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Disabling CSMA/CA


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#1 vooduHAL

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Posted 25 December 2004 - 12:37 AM

I've been all over google and can't seem to find much. Does anyone know of any documentation on disabling CSMA/CA or CSMA/CD in the linux kernel or if this is going to be a function of the NIC itself.

#2 BlackRatchet

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Posted 25 December 2004 - 01:08 AM

I am quite sure this is handled by the NIC itself. What you are talking about is Level 1 or Level 2 on the OSI scale, and it would make sense that it was handled by the card, rather then let the kernel worry about such nimbly, pimbly things.

What are you trying to do exactly? And why/how are you hooking a CSMA/CD and a CSMA/CA on the same physical network segement?

#3 vooduHAL

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Posted 25 December 2004 - 07:49 AM

Ah, just wanting to disable CSMA/CA on my wireless card for some fun. :) Yes, CSMA/CD is a layer 2 function.

#4 thought_poet

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Posted 25 December 2004 - 05:15 PM

Ah, just wanting to disable CSMA/CA on my wireless card for some fun. :) Yes, CSMA/CD is a layer 2 function.

Something tells me your on to something. Whatever your working on vooduhal, let us know when its goes public.. I'm interested allready.

#5 vooduHAL

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Posted 25 December 2004 - 06:58 PM

Actually, there is a known DoS against wireless 802.11b/g networks (And probably any other layer 2 that uses CSMA/CA) that just requires a device that disables it's CSMA/CA and just streams packets at full speed at the network. The idea is that if you have a host that doesn't care of anything else is sending, but every other node on the network does, and just keeps pumping out small frames, the other devices never get a chance to send, and with CSMA/CA being more active than CSMA/CD you realistically should be able to halt the ability for most any device in range to transmit. (In range and on the same channel)

#6 zeroxeal

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Posted 25 December 2004 - 09:53 PM

Hehe that sounds very cool, a friend of mines sister just got a cordless phone, and when it talks to the base station wether it be a call or intercom or w/e. It kills his wireless network, completely, no matter what the channel, he is using a WRT54G with sveasoft, and has 2 laptops, when im next in town with him were going to mess with it and see if we can compact its design and use it to dick with people :), as well as figuring out why its doing it of course.

#7 vooduHAL

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Posted 25 December 2004 - 10:05 PM

The reason the cordless is killing it is because both are ~2.4Ghz devices.

#8 thought_poet

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Posted 25 December 2004 - 10:28 PM

The idea is that if you have a host that doesn't care of anything else is sending, but every other node on the network does, and just keeps pumping out small frames, the other devices never get a chance to send, and with CSMA/CA being more active than CSMA/CD you realistically should be able to halt the ability for most any device in range to transmit. (In range and on the same channel)

That could be really annoying if your a cop in his cop car, with the car its own wireless node.

Or a bank that allows cars to park next to the building even though it depends on wireless cameras for security.

Or any other number of things..

You looking for a way to stop this?

Edited by thought_poet, 25 December 2004 - 10:29 PM.


#9 vooduHAL

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Posted 25 December 2004 - 10:37 PM

Or a bank that allows cars to park next to the building even though it depends on wireless cameras for security.


Think more along the lines of, walking into the bank with a PDA with 802.11*. Although, I can't think of a bank in their right minds that would use IP based wireless cameras over a close circuit TV system. Plus, even if they were using X10 style cameras, you could just use a white noise generator in the right frequency range to knock those out completely anyway.




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