/etc/ntp.conf

# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.

restrict time.stdtime.gov.tw
restrict tock.stdtime.gov.tw
restrict tick.stdtime.gov.tw
restrict clock.stdtime.gov.tw
restrict watch.stdtime.gov.tw 
restrict 127.0.0.1 
restrict -6 ::1
restrict 192.168.9.0 mask 255.255.255.0 nomodify
restrict 10.144.82.0 mask 255.255.255.0 nomodify
restrict 192.168.100.0 mask 255.255.255.0 nomodify

# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server tick.stdtime.gov.tw prefer
server tock.stdtime.gov.tw prefer
server time.stdtime.gov.tw prefer
server clock.stdtime.gov.tw
server watch.stdtime.gov.tw

#broadcast 192.168.1.255 key 42  # broadcast server
#broadcastclient   # broadcast client
#broadcast 224.0.1.1 key 42  # multicast server
#multicastclient 224.0.1.1  # multicast client
#manycastserver 239.255.254.254  # manycast server
#manycastclient 239.255.254.254 key 42 # manycast client

# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available. 
server 127.127.1.0 # local clock
fudge 127.127.1.0 stratum 10 

# Drift file.  Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()'ing
# it to the file.
driftfile /var/lib/ntp/drift

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography. 
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8

啟動 ntp 伺服器
#service ntpd start

設定開機自動啟動
#chkconfig ntpd on

等候數分鐘後檢查是否有連上伺服器
#ntpstat

列出 NTP 和上層 NTP 的狀態
#ntpq -p

Client 端設定
#vi /etc/ntp.conf
restrict 192.168.*.*(server 端 ip)
server 192.168.*.*

設定開機自動啟動
#chkconfig ntpd on

OR

設定 crontab 方式
#vi /etc/crontab
0 * * * * root ntpdate time.stdtime.gov.tw
每小時0分對時一次