Time Synchronisation¶

The system time on all nodes must be synchronized as
a) data is written/read on/from a common, shared file system or even expires after a certain period of time and must be deleted, and
b) system logs are maintained independently but entries must be able to be associated with each other.

• Add your own time server to /etc/ntp/ntpservers:
  

     128.243.21.16 #marian.cs.nott.ac.uk
     128.243.21.17 #robin.cs.nott.ac.uk
     128.243.21.18 #tuck.cs.nott.ac.uk
     128.243.21.19 #pat.cs.nott.ac.uk
  

• Modify /etc/ntp.conf in order to permit systems on the subnet to synchronise with this time service:
  

     # -- CLIENT NETWORK -------
     restrict 192.168.199.0 mask 255.255.255.0 nomodify notrap
     broadcastclient
  

• Modify /etc/ntp.conf and add further time servers:
  

     # --- OUR TIMESERVERS -----
     server 128.243.21.16 #marian.cs.nott.ac.uk
     restrict 128.243.21.16 mask 255.255.255.255 nomodify notrap noquery
     server 128.243.21.17 #robin.cs.nott.ac.uk
     restrict 128.243.21.17 mask 255.255.255.255 nomodify notrap noquery
     server 128.243.21.18 #tuck.cs.nott.ac.uk
     restrict 128.243.21.18 mask 255.255.255.255 nomodify notrap noquery
     server 128.243.21.19 #pat.cs.nott.ac.uk
     restrict 128.243.21.19 mask 255.255.255.255 nomodify notrap noquery
  

• Make the NTP daemon start at bootup. Enter at the command line of the master node and each slave node:
  

     /sbin/chkconfig  --add ntpd
     /sbin/chkconfig  ntpd  on
  

• Start the NTP daemon. Enter at the command line of the master node and each slave node:
  

     /sbin/service ntpd start