There are plenty of solutions for blocking an IP address from accessing your website.

How to block IP addresses from your site:

• http://goo.gl/2HL5gv (.htaccess)
• http://goo.gl/PhZ2BU (Hostgator)
• http://goo.gl/eyjkpN (Bluehost)
• http://goo.gl/UPJfis (GoDaddy)