1.安装ntp服务
    首先检查是否已安装ntp服务，如果未安装，请先安装；可以使用命令安装或者使用源码编译安装，我是使用源码编译安装的；
    检查安装命令：rpm –qa | grep ntp
    安装命令：apt-get install ntp

    源码编译：

    首先进入源码目录

./configure 
--prefix=/usr \
--bindir=/usr/sbin \
--sysconfdir=/etc \
--enable-linuxcaps \
--with-lineeditlibs=readline \
--enable-all-clocks \
--enable-parse-clocks \
--enable-clockctl

make
make install

2.配置/etc/ntp.conf

    2.1时间服务器配置
    配置网络ntp服务器地址使用server关键字，格式：server [ip or hostname] [options...]，在server后面写服务器地址（可以使IP或主机名），options这里最长使用的prefer，表示优先使用的服务器。
    
    一定要记得配置下面2行，意思是无法链接网络服务器的情况下，使用本地时间作为时间源

server 127.127.1.0
fudge 127.127.1.0 stratum 6

    
    2.1权限配置
    权限配置使用restrict关键字，格式：restrict [address] mask [mask] [parameter]
    其中parameter的参数主要有：
    ignore：拒绝所有类型的ntp连接
    nomodify：客户端不能使用ntpc与ntpq两支程式来修改服务器的时间参数
    noquery：客户端不能使用ntpq、ntpc等指令来查询服务器时间，等于不提供ntp的网络校时
    notrap：不提供trap这个远程时间登录的功能
    notrust：拒绝没有认证的客户端，要注意，4.2版本以后的ntp不能添加此选项，否则对时会出现no data错误
    nopeer：不与其他同一层的ntp服务器进行时间同步

    limited：限制对时频率

    一般使用默认配置，不用修改
    
3.启动ntp服务

service ntp start
service ntp restart
service ntp stop

    启动后需要过5分钟左右才能正常对时，刚开始会报错
    
4.测试
  

 ntpdate -d 127.0.0.1

5.附ntp.conf

# /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


# You do need to talk to an NTP server or two (or three).
#server ntp.your-provider.example
server 127.127.1.0 
fudge 127.127.1.0 stratum 8


# pool.ntp.org maps to about 1000 low-stratum NTP servers.  Your server will
# pick a different set every time it starts up.  Please consider joining the
# pool: <http://www.pool.ntp.org/join.html>
#pool 0.debian.pool.ntp.org iburst
#pool 1.debian.pool.ntp.org iburst
#pool 2.debian.pool.ntp.org iburst
#pool 3.debian.pool.ntp.org iburst


# 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 limited
restrict -6 default kod notrap nomodify nopeer noquery limited

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

# Needed for adding pool entries
restrict source notrap nomodify noquery

# 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