Local NTP server setup

local_ntp_setup.txt

ntp ref:
------------------------------
http://serverfault.com/questions/204082/using-ntp-to-sync-a-group-of-linux-servers-to-a-common-time-source/204138#204138
http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm
http://askubuntu.com/questions/14558/how-do-i-setup-a-local-ntp-server
http://www.thegeekstuff.com/2014/06/linux-ntp-server-client/
http://www.linuxsolutions.org/faqs/generic/ntpserver
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/s1-Understanding_the_ntpd_Configuration_File.html
------------------------------

##### local npt server
ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
+100tx-f1-0.c720 216.218.192.202 2 u 23 64 377 68.491 -10.384 6.690
+ec2-52-6-160-3. 209.51.161.238 2 u 26 64 377 1.204 -7.624 6.579
+biisoni.miuku.n 209.118.204.201 3 u 25 64 377 68.883 -11.218 6.572
*x.ns.gin.ntt.ne 18.26.4.105 2 u 25 64 377 9.036 -5.628 5.948

##### Creating the NTP Master Server
### Step 1: Edit ntp.conf

# 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 127.0.0.1 
restrict -6 ::1

# Hosts on local network are less restricted.                                                                               
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap                                                                    
#TODO: add custom network servers access to query
#10.11.2.56 
restrict 10.11.2.0 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).
# Use the local clock
# http://www.ntp.org/ntpfaq/NTP-s-refclk.htm#AEN4565
#TODO: enable local ntp server as secondary source
server 127.127.1.0 iburst prefer
fudge  127.127.1.0 stratum 10
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

#broadcast 192.168.1.255 autokey # broadcast server
#TODO: add custom network broadcast address
broadcast 10.11.2.255
#broadcastclient # broadcast client
#broadcast 224.0.1.1 autokey # multicast server
#multicastclient 224.0.1.1 # multicast client
#manycastserver 239.255.254.254 # manycast server
#manycastclient 239.255.254.254 autokey # manycast client

### Step 2: Restart the NTP daemon
service ntpd stop
ntpdate -b 0.centos.pool.ntp.org
service ntpd start
### Step 3: Configure NTP to start on reboot
chkconfig ntpd on

ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*LOCAL(0) .LOCL. 10 l 2 64 1 0.000 0.000 0.001
10.11.255.255 .BCST. 16 u - 64 0 0.000 0.000 0.001

##### Configuring the Client Machines
### Step 1: Edit ntp.conf
# Hosts on local network are less restricted.                                                                               
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap                                                                    
#10.11.2.56 
restrict 10.11.0.0 mask 255.255.0.0 nomodify notrap

# Use public servers from the pool.ntp.org project. 
# Please consider joining the pool (http://www.pool.ntp.org/join.html). 
server 10.11.2.56 iburst prefer
#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 

### Step 2: Restart the NTP daemon
service ntpd stop
ntpdate -b 10.11.2.56
service ntpd start
### Step 3: Configure NTP to start on reboot
chkconfig ntpd on

ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*10.11.2.56 .LOCL. 11 u 2 64 1 0.000 0.000 0.001