{pkgs, ...}: {
  boot = {
    kernelPackages = pkgs.linuxKernel.packages.linux_rpi4;
    initrd.availableKernelModules = [
      "xhci_pci"
      "usbhid"
      "usb_storage"
    ];
    loader = {
      grub.enable = false;
      generic-extlinux-compatible.enable = true;
    };
  };

  fileSystems = {
    "/" = {
      device = "/dev/disk/by-label/NIXOS_SD";
      fsType = "ext4";
      options = ["noatime"];
    };
  };

  # Open ports for DHCP server.
  networking.firewall.allowedUDPPorts = [
    53
    67
  ];

  # Enable WebOne HTTP proxy.
  services.webone.enable = true;
}