NTP

Port number: UDP 123

date

• # date --> check current system time.
• Thu Sep  2 05:08:43 NZST 2010

• # date MMDDhhmmYYYY  --> define the time manually.

• # date -u --> check time with timezone UTC
• Wed Sep  1 17:09:12 UTC 2010

hwclock

• # hwclock
•  --> check bios time.
• # hwclock -w
•  --> write the system time into bios.

ntpdate

• # ntpdate  time.nist.gov
• --> sync system time with outside time server of time.nist.gov.
• (service NTP should be shutdown before the command using)

NTP client define NTP server where sync. time from.

• # vim /etc/ntp/ntpservers
• # clock.redhat.com
• # clock2.redhat.com
• # 10.11.0.160

NTP server bring up

• # vim /etc/ntp.conf
• --> configuration file
• # service ntpd start
• # chkconfig ntpd on

Timezone change (e.g. NewZealand)

• # cp /usr/share/zoneinfo/Etc/GMT+12 /etc/localtime

or

• # cp /usr/share/zoneinfo/ZN /etc/localtime

or

• # vi /etc/sysconfig/clock

Time server in Taiwan

• tock.stdtime.gov.tw ( 211.22.103.157 )
• tick.stdtime.gov.tw ( 118.163.81.62 )
• time.stdtime.gov.tw ( 118.163.81.61 )

On your Time server, review time sync. status with Time server ( stratum 1 )

• # ntpq -p

Make sure the NTP port 123 not be block by Firewall

• netstat -tlunp | grep ntp