refactor: complete overhaul

systems/server/config/networking.nix

@@ -0,0 +1,39 @@
+{
+  lib,
+  flake,
+  ...
+}: let
+  inherit (flake.config.machines.devices) server;
+in {
+  networking = {
+    hostName = server.name;
+    networkmanager.enable = true;
+    nftables.enable = true;
+    useDHCP = lib.mkDefault true;
+    firewall = {
+      enable = true;
+      allowedTCPPorts = [
+        22 # SSH
+        25 # SMTP
+        139 # SMTP
+        587 # SMTP
+      ];
+    };
+  };
+  services = {
+    avahi = {
+      enable = true;
+      openFirewall = true;
+      nssmdns4 = true;
+      publish = {
+        enable = true;
+        userServices = true;
+      };
+    };
+    sshd.enable = true;
+    openssh = {
+      enable = true;
+      settings.PasswordAuthentication = false;
+    };
+  };
+}