Comments on: Network Time Protocol (NTP) Server and Clients Setup in Ubuntu

By: Josir

Josir — Fri, 10 Sep 2010 15:13:46 +0000

When ntp client service is installed, how often does it goes to ntp server to synchronize time ?

By: harry

harry — Thu, 18 Jun 2009 06:43:05 +0000

What do i do if i want to change default client port (123) to some other port dynamically.

i.e. whenever i need to send a request, i need to send it through some dynamically set port.

By: AlexKleider

AlexKleider — Mon, 27 Apr 2009 06:37:55 +0000

I found this part confusing:
“”"
Configuring NTP client

You need to edit the /etc/ntp.conf file you need to point the following settings to NTP server ip address

sudo nano /etc/ntp.conf

Server configuration settings

server 192.168.1.1

Restrict the type of access you allow these servers. In this example the servers are not allowed to modify the run-time configuration or query your Linux NTP server.

restrict default notrust nomodify nopeer

Localhost configuration

restrict 192.168.1.1

In this case the mask statement has been expanded to include all 255 possible IP addresses on the local network.

“”"
It’s not clear to me just what is to be placed in the client configuration file.
I would expect something like:

server 192.168.1.1
restrict 192.168.1.1

.. but it’s not clear exactly what.
‘nomodify’ seems wrong since you do want the server to modify the clients time, do you not?

By: Dummy00001

Dummy00001 — Fri, 22 Aug 2008 14:10:56 +0000

I would recommend OpenNTPd.

Much less fuss to configure and works in real-world much better than the legacy “ntpd”.

I have used “ntpd” for many years and it is P.I.T.A. to use and require constant baby-sitting. openntpd on other hand has sensible default setup and just works.

By: Kubuntu User

Kubuntu User — Wed, 06 Aug 2008 18:16:15 +0000

Is this an alternative (CLI based) to using the build in way ?

In Kubuntu 8.04 I only have to go to

K-Menu -> System Settings -> Date & Time
Press the Administrator Mode… button
Activate Set date and time automatically
Alt. Choose a pool OR manually enter a name/IP of an internal NTP server
Click Apply

I have been using since Kubuntu 6.06, and find it pretty simple to all the CLI work.

By: admin

admin — Wed, 06 Aug 2008 15:57:10 +0000

@ryan

You want to change NTP server default port number

By: Ryan Harrington

Ryan Harrington — Wed, 06 Aug 2008 15:19:37 +0000

I come to your blog on a regular basis, your articles are usually better explained. You should add more info to your post on how to change ports and configure the server.

By: admin

admin — Tue, 05 Aug 2008 10:26:08 +0000

@thomas

I have updated the ntp check command in the main article

By: Thomas

Thomas — Tue, 05 Aug 2008 07:54:16 +0000

“”"If your ISP runs a time server for you it is worth including it in your server list as it will often be more accurate than the pooled servers and will help keep the load down on the pool.”"”

No likely to be more accurate, but it is likely to have lower RTT and therefore lower jitter.

“”"sudo ntpq -p”"”

“sudo ntpq -np” is usually just as good if not better. It avoids reverse DNS lookups which sometimes don’t exist and usually don’t match the forward lookup anyway.

“”"You’ll have to allow UDP traffic on source/destination port 123 between your server and the Stratum 1/2 server with which you are synchronizing.”"”

If you’re going through a firewall you don’t need anything better than stratum 2 or 3 servers. The latency of the firewall is going to negate whatever increased accuracy you might expect from a stratum 1, so you’ll just be loading it up for no good reason.

Check out https://help.ubuntu.com/community/UbuntuTime

By: h9290

h9290 — Tue, 05 Aug 2008 06:34:31 +0000

can’t all this be done in Ubuntu by simply clicking the time,edit and then time setting and changing it there through the configuration ?