由于多台机器时间不一致问题，经常会导致很烦的事情发生，所以就自己配置了一台NTP服务器喽！
一、安装ntp
yum install -y ntp ntpdate
二、配置
配置文件位置：/etc/ntp.conf
内容如下:
# 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 192.168.0.0 mask 255.255.0.0 nomodify notrap # Permit all access over the loopback interface. This could # be tightened as well, but to do so would effect some of # the administrative functions. # 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 202.120.2.101 prefer server 0.centos.pool.ntp.org server 1.centos.pool.ntp.org server 2.centos.pool.ntp.org server 3.centos.pool.ntp.org server time.pool.aliyun.com server time1.aliyun.com #broadcast 192.168.1.255 autokey # broadcast server server 127.127.1.0 # LCL does't sync fudge 127.127.1.0 stratum 10 #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 # Disable the monitoring facility to prevent amplification attacks using ntpdc # monlist command when default restrict does not include the noquery flag. See # CVE-2013-5211 for more details. # Note: Monitoring will not be disabled with the limited restriction flag. #disable monitor
三、启动服务
systemctl start ntpd.service
设为开机启动
systemctl enable ntpd.service
定时重启服务
*/30 * * * * systemctl restart ntpd
四、使端口通过防火墙
firewall-cmd --permanent --add-port=123/udp firewall-cmd --reload
五、查看服务器同步状态
ntpq -p ntpstat
六、客户端同步
Linux：
ntpdate 192.168.0.2
crontab：
*/5 * * * * ntpdate 192.168.0.10
Centos7定时同步脚本：
systemctl enable crond yum install -y ntp mkdir -p /home/logs/ntpsync/ ntpdate 192.168.0.10 >>/home/logs/ntpsync/datesync.`date +\%Y\%m\%d` 2>&1 echo "*/5 * * * * /usr/sbin/ntpdate 192.168.0.10 >>/home/logs/ntpsync/datesync.`date +\%Y\%m\%d`.log 2>&1 " >> /var/spool/cron/root #
六、问题
1、自行配置的ntp服务器，无法同步自身时间
答案：经过测试，大多数公共服务器都不能使用，更换公共NTP服务器就好
2、客户端无法同步自行搭建的NTP服务器时间
答案：两种可能：1)、ntp server 自身还未完成本地时间同步 2)、ntp server 防火墙问题
