linux服务器时间同步

准备

　　使用的命令是ntpdate，我用的系统是centos6.9，可以用yum install ntp进行安装。准备工作结束

进行同步

　　安装完ntp服务，service ntpd start|stop|restart 就可以进行服务控制。chkconfig ntpd on|off 进行开机启动配置。

　　怎么配置呢？默认配置文件是/etc/ntp.conf。在网上折腾了一溜够，下面是我的配置文件：

# For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).

driftfile /var/lib/ntp/drift

# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
restrict -6 ::1

# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
restrict 192.168.99.0 mask 255.255.255.0 notrap nomodify  # 允许内网其他机器同步时间，不过这个配置我现在还没啥用，因为我就一台机

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server time.nist.gov prefer # 这个是美国同步时间的服务器，可以在网上搜到更多，有搜到一个中国的，但是没法用，所以就没用了
server 1.centos.pool.ntp.org iburst
server 2.centos.pool.ntp.org iburst
server 3.centos.pool.ntp.org iburst

# 外部时间服务器不可用时，以本地时间作为时间服务
server  127.127.1.0     # local clock
fudge   127.127.1.0 stratum 10

#broadcast 192.168.1.255 autokey        # broadcast server
#broadcastclient                        # broadcast client
#broadcast 224.0.1.1 autokey            # multicast server
#multicastclient 224.0.1.1              # multicast client
#manycastserver 239.255.254.254         # manycast server
#manycastclient 239.255.254.254 autokey # manycast client

# Enable public key cryptography.
#crypto

includefile /etc/ntp/crypto/pw

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8

# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats

　　然后重新启动服务就好了。但是，怎么证明生效呢？修改系统时间到一个过去的值，date -s 11/03/2009，过一段时间时间正确了，就成功了

一些其它的时间同步服务器

time.nist.gov
time.nuri.net
0.asia.pool.ntp.org
1.asia.pool.ntp.org
2.asia.pool.ntp.org
3.asia.pool.ntp.org

　　除了我用的那个我都没验证，自己验证下吧。