virtualbox.org

Hello all,

So I am not very knowledgeable on Virtual Machines or networking, which is proving challenging for me to set up an analytical chemistry instrument called an FTIR. I'll give you a summary of the problem and hopefully someone can help (it doesn't actually involve knowing about analytical chemistry).

The FTIR uses a 16-bit software for me to control it, but I have a 64-bit Windows7 computer. I set up a Windows XP VM and the software is working. The problem comes when I want the guest OS to be the one communicating through the crossover cable with the FTIR. Here's a schematic of the layout:

FTIR -------crossover-cable--------computer (host)-----virtual machine on host (guest)

I need the host to essentially act as the middle man between the guest and the FTIR, and just funnel the packets of data between the two. As one may have gathered from the connection type, the FTIR has an IP address that has to be set... and the entirety of this problem revolves around getting the three IP addresses worked out (the one for the LAN card on the PC, the one for the Virtual Machine from the host PC, and the one inside of the guest machine). Let's say the FTIR IP is xxx.yyy.fff.70 (where x,y, and f are actual numbers) and the subnet mask for this address is 255.255.0.0. Which of the three IP address should match the FTIR's, and then what should the other IP addresses be for the host to simply act as a funnel to the guest? Also what would the subnet masks be for these IP addresses? If anyone has any ideas I'd greatly appreciate it, and I will send out more information if it is needed.

Thank you for any help!!

-TE

I don't know much about networking, but I have a couple Ideas. Assuming you don't need to the FTIR network to be connected to any other machines, try setting the guest network to Bridged, the FTIR to 192.168.0.70, the host network card to 192.168.0.71, and the guest network adapter to 192.168.0.72. Subnet 255.255.255.0 on all three. gateway, i have no idea. Try turning on Ping in the XP guest, then see if you can ping the FTIR (192.168.0.70) with the guest. If the FTIR has pinging commands, try pinging 192.168.0.72 (the guest) from the FTIR.

I agree that bridged networking is the obvious solution. What happens with bridging is that the bridge software acting with the NIC driver makes the vm perform as if it was directly connected to the network. Communication between the guest OS and the machine on the physical network is transparent to the host OS.

What the IP of the host NIC is does not matter in this case. The host OS does not see the traffic. The filtering is done at the network level. Also the default gateway address can be blank because the only traffic is direct traffic from one PC to the other. (You only need a default gateway if you want to forward traffic to some other network or some other IP subnet).

As scottgus1 said, the IP address has to be different for each device but the subnet mask must be identical. 255.255.0.0 should be fine as long as the first two octets of the IP address are the same in both of the IP addresses (ie the xxx.yyy of your example). xxx.yyy.0.71 and xxx.yyy.0.72 should be fine.

I have heard of some people having trouble running bridged networking on a crossover cable connection. If this affects you, you may have to connect the instrument and the host PC using standard patch cables and a hub/switch.

Thanks! I will try that. I forgot to include some of the history. I had it set up as NAT, had the host-FTIR IP set to the default FTIR IP (starts with a different octet than the next IP, but I can't remember what that octet is), the connection to the VM from the host set to 192.168.0.70, and then the guest IP set to automatic, and that worked for a while. Then I came back in one day and it had stopped working. The guest was no longer detecting a network cable. My point here is that the default NAT can work, but I don't know why it stopped working. Might need to tackle that problem if the bridged connection doesn't work.

Thanks again,

TE

Bridged networking worked! I got the Instrument Installer to recognize the host pc (which is actually the guest in this case), the instrument to recognize the host, and then the instrument to send its serial number (a data packet) back to the computer and have it recognize it. Buuuuut my computer froze and now BIOS won't start . Luckily the computer is under warranty. Thanks for the help guys! Hopefully my problems with getting this stupid thing set up end soon.