ConfigServer Firewall, also known as CSF, is a firewall configuration script created to provide better security for your server while giving you an advanced, easy to use interface for managing firewall settings. CSF configures your server’s firewall to lock down public access to services and only allow certain connections, such as logging in to FTP, checking email, or loading websites.
ConfigServer Firewall also comes with a service called Login Failure Daemon, or LFD. LFD watches your user activity for excessive login failures which are commonly seen during brute force attacks. If a large number of login failures are seen coming from the same IP address, that IP will immediately be temporarily blocked from all services on your server. These IP blocks will automatically expire, however they can be removed manually through the ConfigServer interface in WebHost Manager. In addition to removing IPs, CSF also allows you to manually whitelist or blacklist IPs in your firewall, as well as real-time monitoring for automatic IP blocks in LFD. Configuration details are covered in Managing Your CSF Firewall.