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Wi-Fi Direct



 
 
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  #1  
Old April 26th 17, 08:51 PM posted to alt.comp.hardware
Maelmoro
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Posts: 3
Default Wi-Fi Direct

Do you know if Wi-Fi Direct is bases on 2.4GHz or 5GHz as usual wireless
network?

I can't detect the Wi-Fi Direct of my Samsung TV with Wifi Analyzer
(https://play.google.com/store/apps/d...nalyzer&hl=en),
any idea? should I detect it?

Max
  #2  
Old April 26th 17, 09:31 PM posted to alt.comp.hardware
John McGaw
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Posts: 666
Default Wi-Fi Direct

On 4/26/2017 3:51 PM, Maelmoro wrote:
Do you know if Wi-Fi Direct is bases on 2.4GHz or 5GHz as usual wireless
network?

I can't detect the Wi-Fi Direct of my Samsung TV with Wifi Analyzer
(https://play.google.com/store/apps/d...nalyzer&hl=en),
any idea? should I detect it?

Max


The specification at https://www.wi-fi.org/discover-wi-fi/wi-fi-direct
says: "Does the specification underlying the Wi-Fi Direct certification
program work on both frequency bands?

Yes, the specification underlying the Wi-Fi Direct certification program
supports operation in both 2.4 GHz and 5 GHz. Devices operating in the 2.4
GHz frequency band only and devices operating in both the 2.4 GHz and 5 GHz
frequency bands can be certified under the Wi-Fi Direct program. Not all
Wi-Fi Direct-certified devices support both frequency bands, however, so
you should check which bands your devices support.
"
I take this to mean that it _can_ operate on both bands but not that every
device will operate on both.

BTW: there are so many security flaws concerning Samsung's OS in general
and Wi-Fi Direct specifically that I'd hesitate to do anything with it
until the 40+ known security faults are patched.
  #3  
Old April 27th 17, 06:47 PM posted to alt.comp.hardware
Maelmoro
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Posts: 3
Default Wi-Fi Direct

BTW: there are so many security flaws concerning Samsung's OS in general
and Wi-Fi Direct specifically that I'd hesitate to do anything with it
until the 40+ known security faults are patched.


I'm not worried about security problems but magnetic field in my house,
I have 2 little children..

Since I usually disable my router WiFi (as a strong precaution, I know
it's not established it's harmful..) I'd like to do the same with Direct
WiFi of my TV Samsung UE50J6200AKX. How to? It seems you can't..

And what I asked as first was: why can't I detect the Direct WiFi with
my WiFi Analyzer as any other WiFi? Maybe because when it's not used
there's not field.. ?
  #4  
Old April 27th 17, 06:58 PM posted to alt.comp.hardware
John McGaw
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Posts: 666
Default Wi-Fi Direct

On 4/27/2017 1:47 PM, Maelmoro wrote:
snip...
And what I asked as first was: why can't I detect the Direct WiFi with my
WiFi Analyzer as any other WiFi? Maybe because when it's not used there's
not field.. ?


From the little I understand about Direct Wi-Fi, if it is not talking to
an established device it does nothing and nothing is being transmitted.
There is some sort of process built in that allows the pairing and it seems
likely that you would need to go through that pairing process to get it to
'talk'. There was some mention of the pairing needing to be accomplished in
30 seconds or something like that so you would have to do your detecting
during that time window.
  #5  
Old April 27th 17, 11:44 PM posted to alt.comp.hardware
Paul[_26_]
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Posts: 832
Default Wi-Fi Direct

Maelmoro wrote:
BTW: there are so many security flaws concerning Samsung's OS in
general and Wi-Fi Direct specifically that I'd hesitate to do anything
with it until the 40+ known security faults are patched.


I'm not worried about security problems but magnetic field in my house,
I have 2 little children..

Since I usually disable my router WiFi (as a strong precaution, I know
it's not established it's harmful..) I'd like to do the same with Direct
WiFi of my TV Samsung UE50J6200AKX. How to? It seems you can't..

And what I asked as first was: why can't I detect the Direct WiFi with
my WiFi Analyzer as any other WiFi? Maybe because when it's not used
there's not field.. ?


