You all know that now configserver decided to close down its business and now CSF firewall is no more available by them. But all old servers which already have it installed can still use it. Although new updates are not available but all old available functions will keep functioning until its supported in recent versions of cPanel or Directadmin servers etc.
In addition to that if you want to install it on your new cPanel or Directadmin server then follow these commands to install latest version of ConfigServer CSF Firewall.
Navigate to the /usr/src directory:
cd /usr/src
Remove any previous CSF archive (if it exists):
rm -f csf.tgz
Download the CSF archive.
wget https://xoftmade.net/csf.tgz
Extract the CSF archive.
tar -xzf csf.tgz
Navigate into the extracted CSF directory.
cd csf
Run the installation script.
sh install.sh
After installation you will receive a confirmation message that CSF firewall is now installed. Now you have to login your WHM server as root user and go to CSF Firewall, as default firewall becomes in Test mode. So to enable the firewall go to CSF Firewall Configurations and disable the test mode.