Discarding Packets from LAN Programatically

[suezkhan]

:oops:somebody plz let me know how i can stop or discard a packet over LAN using C. i mean is there any liberary or Header file which should i use in order to discard suppose SYN packets not to reach a specific application.
actually i am working on a firewall type application which would discard either TCP or othere packets on the basis of a policy. so is there any way out here to deal such situation..
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