[vbox-dev] VirtualBox blocks 127/8 (loopback) subnets for intnet

[Alexey Eromenko]

One major difference between old VirtualBox and new one is at the MAC
level filtering at layer 2.

To achieve network similar to VirtualBox 2.x, you need:
VM->Settings->Network->Adapter [X]->Advanced->Promisc. Mode = "Allow All".

If your application used to work with VBox 2.x, it will work with v5.x
and this setting.

Best wishes,
-Technologov