A Youtube video suggests there is a "Networking" menu
in the TV on-screen (OSD) menu.

In there, you can select "Wi-Fi" or "Wired" connection.

If you flip it to Wi-fi, then you could use your RF sniffer
to detect activity. The sniffer in the Youtube video, showed
a Samsung set probing the airwavea about every three or four
seconds or so.

If you flip the connection to "Wired", the Wifi activity is
supposed to stop.

The Samsung site does not have a manual for your exact TV. The
PDF download is "generic" and "useless'.

The TV has an onscreen manual, which may or may not explain
this stuff.

Like, would the networking panel have a separate tick
box for Wi-Fi Direct ? Dunno. Since the documentation
system is not set up, to allow us to help you.

*******

Disassembling a Samsung TV looks pretty simple.

This one doesn't appear to have a Wi-fi module. A Wifi module
should have a rectangular metal can over top of it, just
like the tuner module on the input board has both a
shield, and a F-series coax connector.

http://www.techrepublic.com/pictures...v-un55d6300sf/

Viewed from the back, that TV has three PCBs. The one on the left
is the Input/VideoProcessor board. It accepts a number of HDMI
signals, the board has a TV tuner module with coaxial connector.
It has a processing chip with external memory (that does video
enhancement, adjusts the LED light level for better dynamic
contrast). On that TV, the board on the left (viewed from the back),
is the only "Smart" board.

Some TVs, the Smart part is a separate Android kind of processor
board. That's because the dedicated video processor chip, isn't usually
intended to "do everything". But times change, the level of integration
is constantly increasing, so anything is possible.

The middle PCB in that picture, is the LCD panel driver. It converts
the low-amplitude, differential, parallel bus ribbon cable from the
left board, into a higher voltage scan pattern to drive the LCD.

The right-most board is the power converter.

On one Samsung TV, the input board appears to have an actual black "bump"
for a Wifi module. The Wifi module should be inside its own tin can,
so it doesn't "spray" any adjacent chips with RF and cause them to
malfunction. That's called EMI containment. And vice-versa. the tin
can prevents processor digital emissions, from upsetting the Wifi
amps and stuff.

The main message of the above web-link, is the unit appears to be
easy to take apart. However, there are various random wires from
switches of various sorts on the chassis, and you have to be
careful with those. The demo unit on the web page, doesn't appear
to use any glues, or wire assemblies designed to destruct as soon as you
open the unit.

A good design, would have a sticker over one of the back panel
screws, marked "Warranty Void if removed". So that's the only
logistical barrier to examination, is the potential for a
Warranty sticker to be placed on one of the screws. That
scheme is used on ATX power supplies, to keep people out :-)

If you purposely switch on the Wifi, you may be able to localize
where the Wifi signal is located. And then come up with a solution.

If it was my TV set, and I felt that strongly about it, I would
find the Wifi module inside the unit, and "take action". For
regular Wifi antennas, I would replace the antenna cable with a
50 ohm terminator SMA. (There could be two antennas.) That prevents
emission of Wifi signals, and keeps the electronics happy
(SWR = approx 1.0). If the unit uses patch antennas, it's a
Module-On-Board design, then it may be too difficult to find a nice
neat-and-clean mod to disable it.

Using your sniffer, and "turning up" the Wifi temporarily (i.e. use
ordinary Wifi protocol, not Wifi Direct), may at least allow finding
the side of the TV with the module. (The TV could probe the room
every three or four seconds.) Shielding can be difficult. Building
a Faraday cage, you cannot make a complete cage. Using absorptive mats,
the signal would be attenuated (perhaps below health-effects level),
but the signal might not be completely eliminated.

Paul
  #6  
Old April 28th 17, 08:33 PM posted to alt.comp.hardware
Maelmoro
external usenet poster
 
Posts: 3
Default Wi-Fi Direct

On 27/04/2017 19:58, John McGaw wrote:
On 4/27/2017 1:47 PM, Maelmoro wrote:
snip...
And what I asked as first was: why can't I detect the Direct WiFi with
my WiFi Analyzer as any other WiFi? Maybe because when it's not used
there's not field.. ?


