I have Ubuntu 10.04 guest on Windows XP host. I need to use a specific VPN software that works only on Windows. How should I configure virtualbox/guest so that the VPN connection would be visible on guest?
I already tried NAT and bridged network settings. With both of these options I get only normal internet connection to work, but sites requiring VPN don't work on guest, only on host.
NAT is the right choice.
I guess that your VPN client is set to only route the traffic to the company network through the vpn tunnel. This messes with the virtual network interfaces from VirtualBox. I have seen this on a Ubuntu Host with a Windows Guest. Cisco VPN Client's "allow local lan access" could also cause this behaviour.
To verify this, start your VPN and then
Start cmd.exe on your Windows host and type:
[1] tracert something.restricted.to.vpn.mycorp.com
[2] tracert www.google.com
Start a terminal in your Ubuntu VM and type:
[3] tracepath something.restricted.to.vpn.mycorp.com
If the first few lines from [2] and [3] are similar and [1] looks completely different then you have to dig in your vpn client's settings.