Please refer the following steps to install CSF firewall on your server:
Step a : SSH into your server
Step b : Download CSF from “https://www.configserver.com/free/csf.tgz”
wget https://www.configserver.com/free/csf.tgz
Step c : You must now extract the downloaded file
tar -xzf csf.tgz
Step d : After the extraction, you must proceed with installing csf using the following command
cd csf
sh install.sh
You can check it under the WHM’s menu >> Plugins >> ConfigServer Security&Firewall.