gistfile1.php

<?php
$allow = '192.168.1.1';

if ( ! isset($_SERVER['REMOTE_ADDR']) OR ( $_SERVER['REMOTE_ADDR'] != $allow ) ): ?>

    <h1>Not yet!</h1>

<?php 
else:

/**
 * Front to the WordPress application. This file doesn't do anything, but loads
 * wp-blog-header.php which does and tells WordPress to load the theme.
 *
 * @package WordPress
 */

/**
 * Tells WordPress to load the WordPress theme and output it.
 *
 * @var bool
 */
define('WP_USE_THEMES', true);

/** Loads the WordPress Environment and Template */
require( dirname( __FILE__ ) . '/wp-blog-header.php' );

endif;