CAIDA : research : traffic-analysis

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Ongoing Research

Realtime Traffic Monitoring

CoralReef Monitoring of optical networks is done with an optical splitter which diverts a small fraction of the light from the optical fiber to the monitor device. The CoralReef report generator produces graphs and tables for various types of information found, including by protocols, application, and hosts measured in packet, bytes and flow tuples.

A list of Realtime traffic monitors at CAIDA is made available, as well as graphs and charts generated from their measurements.

Previously Completed Research

Remote physical device fingerprinting

We introduce the area of remote physical device fingerprinting, or fingerprinting a physical device, as opposed to an operating system or class of devices, remotely, and without the fingerprinted device's known cooperation. We accomplish this goal by exploiting small, microscopic deviations in device hardware: clock skews. Our techniques do not require any modification to the fingerprinted devices. Our techniques report consistent measurements when the measurer is thousands of miles, multiple hops, and tens of milliseconds away from the fingerprinted device, and when the fingerprinted device is connected to the Internet from different locations and via different access technologies. Further, one can apply our passive and semi-passive techniques when the fingerprinted device is behind a NAT or firewall, and also when the device's system time is maintained via NTP or SNTP. One can use our techniques to obtain information about whether two devices on the Internet, possibly shifted in time or IP addresses, are actually the same physical device. Example applications include: computer forensics; tracking, with some probability, a physical device as it connects to the Internet from different public access points; counting the number of devices behind a NAT even when the devices use constant or random IP IDs; remotely probing a block of addresses to determine if the addresses correspond to virtual hosts, e.g., as part of a virtual honeynet; and unanonymizing anonymized network traces.

Remote physical device fingerprinting paper

Spectroscopy of traceroute delays

We analyze delays of traceroute probes, i.e. packets that elicit ICMP TimeExceeded messages, for a full range of probe sizes up to 9000 bytes as observed on unloaded high-end routers. Our ultimate motivation is to use traceroute RTTs for Internet mapping of router and PoP (ISP point-of-presence) level nodes, including potentially gleaning information on equipment models, link technologies, capacities, latencies, and spatial positions. To our knowledge it is the first study to examine in a reliable testbed setting the detailed statistics of ICMP response generation.

We find that two fundamental assumptions about ICMP may not hold in some cases in modern routers, namely that ICMP delays are a linear function of packet size and that ICMP generation rate is equal to the capacity of the interface on which probes are received. The primary causes of these violations appear to be internal segmentation of packets into cells and limiting of ICMP packet rates and bit rates inside a router. Our results suggest that the linear model of packet delay as a function of packet size merits revisiting for certain router models and time resolutions. Our findings also suggest possibilities of developing new techniques for bandwidth estimation and router fingerprinting.

Spectroscopy of traceroute delays paper

Publications

Publications regarding traffic analysis can be found under the Measurement Methodology category, but not all listed papers pertain specifically to traffic analysis.