That script completely depends on the Xniff ActiveX dll. And as said in many threads about that ActiveX, it does not work properly. It is not 100% compatible with wireless connections, it has issues with several non-wireless adaptors and it has some other general issues which can cause even bigger trouble (like silent crashes when you close Messenger. Aka: you will not notice it, but yes, Messenger _will_ often crash when you exit it).
Not to mention that all that stuff was back when there was no Vista or Win7, thus on XP. And now, on top of that, Vista and Win7 are known to have issues with ActiveX's. Issues in the sense that a lot of perfectly working ActiveX's on XP are not compatible with the new OSs.
And since Xniff was never a perfect written ActiveX to begin with (thus even for XP) you can make the math...
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Oh, and I forgot to mention that together with the 'native' problems of Xniff as described above, it might also be possible that the ports used by Messenger to send such data are changed, or used in a different way, or that other ports have been added which aren't checked in the script.
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And a third thing (and this is the last "and" I can come up with for now
), the protocol has been changed a lot since then too. And this might or might not have an influence on those particular data packets checked by the script (to make sure I would need to check that. But I
cba because it wouldn't work anyways in so many cases because of all the other reasons given above).
So, consider that script (and similar ones) depricted until further notice.
/ 
