When you send out a packet using raw sockets, you basically construct the packet inside a buffer, so whenyou need to send it out, you simply give the operating system the buffer and the size of the packet. Workingdirectly on the buffer is not easy, so a common way is to typecast the buffer (or part of the buffer) intostructures, such as IP header structure, so you can refer to the elements of the buffer using the fields ofthose structures. You can define the IP, ICMP, TCP, UDP and other header structres in your program. Thefollowing example show how you can construct an UDP packet: