Snort is an open-source network intrusion detection and prevention software. It uses a variety of methods to detect, including rule-based detection, anomaly detection, heuristic analysis http://www.aliyun.com/zixun/aggregation/10374.html "> network traffic detection." Its working mode includes: sniffer, data packet recorder, network intrusion detection system.
The sniffer mode simply reads packets from the network and displays them as a continuous stream on the terminal. The packet logger mode logs the packet to the hard disk. Network intrusion detection mode is the most complex and configurable. We can have snort analyze the network data stream to match some of the user-defined rules and take some action based on the test results.
Snort version 2.9.1 adds new features, including major preprocessing and rule options, and fixes multiple bugs.
Software Information: http://www.snort.org/
Download Address: Http://www.snort.org/snort-downloads