Protocol (NTP).

The Network Time Protocol daemon () is a daemon that synchronizes the system time with time servers using the Network Time Protocol ().

Website: http://www.ntp.org

Man page: http://linux.die.net/man/8/ntpd

Wikipedia: http://en.wikipedia.org/wiki/Ntpd

243 questions
42
votes
4 answers

Do I need to run ntpd in my EC2 instance?

I'm working on getting some servers running in the EC2 environment and I'm noticing some errors with ntpd trying to sync (using CentOS). I was reading on this site and the impression I get is that I don't need to run ntpd since EC2 is Xen and the…
ahanson
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34
votes
4 answers

How can I compare an ntp server's time to my server's time?

I have ntpd running on a box. I want to see how the time on the box compares to the time retrieved from ntp.ubuntu.com. Is there an easy way to do this?
John Bachir
  • 2,394
31
votes
4 answers

How to prevent ntpd to listen on 0.0.0.0:123?

ntpd listens on numerous interfaces by default, I only want it to listen on 127.0.0.1:123 since I only want the localhost to sync the time. How to do that, I tried by editing /etc/default/ntp on Debian Wheezy: NTPD_OPTS='-4 -I 127.0.0.1' But it…
JohnnyFromBF
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28
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3 answers

How far is "too far off" for ntpd? Can it get there by a sudden jump to heavy load? Can this be overridden?

In many primers on ntpd, like this one, there's always a warning that ntpd will stop resetting the clock "[if] your clock is too far off." How far off is "too far off"? Also, if a server takes a sudden jump to heavy load, for example from total…
user144330
27
votes
4 answers

What is NTP dispersion and how do I control it?

We roll out Ubuntu 14.04 servers on isolated networks, running ntpd 4.2.6p5, configured to use multiple NTP servers as provided by customers (no access to pool.ntp.org). Our dumb terminal client devices run an old version of BusyBox (1.00-rc2) and…
Jeff
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25
votes
9 answers

Why is ntpd not updating the time on my server?

I have ntpd running on my server. It's all the default settings, except I commented out its ability to be a server to other machines: # restrict -4 default kod notrap nomodify nopeer noquery …
John Bachir
  • 2,394
24
votes
10 answers

Compare NTPD and ntpdate

What are the pros and cons between these two ways to synchronize your server? It seems to me that your server would probably not drift more than 1 second every day, so ntpdate on a crontab would be ok. But I heard you could use redundant NTP servers…
Unknown
  • 1,765
22
votes
6 answers

Things to consider when running public NTP servers

So, it recently dawned on me that since I have 3 GPS clocks in my network, I could, technically, give back a little and serve time to the rest of the world. So far I've not quite seen any downsides with this ideas, but I have the following…
Stuggi
  • 3,656
22
votes
3 answers

Where can I look up for the ntpd log?

I didn't find any ntpd log file in /var/log. I am wondering where can I find those log files, thanks!
David Liu
  • 323
19
votes
2 answers

Why does ntpd listen on so many ports/addresses?

I’ve noticed this for a while, and it’s never made any sense to me: Why does ntpd need to listen on so many addresses? For example, a Debian machine: $ netstat Proto Local Address Foreign Address Program name udp 0.0.0.0:123 0.0.0.0:* …
Abraham Vegh
  • 1,055
18
votes
3 answers

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 http://www.pool.ntp.org/join.html for # more information. pool…
user3141592
  • 283
14
votes
2 answers

ntpdate and ntpd failing to sync clock on Linux

I have a strange problem with one of my servers. ntpd and ntpdate fail to work, but debugging shows no errors at all. At first I thought maybe a local or network firewall was blocking UDP port 123, but that is not the case- this server can talk…
Crash Override
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14
votes
2 answers

Does NTP daemon set the host timezone?

If I am using NTP daemon or ntpdate command, do I need to worry about changing the timezone? Should I re-configure the timezone using cron job to guarantee the accuracy of the server time? I am using ubuntu server.
Khaled
  • 37,789
12
votes
1 answer

NTP Service Auto-Discovery

Are there any methods I could use to provide auto-discovery for NTP? I recently moved to a new job that has a parent company that recently started providing Active Directory. I've been implementing SSSD & other stuff authenticating against AD and…
Keith Shannon
  • 132
12
votes
7 answers

Local or public NTP servers?

For a relatively large network (thousands of hosts) - what are the arguments for and against running a locally managed (pool of) NTP server(s) (perhaps periodically set via some public NTP server) and having all other hosts on the network use that…
BeeOnRope
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