Apache web server (.htaccess)

If your site runs on Apache, you can use an .htaccess file in your site's root directory to block an IP adderss or subnet from accessing your site.

One IP: Deny from 1.2.3.4
Two or more IPs: Deny from 1.2.3.4 1.2.3.5 1.2.3.6
Subnet: Deny from 1.2.3