Comments on: Keeping your System clock current, automatically via Network Time Protocol (NTP)

By: Shane Bishop

Shane Bishop — Sun, 24 May 2009 04:51:43 +0000

Just because I’ve noticed hits on the url above (which no longer works), here’s the proper one:
http://ntp.shanebishop.net/eluna/
The ‘server’ is now processing over 200 clients, and still uses virtually no resources on a P3 1.0 Ghz with 368MB RAM.

By: Shane Bishop

Shane Bishop — Sun, 09 Nov 2008 14:48:41 +0000

ntp is still the best solution. It takes into account other factors to keep your clock time stable all the time, whereas ntpdate is accurate only at the time you run it. Most of the time, that doesn’t matter, but if you have a system that gets heavily loaded, or has some other odd factors, your time can really get messed up by the time you run ntpdate again. Besides, ntp uses no resources, and is still easier to setup, even if the gui doesn’t work on 8.04:
apt-get install ntp
That’s it, it’s already configured, it gets started automatically when you install it, and it will always be running.
If you want proof on the resources, check out http://jabber.shanebishop.net/eluna/ … The memory graph doesn’t really tell you much, but it’s currently using 300k of RAM, and serving from 30-100 ntp clients at any given time.

By: Richard

Richard — Fri, 23 May 2008 10:50:07 +0000

COMMENT: On Ubuntu 8.04 the graphical configuration of ntp does not work! Also, ntp is a bit of overkill for what most users need, since it runs continuously in the background, keeping the clock in sync with millisecond accuracy. Hence, remove ntp, in favour of ntpdate, and set things up following the comment of “January 8th, 2007 at 2:50 am” above.

NOTE: Ubuntu 8.04 seems to have problems with cron, so things may still not work as expected.

By: jj

jj — Thu, 13 Mar 2008 01:35:00 +0000

You can do the above graphically by:
#1 Selecting System>Administration>Time&Date OR Rt clicking the Time & Date in the Upper Rt corner of the screen OR at the CLI enter “time-admin”
#2 enter your password
#3 In the resulting configuration drop-down box select “Keep Synchronized w/Internet Servers” in lieu of “Manual”
#4 Press the install button to install the alternate /etc/ntp.conf download package.
#5 Confirm your NTP server by double-clicking the “Select Server” button. On Feisty the Ubuntu server is set by default and should be enough for the desktop.

By: Name

Name — Mon, 08 Jan 2007 02:50:59 +0000

“Setting and maintaining the time
The ntpdate utility can be used to set time to the current time using a clock server. The one I use is clock.psu.edu as follows:
# ntpdate -u clock.psu.edu

Theoretically, you should be able to run the ntpd daemon to connect to a server and keep your machine clock correctly synchronized at all times. However, I’ve never been quite successful in finding a server willing to support this.
Using cron to maintain correct time
The cron daemon runs services hourly, daily, weekly and monthly. These services are executable script files maintained in these directories:
/etc/cron.hourly
/etc/cron.daily
/etc/cron.weekly
/etc/cron.monthly

Here is the file I use: /etc/cron.weekly/setclock.cron
#!/bin/bash

clock=clock.psu.edu

/usr/sbin/ntpdate -u $clock >& /dev/null

The reason for the >& /dev/null redirection is that you want to make sure that cron scripts send nothing to standard output or standard error. If you want to use this script, make sure it is executable:
# chmod +x /etc/cron.weekly/setclock.cron”

By: Name

Name — Mon, 08 Jan 2007 02:45:15 +0000

Isn’t this a better way of doing it:

http://www.cs.wcupa.edu/~rkline/Linux/odds-ends.html