Creating and Using UDP Sockets
As shown in the example of the last section, UDP datagrams are sent and received via sockets. However, unlike TCP sockets, there is no step in which you connect() the socket or accept() an incoming connection. Instead, you can start transmitting and receiving messages via the socket as soon as you create it.
UDP Socket Creation
To create a UDP socket, call socket() with an address family of AF_INET, a socket type of SOCK_DGRAM, and the UDP protocol number. The AF_INET and SOCK_DGRAM constants are defined and exported by default by the Socket module, but you should use getprotobyname(" udp ") to fetch the protocol number. Here is the idiom using the built-in socket() function:
socket(SOCK, AF_INET, SOCK_DGRAM, ...