Install Procedure for ntp-server¶

Requirements¶

To install ntpd you will need the following:

• a installed and supported operating system (e.g. CentOS 6.x)
• root-access
• a fast internet connection

Preliminary Note¶

This procedure is based on a documentation supplied by

• http://www.cyberciti.biz/faq/rhel-fedora-centos-configure-ntp-client-server/
• http://http://www.gtkdb.de/index_7_576.html
• http://linuxwave.blogspot.com/2007/08/setting-up-your-own-ntp-server.html

Install¶

Install ntp:

yum install ntp

Configure ntp Server¶

vim /etc/ntp.conf

Use external ntp-Server as reference
Basically the ntp.conf is ready configured, so there is nothing to change¶

If there is need to use additional or different ntp-server then add it to the server section

Use internal clock as reference¶

This is only necessary if there is no reliable time-source or ntp-server available at all

server 127.127.1.0     # local clock
fudge  127.127.1.0 stratum 4          # set stratum to any value from 0 to 16, the higher the safer, defaults to 10, 4 is working with WinXP and Win7

Start ntp Server¶

manually start ntp Server:

/etc/init.d/ntpd start

automatically start the service at boot time:

/sbin/service ntpd on

you can check the runlevels by

/sbin/chkconfig --list ntpd

you should get an output like:

ntpd     0:off   1:off   2:off   3:on   4:off   5:on   6:off

configure firewall¶

Open NTP Port (123) on Iptables Firewall

system-config-firewall-tui

add port 123:udp

check if settings are ok

cat /etc/sysconfig/iptables

You should have following line before COMMIT:

-A RH-Firewall-1-INPUT -m state --state NEW -p udp --dport 123 -j ACCEPT

Restart Iptables Firewall:

/etc/init.d/iptables restart

Usage¶

try to connect via windows machine and enter as a internet-time-source the ip-adress of the new ntp-server. (e.g. 192.168.2.53)

try to connect via linux machine and use to sync time:

ntpdate 192.168.2.53