Port the old system to a more advanced setup.

config/config.sample.php

@@ -0,0 +1,15 @@
+<?php
+
+return [
+    /**
+     * The security works by checking if the request is made from an authorized IP-address.
+     *
+     * The address is configured as an IP-address and a subnet mask. In order to verify the entire IP-address, specify
+     * 32 for the mask. This option only supports IPv4 for obvious reasons.
+     */
+    'security' => [
+        'mask' => 8,
+        'address' => '127.0.0.1',
+    ],
+    'state_file' => __DIR__ . '/open.flag',
+];