From the little I understand about Direct Wi-Fi, if it is not talking
to an established device it does nothing and nothing is being
transmitted. There is some sort of process built in that allows the
pairing and it seems likely that you would need to go through that
pairing process to get it to 'talk'. There was some mention of the
pairing needing to be accomplished in 30 seconds or something like that
so you would have to do your detecting during that time window.


Samsung support told me that I haven't to be worried because when the TV
is off even if my mobile phone detect the TV this isn't "WiFi" but a
weak Bluetooth.

And only when you establish a connection the Direct WiFi works, so only
at this time there's a WiFi field around.

Do you think it's right?
  #7  
Old April 28th 17, 09:59 PM posted to alt.comp.hardware
Paul[_26_]
external usenet poster
 
Posts: 832
Default Wi-Fi Direct

Maelmoro wrote:
On 27/04/2017 19:58, John McGaw wrote:
On 4/27/2017 1:47 PM, Maelmoro wrote:
snip...
And what I asked as first was: why can't I detect the Direct WiFi
with my WiFi Analyzer as any other WiFi? Maybe because when it's not
used there's not field.. ?


From the little I understand about Direct Wi-Fi, if it is not talking
to an established device it does nothing and nothing is being
transmitted. There is some sort of process built in that allows the
pairing and it seems likely that you would need to go through that
pairing process to get it to 'talk'. There was some mention of the
pairing needing to be accomplished in 30 seconds or something like
that so you would have to do your detecting during that time window.


Samsung support told me that I haven't to be worried because when the TV
is off even if my mobile phone detect the TV this isn't "WiFi" but a
weak Bluetooth.

And only when you establish a connection the Direct WiFi works, so only
at this time there's a WiFi field around.

Do you think it's right?


https://en.wikipedia.org/wiki/Wi-Fi_Direct

"Wi-Fi Direct negotiates the link with a
Wi-Fi Protected Setup system that assigns
each device a limited wireless access point.

The "pairing" of Wi-Fi Direct devices _can_
be set up to requi

* proximity of NFC (near field communication)
* a Bluetooth signal
* button press on one or all the devices.
"

Other articles I could find, don't even mention that.

One of the Bluetooth standards even introduced data
carriage over Wifi, as part of Bluetooth. The Bluetooth
in that case, set up the basic connection, and once the
connection was in place, a parallel connection using
Wifi could be used to enhance the data rate. And this
was considered to be a Bluetooth connection, even though
the Wifi hardware was being used for carriage.

*******

Then the article here says:

http://www.samsung.com/au/support/skp/faq/1048477

"Tap Wi-Fi Direct.

The device will scan for Wi-Fi Direct devices automatically
"

That appears to be done from an Android SmartPhone,
but it implies the TV set is "listening" on the Wi-fi
interface.

*******

https://www.wi-fi.org/discover-wi-fi/wi-fi-direct

"Wi-Fi Direct devices emit a signal to other devices
in the area, letting them know a connection can be made.

Users can view available devices and request a connection,
or may receive an invitation to connect to another device.

When two or more Wi-Fi Direct-certified devices connect
directly, they form a Wi-Fi Direct Group using
Wi-Fi Protected Setup (WPS) and the latest Wi-Fi security
[WPA2???]
"

So that agrees with the scenario in the Samsung article. The
first sentence suggests an SSID mechanism, but it could just
as easily be done by the subtending device only running its
receiver, and "answering" when probed.

Then another paragraph says:

"Mobile phones, cameras, printers, PCs, and gaming devices
connect to each other directly...

Connecting Wi-Fi Direct-certified devices is easy and simple,
with:

the push of a button

tapping two NFC-capable devices together

or entering a PIN.

Moreover, all Wi-Fi Direct connections are protected by WPA2
"

*******

Are you feeling safe yet ? :-\

The description is wishy-washy enough, to have
been written by the Bluetooth group.

Each of these manufacturers should be providing documentation
of their own, and not blowing this stuff off. It should
state in the downloadable PDF manual, how each and every
device works.

*******

This is more technical - see page 2 "Group Formation"

http://www.it.uc3m.es/pablo/papers/p...wifidirect.pdf

Paul
 




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