Modify the file /etc/ntp.conf
restrict xxx nomodify notrap nopeer noquery #xxx local IP address where
the restrict 127.0.0.1
the restrict XXX XXX mask 255.255.255.0 nomodify notrap # ntp to allow synchronization segment
Server 127.127.1.0
Fudge 127.127.1.0. 8 Stratum