linux设置自动同步服务器时间

最近遇到一个问题，由于两台服务器时间的问题，经常导致用户登录由于时间差问题而报错，再三百度，最后整理了一下修改linux定时同步的操作（本方法适用于有自己时间服务器，没有的只限于借鉴）

首先确认，我们的服务是否已经安装了ntp服务

如果没有安装，需要先安装ntp服务

安装完ntp之后，编辑ntp.conf  

vi /etc/ntp.conf

可以看到文件中内容

# 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

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 127.0.0.1
#server 1.centos.pool.ntp.org
#server 2.centos.pool.ntp.org

#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

# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available.
# local clock
#fudge  127.127.1.0 stratum 10

# 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

　　在文件中 可以看到修改标出来的ip地址，改为自己的时间服务器地址，也可以是域名

修改后保存退出

命令行输入

crontab -e

　　设置定时任务，其这里设置的是

* * */1 * * /usr/sbin/ntpdate 127.0.0.1 >> /home/logs/ntpd.log

　同样修改ip地址 
然后创建日志文件夹用来存放日志

mkdir /home/logs

　　ok 大功告成，过几分钟在日志文件夹可以看到日志文件，浏览会发现，时间差不超过0.01s .一般来说是够用了的