NTP

学习地址：

• https://www.tecmint.com/synchronize-time-with-ntp-in-linux/

Protocol

The Network Time Protocol (NTP) is a protocol used to synchronize computer system clock automatically over a networks. The machine can have the system clock use Coordinated Universal Time (UTC) rather than local time.

ntpdate

The most common method to sync system time over a network in Linux desktops or servers is by executing the ntpdate command which can set your system time from an NTP time server. In this case, the ntpd daemon must be stopped on the machine where the ntpdate command is issued.

Installation:

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$ apt-get install ntpdate

Example:

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$ sudo ntpdate 1.ro.pool.ntp.org

In order to just query the server and not set the clock and use an unprivileged port to send the packets from, in order to bypass firewalls, issue ntpdate with the below flags:

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$ sudo ntpdate -qu 1.ro.pool.ntp.org

Always try to query and sync the time with the closest NTP servers available for your zone. The list of the NTP server pools can be found at the following address: https://www.pool.ntp.org/en/

此后可以通过 date 指令查看系统时间。