Hello everybody! Is it possible to transfer the payload over WiFi without connection? Maybe in the hello package, where we introduce ourselves to each other or some “extended” ping? In the terminology is not very strong. Direct or tell me, maybe there are already solutions on this topic?

*What for? Being already in the network, the ability to share information with other devices from another network.

Thanks a lot, everyone!

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    With other devices from another network will not work - you do not have a routable address, you will be given it only after authorization on the access point. - Smithson
  • But we see this device in the list of networks? So we can send something to him, right? At least a connection request. Why not send him a command instead. Encryption is postponed until later. - Alexander

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Share - unlikely. To listen is theoretically ...

  1. If all the adapters of the host and the drivers for them have a “monitor mode” (monitor mode), allowing you to listen to absolutely all the packets that go through the same Wi-Fi channel . Other options may be limited.
  2. If packets are transmitted unencrypted.
  3. If the networks between which interaction is planned are on the same Wi-Fi channel (a consequence of the first item):
    • What is usually avoided, because different networks on the same channel interfere with each other (reduce performance / range).

... but such a situation can only be created independently, "in nature" this does not occur.

This is assuming that each client has only one Wi-Fi adapter. If there are several, they can work independently of each other and transfer packets between themselves. But it is trite.

  • The first client is a phone or tablet, respectively, one network card, one stream. Protection / encryption - you might think later, because you first need a principle. What to watch? I understand correctly, if there is a stable connection, then the data exchange options are already limited? I do not need much, not video and not sound, elementary binary. - Alexander
  • @Alexander find out which of them has monitor mode and access to it. If only one of them, the connection will come out one-way, if at all. - D-side
  • I read that BLE exchange an additional package, that is, for example, says "I am a beacon from eppl." Can this be used? For example, with a substitute SSID after each successful action. All of the Anroid and iPhone / * devas have the ability to monitor networks, and how to use it. I would also like to understand, is it possible, knowing the algorithm, to do all this in the invisible mode? - Alexander
  • @Alexander every 100 ms (usually) access points declare themselves using a beacon frame , the question is who will hear them. Devices that are not connected to any network, switch between channels and look for these frames. In theory, in these frames it is possible to transmit some kind of payload, but again, this is a one-way communication, since it is impossible to answer them (in a regular way). If you want more internal details, you can ask a question on the NE.SE , since I don't know very much :) - D-side
  • And no, “tracking mode” is not the same as “network search mode”. The latter is at all (what I saw). But the first is not so spread. - D-side