Abstract: The eclipse attack is a malicious attack method in the blockchain system. Attackers achieve the purpose of deception and control by monopolizing the network of victim nodes. It is known from actual  blockchain applications that there is no good way to defend against eclipse attacks. Therefore, in order to solve this problem, a dynamic defense model for solving eclipse attacks based on the POW consensus blockchain system is designed, which is based on mutual evaluation mechanism between nodes. Specifically, based on kademlia algorithm, it evaluates and stores a level for every node on the result of mutual evaluation between clients to design a level evaluation mechanism. The nodes select normal peer nodes as their neighbors and avoid malicious nodes according to the relation between level value and level limitation value. Experiments have proved that this method can effectively resist eclipse attacks. This method improves a series of defense strategies previously proposed. It does not need to change the protocol and network of the blockchain system. It can successfully resist eclipse attacks with a high probability, and the overhead  generated by the model is also very small, which is very suitable for actual deployment.

Key words: eclipse attack, POW consensus, dynamic defense, level value, blockchain protocol

摘要： 日蚀攻击是区块链系统中一种恶意攻击手段，攻击者通过垄断受害节点网络，达到欺骗、控制目的。从实际区块链应用中得知，目前为止还没有防御日蚀攻击的好方法，因此为了解决该问题，设计了一种针对POW共识区块链系统的日蚀攻击动态防御模型，其基于节点间互相评价机制。具体来说，通过综合客户端之间互相评价的结果，基于kademlia算法和设计的等级值评估机制，为每个节点评估、存储一个等级，节点根据等级值和等级限定值之间的关系选择正常对等节点作为邻居，以避免恶意节点。经过实验证明，该方法可以有效抵御日蚀攻击。该方法改进了先前提出的一系列防御策略，无需对区块链系统协议、网络等进行更改，能够较高概率地成功抵御日蚀攻击，并且模型产生的开销也很小，非常适合实际部署。

关键词: 日蚀攻击, POW共识机制, 动态防御, 等级值, 区块链协议