Add option for networkmanager configuration.

config/networking.nix

@@ -7,7 +7,7 @@ with lib;
 let
   inherit (config.machine) networkD;
 in
-{
+mkIf (!elem "networkmanager" config.machine.conffiles) {
   networking = {
     inherit (config.machine) hostName;
     useNetworkd = networkD.enable;

config/networkmanager.nix

@@ -0,0 +1,26 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}:
+
+with lib;
+mkIf (elem "networkmanager" config.machine.conffiles) {
+
+  networking = {
+    inherit (config.machine) hostName;
+  };
+
+  networking.networkmanager = {
+    enable = true;
+    plugins = with pkgs; [
+      networkmanager-openconnect
+    ];
+  };
+
+  environment.systemPackages = with pkgs; [
+    networkmanagerapplet
+    networkmanager_dmenu
+  ];
+}

config/users.nix

@@ -48,6 +48,7 @@ let
           ])
           ++ (optional config.programs.virt-manager.enable "libvirtd")
           ++ (optional config.virtualisation.virtualbox.host.enable "vboxusers")
+          ++ (optional config.networking.networkmanager.enable "networkmanager")
           ++ (optional (withDocker && !withPodman) "docker")
           ++ (optional withPodman "podman");
         shell = "${pkgs.zsh}/bin/zsh";