How do I synchronise my single Debian Linux desktop clock to network?

by on October 22, 2005 · 4 comments· LAST UPDATED October 9, 2007

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You will find lots of tutorials about how to setup NTP server. However if you just wanna synchronize single Linux desktop connected via A/DSL Internet connection use ntpdate command. It is very easy to configure and install ntp client. Following instructions are only compatible with Debian / Ubuntu Linux.

ntpdate client

ntpdate sets the local date and time by polling the Network Time Protocol (NTP) server(s) given as the server arguments to determine the correct time. It must be run as root on the local host. A number of samples are obtained from each of the servers specified and a subset of the NTP clock filter and selection algorithms are applied to select the best of these. Note that the accuracy and reliability of ntpdate depends on the number of servers, the number of polls each time it is run and the interval between runs.

Install ntpdate utility

ntpdate command sets the local date and time by polling the Network Time Protocol (NTP) server(s).

# apt-get install ntpdate

You are done by default /etc/default/ntpdate file is use to point pool.ntp.org server .

Allow access to NTP client via Iptables firewall

NTP client uses the udp port 123 to communicate with NTP server. Following rule opens/allows NTP client outgoing request:

# NTP outgoing client request
iptables -A output -p udp -s 192.168.1.1 --sport 1024:65535 -d 0/0  --dport 123 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A input -p udp -s 0/0 --sport 123 -d 192.168.1.1  --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT

Add above rules to your existing iptables script. Please note if you have more than 2-3 computers, then it is better idea to setup your own NTP server. I will write on ntpserver configuration later on.

For more information visit public ntp time server for everyone NTP pool website and read ntpdate man page.

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{ 4 comments… read them below or add one }

1 Anonymous October 25, 2005 at 5:03 pm

hehe thanks a lot for NTP iptables rule was looking at google

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2 Baskar January 25, 2007 at 6:31 pm

Hi,
you told that how to configure own ntp server.
i want to configure my local host into ntp server
for that what i have to do and how to sync with this server from client
please send step by step configuration
reply to my mail id namazhwar.baskar@idearc.com
its urgent
Thanks in advance

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3 Jaison Lucas September 2, 2008 at 10:05 am

I want to sync my debain system time using NTP with my Windows 2003 server. Both are in same IP range and can be pinged.
Please help me with the ntp.conf file.

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4 woolie January 10, 2013 at 3:30 pm

here’s a one-liner with “ntpclient” (if you can find it in your repos – it works on Slackware based Tiny core Linux):

$ sudo ntpclient -s -c 1 -h ca.pool.ntp.org

this will do a one-time synchronization.
be sure to pick your CORRECT regional pool of time servers from:
http://www.pool.ntp.org/zone

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