از این طریق مسدود کردن آی پی روی پوشه ادمین هست و من خودم هنوزتست نکردم این هم متن آموزش
For added security, if your staff use fixed IP addresses, you can add even more protection to your admin area by restricting access to a specific set of IPs. This is done by creating a file with the name .htaccess within your WHMCS admin directory, with the following content:
order deny,allow allow from 12.34.5.67 allow from 98.76.54.32 deny from all
You can specify as many different allow from lines as you require. Or you can even allow entire IP subnet's by specifying just the first part of an IP, for example: "12.34.". This is called Htaccess IP Restriction.