Blocking forwarding of packets in WLAN

[Claudio Lavecchia <Claudio.Lavecchia@eurecom.fr>]

Hello you ppl,
 
I am a real newbie to iptables/ipchains/netfilter issues, so please if 
any of you can help me, please consider my illetteracy.
I have a really simple question for which I did not find an answer 
browsing the website.
 
If I understood correctly there are no C APIs to iptables and this leads 
me to troubles: I am writing a linux daemon that monitors network 
traffic and does something when some conditions occur. I work with 
mobile ad-hoc networks where each node acts as a relay for other nodes 
traffic, so the background are WLANs.
I need to write a C function that blocks forwarding of packets that come 
from a given node of the network, identified by its MAC address.
 
Prototype for my function is then:
 
void block_forwarding(char * MAC_address);
 
Is this feasible someway using iptables? Can anyone give me a precise 
hint on how to do that? I would be truly grateful if someone could help me.
 
Thanks
 
Claudio