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04-07-2004, 04:31 PM #1Disabled
- Join Date
- Oct 2003
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- Portugal
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- 77
HOW-TO: use NTP to keep your system clock accurate to one thousandth of a second
There is a wonderful net standard called NTP that can synchronize system clocks. You may already have followed someone's advice and used 'ntpdate' or 'rdate' to set the time on your server. But NTP is really designed to keep a large network of clocks perfectly synchronized. Not just accurate to the second, but to the millisecond! Here's how to set it up.
First, make sure you have some kind of firewall running. This is generic information really, not specific to NTP, but you should always run a firewall if you have a publically available server. In this case, it may protect you from yet-undiscovered flaws in your NTP client.
Now to properly use NTP, you need to have the full set of NTP tools. You may already have them installed; you can check by running the following as root:
rpm -q ntp
If it says it is not installed, then you need to download and install the appropriate RPMs. Head over to http://www.rpmfind.net/linux/rpm2htm....php?query=ntp and find the right package for your operating system. Download the RPM, and install it as root:
rpm -ivh ntp-*.rpm
Now, you have to configure it. I've done all the hard work and found some reliable servers with open access policies ... all you have to do is copy my files!
You need to edit your /etc/ntp.conf file and REPLACE the contents with the following:
PHP Code:restrict default nomodify notrap noquery
restrict 127.0.0.1
server now.okstate.edu
server clock.nyc.he.net
server clock.via.net
server ntp-2.vt.edu
server 127.127.1.0 # local clock
fudge 127.127.1.0 stratum 10
driftfile /etc/ntp/drift
PHP Code:now.okstate.edu
clock.nyc.he.net
clock.via.net
ntp-2.vt.edu
Now run the following:
chkconfig --level 345 ntpd on
service ntpd restart
And you're all done! The ntpd program is running in the background, accurately keeping time down to the millisecond, with absolutely no drift. Your clock will always be accurate!
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06-28-2004, 10:29 PM #2WHT Addict
- Join Date
- May 2004
- Posts
- 119
not good enough. I want mine close to one millionth of a second!
only joking but couldnt resist saying it!
thanks for this thread, i know about the time feature, but wanted to learn more info on it.
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07-10-2004, 03:27 PM #3Newbie
- Join Date
- Jul 2004
- Location
- Italy
- Posts
- 6
implemented except for...
chkconfig --level 345 ntpd on
service ntpd restart
commands not found....
suppose it will start on next system startup the same as already preconfigured as remmed...
thanks for the info
c.klemp
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07-13-2004, 07:36 AM #4Junior Guru Wannabe
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- May 2004
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- 66
if i may ask
what is the purpose of letting your time accurate . what would i loose if its not ???
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07-13-2004, 09:40 AM #5Registered User
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- Jan 2001
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- Vienna, Austria
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dead will rise from their graves and sun will disapper for the next 23 years.
Nothing, you will just have non accurate system clock
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08-28-2004, 03:51 PM #6Temporarily Suspended
- Join Date
- Aug 2004
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- 49
Thanks Doggy forthis information, I have used it on my server because I use a lot of cron jobs and want to keep the time acurate.
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04-08-2005, 05:40 AM #7Junior Guru Wannabe
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- Jun 2003
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- Portugal
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- 31
Just a quick notice, you can use pool.ntp.org to fetch random servers instead of pointing to single hosts. Check ntp.org for more informations. I have it working on my network and it works like a charm
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04-21-2005, 03:51 PM #8Junior Guru Wannabe
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- Mar 2005
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- Cardiff, Wales, UK
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- 46
Originally posted by naguib2000
if i may ask
what is the purpose of letting your time accurate . what would i loose if its not ???Jonathan Wright (Technical Director, JAB Web Solutions Limited).
UK Hosting and Reseller Hosting from JAB Web Solutions
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04-29-2005, 11:28 AM #9Web Hosting Guru
- Join Date
- Oct 2004
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- 305
Originally posted by VisiGod
Just a quick notice, you can use pool.ntp.org to fetch random servers instead of pointing to single hosts. Check ntp.org for more informations. I have it working on my network and it works like a charm
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05-21-2005, 04:52 PM #10Web Hosting Evangelist
- Join Date
- Feb 2001
- Location
- UK
- Posts
- 461
Centos?
I looked at the download options for the tools but I couldnt see an option for centos, can it be done for this os?