Centos7时间同步Chrony（替代ntp软件）

yum -y install chrony
systemctl enable chronydsystemctl start chronyd
vim /etc/chrony.conf

# 使用 pool.ntp.org 项目中的公共服务器。以server开，理论上想添加多少时间服务器都可以。# Use public servers from the pool.ntp.org project.# Please consider joining the pool (http://www.pool.ntp.org/join.html).server 0.centos.pool.ntp.org iburstserver 1.centos.pool.ntp.org iburstserver 2.centos.pool.ntp.org iburstserver 3.centos.pool.ntp.org iburst
# 根据实际时间计算出服务器增减时间的比率，然后记录到一个文件中，在系统重启后为系统做出最佳时间补偿调整。# Record the rate at which the system clock gains/losses time.driftfile /var/lib/chrony/drift
# 如果系统时钟的偏移量大于1秒，则允许系统时钟在前三次更新中步进。# Allow the system clock to be stepped in the first three updates if its offset is larger than 1 second.makestep 1.0 3
# 启用实时时钟（RTC）的内核同步。# Enable kernel synchronization of the real-time clock (RTC).rtcsync
# 通过使用 hwtimestamp 指令启用硬件时间戳# Enable hardware timestamping on all interfaces that support it.#hwtimestamp *
# Increase the minimum number of selectable sources required to adjust the system clock.#minsources 2
# 指定 NTP 客户端地址，以允许或拒绝连接到扮演时钟服务器的机器# Allow NTP client access from local network.#allow 192.168.0.0/16
# Serve time even if not synchronized to a time source.#local stratum 10
# 指定包含 NTP 身份验证密钥的文件。# Specify file containing keys for NTP authentication.#keyfile /etc/chrony.keys
# 指定日志文件的目录。# Specify directory for log files.logdir /var/log/chrony
# 选择日志文件要记录的信息。# Select which information is logged.#log measurements statistics tracking

# Use public servers from the pool.ntp.org project.# Please consider joining the pool (http://www.pool.ntp.org/join.html).server s1a.time.edu.cn iburstserver ntp.aliyun.com iburst
# Allow NTP client access from local network.allow 192.168.8.0/24

systemctl enable chronydsystemctl restart chronyd
# 查看时间同步状态timedatectl status# 开启网络时间同步timedatectl set-ntp true

# Use public servers from the pool.ntp.org project.# Please consider joining the pool (http://www.pool.ntp.org/join.html).server 192.168.8.5 iburst
# Allow NTP client access from local network.allow 192.168.8.5

systemctl enable chronydsystemctl restart chronyd
# 查看时间同步状态timedatectl status# 开启网络时间同步timedatectl set-ntp true

# 查看 ntp_serverschronyc sources -v
# 查看 ntp_servers 状态chronyc sourcestats -v
# 查看 ntp_servers 是否在线chronyc activity -v
# 查看 ntp 详细信息chronyc tracking -v

# 查看日期时间、时区及 NTP 状态timedatectl
# 查看时区列表timedatectl list-timezonestimedatectl list-timezones |  grep  -E "Asia/S.*"
# 修改时区timedatectl set-timezone Asia/Shanghai
# 修改日期时间（可以只修改其中一个）timedatectl set-time "2019-09-19 15:50:20"
# 开启 NTPtimedatectl set-ntp true/flase