Ntpd assistance

[James Hong]

 i had a machine where internal clock runs 1.5 times faster than normal
clock.
as a result time will be about 5min faster every 30min or so.
if internal clock is busted like mine, ntpd will not be able to sync time.
It takes as long as few days to sync few min on your unix clock.

Also if i remember correctly unix keeps internal clock and system clock
separatly.

read 
http://www.eecis.udel.edu/~mills/ntp/html/ntpd.html


PS. use closer tier 2 or tier 3  and multiple sources (as long as they are
public)


-----Original Message-----
From: owner-freebsd-questions at freebsd.org
[mailto:owner-freebsd-questions at freebsd.org] On Behalf Of Rob
Sent: Thursday, September 23, 2004 2:37 PM
To: freebsd-questions at freebsd.org
Subject: Re: Ntpd assistance

alden.pierre wrote:
> /etc/rc.conf contains the following:
> 
> ntpdate_enable="YES"
> ntpdate_flags="timex.cs.columbia.edu"
> xntpd_enable="YES"        # Run ntpd Network Time Protocol
> 
> /etc/ntpd.conf contains the following:
> 
> driftfile    /etc/ntp/drift
> server 65.211.109.1
> server 65.211.109.11
> server 209.51.161.238
> server 128.59.59.177

Use /etc/ntp.conf (NOT ntpd.conf).

I would configure this system as follows:

/etc/rc.conf:

ntpdate_enable="YES"
ntpdate_flags="-b 65.211.109.1 65.211.109.11 209.51.161.238 128.59.59.177"
xntpd_enable="YES"


/etc/ntp.conf:

#--------------------------
# prohibit general access to this service
#--------------------------
restrict default ignore

#--------------------------
# localhost has full access to the server
#--------------------------
restrict 127.0.0.1

#--------------------------
# servers to query
#--------------------------
server 65.211.109.1
restrict 65.211.109.1

server 65.211.109.11
restrict 65.211.109.11

server 209.51.161.238
restrict 209.51.161.238

server 128.59.59.177
restrict 128.59.59.177

#--------------------------
# files to use
#--------------------------
driftfile /var/db/ntp.drift


-------------------------------------------------

The idea is, that, at boot up, you force instant time synchronization with
ntpdate, using the list of servers in ntpdate_flags="-b ....".
(check the man page of ntpdate and the -b flag).
Then you allow ntpd to start (xntpd_enable = "YES"), that will keep the time
in sync with the servers in /etc/ntp.conf.
As a regular user, verify nptd's sync behaviour with:

    ntpq -np

I hope that helps.
Rob.


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