virtualbox.org

BillG wrote: Starting a new thread would be a good idea, since this discussion has little or nothing to do with your original post.

If you have only just discovered that the vm emulates a wired Ethernet NIC, you have a fair way to go in understanding how this all works!

You're right, but IMHO it makes no sense starting a new topic/continuing this dialog (I hope, it means what I think ).
I've tried today: using ethernet device to bridged interface, the VM receives all packets with its own MAC addres, while the bridge with wlan receives the wifi adapter's MAC in packets, as target.
I don't know why, but AFAIK, it can't be changed, so I gave it up.

H.Z. wrote:I've tried today: using ethernet device to bridged interface, the VM receives all packets with its own MAC addres, while the bridge with wlan receives the wifi adapter's MAC in packets, as target.

I am not surprised, you are basically piggybacking the wifi link of the host, and wifi hardware would expect a P2P connection over a wifi link, but then gets 2 clients instead of a single one. I have to say, i am already surprised it works in the first place (the whole bridging on a wifi link), so here your hardware is just replacing the "bad" MAC with the one that made the link, and there you go.

YEAAAH!
It has been solved!!!!
I was set up a bridge (br0) on vm1 which contains interface eth0.
Then...

ebtables -t broute -A BROUTING --protocol IPv4 --ip-dst 172.31.1.0/24 -j redirect

After installing package ebtables, and issue the above command, it started to work.
Hmmmm... resolving this problem, required about 4 days, BUT IT WORKS, AND I'M VERY-VERY HAPPY!