In many places and tutorials I see people add this line to their iptables:
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
And they do it only and only for "INPUT". What about OUTPUT and FORWARD?
For OUTPUT: Is it due to the fact that normally everything goes out (OUTPUT) will be allowed? (
For FORWARD: they assume that their firewall machine is also FTP server too(!) otherwise if FTP machine in behind the firewall we need another rule for FORWARD too.