There is an IP device with an unknown IP. How can you find it if the basic subnet scan fails?

Question

Electronics

There is a Chinese network controller, which had an unknown IP set a long time ago. It is not in the main subnets, I connected it directly - there is a link, packets are coming. Reset to the factory, too, alas, no. Is it possible to calculate its subnet or IP using WireShark?

Answer 1

there is a link, packages are coming

does not mean that the device has an IP.
Alternatively, connect the device to a normal LAN and ping the boardcast address (*.255). After look at the arp table from where they pinged. Further on the MAC from the label of the device, look for the IP.
Alternatively, for Linux, there is a ready-made solution in the form of arping

Answer 2

So you lost it somewhere and forgot the address? Or is the box in your hands and you just need to find out the network settings?
If the latter, then find a hub (which is difficult now), stick it into the gap and use a warshark. An alternative to a hub is passive tap. You need two setevukh, three sockets and a little vitukha)
for example