The technique of OS fingerprinting has been well documented. It lets you identify the operating system used by a remote host with a fair degree of certainty. Indeed, OpenBSD even supports this in its filter engine; for example, you can write a rule that assigns mail traffic from Windows machines to a lower-priority bandwidth queue than that from other machines (since such traffic is usually the result of a virus).

However, researcher Tadayoshi Kohno has come up with a much more sophisticated approach, based on measuring clock skew across TCP packets. The idea is that every machine has a slightly different skew to their internal clock, and almost all TCP stacks timestamp packets using their internal clock as a reference point. By identifying the clock skew used for a particular PC, e.g. a laptop, you can track that machine’s movement as it moves around the Internet, perhaps connecting from several different countries or via different dial-up nodes.

All very ingenious, and with no end of big brother implications. Read more in this article at ZDNet Australia, or for the full technical details, check out his original research paper.

From a map of Dublin to … a map of the whole United States. But this one’s Google-style.

http://maps.google.com/ is yet another cool-looking application to come out of Google Labs.

It has a funky real-time dynamic-HTML interface that lets you interactively zoom in and out of maps, drag-scroll using the mouse, and (very cool) do location-sensitive searches.

For example, if I search on ‘pizza in st paul, mn’ Google will jump to the St Paul, Minnesota section of the map and then highlight all the Pizza shops on the map. I can then click on individual jobs for more details, or even get directions there.

Let’s hope this makes it to Ireland someday…

(If you’re interesting in how they implemented the slick user interface, there’s a good analysis here. Also check out this amazing satellite map of Switzerland, which has a similar interface, and this Java-based map of Ireland / Europe.)