Host Only NIC: VM exclusivly needed

[RalphJK]

As to configure VMs in part of a complex simulated network including an Multi-NIC FirewallRouter such as ClearOS it is needed, that the Virtual NICs on the - in my case - Windows-Host does only have the VirtualBox-Option, not any other of Windows, even TCP/IP enabled - thats for the VMs behind the VM and Host should NOT be able to direvt communicate via TCP/IP.

Szenario:

• ClearOS with dedicated physical NIC as WAN-Bridge (VirtualBox and TCP/IP on Host enabled)
• 4 VirtualNICs vor VM only - on the Host only VirtalBox-Option enabled, TCP/IP disanbled

Initial Configration of VirtualNICs in VirtualBox works well. In 2nd step disabling other Options in Windows NIC Manager incl. ZCP/IP, except VirtualBox.

This works well so far, setup of ClearOS as FirewallRouter and ClientVMs in different VirtualNetworks, attached to the ClearOS - incl. Routing and Firewall works well.

Problem: Starting VirtualBox completely new, a Warning is displayed networking failures on the VirtualNICs. Thsi is caused by the missing TCP/IP - Host address, which is deleted in the VirtualBox-VirtualNIC-HostOnly Adapter - it displays 0.0.0.0/0.0.0.0

This can be temporarily cleared by setting IP-Addresses on the VirtualNIXCs in VirtualBox, but it is back again on next start. You can bypass the warning by "Ignore" ad everything works well, but if you need to change any other default value, you have to temporaily set ip-addresses to finalize the dialog.

Request: An Option to disable Host-TCP/IP on Virtual Host-Only-NICs or create a new type of adapter "VM-Only".

[RalphJK]

Searching the net i found out that "Internal Network" seem to fullfill the requested solution.

But the official Documentation here is right now telling https://www.virtualbox.org/manual/ch06.html#network_internal

Internal Networking is similar to bridged networking in that the VM can directly communicate with the outside world. However, the "outside world" is limited to other VMs on the same host which connect to the same internal network.

which seems like any of the statements must be wrong, either the results in the internet or the documentation here. Testing the Internal Network on an VM-Client results as it is not able to connect neither to the host nor to the outside world.

[Socratis]

︎See if the following can help you:

	VM <-> Host	VM1 <-> VM2	VM -> Internet	VM <- Internet
HostOnly	+	+	-	-
Internal	-	+	-	-
Bridged	+	+	+	+
NAT	-	-	+	Port forward
NATService	-	+	+	Port forward

For more details, as you figured out already, please read in full ch. "6. Virtual networking".

May I also suggest something? It's usually better and faster, if issues like this one (configuration, question) get first addressed in the ​VirtualBox forums. More than 95% of the issues are resolved over there, which keeps the developers focusing on the bug fixes and enhancements, and there is no need for another ticket to keep track of. For example, yours is most probably not a bug and someone from the developers has to deal with it and close it as "Invalid".

[Frank Mehnert]

The internal network connects VMs. It's possible to attach a DHCP server to the internal network but that has to be done explicit. NATService (we call it 'NAT network' actually starts an internal network and attaches a NAT engine to that network. It's also possible to attach several VMs to a single NAT network.