Using ntp with Red Hat Linux/Fedora Core
Here are the steps to configure Network Time Protocol (ntp) with Red
Hat
Linux/Fedora Core.
1. Select time servers. I recommend using three ntp servers from pool.ntp.org; you may specify your
country code when selecting servers from the ntp pool for the most accurate
results. Please see http://www.pool.ntp.org/
for more information.
2. Edit /etc/ntp.conf and add the time servers in the "OUR
TIMESERVERS"
section. In this example, I am using the three timeservers 0.us.pool.ntp.org, 1.us.pool.ntp.org, and 2.us.pool.ntp.org.
vi /etc/ntp.conf
/OUR TIMESERVERS
Add:
restrict 0.us.pool.ntp.org mask 255.255.255.255 nomodify notrap
noquery
restrict 1.us.pool.ntp.org mask 255.255.255.255
nomodify notrap noquery
restrict 2.us.pool.ntp.org mask 255.255.255.255
nomodify notrap noquery
server 0.us.pool.ntp.org
server 1.us.pool.ntp.org
server 2.us.pool.ntp.org
3. Before starting the ntpd daemon, run ntpdate to
synchronize your clock with a time server. ntpd will not
synchronize your clock
with a time server if your system clock is significantly off NTP time.
ntpdate -u 0.us.pool.ntp.org
As an alternative, you can add your time servers to /etc/ntp/step-tickers.
You do not need to manually run ntpdate to synchronize your
clock as ntpd
will query these time servers if your clock is significantly off
NTP
time.
4. Configure ntpd to start with the next system boot.
/sbin/chkconfig ntpd on
5. Start the ntpd daemon immediately.
/sbin/service ntpd start
The graphical user interface utility redhat-config-date (Red
Hat Linux) or system-config-date
(Fedora Core) may
also be
used to administer NTP.
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Last modified: 07/18/2005