NAT Usage in Residential Broadband Networks
Many internet customers use Network Address Translation (NAT) when connecting to the Internet. To understand the extend of NAT usage and its implications, the authors explore NAT usage in residential broadband networks based on observations from more than 20,000 DSL lines. They present a unique approach for detecting the presence of NAT and for estimating the number of hosts connected behind an NAT gateway using IP TTLs and HTTP user-agent strings. Furthermore, they study when each of the multiple hosts behind a single NAT gateway is active. This enables one to detect simultaneous use. In addition, they evaluate the accuracy of NAT analysis techniques when fewer information is available.