打算将11台Linux集群时间同步一下，操作系统都为Ubuntu 11.04 x86 64位
选定其中一台133.133.10.2作为时间服务器（ntp server），其他节点与该节点进行时间同步。
1、在133.133.10.2（monitor）上安装ntp server。
root@monitor:~# apt-get install ntp
2、修改/etc/ntp.conf如下：（参考了http://blog.sina.com.cn/s/blog_6b86fdc50100ojfn.html）
# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help
driftfile /var/lib/ntp/ntp.drift
# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
# Specify one or more NTP servers.
# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# more information.
#server 0.ubuntu.pool.ntp.org
#server 1.ubuntu.pool.ntp.org
#server 2.ubuntu.pool.ntp.org
#server 3.ubuntu.pool.ntp.org
# Use Ubuntu's ntp server as a fallback.
#server ntp.ubuntu.com
server 127.127.1.0 minpoll 4 maxpoll 5
fudge 127.127.1.0 stratum 2
# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details. The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
#
# 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
restrict -4 default kod nomodify noper
restrict -6 default kod nomodify noper
# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1
# Clients from this (example!) subnet have unlimited access, but only if
# cryptographically authenticated.
#restrict 192.168.123.0 mask 255.255.255.0 notrust
# If you want to provide time to your local subnet, change the next line.
# (Again, the address is an example only.)
#broadcast 192.168.123.255
# If you want to listen to time broadcasts on your local subnet, de-comment the
# next lines. Please do this only if you trust everybody on the network!
#disable auth
#broadcastclient
首先重启一下ntp服务
root@monitor:/etc#/etc/init.d/ntp restart
再运行
root@monitor:/etc# ntpdate -q 127.0.0.1
得到
server 127.0.0.1, stratum 3, offset -0.000003, delay 0.02565
23 Sep 17:12:00 ntpdate[11502]: adjust time server 127.0.0.1 offset -0.000003 sec