(Snort has three working modes: sniffer, packet recorder and network intrusion detection system. Sniffer mode simply reads packets from the network and displays them on the terminal as a continuous stream. The packet recorder mode records packets to the hard disk. The network intrusion detection mode is the most complex and configurable. We can let snort analyze the network data flow to match some user-defined rules, and take certain actions according to the detection results. This document contains the following attachments:)