added system to dirs

modules/system/ssh/default.nix

@@ -0,0 +1,24 @@
+{ pkgs, config, lib, ... }:
+
+let
+  cfg = config.system.ssh;
+in
+{
+  options.system.ssh = {
+    enable = lib.mkEnableOption "enables ssh";
+  };
+
+  config = lib.mkIf cfg.enable {
+    # enable and configure openssh
+    services.openssh = {
+      enable = true;
+      settings = {
+        PasswordAuthentication = true;
+        PermitRootLogin = "no";
+        X11Forwarding = false;
+      };
+    };
+    # open firewall
+    networking.firewall.allowedTCPPorts = [ 22 ];
+  };
+}