Use localhost SSH for password-less NixOS rebuilds

Makefile

@@ -1,5 +1,6 @@
 switch:
-	sudo nixos-rebuild switch --flake path://$(PWD)#
+	nixos-rebuild switch --target-host root@localhost \
+    --build-host root@localhost --flake path://$(PWD)#panacea
 
 update:
 	nix flake update --commit-lock-file

modules/networking.nix

@@ -144,4 +144,15 @@ in
       iptables -t mangle -D nixos-fw-rpfilter -p udp -m udp --dport ${wireguard_port} -j RETURN || true
     '';
   };
+
+  # Enable localhost SSH
+  services.openssh = {
+    enable = true;
+    openFirewall = false;
+    startWhenNeeded = true;
+    settings = {
+      PermitRootLogin = "without-password";
+      PasswordAuthentication = false;
+    };
+  };
 }