[ntp:questions] Re: NTP for dummies

Richard B. Gilbert rgilbert88 at comcast.net
Thu Oct 6 18:55:35 UTC 2005

john h wrote:

>Hooray for your email. I have precisely the same problems. I don't want to
>build a watch, I just want to know what time it is. I have a GPS time source
>and want it to synchronize my bag of 15 computers consisting of several
>flavors of RedHat Linux, win 98, win NT 4, win2000 winxp.
>I got win xp working all I had to do was give it the ip address of my
>timesource. but Linux!!! i still don't understand. I can get ntp started but
>it refuses to sync and  I never see my systems time match that of my stratum
>1 timeserver
>Thanks to your respondants I have renewed hope that my head will recover.
>"Cam" <camfarnell at cogeco.ca> wrote in message
>news:433CC6BF.80905 at cogeco.ca...
When I installed Red Hat, it asked me what NTP servers to use and built 
a configuration file for me.

The file is called ntp.conf and lives in /etc.

The system startup configures the firewall to allow NTP and a clean 
shutdown, I believe, closes the firewall against NTP again.  Linux is 
not for the faint hearted.   If you think the NTP documentation is bad, 
you haven't really looked at Linux documentation (or any Unix 
documentation for that matter).   It's by geeks for geeks and no holds 
barred.  In principle, you're supposed to be able to read the source 
code to figure out how it works and to be able to modify it if you don't 
like the way it works!!!!

A bare bones ntp.conf looks like this:

# Define a drift file.  ntpd uses this to save the current value of the 
frequency correction to the clock
# oscillator.  The file is read at startup and the value is used as an 
initial estimate which is subsequently
# refined by ntpd.
driftfile /var/ntp/ntp.drift
# Define some servers
server <ip address of server 1> iburst
server <ip address of server 2> iburst
server <ip address of server 3> iburst
server <ip address of server 4> iburst

Best practice is to use four or more servers.  One works but if 
something happens to it or to your network connection to it, you're 
toast!   Two servers are practically guaranteed to cause problems.  
Don't do it!   Three work but if anything happens to one. . . .

You can add all sorts of fancies to the above if you take the trouble to 
read and understand the HTML documentation in the html subdirectory.  
The above should work.  If not, you have a Linux problem rather than an 
NTP problem.

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