Setting up NTP in Centos 6.6

Setting up NTP in Centos 6.6

 First we need to make sure we have the correct date, time, and timezone. You can verify with:

# cat /etc/localtime

Set your time zone with (for Phoenix AZ USA)

#cp /usr/share/zoneinfo/America/Phoenix /etc/localtime


Now check date

# date
Sun Mar 29 01:10:44 MST 2015

You can verify this at the hardware level with:

# hwclock -r
Sun 29 Mar 2015 01:13:51 AM MST  -0.156631 seconds

If  these are incorrect then we can set the OS first and then update the hardware with the date command. The syntax is: date "day month year hh:mm:ss" So if we wanted to change this to March 2 2015 at 1:00pm we would use:

# date -s "2 MAR 2015 13:00:00"

When we have the date correct in the OS we can update the hardware with:

# hwclock -w

Now that we have the correct date and time lets install and setup ntp. First lets install ntp if not already installed.

# yum -y install ntp

Next edit the the ntp.conf file so we are using the correct time servers.

# vi /etc/ntp.conf

I usually use the public servers from the pool.ntp.org project of:
server 0.centos.pool.ntp.org iburst
server 1.centos.pool.ntp.org iburst
server 2.centos.pool.ntp.org iburst
server 3.centos.pool.ntp.org iburst

After you have those in lets start the service and make sure it is on in startup.

# service ntpd start
Starting ntpd:                                             [  OK  ]
# chkconfig ntpd on

Now lets verify the setup by looking at our peers.

# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*deekayen.net    209.51.161.238   2 u   43   64    3   75.257  -22.456   3.017
 origin.towfowi. 204.9.54.119     2 u   43   64    3   31.405  -14.629   2.683
 NTP2.playallian 129.6.15.30      2 u   43   64    3   50.576  -14.090   3.465
 sola-dal-09.ser 10.0.77.54       4 u   42   64    3   59.879   -1.507   2.629