一個網際網路端對端服務仲介之設計與雛型製作

Abstract

網際網路協定第四版本 (Internet Protocol version 4)早在九零年代初期就被發表出來，並且是目前在網際網路上被廣泛使用的通訊協定。但是隨著網際網路使用者的迅速增加，IPv4的位址數量早已不敷使用。NAT (Network Address Translator) 的使用讓大量的網際網路使用者利用少量的IPv4 address來連上Internet可以達到減緩IPv4 位址不夠用的問題。然而，NAT雖然提供了連結Internet的便利性，它卻同時破壞了原有的Internet架構，讓NAT外部的使用者無法透過IPv4 address來定位NAT內部的使用者，並且導致NAT內部的使用者無法對外提供網際網路服務 (Internet Services)。 網際網路協定第六版本 (Internet Protocol version 6) 在九零年代中晚期被發表出來。它把位址的長度從32 bits擴展到128 bits，同時徹底解決了位址不敷使用的問題。然而，IPv6的規格雖然目前被廣泛的討論，它的使用普及性卻是進展緩慢。在IPv6真正普及之前，IPv4網路裡的NAT問題將持續存在。 本篇論文提出一個完整的系統架構來解決NAT內部的使用者無法對外提供Internet Service的問題。有鑑於現有的相關研究都因使用的不便利性而無法普及，本論文的系統設計是針對使用的便利性做最佳化，並且引用點對點 (Peer to Peer) 網路架構來增進效能。另外，本篇提出了Passive TCP Splice以及Pure TCP Splice兩個kernel layer的實做方法來增進系統效能，在本文中將探討完整的實做方法。 本篇的系統架構亦可套用到解決IPv4/IPv6 Translation以及Firewall Traversal問題。另外，亦可支援連上家用網路的電腦周邊設備的使用，讓使用者在家用網路的NAT外部亦能使用NAT內部的電腦周邊設備。

Internet Protocol version 4 (IPv4) was devised in early 90’s and is broadly used in Internet nowadays. However, the rapidly increasing number of Internet users leads to the insufficiency of IPv4 addresses. NAT (Network Address Translator) was later devised to allow many Internet users to access Internet simultaneously using one single IPv4 address. However, while providing the convenience of accessing the Internet, NAT also breaks the original Internet structure. Users outside NAT can not use IPv4 addresses to locate the users inside NAT, and users inside NAT can not provide Internet services to the users outside NAT. Internet Protocol version 6 (IPv6) was devised in mid 90’s. IPv6 extends the IP address from 32 bits to 128 bits and completely solves the insufficiency of IP addresses. However, the transition to 128-bit IPv6 addresses has been proceeding slowly. The problem of NAT would remain until IPv6 become popular. This thesis proposes a system to solve the problem of NAT. To avoid the inconvenience of the related work, the main guideline of this thesis is to make the system easier to be deployed. Furthermore, peer-to-peer network structure is introduced to this system to improve performance. In addition, this thesis proposes two new techniques: Passive TCP Splice and Pure TCP Splice to improve system performance. This system can be applied to IPv4/IPv6 Translation and Firewall Traversal. Furthermore, it can support computer peripherals which connect to home network. Users can use this system to control their computer peripherals in their home network while travelling outside.