Uma abordagem complementar à tradução de endereços para conectividade transparente

Abstract

Traditional NAT is an extremely common technique, employed on routers in order to share on single Internet connection among many computers of a local network. This technique has been responsible for the survival of IPv4 with its limited address space, and is virtually transparent to many of the Internet application: those that uses the classic client-server architecture. However, P2P applications are ever more common, and are already responsible for about half of the world Internet traffic. Those applications require special settings on the router to be functional through NAT. This work introduces an approach to bring the original NAT transparency to the P2P network applications, where the very peers must be accessible and provide services directly to other peers. In this approach the operating system s network infrastructure is modified in order to provide automatically and transparently the NAT traversal needed by those applications. This is done through the standard POSIX interface and usual system calls for network access, extending their standard behaviors. In the new approach, the operating system takes part on the NAT process, using a protocol from UPnP family to configure the router and hides its complexities from applications and users. These applications then can use the network interface as if they were directly connected to the Internet, not requiring any special protocol implementation or extra user configuration action, since the NAT traversal job is automatically performed by the operating system. Tests using a reference implementation and existing network applications supports the feasibility of the approach.