A Complementary Approach for Transparent NAT Connectivity

NAT has been responsible for the survival of IPv4 and in essence should not be left out in IPv6. NAT are virtually transparent to client-server applications that generally do not require special configuration to work properly. However, P2P applications are responsible for generating about half of Internet traffic and require special settings on home routers to support outside connections. This paper presents a complement to the UPnP IGD protocol, including changes in the core of the Linux operating system, to make NAT traversal transparent to home and small office users in the use of P2P applications or in providing services to the outside world. Our approach overcomes some of the major limitations of NAT solutions, by extending existing standard behaviours. In the proposed solution, current applications need no changes once the transparency is provided through the improvement made in the network related system calls. Tests using a reference implementation and network applications supports the feasibility of the approach. Keywords-Network Address Translation; NAT traversal; UPnP; home networks.