NAT Technology and Its Application Based on Netfilter

NAT is one of the most important technologies to resolve the lack of IPv4 addresses, and has been widely applied in the extension of LAN for Internet. This paper details on the NAT technology and its implementation principle based on Netfilter in Linux 2.4 kernel. With the Netfilter technology, it builds up a LAN in the laboratory accessed to Internet, and the outline of the LAN is also presented.