Based on the analysis of the covert channel＇s working mechanism of the internet control message protocol （ICMP） in internet protocol version 4 （IPv4） and Internet Protocol version 6 （IPv6）, the ICMP covert cha...Based on the analysis of the covert channel＇s working mechanism of the internet control message protocol （ICMP） in internet protocol version 4 （IPv4） and Internet Protocol version 6 （IPv6）, the ICMP covert channd＇s algorithms of the IPv4 and IPv6 are presented, which enable automatic channeling upon IPv4/v6 nodes with non-IPv4-compatible address, and the key transmission is achieved by using this channel in the embedded Internet terminal. The result shows that the covert channel＇s algorithm, which we implemented if, set correct, the messages of this covert channel might go through the gateway and enter the local area network.展开更多
Participant observation is often applied in qualitative research to help researchers obtain the overall,useful data,which will lead researchers to gain the knowledge that the academia tries to.However,different levels...Participant observation is often applied in qualitative research to help researchers obtain the overall,useful data,which will lead researchers to gain the knowledge that the academia tries to.However,different levels of participant observation,mainly the covert and overt participant observation,have aroused heated discussions among scholars.Field researchers are faced with many problems when doing research,such as whether they should be a covert participant observer or an overt one;what the research will get when they are in different roles and etc.In order to solve those problems,this article tries to provide some effective methods to field researchers,especially to the new ones.This article mainly talks about two types of participant observation:covert and overt participant observation;tries to explore the issues caused by them and the strategies to help researchers deal with such issues.Finally,in qualitative research,when faced with different fieldworks,researchers should adapt themselves to choosing participant roles flexibly and appropriately.展开更多
现有存储型网络隐蔽信道的研究主要根据不同协议中不同字段来隐藏信息。在众多协议中,例如TCP、UDP协议,对其研究较多,而OSFP使用广泛却在国内研究较少。针对OSPF协议下的Hello报文进行分析可以构建网络隐蔽信道的字段。从所有可能字段...现有存储型网络隐蔽信道的研究主要根据不同协议中不同字段来隐藏信息。在众多协议中,例如TCP、UDP协议,对其研究较多,而OSFP使用广泛却在国内研究较少。针对OSPF协议下的Hello报文进行分析可以构建网络隐蔽信道的字段。从所有可能字段中选择Authentication、Router Dead Interval和Neighbor三个字段分别使用随机值模式、值调制模型和序列模式进行构建三种隐蔽信道,利用微协议技术优化信道,并将三种隐蔽信道组合成一个传输速率更高的隐蔽信道模型。经过验证,该模型具有一定的可行性和隐蔽性,可为存储型网络隐蔽信道构建技术提供一定的理论支持和技术支撑。展开更多
基金Supported by the National Natural Science Foun-dation of China (90104005 ,66973034)
文摘Based on the analysis of the covert channel＇s working mechanism of the internet control message protocol （ICMP） in internet protocol version 4 （IPv4） and Internet Protocol version 6 （IPv6）, the ICMP covert channd＇s algorithms of the IPv4 and IPv6 are presented, which enable automatic channeling upon IPv4/v6 nodes with non-IPv4-compatible address, and the key transmission is achieved by using this channel in the embedded Internet terminal. The result shows that the covert channel＇s algorithm, which we implemented if, set correct, the messages of this covert channel might go through the gateway and enter the local area network.
文摘Participant observation is often applied in qualitative research to help researchers obtain the overall,useful data,which will lead researchers to gain the knowledge that the academia tries to.However,different levels of participant observation,mainly the covert and overt participant observation,have aroused heated discussions among scholars.Field researchers are faced with many problems when doing research,such as whether they should be a covert participant observer or an overt one;what the research will get when they are in different roles and etc.In order to solve those problems,this article tries to provide some effective methods to field researchers,especially to the new ones.This article mainly talks about two types of participant observation:covert and overt participant observation;tries to explore the issues caused by them and the strategies to help researchers deal with such issues.Finally,in qualitative research,when faced with different fieldworks,researchers should adapt themselves to choosing participant roles flexibly and appropriately.
文摘现有存储型网络隐蔽信道的研究主要根据不同协议中不同字段来隐藏信息。在众多协议中,例如TCP、UDP协议,对其研究较多,而OSFP使用广泛却在国内研究较少。针对OSPF协议下的Hello报文进行分析可以构建网络隐蔽信道的字段。从所有可能字段中选择Authentication、Router Dead Interval和Neighbor三个字段分别使用随机值模式、值调制模型和序列模式进行构建三种隐蔽信道,利用微协议技术优化信道,并将三种隐蔽信道组合成一个传输速率更高的隐蔽信道模型。经过验证,该模型具有一定的可行性和隐蔽性,可为存储型网络隐蔽信道构建技术提供一定的理论支持和技术支撑。
