setup a Raspberry Pi as an Stratum One NTP server.
it is a private project i have made for myself.
i did not keeped an eye on network security.

the script will override some existing configurations
(a backup of the changed configuration files will be stored to backup.tar.xz)

USE IT AT YOUR OWN RISK

Please give me a 'Star', if you find that project useful.

                     ╔═══╗       ╔══════╗         ╔══════╗  GPS-Antenna
                   ──╢ s ║       ║RPi as╟RX───────╢GPS-  ║    ═╪═
                     ║ w ║       ║NTP-  ╟TX───────╢module║     │
                     ║ i ║       ║server║         ╠═══╗  ║     │
       ╔══════╗      ║ t ╟───eth0╢      ╟GPIO#4───╢PPS║  ╟─────┘
       ║ RPi  ╟──────╢ c ║       ║      ║         ╚═══╩══╝
       ╚══════╝   ┌──╢ h ╟──┐    ║      ║
                  │  ╚═══╝  │    ╚══════╝
               ╔══╧══╗   ╔══╧══╗
               ║ PC1 ║   ║ PC2 ║
               ╚═════╝   ╚═════╝

• Raspberry Pi (with LAN)
• SD card
• working network environment (with a connection to internet for installation only)
• GPS module with PPS output (Adafruit Ultimate GPS Breakout - 66 channel w/10 Hz updates - Version 3; https://www.adafruit.com/products/746)

• Raspbian Buster Lite (2020-02-13 or newer, https://www.raspberrypi.org/downloads/raspbian/)

assuming,

• your Raspberry Pi is running Raspbian Buster Lite (2020-02-13 or newer),
• and has a proper connection to the internet via LAN.
• and your SD card is expanded,
• and you connected the GPS module direct to the RPi's RX/TX pins of the GPIO and the GPS PPS pin to the RPi' GPIO #4

1. run bash install-gps-pps.sh to install necessary packages and setup Kernel PPS, GPSD, and NTP with PPS support.
2. reboot your RPi with sudo reboot
3. in case you have a RPi3, RPi3+ or RPi0w with a built-in bluetooth adapter, please run sudo raspi-conf and disable the bluetooth adapter there. otherwise the built-in bluetooth adapter will block the serial port of the GPIO pins.

done.