virtualbox.org

I've just moved house/office and now have a cable modem for my broadband instead of ADSL, which means I can't use my existing router (an ADSL one). A replacement is on order but I'm keen to get a webserver visible to the outside world ASAP, as well as to be able to share the internet connection, and I was wondering whether I might somehow be able to use VirtualBox to provide a makeshift router, with a purpose-built firewall/router Linux distro such as ipcop running in a VM? I'm no router expert but as I understand it, the basic requirements are 2 NICs and software to provide NAT, port forwarding, etc. Could the connection to the host not be equivalent to the WAN side of the router equation, and the ipcop (or whatever) guest handle the LAN side?

Looking for input from someone with a better grasp of these things than I have

You can use http://www.untangle.com for that. We use Untangle for a few years now for our own company and at our customers and are very satisfied with it. But until now, we only used it in VMWare Server. As VMWare in the Moment does not support Windowas 7 as Host, we tried Untangle in VirtualBox, but the performance is very poor.

Yes you can. I do that all the time - I have a Linux machine which reflects (*) the physical NICs (one connected to modem, one to LAN, one to wireless access point) directly to virtual NICs in a Windows 2003 vm. I then have MS ISA Server 2006 doing all the network (internet, cabled, wireless) routing and firewalling as if connected to the actual network.

Of course you can use a different OS, I just use WS2003/ISA Server for historic reasons.

(*) By which I mean the physical adapters in the host are each individually bridged to the virtual adapters exposed by the VM