A good way to protect you from unwanted visitors is using an IP-Filter. You can do this using PHP or a configuration-file for your webserver. I like the PHP way, because it is possible kind of server. Now only you or somebody using your IP-Address will be able to see the site. Everybody else is forwarded to another site. Just copy and paste the following code at the beginning of your index.php-file in the WordPress root folder on the server:

/*** The IP-protectection for development time ****/
$userip = ($_SERVER['REMOTE_ADDR']); // The IP of the visitor
$ip = '127.0.13.37'; // Enter your IP here

if ($userip != $ip) {
	header("Location:http://www.company.old/"); // the URL of another site, take Google for example
} else{
	// do nothing, go on to wordpress
}

Another way is using a server configuration, like .htaccess on Apache:

Order deny,allow
deny from all
allow from 94.136.31.33

Somebody who knows your IP-Address still can get in, so if security is really important, you should add some more security measures.