Hi,
We have recently deployed a system for determining the physical location
of Internet hosts called Octant. Given a host that responds to ICMP
pings, Octant determines the boundaries of the region in which the node
is likely to lie, and displays the result using Google maps:
http://www.cs.cornell.edu/~bwong/octant
Behind the scenes, Octant consists of two parts:
- a comprehensive framework for efficiently representing and
combining a system of constraints.
- a set of mechanisms (aka "crazy hacks") to extract useful
and tight constraints on where nodes are likely to be, without
resulting in an unsatisfiable set of constraints.
Our website describes the general framework Octant provides. One key
feature is that the framework permits reasoning about positive
constraints (where a node may be located), as well as negative
constraints (where a node is unlikely to be). Another key feature is
that Octant can reason about concave regions (e.g. "node is in the
Boston area but not in Cambridge") using Bezier regions. Finally, Octant
can reason in the presence of uncertainty (e.g. "this node is within
30km. of this other one in the Ohio area").
Figuring out the physical location of nodes based solely on network
measurements is challenging. Routes don't necessarily follow
great-circle distances, slow nodes appear to be "off the map," routers
add delays that are hard to predict, and generally network measurements
are difficult to perform accurately. We have developed various
mechanisms for these challenges. Our evaluation indicates that we get a
median error of 22 miles, factor of 3 better than previous schemes for
geolocalization.
So, check Octant out if you are interested in a free geolocalization
service (or you want to cyberstalk that person who has been connecting
to your SSH port or sending you unwanted addresses). Two caveats: for
security reasons, we do not geolocalize arbitrary IP addresses, and the
current deployment is limited to North America (though we hope to deploy
in Europe+Asia in the future).
Thanks,
Bernard Wong, Ivan Stoyanov, Gun Sirer.
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