as we couldn't find a solution in the German-speaking section, I'll try to translate the problem to English.
I am new to VBox, so here are some preliminary notes. For the last years I used for my own company and at my customers VMWare Server as VM Solution ad was quite satisfied with it (not speaking about these horrible Version 2.x...). Since the final release of Windows 7 is available over Technet, we are testing it intensively. It seems to be a lot better than Vista, but that's not difficult...
On this machine, we always had some VM's, some simply for testing, but also some for productive purposes. One productive Application was the free Network Gateway "Untangle", which we use at our customers for about 2 years now. It works like a charm. But in the moment VMWare Server AND VMWare Workstation are not running stable under Win 7. The VM's work, but Win 7 produces several BSOD's per day, with this Software installed. So we had to look for an alternative and we found VirtualBox. We like it very much, it already supports Win 7 and we can imagine to switch completely to VBox at all our customers.
But now our current problem with VBox and Untangle running as Guest. So far it's not possible to have traffic between the local network and the internet being routed through Untangle. The Network-Functionality in VBox seems to be completely different as in VMWare and although I've read the documentation carefully, I obviously don't understand it. Here's our Configuration:
Host: Intel Q9550, 8 GB RAM, 2 NIC's (Realtek), Win 7 Ultimate 64 Bit. One NIC is configured as usual and connected to the local Network via Switch. The other is directly attached to the router. The ONLY binding that this NIC in Windows has, is the "VirtualBox Bridged Networking Driver". No TCP/IP, no Client for MS Networks, nothing. That's the way, we always had this with VMWare before. We configured this NIC in VBox as bridge, and in Untangle this NIC gets a static IP, according to the routers' settings. This is in Untangle the so called "external adapter". This seems to be correct, as Untangle reaches the internet through this connection, f.e. for fetching program-modules and updates. So I think, the problem has to be the other NIC. In Untangle this "internal adapter" has to be bridged to the "external adapter". First, it seems to be logical to me, to have this NIC in VBox to be configured as "NAT", but when I do that, I can't even reach Untangle from the local network. So the only way was to set this NIC also to "bridged" in VBox. When I do this, I can reach Untangle from the local Network, Untangle is connected to the internet, but no data goes through Untangle, not in both directions, neither in, nor out.
I hope, this description is quite understandable, I apologise for my bad English. I appreciate any help or hint!