ipfw2 deep packet filtering

[Paul Bridger]

Hi

I'm trying to solve a problem with ipfw2, so would be grateful for help 
from anyone on the list with moving things forward.

I would like to understand if it's possible to discover the real MAC 
address of a packet that has been NAT'd by another device.  The scenario 
for using this would be for hosts on a wireless LAN that connect to a 
wireles router which NAT's their connection and then routes the packets 
to another LAN (across a wire) where a FreeBSD server performs firewall 
packet filtering via ipfw2.  As all the connections from the hosts on 
the wireless LAN have had their MAC and IP addresses NAT'd to that of 
the wireless router, it is difficult to distinguish between hosts, 
unless some form of deep packet inspection could be performed to 
discover the true MAC address.  Is this something that would be possible 
with ipfw2?

Thank you.

-Paul