linux定时同步时间

# /etc/ntp.conf
driftfile /var/lib/ntp/ntp.drift

# Use the local system clock as a reference if all else fails
server 127.127.1.0 minpoll 4 maxpoll 4 prefer
fudge 127.127.1.0 stratum 10

# Specify one or more NTP servers
server 0.pool.ntp.org
server 1.pool.ntp.org
server 2.pool.ntp.org
server 3.pool.ntp.org

# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for details.
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.

# By default, exchange time with everybody, but don't allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery
restrict -6 default kod notrap nomodify nopeer noquery

# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1