A Study And The Realization Of The Sniffing Mode Under Switched Network Surroundings

Nowadays, with the development of network, sniffing has been a very familiar word to us, the function of which is like a two-edged sword. On the one hand , sniffer can be used as an attack tool by hackers;0n the other hand , it is an important means to do network anylysis and management. As the popular use of swithboard, the former mode, under network sharing has been replaced by another mode, which happens in the swithed network surroundings. As everyone knows, because of consideration on security, there are many problems existing in TCP/IP protocols .As a member of TCP/IP protocol ,ARP protocol also meets this kinds of leat .However, the sniffing mode under switched network surroundings just takes advantage of this leak to perate. The leak is also used as a main attack method by hackers. Therefore, it is worthy to do a deep research on sniffing. The aim of this thesis is to analyze the leak of ARP protocol, to point out how to sniff by using this leak and how to prevent sniffing.This thesis firstly introduces the current situation of sniffing and some basic knowledge one network security. in chapter two , the author analyzes the leak existing in ARP protocol and points out how to use it to attack, In chapter three , the author Introduces some data structres and core functions used in Winpcap and Libnet,in chapter four , the author analyzes each function of sniffer realizing program and makes a conclusion that this program mode has been improved. In the end , the author gives several suggestions for sniffing.