Design And Implementation Of A Computer Network Protocol Stack Teaching System Based On Libpcap

With the increasing use of computer networks,society's demand for talents who can understand and are qualified to use computer networks is increasing day by day.In fact,computer networks have always been considered by the students of the Department of Computer Science and Technology as one of the difficult-to-master courses,because of the large structure and numerous communication protocols.From the perspective of practical teaching,adopt the method of let students manually implement the core functions and protocols of the computer network protocol stack one by one,to achieve the purpose of mastering computer networks.At the same time,we give a way to design and implement the computer network protocol stack,according to the TCP/IP five-layer model and a series standards of IETF RFC,which based on Libpcap.Due to Libpcap,system bypasses the network protocol stack of the operating system to directly receive and send packets from the network card,encapsulates it as the physical layer of the system,and then implements the link layer above the physical layer to accomplish the reception and transmission of frames.The network layer,transport layer,and Socket Interface layer are sequentially implemented to receive and send packets,segments and messages,respectively.The entire system is designed and implemented in an object-oriented manner.The programming interface is well-designed to minimize the degree of coupling between protocols,allowing students to understand and implement every single protocol step by step,master the computer network protocol stack gradually,and then master the computer networks.The system uses the virtual machine platform as the debugging and running environment,which not only reduces the trouble of the environment configuration,but also avoids the interference of the external network data.Starting from two actual application cases,the process of data sending and receiving between two hosts are analyzed in detail.Meanwhile,the experimental purpose gets much clearer through this way.