PXE booting server in VirtualBox network configuration

Try this:

1. Setup the virtualbox to use 2 adapters:
   • The first adapter is set to NAT (that will give you the internet connection).
   • The second adapter is set to host only.
2. Start the virtual machine and assign a static IP for the second adapter in Ubuntu (for instance 192.168.56.56). The host Windows will have 192.168.56.1 as IP for the internal network (VirtualBox Host-Only Network is the name in network connections in Windows). What this will give you is being able to access the apache server on ubuntu, from windows, by going to 192.168.56.56. Also, Ubuntu will have internet access, since the first adapter (set to NAT) will take care of that.
3. Now, to make the connection available both ways (accessing the windows host from the ubuntu guest) there's still one more step to be performed. Windows will automatically add the virtualbox host-only network to the list of public networks and that cannot be changed. This entails that the firewall will prevent proper access.
4. To overcome this and not make any security breaches in your setup:
   • go to the windows firewall section, in control panel,
   • click on advanced settings. In the page that pops up,
   • click on inbound rules (left column), then on new rule (right column). Chose custom rule, set the rule to allow all programs, and any protocol. For the scope, add in the first box (local IP addresses) 192.168.56.1, and in the second box (remote IP) 192.168.56.56. Click next, select allow the connection, next, check all profiles, next, give it a name and save.

That's it, now you have 2 way communication, with apache/any other service available as well as internet. The final step is to setup a share. Do not use the shared folders feature in virtualbox, it's quite buggy especially with windows 7 (and 64 bit). Instead use samba shares - fast and efficient.

Follow this link for how to set that up: https://wiki.ubuntu.com/MountWindowsSharesPermanently

There is absolutely zero requirement for the DHCP server to be the same machine as the TFTP server (there's no such thing as a "PXE server"). You simply configure the DHCP server to provide the necessary DHCP options for PXE booting. Good luck managing that on a dinky toy consumer router, though.