• tether - script to start USB tethering
• 49-android.rules - udev rule to start tethering on device hotplug
• tether.service - systemd service launched by udev
• usb0.link - systemd-networkd link configuration
• usb0.network - systemd-networkd interface configuration

Linux machine running systemd+udev+networkd+resolved

• Install Android SDK and set path to adb binary in tether script.

• Attach your Android device.

• Get major and minor of your device with lsusb command:

    $ lsusb | grep HTC
    Bus 001 Device 088: ID 0bb4:0004 HTC (High Tech Computer Corp.)
  

• Get product attribute for your device:

    $ udevadm info -a -p $(udevadm info -q path -n /dev/bus/usb/001/088) | grep ATTR{product}
        ATTR{product}=="ZP900S"
  

• Set product attribute in 49-android.rules.

• Configure DNS.

  You can get DNS servers used by your device with:

    $ adb shell getprop net.dns{1-4}
  

  Alternatively, use public DNS servers:

    $ cat >> tether.network <<EOF
    # Google Public DNS
    DNS 8.8.8.8
    DNS 8.8.4.4
    EOF
  

• Install script, systemd service and udev rules:

    $ sudo make install
  

• Use systemd-networkd DNS configuration:

    # ln -sf ../run/systemd/network/resolv.conf /etc/resolv.conf
  

• Re-attach device.

• Internet should work now.

• https://github.com/dpavlin/android-adb-usb-tether
• https://github.com/ajasmin/android-linux-tethering
• https://bugzilla.mozilla.org/show_bug.cgi?id=735547#c1