基于网络计数器的隐蔽信道

为了避免基于存储的网络隐蔽信道通过操纵报文头部实现信息的隐蔽传输的局限性，提出利用网络计数器作为存储体构建隐蔽信道，编码者和译码者之间不需要建立直接的网络连接，从而躲开防火墙和各种入侵检测系统的监管.把信道建模成有噪声的一般离散无记忆信道，并用C语言实现了离散信道容量的迭代算法计算信道容量，利用多个计数器并行传输多位信息等方法提高传输率，采用伪随机序列对发送信息进行扰码的技术增强信道的隐蔽性和抗噪性.通过实验分析几种参数和信道性能的关系，结果表明了隐蔽信道的可行性.

Research of Covert Channels Based on Web Counters

To avoid the limits of previous network storage covert channels which transmit covert information generally through packet head manipulation, a new idea was presented by using the plentiful, public Web counters for storage to construct a covert channel. Therefore, the encoder and the decoder do not need to establish a direct network connection, thus avoid the surveillances of many firewalls and intrusion detection system (IDS). A general noisy discrete memoryless channel (DMC) was modeled and the iteration algorithm of the DMC’s capacity was realized by C program language to compute the channel capacity. Several methods such as using multiple counters to increase rate were presented. One technique using pseudo random sequence to scramble the sending information was used to enhance the covertness and the anti noise capability of the channel. The relationships between parameters and channel’s performance were analyzed through experiment. The result shows that the covert channel is feasible.