Filtering Bridge Traffic on layer IP

[antonio.tommasi at unile.it]

Hi to all,
i've configured a freebsd box bridge. This machine have 2 ethernet card
and i configure them with one ip address. I also configure firewalling
with ipfw on this box.
Is there a possibility to filter bridged traffic with ipfw on layer IP?
I need to allow some machine with some ip to access to internet and the
other not.
I cannot implemet nat-firewalling because i need to not change actual ip
configuration on my lan.
Have you any suggestion?
Thanks in advance
Antonio