9Advanced topics
9.11Allowing a virtual machine to start even with unavailable CD/DVD/floppy devices
When, on VM startup, a CD, DVD or floppy device is unavailable, VirtualBox by default prints an error message and refuses to start the virtual machine. In some situations this behavior is not desirable.
The behavior can be changed for the CD/DVD drive with the following configuration change command:
VBoxManage setextradata "YourVM" "VBoxInternal/Devices/piix3ide/0/LUN#2/Config/AttachFailError" 0
The equivalent command for the floppy drive is:
VBoxManage setextradata "YourVM" "VBoxInternal/Devices/i82078/0/LUN#0/Config/AttachFailError" 0
You will still get a warning message that a device is not available. Some guest oper- ating systems may show strange behavior when using saved state or snapshots, espe- cially if a previously mounted medium is no longer available when the virtual machine is resumed.
9.12 Fine-tuning the VirtualBox NAT engine
9.12.1 Configuring the address of a NAT network interface
In NAT mode, the guest network interface is assigned to the IPv4 range 10.0.x.0/24 by default where x corresponds to the instance of the NAT interface +2 of that VM. So x is 2 if there is only once NAT instance active. In that case the guest is assigned to the address 10.0.2.15, the gateway is set to 10.0.2.2 and the name server can be found at 10.0.2.3.
If, for any reason, the NAT network needs to be changed, this can be achieved with the following command:
VBoxManage modifyvm "My VM"
This command would reserve the network addresses 192.168.0.0 ...
192.168.254.254 for the first NAT network instance of “My VM”. The guest IP would be assigned to 192.168.0.15 and the default gateway could be found at 192.168.0.2.
9.12.2Configuring the boot server (next server) of a NAT network interface
For network booting in NAT mode, by default VirtualBox uses a
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