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path: root/modules/wireguard.nix
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{ config, pkgs, ... }:

let
  inherit (pkgs) iptables;

  wireguardPort = 51820;
  wireguardIPv4 = number: subnet: "10.123.10.${number}/${subnet}";
  wireguardIPv6 = number: subnet: "fd0f:123::${number}/${subnet}";

  wireguardInterface = "wg0";
  externalInterface = "enp1s0";

  peerIPs = peerNumber: [
    (wireguardIPv4 peerNumber "32")
    (wireguardIPv6 peerNumber "128")
  ];
  peers = [
    # mel
    {
      publicKey = "vnZoHXapCLLUhZ8A8R5W0iJ8LpWVLve29z41kkoT0BU=";
      allowedIPs = peerIPs "2";
    }

    # andrei
    {
      publicKey = "qqU4uYImLfUohIwl4KBshPtTINFcs0JVALjbmwpfxRg=";
      allowedIPs = peerIPs "3";
    }
  ];

in
{
  age.secrets.wireguard-private-key = {
    file = ../secrets/wireguard-private-key.age;
  };

  # enable nat, to rename internal wireguard ips to external ip (w/ iptables)
  networking = {
    nat = {
      enable = true;
      internalInterfaces = [ wireguardInterface ];
      inherit externalInterface;
    };

    firewall = {
      allowedUDPPorts = [ wireguardPort ];
    };
  };

  # enable kernel support for ipv6 forwarding
  boot.kernel.sysctl = {
    "net.ipv6.conf.all.forwarding" = 1;
    "net.ipv6.conf.default.forwarding" = 1;
  };

  networking.wireguard.interfaces.${wireguardInterface} = {
    inherit peers;

    # ip address of server + subnet of network
    ips = [
      (wireguardIPv4 "1" "24")
      (wireguardIPv6 "1" "112")
    ];
    listenPort = wireguardPort;

    # route wireguard traffic to the internet
    # also requires clients to have dns set. (i think)
    # to avoid, maybe? use wg-quick + dnsmasq?
    postSetup = ''
      ${iptables}/bin/iptables -t nat -A POSTROUTING -s ${wireguardIPv4 "0" "24"} -o ${externalInterface} -j MASQUERADE
      ${iptables}/bin/ip6tables -t nat -A POSTROUTING -s ${wireguardIPv6 "0" "112"} -o ${externalInterface} -j MASQUERADE
    '';

    postShutdown = ''
      ${iptables}/bin/iptables -t nat -D POSTROUTING -s ${wireguardIPv4 "0" "24"} -o ${externalInterface} -j MASQUERADE
      ${iptables}/bin/ip6tables -t nat -D POSTROUTING -s ${wireguardIPv6 "0" "112"} -o ${externalInterface} -j MASQUERADE
    '';

    privateKeyFile = config.age.secrets.wireguard-private-key.path;
  };
}