Devolo

Billie Erin Walsh bilwalsh at swbell.net
Thu May 21 16:44:14 UTC 2009


Eberhard Roloff wrote:
> Billie Erin Walsh wrote:
>
>   
>>> On the one hand, the
>>>   electrictiy meter is the natural limit of your network. So when all of 
>>> your town can connect to your network, then you are the one that is 
>>> paying for all of the towns electricity bills. ;-)) Just let me know 
>>> which town you are living in, I would love to move.
>>>   
>>>       
>>  From the Devolo website:
>>
>> "Is the electric meter a natural boundary of the dLAN® network? Can my 
>> neighbour intrude on my network? Only in rare cases does the electric 
>> meter attenuate the signal to that extent. Therefore, for security 
>> reasons, we recommend that you always use the device's internal 
>> encryption. Enable it by entering a password other than the factory 
>> password or using the encryption button."
>>     
>
> okay. What is called "rare cases" here, in reality did not happen to me 
> once, having done about 50 installations. You might not believe it, but 
> I always have a spare device that I use to try to test from "outside". 
> Furthermore the key here is "encryption"
>   

"Rare cases" here means that the meter will _not_ attenuate the signal. 
The signal will pass through. They admit it.

I don't know how you attach the device before the meter.

>
>   
>> If one Devolo can encrypt it another would be able to de-encrypt it.
>>     
>
> Sure, otherwise it would not work.;-) The emphasis here is on "shared 
> key", which you might know from your wireless networks
>   
>> Again, from Devolo:
>>
>>
>> Hogwash! Anyone with a decent knowledge of radio could "de-modulate" the 
>> signal in a matter of seconds. After that they have access to the "raw 
>> data" and encryption information becomes available.
>>
>>     
> While hacking wireless it more or less a hobby for malicious kids, I 
> cannot recall a single incident where this happened to dLAN.
>   

Many years ago there was a device that used yur house wiring for an 
intercom connection. It worked well until people learned that their 
neighbors could listen in on what was going on in your house. Then sales 
dropped like a rock. I admit that the devices did not use any form of 
encryption but it does prove that the signals do pass through the lines 
outside your house.

> Just to iterate:
> (Almost) always your network is separate within your household so no one 
> outside your household can get physical access to it AND additionally it 
> is encrypted with a key that is common to your own devices, and only to 
> your own devices.
>   

And the signal is modulated. That means that they use probably either FM 
or AM to piggyback the signals on the wiring. Both of which are dead 
easy to detect [ de-modulate ]. The only difficulty is finding the exact 
frequency, but that only takes a good radio receiver that will tune over 
a _very_ large range of frequencies.

Devolo admits that once the signal is de-modulated the encryption key 
can be broken, Just as any form of encryption can be.

>   
>>> So instead of spreading FUD, you better read it up or try it out for 
>>> yourself.
>>>   
>>>       
>> Maybe you need to brush up on your radio theory and application.
>>     
>
> I fully agree with you on that one.
>
> Unfortunately even brushing up my poor radio knowledge will not help me 
> to crack devolo networks in any foreseeable way.;-))
>   

Get a position close by and find the frequency of the modulated signal. 
Crack through the encryption. [ Most people will only use something 
simple ] Set up another device with the same encryption and put the 
output through either the electrical lines or use a radio to insert the 
signal directly on the wiring. You now have complete access. No more 
difficult really that hacking into a wifi system.

