中文摘要：

软件定义网络（Software-defined Networking,SDN）是实现传统网络体系中的应用层、控制层和数据层解耦的一种新型网络架构。本文研究该网络环境下的隐蔽通信问题,基于OpenFlow控制器与交换机之间的交互特性,提出一种基于响应报文次序组合调制的多流时间式隐信道设计方案,该方案利用控制器与多交换机之间的链路层发现协议（Link Layer Discovery Protocol,LLDP）响应报文到达的次序分布构建组合累计分布函数并调制秘密信息。仿真实验结果表明所提方案具有较好的隐蔽性和鲁棒性。

英文摘要：

Software-defined networks（SDN）,different from traditional network,is a new network architecture with the separation of application layer,control layer and data layer. In this paper,covert communication in SDN is studied,a multiple-flow timing channel scheme is proposed based on the interaction characteristic between Open Flow controllers and switches,which utilizes the arriving time of reply packets in link layer discovery protocol to transmit secret messages. Simulation results show that the proposed scheme can achieve well covertness and robustness.