I have a Linux laptop running a PXE server. I run the PXE server on the wired port so I can connect computers to it directly. When the Ethernet port is connected I can use PXE to boot a VirtualBox machine using a bridged network. (Bridged to wired of course.)
When there is a cable connected to the Ethernet port, everything works just fine. But I'd like to be able to test the PXE server when I reconfigure it without connecting something to the Ethernet port.
When the virtual machine tries to get an IP address I see that there is a DHCP discover received and a DHCP offer is send, but the DHCP request and acknowledge never occur. As I said before, it works flawless when a cable is connected.
I have considered using a loopback connector, but I'm not sure that this will work and don't see this as a real solution. Maybe something like a TUN/TAP interface will do the trick?