How to install csf:
wget http://www.configserver.com/free/csf.tgz
tar zxvf csf.tgz
cd csf
./install.sh
To test all the iptable modules are available
./csftest.pl
If you are running apf_bfd firewall, it has to be removed for csf works
./remove_apf_bfd.sh
To configure csf config file to implement firewall as per our need
vi /etc/csf/csf.conf
TESTING = “1″
(We will change it to zero “0″ when we finished and sure we have configured correctly)
TCP_IN = “20,21,22,25,53,80,110,143,443,465,587,993,995″
TCP_OUT = “20,21,22,25,53,80,110,113,443″
UDP_IN = “20,21,53″
UDP_OUT = “20,21,53,113,123″
(Put your all ports which you want to be open on your server for incoming & outgoing traffic seperated by comma)
PORTFLOOD = “80;tcp;20;5″
(To protect your server any specific port from DOS attacks, you can define it in PORTFLOOD tag. By default its empty and i did like to limit 20 connections per 5 sec to port 80 (webserver))
After this save the file and restart the csf service
# /etc/init.d/csf start
If you completed with configuation and sure that every rules is implemented correctly then change Testing from 1 to 0 for run CSF permanently.
TESTING = “0″
and restart the service again to activate it
/etc/init.d/csf restart
