TCP/IP
Let’s learn about the TCP/IP protocols, the nc(1) command-line utility, and the net package.
We'll cover the following...
TCP/IP protocols
TCP/IP is a family of protocols that help the internet operate. Its name comes from its two most well-known protocols: TCP and IP. TCP stands for transmission control protocol. TCP software transmits data between machines using segments, which are also called TCP packets. The main characteristic of TCP is that it is a reliable protocol, which means that it makes sure that a packet is delivered without requiring any extra code from the programmer. If there is no proof of packet delivery, TCP resends that particular packet. Among other things, TCP packets can be used for establishing connections, transferring data, sending acknowledgments, and closing connections.
When a TCP connection is established between two machines, a full-duplex virtual circuit, similar to a telephone call, is created between those two machines. The two machines constantly communicate to make sure that data is sent and received correctly. If the connection fails for some reason, the two machines try to find the problem and report it to the relevant application. The TCP header of each packet includes the source port and destination port fields. These two fields, plus the source and destination IP addresses, are combined to uniquely identify every single TCP connection. All these details are handled by TCP/IP as long as we provide the required details ...