Linux bridged firewall - monitor traffic & block IP

Hi All,

I successfully configured a DEBIAN Lenny bridged firewall
using ebtables.
The bridged interface is br0.
The ethernet interface are eth0 & eth1 respectively.

All the traffic are transparently passing my firewall but i need to find & block temporarily the bandwidth abusers.
Can someone help me how to block ip temporarily using IPTABLES ?

This may point you in the right direction:

Linux Network IP Accounting