Ubuntu集群 配置ntp服务

1、概述

NTP（Network Time Protocol）是用来使计算机时间同步化的一种协议，它可以使计算机对其服务器或时钟源（如石英钟，GPS等等)做同步化，它可以提供高精准度的时间校正（LAN上与标准间差小于1毫秒，WAN上几十毫秒），且可介由加密确认的方式来防止恶毒的协议攻击。（来自 百度百科）

2、集群状况

现在又4台Ubuntu主机，选择其中一台作为提供ntp服务的主机（server01）。

3、安装ntp服务

在提供ntp服务的主机上安装ntpserver:

apt-get install ntp

4、配置ntp服务参数

# /etc/ntp.conf, configuration for ntpd; see ntp.conf() 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 -- (LP: #). See http://www.pool.ntp.org/join.html for
# more information.
#server .ubuntu.pool.ntp.org
#server .ubuntu.pool.ntp.org
#server .ubuntu.pool.ntp.org
#server .ubuntu.pool.ntp.org

# Use Ubuntu's ntp server as a fallback.
#server ntp.ubuntu.com
server 127.127.1.0 minpoll  maxpoll
fudge 127.127.1.0 stratum 

# 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 - default kod notrap nomodify nopeer noquery
restrict - default kod notrap nomodify nopeer noquery

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

# Clients from this (example!) subnet have unlimited access, but only if
# cryptographically authenticated.
#restrict 192.168.123.0 mask 255.255.255.0 notrust

...skipping one line

# 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

5、测试ntp服务

在提供ntp服务的服务器上运行：

ntpdate -q 127.0.0.1

得到结果：

server 127.0.0.1, stratum , offset -0.000018, delay 0.02568
  Sep :: ntpdate[]: adjust time server 127.0.0.1 offset -0.000018 sec

说明启动正常。

6、其它主机用它来同步时间

在需要同步时间的主机上执行：

ntpdate server01

见结果如下：

 Sep :: ntpdate[]: adjust time server 192.168.1.154 offset 0.497131 sec

server01可以是主机名也可以是ip。

7、设置定时同步时间

使用crontab：

crontab -e

设置一小时校准一次：

* */ * * * /usr/sbin/ntpdate server01