Pass through mac address on captive portal (Spoof mac address)

[g33k]

greeting all,

i'm very newbie in this pfsense firewall and network security as well. i just wan to ask the expert out there a few questions.. Actually i have a situation, where i enable captive portal on my network (Access Point  with no authentication). In my network there have 3 laptop connect via wireless. all that 3 laptop i use
"pass-through mac address" method in order for them to connect to the internet. The problem i face here is, when one of this 3 laptop mac address been spoof , he(attacker) be able to by pass the authentication of the captive portal. i realize that the attacker use the mac-spoofing technique to manipulate his original mac addresss into one of this 3 wireless laptop mac address.  so, my question here is, how do i prevent this kind of technique?
is there any configuration should i implement on pfsense?
is there any expert suggestion?
pls… help me.. i really need ur help dude....  :'( :'( :'(

ur feedback are highly appreciated. Thanx!!  ;)

[Still]

Implementing access control based on MAC addresses alone is a no no IMO. , you better use the simple user manager in the captive portal itself, assign each client a username and pass and thats it, preferably to be a https login page..

my 2cents.