摘要：Unknown network bitstream identification is the foundation for managing the relevant network and it can also support the further study on network countermeasures techniques.First, the main issues of unknown network bitstream identification such as encrypted and unencrypted bitstream identification,characteristic parameters mining of bitstreams,bitstreams clustering, frequent sequences mining and protocol format analysis are analyzed.Then, according to the internal relations of these issues, a multilevel scheme for unknown network bitstream identification is proposed,and the corresponding schemes are also provided to specific issues. Finally,while the relevant experimental results are presented, future research directions are discussed.The related research results have significance as reference for conducting further research on unknown network bitstream identification.%未知网络比特流识别是对相应网络实施有效监管的基础，也可为进一步开展相应网络中的对抗技术研究提供支持。首先，分析了未知网络比特流识别过程需要解决的加密与未加密比特流识别、比特流特征参数提取、比特流聚类、比特流频繁序列挖掘及协议格式分析等关键问题；同时，根据相关问题的内在联系，提出了一种多级的未知网络比特流识别方案，并针对具体问题给出了对应的解决方案；最后，在展示相关实验结果的基础上，阐述了进一步的研究方向。相关成果对深入开展未知网络比特流识别技术研究具有一定的借鉴意义。
