Covert channel is a transfer scheme which can leak confidential information in information system covertly. Network covert channel is crucial to network data security protection and even to cloud computing platform' s, and becomes the focus of the information security field. In this paper, we present an example of network time covert channel which is based on the time intervals of SSH packets. The SSH protocol-based interval characteristics are analysed and a new detection approach based on Bayesian classifier is designed. The experiment results show that the covert channels can be detected at the accurate rate of 95% using this approach, which shows that the detection performance is excellent.%隐蔽信道是一种能够以难以察觉的方式泄漏信息系统机密信息的通信方式.网络隐蔽信道是信息安全领域的研究热点,对保护网络数据安全以及于云计算平台数据安全至关重要.提出一种基于SSH数据包间隔时间的网络时间隐蔽信道实例；基于SSH协议的时间间隔特征,设计一种基于Bayesian分类器的检测方法；实验结果证明该检测方法能够达到95％的准确率,具有很好的检测性能.
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