Research And Implementation Of DNS-ALG Based On AFT Technology

In recent years, the Internet based on IPv4protocol is developimng very quickly, but the lack of IP addresses is the bottleneck of its development, so IETF proposed IPv6protocol to solve this problem. The transition from IPv4to IPv6is a gradual process and these two protocols will exist for a long time together. IPv6transition technologies are becoming a bridge between these two protocol networks to communicate with each other. AFT technology is an effective IPv6transition technology, it converts address and protocol of packets on the gateway which is located in the edge of the IPv6/IPv4networks, and does not need to make any changes of the hosts in the networks to achieve mutual visits between different protocol networks. AFT technology combined with DNS implement DNS-ALG which can handle upper layer protocol to improve the application of the AFT technology.This paper implements the AFT and DNS-ALG on a company’s software development platform. The process of AFT mainly includes the address translation and protocol conversion. The address translation includes stateless and stateful translation. Stateless address translation uses DNS64prefix or IVI prefix as translation tools, stateful address translation uses address in address pools or address of the specified interfaces. DNS-ALG makes DNSv6and DNSv4packets to convert with each other, mainly dealing with Question section and Resource Record section in DNS packets.This paper describes IPv4and IPv6first, then, analyzes and compares the current main IPv6transition technologies, proposes address and protocol translation program on this basis, and describes the detail process of AFT. Based on the analysis of DNS packets, a detail program to achieve DNS-ALG is designed. Finally, the functional and performance of DNS-ALG are tested to verify the design result.