How, pray tell, is a panel-mounted LED, tied directly to the DC
power output of a power supply, going to emit anything useful?

uhhhh .... well it's the led " IR " ports. they are
all over the place these days. front of my computer, on handhelds , on
printers , cameras , PDAs etc. we generally ignore them , and
fail to remember their presence. ( I disconnected the one on the
front of my computer and my printer just in case , since I don't use
'em for anything )



Also, you didn't read my orginal post far enough. It IS very
possible to eavesdrop on LAN traffic across copper cables via their
emissions. It's just that the equipment it takes to reliably do so, from
any reasonable distance in situations where you do NOT have access to a
direct connection, is well out of the realm of tools that the
'consumer' can easily get (or know how to use).


naturally the government has been doing it for decades ...
civilians are just recently getting into it. " extremely " simple
wideband preamplifiers ( available at radioshack or from lan dealers
on ebay ) are all that it takes to get into the act. just plug one or
two into a hand held 15 element log yagi antenna ( also common on
ebay ) your datamodem on the other end and if sufficient signal is
present ... you've got copy. ( obviously it's bit more than this , but
I don't want this to become a " how to " . the info is commonly
available on the web , tho )
since you are a ham ... you'll understand this :
just get a cheap ( $15 to $45 on ebay ) signal level meter.
( I use a modified cushman ce-24 ) ... mod the I.f. to " wide "
( jump the filters ) tap the I.F. before the detector and schmidt the
output to a logic level. " presto " a wideband supersensitive signal
receiver that can tune and detect / output digital signals. it's that
easy.
tune " any " selective level meter ( with a small external antenna )
across the lowest bands and listen to the " immense " jumble of
computers radiating from ALL OVER your neighbor hood. there will be so
many ( if you live in any average metro area ) that you have to
drive up , outside people's houses to make sense of all of them. it's
a mess , there are so many.
the cable company also makes it VERY easy in my part of the world ,
as the cable connections are ALL outside people's houses in a
green box , partially buried , out near the curb ... outside every
house. no electric or other wires to be seen , here , all in the
ground .. right at the curb. clean looking but doesn't contribute much
to security. " all " of the signals , running loose in / on your
computer ... leak out on your cable modem connection wire
) phone lines for DSL ) , on the coaxial shield. kinda makes it too
easy sometimes. the same goes for your electric lines. those so called
" common mode " RF filters do VERY little to remove the signal from
the ground wires in your home AC power system. they do seem to
vanish at the local transformer , for some reason.




the most common ways to eavesdrop on computers via RF or IR are to
listen to the immensely powerful raster scan from a computer CRT.

...A method which I'm in doubt even works. Even if there is
something to it, I'll bet it doesn't work with flat-panel displays,
which barely emit anything at all outside of their shielding.

try reading the Google links that I mentioned and see if you still
don't . it wouldn't be a billion dollar industry if it didn't exist.
ever been to the new CIA building ?
they have an interesting display of eavesdropping equipment there
on public display ( or did have at least ) lots of the van eck stuff
is there. it's WAY old stuff compared to what they have nowadays.
they consider the stuff shown on the web to be so old and dated ( the
RF eavesdropping equipment ) it's laughable to them.



Then I suppose I should be grateful I have obscured glass in the
garage. ;-)

well ......remember that it's a IR signal source and IR can pass
through some ( apparently ) opaque glass surfaces and has a nasty
habit of bouncing / reflecting off stuff that we wouldn't ordinarily
think it would. there are " laser " inferometers that you can bounce
off a plane of glass and get a scatter beam return that can contain
the original optical energy and " any " other optical energy from
behind the glass. ( actually a optically generated sub carrier of
some lower bandwidth than optical freqs ... but certain angles of
attack from behind pass through and leave too little of a signature )
the 60 hz signal created by ordinary house lighting is easily "
optically " ( and on audio freqs too ) filtered off the signal path.
if " the boys " want into any of your optical ports , a simple
fiber scope under the door or through a lock hole will do the trick
easily.
surely most of us don't have anything going on " the boys " would ever
be interested in ...... but it's information worth thinking about ,
never the less.

guard your IR ports, " all " of the CPU freqs ( of everything in your
box and there are many , esp on accessory cards ) and the raster scan
leakage / rf signals present in your computer systems. it's difficult
to do ( crappy or NO shielding on about everything ) ... much more
than people expect. air broadcast , your cable and your home power
wiring are your worse enemies in that respect.
( freqs of 15khz to .45 megs .... freqs of 266 mhz to 3 gigs and
.... 902 nm IR. all this changes a lot , tho )


I seem to have to run hard to keep up with all the new stuff ..just
when I get comfortable with something new ..it seems like 10 more new
" things " pop up. it's exhausting at times ... and often I think
that a certain amount of blissful ignorance is a good thing , too. ha
ha ah ah aha ha ah sometimes it's better just not to know.
who needs it ?

73s
the K man ............