A Dynamic-configurable NAT Approach to Communicate with Hosts inside a Private Network

• Main Authors: Hung-Chun Chang, 張鴻駿
• Other Authors: Chien-Chao Tseng
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/20456754767668552520

碩士 === 國立交通大學 === 資訊工程系 === 90 === NAT is a widely deployed solution to IP address depletion problem in IPv4. With NAT, we can use private IP addresses to save the IPv4 address space. However, traditional NAT would only allow outbound sessions (from a private network to the public network), i.e. a host in the public network can’t establish an inbound session toward a private network. Therefore, a host in the public network can’t communicate with a host in a private network except that the latter has a static address binding or has established an outbound session with the former. There have been several solutions to the above problem, but all of them suffer from some drawbacks or side effects. Therefore, in this thesis we present an approach named Dynamic-configurable NAT (DCNAT) to resolving the inbound session problem. In the approach, with an add-on NAT Agent on the NAT router, an inbound session can be dynamically configured through a registration procedure. That is, hosts in the public network (e.g. the Internet) can communicate with hosts within a private network after registering an inbound session with the NAT Agent. The presented DCNAT can be further enhanced to support applications with multicast data delivery. With the multicast-capable DCNAT (MDCNAT), an ICP (Internet Content Provider) can simply provide the subscription information of the subscribers and a copy of data to an MDCNAT proxy. The proxy can register, on behalf of all subscribers, with all MDCNAT-enabled NAT routers, and then sends a copy of data to each MDCNAT-enabled NAT routers involved. On receiving the data, a Multicast Agent in each designated NAT router will send the data to the subscribers within the private network via a multiple-unicast forwarding procedure or a subnet multicast.