>>> Again there is nothing like a network cable, indeed! It is very cheap, 
>>> very fast and very secure. Just when ethernet cabling is no option and 
>>> wireless is lousy, then these devices do a great job. In most cases, 
>>> they are simply WAY better than wireless.
>>>   
>>>       
>> Agreed as to cabling. However wifi connections don't need to be poor. If 
>> properly done, and with proper equipment, it should be very successful.
>>     
>
> Sure, but wifi lacks two things:
>
> Performance usually is pretty poor and it gets even worse when more than 
> two machines want to eat up your wireless bandwidth. Sadly this does NOT 
> improve much with Draft-N. In comparison dLAN is way better in real life 
> situations, although the network bandwidth is also shared with dLAN, 
> just as it is with wireless.
>   

We have five wireless routers around here doing different things on two 
separate networks. One in the living room is for general use and forms 
one side of the link to my workshop. The one in the workshop connects 
back to the one in the living room and gives wireless access to anyone 
in the workshop. One gives backup to our internet access through a 
sprint broadband card. One is set up strictly as a client to one of our 
wireless ISP's. It connects the the repeater on our tower. There is 
another one on that network to give wired/wireless access to that ISP. 
We have six computers that run 24/7 and as many as ten or twelve at any 
given time depending on whats going on around here.

Performance doesn't degrade at all regardless how many are connected 
wired or wireless. [ we have two high bandwidth internet connections ] 
Performance issues might be from a low bandwidth connection rather than 
from a wireless setup.

> Secondly more and more people that I work for, simply do not want to 
> have wireless anymore. They do not want to expose their children and 
> themselves to more radiation that they absolutely must. dLAN is a very 
> welcome alternative here, since your mains doubtlessly are already there 
> in your house and you will not alter their already existing irreducible 
> radiation.
>   

Uh. Yeah. OK. If you think so.

>
>   
>> Personally, if I was setting up a wireless system as the OP mentioned I 
>> would use a Linksys WRT router with dual antennas. Install the DD-WRT 
>> firmware on the router. Remove one antenna and place it in a location 
>> that isn't to obvious on the lower level. After that you can adjust the 
>> power levels on the router and set it up to transmit and receive on both 
>> antennas.
>>     
>
> Sure you can try, but DD-WRT is not needed, although is is really great. 
> The "Antenna-Diversity"-feature is common to any halfway modern routers 
> with more than one antenna.
>   

What kind of power management do you get on a stock router?

> Actually if wireless is what the OP wants to have, it might also make 
> sense to use a much more focused antenna like this
> 0 Euros / 0 Dollars example:
> http://www.heise.de/netze/bilderstrecke/486/an0MTE2MzE5
>   

That's a cute little yagi. One suggestion might be to make sure the 
thing is mounted halfway down the antenna and make the reflector a bit 
longer [ well, maybe more than one ] And also the directors should taper 
down [ get a bit shorter as they get further from the radiator ] towards 
the front of the antenna. If anyone is interested I have a 30db gain 
parabolic I could make a good deal on. Give you solid reliable 
connections out to about eight mises on 100mw output. Maybe a little 
further with another parabolic on the remote site. The big issue is the 
Fresnel Zone and any trees in the path. 2.4 GHz doesn't penetrate trees 
very well. It's the sap/moisture in the leaves that block the signal. It 
also has to be pretty much line-of-sight.

Actually  much simpler solution is to just drop one antenna down into an 
inconspicuous area of the lower floor. One antenna for the top floor and 
one for the lower floor. Give complete 360 degree coverage. Just 
requires running a short distance with some small coax line.

> But please note: Such an antenna does not work for draft-n connections 
> and 5Ghz WLan will not get any benefit from it, either.
>   

I don't know about "draft-n" [ to lazy to look it up ] but you could 
make a high gain yagi for 5.8 GHz. You want one? Might take a bit to get 
it built but I'll make you a good deal. Parabolic's also work quite well 
at 5.8 [ most microwave antennas are parabolic ]. One ISP link to our 
location comes in on a 5.8 high gain parabolic gets detected and 
rebroadcast on 2.4 with a verticle antenna.

_ANY_ radio signal can gain benefit from a high gain directional 
antenna. A 5.8GHz yagi could be an etched PC board. I've seen some for 2.4.

> Hmmm, apparently I already was able to brush up my radio knowledge a 
> little bit, at least as far as wireless LAN is concerned. ;-)))))))
>
> Kind regards
> Eberhard
>
>
>   


-- 
Treat all stressful situations like a dog does.
If you can't eat it or play with it, 
just pee on it and walk away





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