CSF stands for Configserver security and firewall. CSF is a configuration script built to provide better security to servers , at the same time providing a large number of configuration options and features to configure and secure with extra checks to ensure smooth operation. It helps in locking down public access and to restrict what can be accessed like only e-mails or only websites, etc. To add more power to this, it comes with a Login Failure Daemon (LFD) script that runs all the time to scan for failed attempts to login to the server to detect bruteforce-attacks.