Pppoe padi frames and ipfw

[aldo]

we used to have a pptp server running inside a captive portal this worked great as we ammended the captive portal to allow tc p 1723 and gre
and all worked fine.

now in all or wisdom we want to add the pppoe server a captive portal together on the same interface.

i had a look over the present configuration for ipfw and i can't understand why the padi frames dont seem to get replied to

can any one shed some light on how this could be achieved. I would not have though it was possible to stop this traffic.
there are no special rules in the pf to allow this traffic so i am a bit perplexed as to how we could ammend the captive portal to
suit our present needs ???