init natpmp module thing

modules/natpmp-portforward.nix

@@ -0,0 +1,57 @@
+{
+  lib,
+  pkgs,
+  config,
+  ...
+}: let
+  cfg = config.own.natpmp-portforward;
+in {
+  options.own.natpmp-portforward = {
+    enable = lib.mkEnableOption "enable natpmp port forwarding service";
+    mappings = lib.types.listOf (lib.types.submodule {
+      options = {
+        public = lib.mkOption {
+          type = lib.types.port;
+        };
+        private = lib.mkOption {
+          type = lib.types.port;
+        };
+        protocol = lib.mkOption {
+          default = "tcp";
+          type = lib.types.enum [
+            "tcp"
+            "udp"
+          ];
+        };
+      };
+    });
+  };
+
+  config = lib.mkIf cfg.enable {
+    systemd.services.natpmp-portforward = {
+      requisite = ["network-online.target"];
+      serviceConfig = {
+        Restart = "on-failure";
+        ExecStart = pkgs.writeScript "natpmp-portforward" ''
+          #!${pkgs.bash}/bin/bash
+
+          "${lib.concatMapStrings (x: ''
+              ${pkgs.libnatpmp}/bin/natpmpc -a ${x.public} ${x.private} ${x.protocol} 60
+            '')
+            cfg.mappings}"
+        '';
+      };
+    };
+
+    systemd.timers.natpmp-portforward = {
+      requires = ["network-online.target"];
+      wantedBy = ["timers.target"];
+      timerConfig = {
+        OnBootSec = "1m";
+        OnUnitActiveSec = "1m";
+        AccuracySec = "5s";
+        Unit = "natpmp-portforward.service";
+      };
+    };
+  };
+}