Using Microsoft Loopback Adapter

Using Microsoft Loopback Adapter

The networking capabilities of Virtual Server 2005 can be extended with Microsoft Loopback Adapter. Using Microsoft Loopback Adapter, you can:

• Use Internet Connection Firewall (ICF) to protect virtual networks. ICF checks all communications that cross the connection between your virtual network and the Internet and is selective about which responses from the Internet it allows.
• Provide host-to-guest networking and file sharing without having to use an external network.
• Use Internet Connection Sharing to provide Network Address Translation (NAT) and share a single connection to the Internet between the host operating system and one or more virtual machines.

Configure a virtual machine to use Internet Connection Firewall

You can configure a virtual machine to use Internet Connection Firewall on the host operating system to provide a protective boundary between a network and external computers, as shown in the following table.

Step	Reference
Install Microsoft Loopback Adapter on the host operating system.	Install Microsoft Loopback Adapter
Enable Internet Connection Firewall on a physical network adapter in the host operating system.	For more information, see "To enable or disable ICF" in Help and Support Center
Enable Internet Connection Sharing on the same physical network adapter on which ICF is enabled. Configure ICS so that the physical network adapter shares the connection with Microsoft Loopback Adapter.	For more information, see "To enable ICS" in Help and Support Center
Create a virtual network and configure it to use Microsoft Loopback Adapter.	Create a virtual network
Connect one or more virtual machines to the virtual network that is configured to use Microsoft Loopback Adapter.	Add or remove a virtual network adapter

Configure host-to-guest networking and file sharing

You can configure Microsoft Loopback Adapter to create a network between the host operating system and a guest operating system without having to use the external network, as shown in the following table.

Step	Reference
Install Microsoft Loopback Adapter on the host operating system	Install Microsoft Loopback Adapter
Configure Microsoft Loopback Adapter	On the host operating system, open Network Connections, right-click the local area connection for Microsoft Loopback Adapter, and then select Properties. In the Microsoft Loopback Adapter Properties dialog box, verify that the Virtual Machine Network services check box is selected. Click Internet Protocol (TCP/IP), and then click Properties. On the General tab, click Use the following IP address, and then type the IP address and subnet mask (such as 192.168.1.1 and 255.255.255.0). Important You can use any Transmission Control Protocol/Internet Protocol (TCP/IP) address, but it is best to choose one from a reserved range of non-routable TCP/IP addresses. For example, TCP/IP addresses of the form 192.168.x.y, where x is a value from 0 through 255 and y is a value from 1 through 254, are non-routable. The value you choose for x must be the same on the host operating system and each guest operating system that is to be part of this virtual network. If your primary Ethernet connection uses one of these non-routable addresses, you must choose a different value for x to assign to Microsoft Loopback Adapter. Click OK, and then click Close. Note To perform this procedure, you must be an administrator or a member of the Administrators group. To set up multiple network connections using Microsoft Loopback Adapter, use different subnets. Do not set a value for Default gateway.
Configure file sharing on the host and guest operating system	For more information, see Help and Support Center.

Configure NAT

With network address translation (NAT), you can configure one or more virtual machines to share the host operating system's Internet connection, as shown in the following table.

Note

If IPsec is enabled on the host operating system, you cannot share the Internet connection of the host operating system with virtual machines.

Step	Reference
Install Microsoft Loopback Adapter on the host operating system	Install Microsoft Loopback Adapter
Enable Internet Connection Sharing on the physical network adapter that is connected to the Internet. Configure ICS so that the physical network adapter shares the connection with Microsoft Loopback Adapter.	For more information, see "To enable ICS" in Help and Support Center
Create a virtual network and configure it to use Microsoft Loopback Adapter	Create a virtual network
Connect one or more virtual machines to the virtual network that is configured to use Microsoft Loopback Adapter	Add or remove a virtual network adapter