Ban people by IP address
Banning people from your website results in a loss of traffic but there are certain situations where this is necessary. For example, if you run a forum on your website and someone is causing trouble all the time or someone is using an automated program to fill in your contact form that results in you receiving annoying spam mail.
Ban through .htaccess
You can ban single IP's or IP address ranges.
Banning single IP addresses
For each IP address you want to ban, put deny from followed by the IP address.
Banning IP ranges
Works the same way as banning individual IP addresses, but put the range instead of the Individual IP address.
where http://www.site.com/page.html is the URL they will be redirected to.
NOTE: To ban people from an entire Internet Provider find out the IP range that that Internet provider uses and include it in your .htaccess file.
NOTE: Be careful with IP address banning. Make sure you ban only the bad guys and not legitimate traffic!