To install NTPD (Network Time Protocol Daemon) on a Debian-based Linux system, such as Ubuntu, you can use the apt-get or apt command.
To install NTPD using apt-get, run the following command:
sudo apt-get install ntp
To install NTPD using apt, run the following command:
sudo apt install ntp
This will install the NTPD package and the necessary dependencies. Once the installation is complete, you can start the NTPD service by running the following command:
sudo systemctl start ntp
You can also configure NTPD to start automatically at boot by running the following command:
sudo systemctl enable ntp
By default, NTPD uses a list of Internet standard time servers to synchronize the system clock. You can configure NTPD to use a different list of servers by editing the /etc/ntp.conf configuration file. For example, to use the servers provided by the NIST (National Institute of Standards and Technology), you can add the following lines to the /etc/ntp.conf file:
server time.nist.gov server time2.nist.gov server time3.nist.gov server time4.nist.gov server time5.nist.gov server time6.nist.gov
You can also specify a local time server, such as a GPS or radio clock, by adding a server line with the appropriate address or hostname.
After making any changes to the /etc/ntp.conf file, you will need to restart the NTPD service for the changes to take effect. You can do this by running the following command:
sudo systemctl restart ntp