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Subject: Re: Check internet connection status using Matlab
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Date: Fri, 17 Oct 2008 11:53:59 -0500
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Jaime Zamora wrote:
> is there a way to check if I'm connected to the internet using
> matlab?

Only if you add additional hardware to be able to verify a quantum-cryptography
secured connection with a site you have *personally* installed the quantum
cryptography hardware on.

If you do anything less than quantum cryptography, then you will be unable
to tell the difference between *really* being connected to the internet
versus being connected to a private network that is lying and -telling- you
are connected. Oh, sure you can have root certificates and "web of trust"
PGP signed keys, but any of those can be broken with enough time and money
(or bribery or covert operations to steal the keys).


Checking to see whether you are "connected to the internet" is, in practice,
a singularly useless thing to do. Suppose you -are- connected to the "internet"
and the check gives you an honest "Yes" answer. Now what??

Being "connected to
the internet" tells you absolutely nothing about whether you will be able to reach
any particular service at any particular site. The site might be crashed; the site
might be down for routine maintenance; there might be widespread power outages
that took down the network somewhere between you and the site; a back-hole might
have torn up the wires or fibers; a mouse or rabbit or ground-hog might have chewed
apart an important connection on the way; there might be a bug in the network
routing tables; someone might have deliberately "poisoned" the network routing tables;
there might be a denial-of-service attack that is preventing you from reaching the
places you want to go; there might be a bug in someone's firewall rules along the way;
someone's firewall might be deliberately blocking you because you are not authorized
to access the service; someone's firewall might be blocking you because you don't
happen to know the right security codes to get through; your ISP might be blocking you
because the government or a court order requires them to do so (think China, or think
access to Nazi information from inside Germany to outside); your ISP might be
blocking you because you have exceeded your account limits; your ISP might be blocking
you because it is a meddling corporate entity concerned with profits and not with people.
And so on.