1) cd /usr/local/src/
2) download csf: wget http://www.configserver.com/free/csf.tgz
3) tar -xzf csf.tgz
4) goto the csf directory : cd csf
Once it is installed, you can either edit the configuration file from WHM >> Plugins >> “Config Server Security and Firewall” option.
If you don’t have WHM/cPanel on your server, the configuration and all the CSF related files are stored under /etc/csf directory. You need to edit the csf configuration file /etc/csf/csf.conf and make the changes as per your wish.
Once you make the required changes to your CSF configuration file and are sure, you are not going to block yourself out, change the following from
TESTING = “1″
TESTING = “0″
and restart the csf firewall using csf -r command.