I have a Xubuntu 14.10 guest running within VirtualBox on a Windows 10 host. The host is connected to a wired network which requires a proxy to access the outside world. The host is also connected to a VPN. Everything on the host works as expected - Windows can access both the internet and IPs on the VPN. Using tracert I believe Windows bypassing the VPN when connecting to the outside world.
The Xubuntu guest is configured with a single NAT adapter so that it shares the host's VPN connection. The guest can access IPs over the VPN. However, the guest cannot access access the internet.
I'm not a network expert but it seems to me the guest should not need to know the proxy configuration if it is NATd to the host. If the host mediates all of the guest's network activity then the Windows system proxy should take care of everything. However, just in case I have tried setting up a proxy within the guest and it made no difference (it's entirely possible that I did this wrong as Xubuntu seems to require a proxy to be configured via environment variables).
Does this simply mean that I need to properly configure a proxy for the guest OS, or could there be some other problem here?
Any thoughts much appreciated.