Sniffer is a software device that monitors the operation of network data. Protocol analyzer can be used not only for legal network management, but also for stealing network information.

Protocol analyzer can be used for network operation and maintenance, such as monitoring network traffic, analyzing data packets, monitoring network resource utilization, implementing network security operation rules, identifying and analyzing network data, and diagnosing and repairing network problems. Illegal sniffer is a serious threat to network security, because it is essentially undetectable and easy to be inserted everywhere, so network hackers often use it as an attack weapon.

The sniffer was originally introduced by Network General and owned by Network Associates. Recently, Network Associates decided to open another sniffer product division, which was set up as a private enterprise and renamed Network General. Now the sniffer has become the trademark of the characteristic products of the network corporation. Because of the wide use of professionals, sniffers are widely used in all products that can capture and analyze network traffic.