Tip: if you cannot see the .htaccess file in cPanel File Manager, enable Show Hidden Files (dotfiles) in File Manager settings.
To block a specific IP address from accessing your website, add the following rules to the site's .htaccess file:
order allow,deny
deny from IP-ADDRESS
allow from allReplace IP-ADDRESS with the address you want to block, then save the file. These directives use Apache 2.2 syntax; on servers using Apache 2.4, use:
Require all granted
Require not ip IP-ADDRESS
