Detection And Defense Of Malicious Controllers In SDN Controller Cluster

In recent years,Software Defined Network(SDN)technology has developed rapidly.SDN realizes decoupling of the control layer and the data layer.The control layer is responsible for controlling the network and maintaining a global network topology view.The data layer is responsible for packet forwarding.The decoupling of the control layer and the data layer simplifies the management of the network and realizes the programmability of the network,which provides the convenience for the deployment of new network services and the rapid innovation of the network.In SDN networks,the control layer is the core of the entire network.On the one hand,the control layer needs to be responsible for managing the switching devices of the data layer.On the other hand,the control layer needs to provide accurate network status information to the application layer.Its security and reliability are very important.In order to improve network reliability when building a large-scale SDN network,the control layer is usually composed of SDN controller cluster.However,the existence of malicious controllers in the SDN controller cluster poses a serious threat to the security of the SDN network.Based on this background,this thesis implements the detection and protection against malicious behaviors of malicious controllers in the SDN controller cluster,mainly including the protection of the network topology view of the SDN controller cluster and the protection of malicious flow rules issued by malicious controllers.Firstly,due to the insufficient security mechanism on east-west bound interface in original cluster solution of SDN,a malicious controller can destroy the network topology view of the controller cluster through the east-west bound interface.This thesis proposes a topology security cluster scheme based on the Byzantine quorum system.This scheme implements the verification function of the network topology update message on the east-west bound interface of the controller cluster,and then builds a Byzantine quorum system in the cluster to ensure the security of the network topology view of the cluster when malicious controllers exist.When a controller in a cluster updates the topology view of the cluster,it needs to acquire a quorum's verification to complete.In addition,the solution can provide the traces of each controller's update operation for the cluster's network topology view to locate malicious controllers.Secondly,due to the insufficient protection of malicious flow rules on the data layer in the SDN network,the malicious controller in the SDN controller cluster can issue malicious flow rules through the south bound interface to destroy the data layer packet forwarding logic.This thesis proposes a detection and prevention scheme for malicious flow rules based on P4.This scheme classifies malicious flow rules,and uses the data plane programmable features provided by P4 language on the data layer to implement the detection of malicious flow rules on the data layer's switching devices for different types of malicious flow rules.What's more,the scheme provides a method for locating malicious flow rules for network administrators.According to the mapping relationship between the controller and the switch in the SDN network,the network administrator can locate the malicious controllers in the SDN controller cluster,thereby realizing the detection and prevention of malicious flow rules issued by the malicious controller in the SDN controller cluster.Finally,this thesis implements extensive experiments to prove the feasibility of the proposed schemes.The experiments show that the proposed schemes are highly efficient and can effectively detect and prevent malicious controllers in the SDN controller cluster from destroying the cluster network topology view and issuing malicious flow rules.The schemes can improve the security of the SDN controller cluster.