监听接口和跟踪所有的TCP会话的发现

Listens on an interface and tracks all TCP sessions it sees. In the normal case only general information is carried forward (seq#/ack#, negotiated SYN/ACK features, etc). Whenever an anomaly happens - that is a duplicate ACK, SACK response, out-of-order segment, retransmission or others; it captures those packets into a tcpdump file for later deep inspection with Wireshark or other tools. This tool is to be deployed on live hosts and passive monitors to collect reliable condensed data about real-world behavior of TCP on the global Internet. Currently no such quantitative data exist and contribution of such a tool that can be easily run is a significant step in helping further development of TCP algorithms.