CSF is very helpful to allow or deny certain IP address with port in your Linux server. Based on your require block or allowing IP address with Port.

You don't desire to send email alert for specific user from the server, we can ignore that alert

We have already discussed about installing the ConfigServer firewall (CSF) in linux. The post you will be using most common commands and changes in the configuration file.

CSF (ConfigServer Security & Firewall) is an important tool for secured and managing your server and generally more advanced firewall options..