Re: [TSCM-L] {4712} AC power network security?

From: bts <b..._at_charter.net>
Date: Sun, 14 Feb 2010 13:46:49 -0600

Each circuit made to transmit the square wave packets are set to a ground
plain within the box. Each board has a PS with filtering. Then this is run
through the power supple with is filtered.

This means that all of the negative side of the circuit is run through
filtering. (Keep in mind that in order to filter the positive an equal and
opposite negative reaction is generated. But nothing is perfect.)

So now you have a signal leaving the computer, or other device, through the
ground pin of the AC cable. This minimal signal could be, by spec, 100 dB
down from the approx 1 VPP logic signal that is on the positive side. So
3 dB is half, 6dB is a 1/4, 9 dB is an 1/8....

Now we enter the noisy world of AC transmission where nothing is shielded
and no on cares about the induced noise on a 220 line since it will be
filtered before you use it.

So now, Can you find that very small signal riding on the AC amongst all
that noise? Good luck.

-- 
James Greenwold
Bureau of Technical Services
P.O. Box 191
Chippewa Falls, WI54729
715-726-1400
http://www.tacticalsurveillance.com
t..._at_charterinternet.com
On 2/14/10 12:55 PM, "kondrak" <kon..._at_phreaker.net> wrote:
> I'd imagine it could be done, but the transformer is the end of the
> place you could see it, as it blocks any further progress of the signal.
> Thus, you could sit across the street, or nearby on the same leg of the
> transformer, and watch any traffic. This is what the X10 and BPL stuff
> does, allow comms over power lines.
> You can segregate the traffic with a tool like Wireshark, IF you know
> what IP youre looking for and do deep packet inspection. I do not
> consider ANY BPL or X10 to be secure, unless they're running tunneling
> on it with strong encryption (128 bit or better).
> 
> Scott Ehrlich wrote:
>> Is anyone aware of a device/method to monitor TCP/IP network activity
>> on a power line?   People plug devices into the wall all the time.
>> Question is, what known technology is there to watch if a device
>> _might_ be sending out, or even receiving unwanted information via
>> commercial power lines?
>> 
>> People have network monitoring tools on Ethernet connections, but I
>> think we mostly take power connections for granted - the power supply
>> in the device should _only_ provide power.   What if it does more?
>> Next to opening the device and inspecting circuitry, what other
>> options are there to keep an eye on power line activity?
>> 
>> One _could_ say use a scope or other test equipment.  But if you have
>> multiple devices plugged in, or a computer lab or a building/facility
>> to keep track of, then an appliance of some kind to help identify the
>> Ethernet address as though you are performing passive network sniffing
>> would be needed.
>> 
>> Thanks for any insight.
>> 
>> Scott
>> 
>>   

Received on Sat Mar 02 2024 - 00:57:24 CST