I'm running a VM to test a PfSense installation, and would like to be able to test features with the host machine. I found where to change the address explicitly, and to disable VirtualBox's DHCP server, but couldn't figure out how to make it request an address from my guest.
SnapOverflow
There are two ways you can approach this:
1) You will need to install a loopback adapter as a network interface in the host, then bridge the guest network connection with it. You may still get mixed results.
2) Use a micro distribution like Puppy or Tiny Core and setup a second guest that you can use for testing. This is really far more desirable than testing with your host operating system (if you can avoid it).
Using a second virtual as the test client as Goyuix suggested is the easiest and the "proper" way if you're doing this in an environment with other machines. Don't break working configurations to test new configurations. In other words, don't mess up the host to test a virtual. All relevant tests can be performed by multiple virtuals first. If you're trying to test your host OS, create a virtual of your host system.
Bridge mode should work but may have issues with an external DHCP server (your router). Just turn off DHCP on your router and use fixed addressing when not testing the virtual.
You could install a second NIC and bridge to the NIC not connected to your standard network. It will start getting complex if you also want to access the Internet at the same time. If using a second NIC you may also need to change settings to force the interface UP when no cable is plugged in depending on host OS.