Setting up an accounting bridge with OpenBSD

[Geoff White <geoffw_(_at_)_cybertribe_(_dot_)_com>]

Hit there,
I'd like to set up an accounting bridge.
in other words, I'd like to use an OpenBSD box (most likely a soekris)
As a bridge, that will do packet accounting of the traffic passing in one 
interface and out the other.  I'd like to set this up so that the box 
doesn't have need or have any IP addresses  on the bridging interfaces (the 
admin will occur on the third interface) can anybody point me to doc that 
would...

1) tell me the right way to ifconfig the interfaces for address-less 
operation, (in particular how to configure pf to input, log-count packets 
and pass them out another interface)

2) What accounting stuff to use (or do I roll my own)

3) Data display (I suppose I should use MRTG right?)


I'm trying to audit my traffic in my cage so I can see how much bandwidth 
each IP address is using, the end result will be to bill my customers that 
are using WAY too much bandwidth.



Thanks in advance.