Filter ips

[nunezj@xxxxxxxxxxxxx]

Hi everyone

       I have some problems when I want to filter some ips in  my network

 I put this rules in the my script:

 iptables -A INPUT -s 192.168.0.5/32 -d 0/0 -p tcp --dport 20,21 -j DROP

 but it doesn't work. The same I put in the Output rules but it doen't
work....

  How can I make this filter?

regards,

             Jorge Enrique