## 1 Introduction
In summary, this paper makes the following novel contributions:  
* Node Address: For the problem of missing trusted third-party institutions in the process of switching from centralized to decentralized networks, and the problem of wasting resources by using a network-wide consensus approach as a trust module. An algorithm for generating node addresses in overlay networks is proposed. The address information either shows or implicitly contains the logical address in the DHT, the identifier for node identification and the cryptographic seed information, and the difficulty of address generation can be adjusted according to the computing power of the whole network when generating addresses. It achieves malicious node prevention in P2P networks and data security assurance without relying on centralized trusted institutions. * Routing: For existing decentralized network organization methods using a broadcast scheme to find nodes can cause routing bottleneck problems. A decentralized networking scheme based on overlay network containing unreachable nodes is proposed, which implements logical Node ID-based addressing routing between unreachable nodes through a DHT structured scheme. Compared with the broadcast scheme, it improves the node finding efficiency and consumes fewer resources. The entire network does not depend on trusted third-party entities, so it eliminates the performance bottleneck of centralized nodes and preserves the decentralized nature of the original network. * Communication: For the problem that the existing scheme requires a third node of full process assistance or network-wide consensus to transmit data wasting network resources when the two end nodes communicate, the transmission model of data flow under overlay network is proposed, and the data transmission channel is established using two methods, direct connection establishment and third-node relay, according to the type of unreachable nodes at both ends. After the establishment, the two nodes can communicate freely with each other without any limitations such as the amount of data to be transmitted. The scheme in this paper can minimize the consumption of additional network resources compared to existing schemes as long as the network conditions are met. * Evaluation: The three parts of node address generation, virtual network, and communication channel establishment are evaluated in terms of their operational effectiveness by real cluster servers, and their usability and security are verified. Compared with existing centralized and decentralized solutions, our scheme does not rely on any third-party central entity in terms of trust and data transmission, and achieves efficiency improvement in virtual networking and data transmission. It better ensures the privacy of users and realizes device democracy while taking into account the transmission efficiency. The remaining chapters are organized as follows. In the second part, we describe the work related to unreachable node communication solutions in centralized and decentralized networks. The third part explains our model overview, threat model and requirements. The fourth part elaborates the detailed implementation of our model. The fifth part includes relevant experiments on our proposed model and analysis of the results. The sixth part is an analysis and discussion of the experimental results and the role played by each part in the whole. Finally, the seventh part summarizes our model and the results obtained.