Prevent DOS Attack by CSF Firewall

Step 1 : Open the CSF configuration file /etc/csf/csf.conf

Step 2 : In that search for option called CT_LIMIT, by default it will be like CT_LIMIT=0 , change this to CT_LIMIT=90 ,here 90 is the max no.of connections from an IP to your server ( choose this value according to your server usage )

Step 3:Now search for option called CT_PORTS.This option is used to specify the port for which you want prevent DOS attack.Since our aim is to prevent the DOS attck to apache – port 80 , change CT_PORTS = “” to CT_PORTS = “80”