隨著 IoT 設備的成長，以及資安研究的發展，許多已經安裝在世界各地的 IoT 裝置被發現漏洞，而其中一部分甚至無法進行更新、補丁，最終被駭客所利用，組成殭屍網路，進而對網路服務商進行分散式阻斷服務攻擊（Distributed Denial of Service，DDoS），使網路服務商暫時中斷或停止服務，讓正常用戶無法存取，進而造成服務商與使用者在財務與時間上的損失。
　　P2SP 是一種整合 P2P 以及 P2S 的技術，有 P2S 可靠與穩定的傳輸，以及 P2P 下載速度高的優點，但依然有著與 P2S 一樣的缺點，一但 Server 遭受 DoS 或者 DDoS 攻擊，使用者將無法完整下載檔案。
　　本論文設計一套系統，名為 sP2SP，在 P2SP 系統遭到 DoS 或者DDoS 攻擊時，正在下載的使用者依然可以完整下載檔案。

With the growth of IoT devices and the development of security research, many IoT devices that have been installed around the world have been found to have vulnerabilities , and some of them cannot even be updated or patched, and are eventually used by hackers to form botnets. A distributed denial of service (DDoS) attack on the network service provider caused the network service provider to temporarily interrupt or stop the service, making ordinary users inaccessible, thereby causing financial and time losses to the service provider and users.
P2SP is a technology that integrates P2P and P2S. It has the advantages of reliable and stable transmission like P2S and high download speed like P2P, but it still has the same disadvantages as P2S. Once the server is attacked by DoS or DDoS, users will not be able to download the complete file.
We designs a system called sP2SP. When the sP2SP system is attacked by DoS or DDoS, the user who is downloading can still download the entire file.

[1] “Growth in Internet of Things Devices”https://priceonomics.com/the-iot-data-explosion-how-big-is-the-iot-data/ (Accessed on 6/30/2020)
[2] “DDoS attacks in Q1 2020” , https://securelist.com/ddos-attacks-in-q1-2020/96837/ (Accessed on 6/30/2020)
[3] “Content delivery network (CDN)” https://en.wikipedia.org/wiki/Content_delivery_network (Accessed on 6/30/2020)
[4] “P2SP（Peer to Server and to Peer）”https://zh.wikipedia.org/wiki/P2SP (Accessed on 6/30/2020)
[5] ZhiYao Zhong, “Handover: A Mechanism to Improve the Availability of Network Services after Live Migration under Private Networks,” National Central University, Master's degree, Jun 2016.
[6] Hung, Ruei-yih, “Migmod: A Mechanism to Establish a TCP/IP Connection under DDoS Attacks” National Central University, Master's degree, Jun 2019.