846 research outputs found
No NAT'd User left Behind: Fingerprinting Users behind NAT from NetFlow Records alone
It is generally recognized that the traffic generated by an individual
connected to a network acts as his biometric signature. Several tools exploit
this fact to fingerprint and monitor users. Often, though, these tools assume
to access the entire traffic, including IP addresses and payloads. This is not
feasible on the grounds that both performance and privacy would be negatively
affected. In reality, most ISPs convert user traffic into NetFlow records for a
concise representation that does not include, for instance, any payloads. More
importantly, large and distributed networks are usually NAT'd, thus a few IP
addresses may be associated to thousands of users. We devised a new
fingerprinting framework that overcomes these hurdles. Our system is able to
analyze a huge amount of network traffic represented as NetFlows, with the
intent to track people. It does so by accurately inferring when users are
connected to the network and which IP addresses they are using, even though
thousands of users are hidden behind NAT. Our prototype implementation was
deployed and tested within an existing large metropolitan WiFi network serving
about 200,000 users, with an average load of more than 1,000 users
simultaneously connected behind 2 NAT'd IP addresses only. Our solution turned
out to be very effective, with an accuracy greater than 90%. We also devised
new tools and refined existing ones that may be applied to other contexts
related to NetFlow analysis
Dovetail: Stronger Anonymity in Next-Generation Internet Routing
Current low-latency anonymity systems use complex overlay networks to conceal
a user's IP address, introducing significant latency and network efficiency
penalties compared to normal Internet usage. Rather than obfuscating network
identity through higher level protocols, we propose a more direct solution: a
routing protocol that allows communication without exposing network identity,
providing a strong foundation for Internet privacy, while allowing identity to
be defined in those higher level protocols where it adds value.
Given current research initiatives advocating "clean slate" Internet designs,
an opportunity exists to design an internetwork layer routing protocol that
decouples identity from network location and thereby simplifies the anonymity
problem. Recently, Hsiao et al. proposed such a protocol (LAP), but it does not
protect the user against a local eavesdropper or an untrusted ISP, which will
not be acceptable for many users. Thus, we propose Dovetail, a next-generation
Internet routing protocol that provides anonymity against an active attacker
located at any single point within the network, including the user's ISP. A
major design challenge is to provide this protection without including an
application-layer proxy in data transmission. We address this challenge in path
construction by using a matchmaker node (an end host) to overlap two path
segments at a dovetail node (a router). The dovetail then trims away part of
the path so that data transmission bypasses the matchmaker. Additional design
features include the choice of many different paths through the network and the
joining of path segments without requiring a trusted third party. We develop a
systematic mechanism to measure the topological anonymity of our designs, and
we demonstrate the privacy and efficiency of our proposal by simulation, using
a model of the complete Internet at the AS-level
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