Answer by Daniele Santi for Blocking ports with iptables

First of all, default policy for OUTPUT Chain is ACCEPT, so the last line:

ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED

isn't necessary.

Then the first line:

ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED

is redundant too because default policy for INPUT is ACCEPT.

Try with only these two rules and see if it helps:

iptables -A INPUT -d IP -m state --state ESTABLISHED,RELATED -j ACCEPTiptables -A INPUT -d IP -j DROP