Create a .htaccess file and add the following code--changing the IPs to suit your needs--each command on one line each:
deny from 188.8.131.52
deny from 012.34.5.
allow from all
You can deny access based upon IP address or an IP block. The above blocks access to the site from 184.108.40.206, and from any sub domain under the IP block 012.34.5. (012.34.5.1, 012.34.5.2, 012.34.5.3, etc.)
You can also set an option for deny from all, which would of course deny everyone. You can also allow or deny by domain name rather than IP address (allow from .friendsite.com works, etc.)
Grab your new Web Hosting package today and receive a FREE cPanel migration. All plans come with our 30 Day Money Back and 99.9% Uptime Guarantees!