networking: add basic /etc files for networking

modules/environment/networking.nix

@@ -0,0 +1,36 @@
+# Copyright (c) 2019-2021, see AUTHORS. Licensed under MIT License, see LICENSE.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+
+  ###### interface
+
+  options = {
+
+  };
+
+
+  ###### implementation
+
+  config = {
+
+    environment.etc = {
+      # /etc/services: TCP/UDP port assignments.
+      services.source = pkgs.iana-etc + "/etc/services";
+
+      # /etc/protocols: IP protocol numbers.
+      protocols.source = pkgs.iana-etc + "/etc/protocols";
+
+      # /etc/hosts: Hostname-to-IP mappings.
+      hosts.text = ''
+        127.0.0.1 localhost
+        ::1 localhost
+      '';
+    };
+
+  };
+
+}

modules/module-list.nix

@@ -9,6 +9,7 @@
   ./environment/files.nix
   ./environment/links.nix
   ./environment/login
+  ./environment/networking.nix
   ./environment/path.nix
   ./environment/session-init.nix
   ./home-manager.nix