How to make ipfw consider MAC-IP match?

[Igor Robul]

Artem Kuchin wrote:

> Hi!
>
> I have a table with ethernet (MAC) addresses matching IPs. It is
> used to build dhcp config file. But regardless of that any user can
> assign his neighbour ips while that pc is turned off and use it to
> access internet. The local ips are 192.168. and are behind natd.
> I am running 5.3-STABLE and have heard that ipfw2 can in someway
> use MAC addresses, but how do I setup ipfw in such a way that

I use Samba computer names for this. If user changes computer name, then 
he will not be able login to domain, and will not able do his job. I 
dont restrict very much access to Internet, just do accounting.
It is easy  modify my setup to use user names instead of computer names. 
Accounting is done with trafd and 2 or 3 shell scripts. Maybe you need 
something like this?
If you wish, I can post my scripts.