Meanwhile, On The Server...

The server creates a socket that is not connected anywhere. Instead, it binds the socket to its predefined port, and asks the operating system to listen for incoming connections:

 struct sockaddr_in sa; /* Server's address struct  */

 /* initiate machine's Internet address structure   */
 /* first clear out the struct, to avoid garbage    */
 memset(&sa, 0, sizeof(sa));
 /* Using Internet address family                   */
 sa.sin_family = AF_INET;
 /* copy port number in network byte order          */
 sa.sin_port = htons(13);
 /* we will accept connections coming through any IP */
 /* address that belongs to our host, using the     */
 /* INADDR_ANY wild-card.                           */
 sa.sin_addr.s_addr = INADDR_ANY;