1. Default configuration The default configuration can be found in /etc/linuxptp/ptp4l.conf. This is the default.cfg provided by the upstream source. 2. Systemd services The service ptp4l invokes ptp4l on eth0 by default. To adjust the parameters, follow these steps: 1. create a directory /etc/systemd/system/ptp4l.service.d 2. place a file with its name ending in .conf there 3. put these lines into the file, with the parameters adjusted to your needs: [Service] ExecStart= ExecStart=/usr/sbin/ptp4l -f /etc/linuxptp/ptp4l.conf -i eth0 The service phc2sys syncs the system clock with the PTP clock. It is not enabled and started by default. To activate this service, invoke the following commands as root: $ systemctl enable phc2sys $ systemctl start phc2sys It also uses eth0 as the default and can be customized as described above. The service timemaster also isn't enabled and started by default