[LON-CAPA-users] ntp

Scott Harrison lon-capa-users@mail.lon-capa.org
Sun, 24 Feb 2002 21:56:11 -0500

Dear Lars:

> I guess ntp.msu.edu doesn't accept requests
> from us.

I have been using ntp.msu.edu from remote locations without problem.

> To fix this I replaced in /etc/ntp.conf the line ntp.msu.edu
The line in ntp.conf should read (CVS:loncom/ntp.conf):
server  ntp.msu.edu

The line in /etc/step-tickers should read (CVS:loncom/ntp/step-tickers):

> with several lines of time servers that work for us. My question is
> whether this will fix the problem?

To test whether a time server works for you, do this command:

/usr/sbin/ntpdate -b ntp.msu.edu

and see if anything happens.

> I noticed a file
> /etc/ntp/step-tickers. What is this file for? It contains the single
> line ntp.msu.edu. Should I make the same replacement in this file? Finally,

step-tickers causes time to reset itself immediately (without any
considerations of "skew") whenever you type the command
/etc/rc.d/init.d/xntpd restart

If you are using a time server other than ntp.msu.edu, then yes,
replace this.

> will ntp reset time again considering that it was off with that much,
> or should I use rdate to reset time manually the first time?

/etc/rc.d/init.d/xntpd restart should be adequate when manually
kicking the computer in the ....

Additional thoughts...
Ideally, individual institutions rely on their own time servers.

If there really is a skew-bug with xntpd, a forcible
solution might be to have a perfect correction every hour.
For instance, the following might be a crontab entry:
0 * * * * /usr/sbin/ntpdate -s -b -p 8 ntp.msu.edu

For more on ntp, http://www.eecis.udel.edu/~ntp/ is the home site.

My initial diagnosis of the problem that was encountered is that
/etc/ntp.conf was incorrectly formatted so that the xntpd slew
correction algorithm could not do its job.

Perhaps off-list we can get to the bottom of this if there is
something more complicated happening.


> Lars.
> --
> Lars Jensen, TMCC/Vista B200, 7000 Dandini Blvd, Reno NV 89512-3999.
> Internet: <jensen@physics.unr.edu>, http://www.scsr.nevada.edu/~jensen
> Tel: 775.673.7113  FAX: 775.674.7592
> _______________________________________________
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Scott Harrison -- Graduate Student
Microbiology and Molecular Genetics
Mich. State. Univ., East Lansing, MI
harris41@msu.edu, 517-353-0998