Passive detection of nat routers and client counting

Abstract

Network Address Translation (NAT) routers pose challenges to Individuals and organizations attempting to keep untrusted hosts off their networks, especially with the proliferation of wireless NAT routers. Residential NAT routers also create problems for Internet Service Provider (ISP) taps by law enforcement by concealing network clients behind cable or DSL modems: This paper discusses the feasibility and limitations of methods for detecting NAT routers and counting the number of clients behind NAT routers.