一种基于邻居信任评估的虫洞防御机制

移动adhoc网是一种新型无线移动网络，具有无中心、自组织、拓扑结构变化频繁以及开放式通讯信道等特性，因此adhoc网络下的路由协议所面临的安全问题比有线网环境中更为严重。虫洞攻击就是其中的一种，能够对adhoc网络产生致命的影响。在这种攻击下，网络的路由机制将会紊乱，特别是那些依赖通过接收对方的广播报文进行邻居探测的路由协议。本文首先从虫洞形成的根源上入手，重新定义了邻居的概念，强调了邻居作为节点信息转发第一站的功能。然后根据邻居定义，引入简化的Marsh信任模型，将邻居的以往表现作为信任评估的经验来源，再通过具体公式对邻居关系做出判定。在具体的路由过程中，节点根据信任评估值选取高可信度的邻居作为下一跳的转发节点，从而避免虫洞攻击的危害。为了验证方法的可行性，本文将模型应用于OLSR路由协议中并在NS2中进行了仿真。

Defend against Wormhole Attack Based on Neighbor Trust Evaluation in MANET

Mobile Ad hoc Networks(MANET) is a new networking paradigm for wireless hosts. Because of self-organization, dynamic topology and openness of wireless links, the routing security in MANET is more seriously than in wired networks. Wormhole attack is one of the deadly attacks to the MANET, which is executed by two or more attackers by constructing a tunnel to replay the routing protocol. Under this attack, the routing protocol will not work, especially which rely heavily on the reception of broadcast packets as a means for neighbor detection.In this paper we give a new definition of neighbor which stresses the neighbor's function as "the first relay". Then we introduce Marsh model. By gathering data from the neighbor's events the node can evaluate the trustiness of its neighbor. From building the neighbor's trustiness, the false neighbor formed by wormhole attack will be scored lower value because of transmission failures events in MAC layer. When finding the route, the node will choose the higher trust value neighbor to relay the packet. We apply the model in the OLSR protocol and simulate it in NS2.