NTP CONFIG

[Nobody's Hero]

I am fairly familiar with NTP so I dont need a bunch of particulars. Here is what I am trying to achieve. Here at HQ I buillt and NTP server, no drift file or authentication or anything like that. I punched a hole through the firewall to get to th e USNO and a few other sources. All other systems on our network look at my server. Here is my server command from ntp.conf:

server ntp2.usno.navy.mil version 3 prefer
peer ntp2.usno.navy.mil version 3 prefer

The ntp process works great.
However the small pipes at our facilities are getting hammered by ntp, I believe.

How can I tell my server to only poll at a certain interval, or do I have to do it on the ntp client side?

Can I use a minpoll entry on the server line?

Like : server ntp2.usno.navy.mil minpoll 1024

[Pete Randall]

Robert,

I'm sure there's a more elegant NTP way to do this, but I simply sync my other machines once a day via a cron script:

LIST=`cat /etc/hosts |grep "#unixhost" |awk -F# '{ print $3 }'`
for SERVER in $LIST
do
remsh $SERVER /usr/sbin/ntpdate -b yukon
done


Pete

[Paul Eadington_1 · Accepted solution]

You could utilise the minpoll facility on both the clients and the server to reduce the polling time down from the default (64 seconds)

Be aware though that it's calculated as a power of 2 so your 1024 would be 2*1024=more years than you are likely to ever see :)

To get 1024 seconds the minfree value would be 10.

Hope this helps.

[Jeff Schussele]

Hi Robert,

I would doubt that the excessive traffic you're seeing is NTP packets. Have your network people provide packet stats from the last hop router before the NTP server. You'll be looking for port 123/udp traffic.
We have thousands of clients served by just two servers & have never had a problem.
If for some reason you do see loads of 123/udp traffic then I'd suspect a misconfigured client(s) or a runaway client daemon. See if you can track down the source MAC of the traffic.
You can always check the syslog.log on the clients to see how frequently they're requesting NTP updates as well.

Rgds,
Jeff

[Paul Eadington_1]

Erm please substitute minpoll for that minfree that snuck in there !!

Thanks :)

[Nobody's Hero]

Thanks, but I dont like to use ntp date due to the fact that it takes such a big jump sometimes. I've had problems with oracle in the past if my clocks drifted far apart and had to jump forward.


Looking to do it in a way I described.

[Bharat Katkar]

Hi,
Never worked on NTP but see if the following thread provides u any inputs.

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=550229

Please don't mind if it doesn't help. :)
Regards,