nix-config/hosts/toaster/network/mullvad.nix

{ config, lib, ... }:
{
  systemd.network =
    let
      pubkey = "BChJDLOwZu9Q1oH0UcrxcHP6xxHhyRbjrBUsE0e07Vk=";
      endpoint = "169.150.196.15";
      port = "51820";
      addr = [
        "10.74.16.48/32"
        "fc00:bbbb:bbbb:bb01::b:102f/128"
      ];
    in
    {
      netdevs."10-wg-mullvad" = {
        netdevConfig = {
          Kind = "wireguard";
          Name = "wg-mullvad";
        };
        wireguardConfig = {
          PrivateKeyFile = config.sops.secrets."wg/mullvad".path;
          FirewallMark = 34952; # 0x8888
          RouteTable = "off";
        };
        wireguardPeers = [
          {
            PublicKey = pubkey;
            Endpoint = "${endpoint}:${port}";
            AllowedIPs = [
              "0.0.0.0/0"
              "::0/0"
            ];
          }
        ];
      };
      networks."10-wg-mullvad" = {
        matchConfig.Name = "wg-mullvad";
        address = addr;
        networkConfig = {
          DNS = "10.64.0.1";
          DNSDefaultRoute = true;
          Domains = [ "~." ];
        };
        routes =
          map
            (gate: {
              Gateway = gate;
              Table = 1000;
            })
            [
              "0.0.0.0"
              "::"
            ];

        routingPolicyRules =
          [
            {
              Family = "both";
              FirewallMark = 34952; # 0x8888
              InvertRule = true;
              Table = "1000";
              Priority = 100;
            }
            {
              Family = "both";
              SuppressPrefixLength = 0;
              Table = "main";
              Priority = 90;
            }
          ]
          ++ map
            (net: {
              # only route global addresses over VPN
              Priority = 80;
              To = net;
            })
            [
              # Mullvad endpoint
              "${endpoint}/32"
              # "10.0.0.0/8"
              "10.13.37.0/24"
              # 0xa-mgmt
              "10.89.87.0/24"
              # "172.16.0.0/12"
              "172.16.0.0/12"
              # "182.168.0.0/16"
              "182.168.0.0/16"
              # "fc00::/7"
            ];
      };
    };
}