1、配置chrony服务，实现服务器时间自动同步
服务端配置
1 使用的机器是centos7自带chrony
2 修改配置文件
vim /etc/chrony.conf
# 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 iburst #设定时间同步服务器地址
server 1.centos.pool.ntp.org iburst #iburst 选项可加快初始同步速度
server 1.1.1.1 iburst
server 2.2.2.2 iburst
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift #driftfile 根据实际时间计算出计算机增减时间的比率，将它记录到一个文件中，
#会在重启后为系统时钟作出补偿
# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 1.0 3
# Enable kernel synchronization of the real-time clock (RTC).
rtcsync #启用内核模式，系统时间每11分钟会拷贝到实时时钟（RTC）
# 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
# Allow NTP client access from local network.
allow 192.168.0.0/16 #指定一台主机、子网，或者网络以允许访问本服务器
deny 10.0.0.0/24 #指定一台主机、子网，或者网络以拒绝访问本服务器
# Serve time even if not synchronized to a time source.
local stratum 10 #即使server指令中时间服务器不可用，也允许将本地时间
#作为标准时间授时给其它客户端
# Specify file containing keys for NTP authentication.
#keyfile /etc/chrony.keys
# Specify directory for log files.
logdir /var/log/chrony
# Select which information is logged.
#log measurements statistics tracking
3 启动 加入开机自启
systemctl start chronyd
systemctl enable chronyd
客户端配置
vim /etc/chrony.conf
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 10.0.0.173 iburst #服务端地址
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift
# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 1.0 3
# Enable kernel synchronization of the real-time clock (RTC).
rtcsync
# 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
# 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
# Specify file containing keys for NTP authentication.
#keyfile /etc/chrony.keys
# Specify directory for log files.
logdir /var/log/chrony
# Select which information is logged.
#log measurements statistics tracking
启动 加入开机自启
systemctl start chronyd
systemctl enable chronyd
chronyc命令
chronyc命令
help命令可以查看更多chronyc的交互命令
accheck 检查是否对特定主机可访问当前服务器
activity 显示有多少NTP源在线/离线
sources [-v] 显示当前时间源的同步信息
sourcestats [-v]显示当前时间源的同步统计信息
add server 手动添加一台新的NTP服务器
clients 报告已访问本服务器的客户端列表
delete 手动移除NTP服务器或对等服务器
settime 手动设置守护进程时间
sracking 显示系统时间信息
2、实现cobbler+pxe自动化装机
