VirtualBox failed to start with an aliased iface or when two+ VM use the same iface

[MulX]

When I want to attach the interface of my guest machine to an aliased iface of my computer, I don't have error.

I use :

VBoxManage modifyvm <name> -nic1 hostif -hostifdev eth2:0

But I can't start the VM.

I get this error :

Error: failed to start machine. Error message: Failed to open/create the internal network 'HostInterfaceNetworking-eth2:0' (VERR_INTNET_FLT_IF_NOT_FOUND).
Unknown error creating VM (VERR_INTNET_FLT_IF_NOT_FOUND)

Using Gentoo as host, and Debian as guest (but any other guest produce same error)