Allowing only the guest/host on a network with no access to host's resources?

Discussion in 'Virtual PC' started by Chuck Heatherly, May 10, 2005.

  1. Hi,

    I am a computer professional. This means, to me, that I have intermediate
    knowledge in several areas, expert knowledge in a few areas, and that I am a
    freaking idiot in all other areas. Figuring out how to set up Virtual PC and
    networking seems to be the latter category for me. I read and read the help
    file, and the info just doesn't seem to take root in my damn aging brain!

    I need to configure things so that the host machine and guest VM(s) are on a
    virtual network, and the guest(s) have no access to the host's intranet or
    internet resources. From reading the Virtual PC help, it seems I need to
    install the loopback adapter on the host, set its IP address to 192.168.x.y, set
    the guests' network adapter to use the primary NIC, and set its IP to
    192.168.x.z. And make sure the subnet mask for both is the same (
    has been suggested), and that the gateway IP is blank for both.

    Is this all? When I set this up, on the guest VM under Network Connections, the
    Local Area Connection status says "Connected, Firewalled". The host's OS is
    Windows XP SP2. I have Virtual PC 2004 SP1 installed. Is there something I
    need to configure with the XP SP2 firewall? Or the guest's firewall, it's XP
    SP2 also.

    I appreciate any replies and direction.
    Chuck Heatherly, May 10, 2005
    1. Advertisements

  2. Chuck Heatherly

    Bill Grant Guest

    If you want the guest machine to be able to see the host but not the
    host's intranet, you set the guest NIC to use the loopback adapter option,
    not the physical NIC on the host. The loopback adapter on the host and the
    virtual NIC in the guest are in the same IP subnet.

    With this setup, the guest can only see the intranet if you configure IP
    routing on the host.

    If you set the guest to use the physical NIC, it looks like just another
    machine on the intranet. It shares the physical NIC on the host. Virtual
    Machine Network Services intercepts the packets addressed to the guest.
    Bill Grant, May 11, 2005
    1. Advertisements

  3. Bill,

    How do I set the guest NIC to use the loopback adapter? The only options I see
    for setting the network adapter in the Virtual PC Settings page are None, Local
    only, the physical NIC, and Shared (NAT). Do I install the loopback adapter on
    the guest OS also?

    Chuck Heatherly, May 11, 2005
  4. Chuck Heatherly

    fede Guest

    How do I set the guest NIC to use the loopback adapter? The only options I
    Hello Chuck
    I had the same problems but is seems I resolved them.
    First, configure the Loopback in the Host and don't forget to check "Virtual
    Machine Network Service" in the general tab.
    After that you will see in the guest virtual machine Edit>settings>Network a
    new network adapter option: "Microsoft Loopback adapter". Choose this option.
    Now you can use Ping to test the connections between the host and guest.
    Remember to configure the firewalls to accept ICMP messages (echo is the one
    for Ping-Pong).

    Best regards and sorry for my poor English.
    fede, May 11, 2005
  5. This is what I cannot figure out. I have the loopback adapter installed on the
    host, when I did that, a "Local Area Connection 2" appeared and I set the IP and
    subnet values for that connection. I didn't see any where to set those values
    on the properties for the network adapter itself. And "Virtual Machine Network
    Service" is set. But I still only see four option values for networking adapter
    for the guest VM: None, Local only, the physical NIC, and Shared (NAT). I
    rebooted the host, I shut down the guest, still no change.

    I have Virtual PC 2004 SP1 with VM Additions installed, is there any newer
    version? Why do people see a "loopback option" for that item and I don't?

    Chuck Heatherly, May 11, 2005
  6. Chuck Heatherly

    Steve Jain Guest

    Maybe I am missing something, but if you don't want the guest(s) to
    have access to the host, why not just use the Local ony networking

    Steve Jain, Virtual Machine MVP
    "This posting is provided "AS IS" with
    no warranties, and confers no rights.
    You assume all risk for your use.
    I am not am employee of Microsoft."
    Steve Jain, May 11, 2005
  7. Steve, I do want the guest to have access to the host, just not to the
    host's intranet or internet resources. So, if the host was running an
    instance of SQL Server, then I would want the guest to be able to
    connect to that server, but not to the outside world directly. Thanks
    for trying to help me figure this out.

    Chuck Heatherly, May 11, 2005
  8. Chuck Heatherly

    Bill Grant Guest

    Something is screwed up if VMNS is present and checked on the loopback
    adapter on the host, but you don't get the option to use it in the virtual

    I would shut down the guest, then reinstall VPC while the loopback
    adapter is enabled on the host.
    Bill Grant, May 12, 2005
  9. Bill, I did this, and then the loopback option DID appear in the network setting
    options in Virtual PC! As soon as I selected that option and restarted the
    guest VM, I was able to connect from the guest to the host, ping it, but was not
    able to access any resources on the host's intranet or internet, which is
    exactly what I wanted. Thanks!

    Chuck Heatherly, May 12, 2005
  10. I figured out why this situation occurred in the first place, where I had
    installed Virtual PC 2004 SP1 and after installing the MS Loopback adapter, it
    didn't show up as an option for the networking adapter. I had the original
    version of Virtual PC 2004 installed, and had installed SP1 when it came out.
    When I took a clean machine and installed VPC w/SP1 using the combo ISO that's
    at MSDN Subscriber Downloads, and then subsequently installed the Loopback
    adapter, it showed up in the networking options correctly.

    I also determined that taking the original copies of VPC 2004 and SP1 that I had
    used on my primary PC and installing them on a clean machine resulted in getting
    the error message:

    The Virtual Machine Monitor driver required by Virtual PC is missing. Please
    reinstall Virtual PC and try again.

    But reinstalling didn't work, every time I'd install VPC 2004 and then the
    separate SP1 patch (the install of which showed a dialog that said "Removing
    applications..." at one point), running VPC would always give me that error.

    I'm posting this detail because I did a search of this group on that error
    message and saw several people asking about it but no replies.

    Thanks again to Bill and Fede for helping me get this figured out!

    Chuck Heatherly, May 13, 2005
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.