update: There is no change in source code. But I know how to discover WiFi packet by Wireshark now. And I know how to set up a NetCat UDP Server.
1. Wireshark, we need configure password in 802.11 section to decrypt WiFi Packets.
2. UDP Server by NetCat:
                    $ nc -4 -u -l 2389
    Client :
                    $ nc -4 -u localhost 2389