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I'm almost certainly messing up some terminology here...
January 4, 2013 1:20 PM   Subscribe

I'm not a network technician but I play one on tv in grad school. How do I get the server connections I need, involving a virtual machine (VMWare Fusion) that needs to talk to an outside device?

I use a cool experimental device that has a built-in server which transmits data back and forth. I currently access it from a Mac OS sytem, which works fine. I'm attempting to access it from a Win 7 virtual machine using VMWare Fusion, and running into problems.

My Win 7 virtual machine connects to the internet via an ethernet cable just fine, (I'm in NAT mode). However, when I plug my device into the laptop instead, I can ping it from the MAC OS host but not from the Win 7 machine. I would like it to talk to *both* the guest and host.

(For context, I have a two-part experiment; the vastly-superior standard implementation of part 1 runs only on Windows, ditto for part 2 runs only on Mac. The standard solution to this problem is two computers, but I work in a semi-mobile lab and don't have this option. yay.)


So far I've turned off all the Win 7's firewalls that I can find and fiddled with the different networking modes without success. Where do I start to diagnose what's going on? VMWare occasionally asks (for flash drives etc.) whether an item should connect to the host or guest - can I examine/alter these preferences once they've been set?

My probably-subpar googling seems to yield mostly attempts to connect to virtual servers, which is not what I want. Help me figure out how to figure this out!
posted by heyforfour to Computers & Internet (15 answers total)
 
How is the device connected to the host?
posted by pharm at 1:24 PM on January 4, 2013


Via ethernet cable. I'm not sure if there's anything else more specific to tell you (if there is, I don't know it.)
posted by heyforfour at 1:26 PM on January 4, 2013


If I understand your problem correctly, you're looking to access a physical device from a guest VM. If that's true, VMDirectPath configuration may well be what you need. If not, I have nothing useful for you in this comment.
posted by thatdawnperson at 1:29 PM on January 4, 2013


Switch the VM from NAT to bridge mode...
posted by iamabot at 1:31 PM on January 4, 2013 [1 favorite]


don't just ping it, use tracert. It will show you where it stops on the way. tracert 123.123.1.23 will show you the hops it takes.
VMs get a MAC address. Does your virtual machine have a usable MAC address?
posted by theora55 at 1:36 PM on January 4, 2013


Seconding iamabot: Switch your VM to use bridged networking.
posted by jjwiseman at 1:45 PM on January 4, 2013


Thatdawnperson is right, I'm trying to access a physical device from a guest VM. I'm fairly sure I tried bridging already, but I'll try that again (as well as seeing if I can get more info from tracert.) Any other places I should look?
posted by heyforfour at 2:16 PM on January 4, 2013


Sorry, I should elaborate: You can try switching to bridged networking mode and see if that helps, because often it does, but I admit that my answer is mostly in the same class as "turn if off, then turn it on again."

If you're connecting the device directly to your mac, then the mac is using a feature called Auto-MDIX to connect to it. I don't know if that might be interacting with VMWare's networking.

Do you configure the device using DHCP or with a static IP? Are you turning on OS X's Internet Sharing on that ethernet port? What are the IPs of your Mac and of the device? Can you try connecting the Mac and the device to an ethernet hub instead of connecting them directly?
posted by jjwiseman at 2:21 PM on January 4, 2013


Find the IP of the device. Is it getting an autoassigned IP (ie 169.x.x.x)? If not, is it on the same subnet as your VM? Can you ping the device from your VM?
posted by wongcorgi at 3:42 PM on January 4, 2013


Thatdawnperson is right, I'm trying to access a physical device from a guest VM. I'm fairly sure I tried bridging already, but I'll try that again (as well as seeing if I can get more info from tracert.) Any other places I should look?

If it is like other research devices I am familiar with that are similar to this, then what it does is send a UDP broadcast out on the network.

The packets it sends are non-routable, which means that NAT mode will not work - you will have to use bridging. The device should grab a DCHP assigned address just fine, so as long as the device and the computer are on the same subnet it should work.

One last wrinkle is to make sure that the windows firewall on both the host and VM are configured to allow for this traffic. You may have to disable it entirely for your private subnet.

If you really absolutely must use NAT for your guest VM, you can get this device to work by using VLAN tagging, but that is a much more complicated thing to set up, and really beyond what we can do for you here.
posted by Pogo_Fuzzybutt at 4:40 PM on January 4, 2013


If you're hooking a single cable straight from the device to the Mac and that's the extent of the network, you'll probably need to set a static IP address with appropriate (almost certainly 255.255.255.0) subnet mask on the VM.
posted by contraption at 6:13 PM on January 4, 2013


(That's with the VM in bridge mode. Remember to change it back to DHCP before you go back to NAT or connect to a normal network.)
posted by contraption at 6:14 PM on January 4, 2013


Thank you all! Unfortunately it turns out I won't have access to the device until monday, but this gives me much more to go on, and sufficient stuff to research in the meantime so I can get everything set up. I'll report back/mark answers once I figure out what it takes to get this working...
posted by heyforfour at 9:39 PM on January 4, 2013


It might be worth booting a Linux VM and seeing if it can see the device. That will at least tell you if it's a problem with the VM configuration, or a problem with Windows configuration.
posted by vasi at 2:43 AM on January 5, 2013


Chiming in late to say the problem's fixed! Bridge mode plus making sure the VM and device were on the same subnet did the trick. Thanks all :)
posted by heyforfour at 8:42 AM on January 17, 2013


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