Configuring time synchronization via the PTP protocol in CentOS

To configure time synchronization via PTP in CentOS:

1. Open the operating system console.
2. Check whether the linuxptp package is installed. To do so, enter the following command:

   dnf list installed

3. If the linuxptp package is not installed, enter the following commands to add the package and enable the ptp4l time synchronization service:

   sudo dnf install linuxptp
sudo systemctl enable ptp4l
sudo systemctl start ptp4l

4. Open the service configuration file. To do so, enter the following command:

   sudo mcedit /etc/ptp4l.conf

5. Enter 1 for the slaveOnly parameter.
6. Save and close the configuration file.
7. Open the file containing the general settings for the service. To do so, enter the following command:

   sudo mcedit /etc/sysconfig/ptp4l

8. In the OPTIONS string, specify the parameters as follows:

   OPTIONS="-f <configuration file> -i <interface name> -S -s"

   where:

   • -f <configuration file> – default name and full path of the configuration file.
   • -i <interface name> – name of the network interface that is used for time synchronization.
   • -S – enables use of software-based timestamps. You can skip this parameter if you want to use hardware-based timestamps. However, first make sure that the equipment supports this capability.
   • -s – enables subordinate time synchronization.

   Example OPTIONS string:

   OPTIONS="-f /etc/ptp4l.conf -i eth0 -S -s"

9. Save and close the general settings file.
10. Allow use of ports 319 and 320 in the firewall for the UDP protocol. To do so, enter the following commands:

    sudo firewall-cmd --permanent --add-port=319/udp
sudo firewall-cmd --permanent --add-port=320/udp

11. Restart the firewall service. To do so, enter the following command:

    sudo systemctl restart firewalld

12. Restart the time synchronization service. To do so, enter the following command:

    sudo systemctl restart ptp4l

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