I known i can do above by using "built-in" internet sharing(System Preference -> Sharing -> internet sharing & wi-fi setting).
but the "built-in" internet sharing lacks some essential functions like bandwidth limit, filter communication between NAT clients and remote server...
i do the essential functions by using PF firewall as NAT, and add rules to NAT clients to limit their bandwidth plus filter their connection.
And now, the problem is how can i make my wi-fi adapter act as wireless access point(AP), so that the NAT clients can connect to my "LAN" networks and apply my rules to them. what commands exist in OS X can do this?