Windows 7 / Networking

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Enabling or Disabling IPv6

You cannot uninstall IPv6 in Windows 7, but you can disable IPv6 on a per-adapter basis. To do this, follow these steps:

1. In Control Panel, open Network And Sharing Center.
2. Click Manage Network Connections and then double-click the connection you want to configure.
3. Clear the check box labeled Internet Protocol Version 6 (TCP/IPv6), and then click OK.

Note that if you disable IPv6 on all your network connections using the user interface method described in the preceding steps, IPv6 will still remain enabled on all tunnel interfaces and on the loopback interface.

As an alternative to using the user interface to disable IPv6 on a per-adapter basis, you can selectively disable certain features of IPv6 by creating and configuring the following DWORD registry value:

HKLM\SYSTEM\CurrentControlSet\Services\tcpip6\Parameters\DisabledComponents

Table-7 describes the flag values that control each IPv6 feature. By combining these flag values together into a bitmask, you can disable more than one feature at once. (By default, DisabledComponents has the value 0.)

Table-7 Bitmask Values for Disabling IPv6 Features in Windows 7

Flag Low-Order Bit	Result of Setting this Bit to a Value of 1
0	Disables all IPv6 tunnel interfaces, including ISATAP, 6to4, and Teredo tunnels
1	Disables all 6to4-based interfaces
2	Disables all ISATAP-based interfaces
3	Disables all Teredo-based interfaces
4	Disables IPv6 over all non-tunnel interfaces, including LAN and PPP interfaces
5	Modifies the default prefix policy table* to prefer IPv4 over IPv6 when attempting connections

*For more information concerning the IPv6 prefix policy table, see the Cable Guy article, "Source and Destination Address Selection for IPv6," at http://technet.microsoft.com/en-us/library/bb877985.aspx.

For example, by setting the value of DisabledComponents to 0xFF, you can simultaneously disable IPv6 on all your network connections and tunnel interfaces. If you do this, IPv6 still remains enabled on the loopback interface, however.

Note For some examples of common flag combinations that can be used to enable or disable different aspects of IPv6 functionality in Windows 7 and Windows Vista, see the Cable Guy article, "Configuring IPv6 with Windows Vista," at http://technet.microsoft.com/en-us/library/bb878057.aspx.

Depending on your scenario, there are other ways of effectively disabling IPv6 on computers running Windows 7, including the following:

• Disable the IP Helper service This service must be running for IPv6 transition technologies such as ISATAP, Teredo, and 6to4 to function on the computer. This service provides automatic IPv6 connectivity over an IPv4 network, and if the service is stopped, the computer will have only IPv6 connectivity if it is connected to a native IPv6 network. Therefore, if your network is not native IPv6, disabling this service on Windows 7 computers effectively disables IPv6 on them. You can use Group Policy to disable this service on targeted Windows 7 computers.
• Use netsh to disable all IPv6 interfaces For example, the following commands will disable all IPv6 transition technologies (Teredo, 6to4, and ISATAP).

  netsh interface teredo set state disabled
  netsh interface ipv6 6to4 set state state=disabled undoonstop=disabled
  netsh interface ipv6 isatap set state state=disabled
  

  You can include these commands in a script and send them inside a Microsoft System Center Configuration Manager (SCCM) package to disable transition technologies on targeted computers.
• Configure Windows Firewall to block IPv6 traffic You could block incoming and outgoing IPv6 protocol 41 (for ISATAP and 6to4) and UDP 3544 (for Teredo) traffic using the Windows Firewall, and you can use Group Policy to push this out to targeted computers. Businesses that implement perimeter firewalls may want to do this as a best practice for safeguarding their networks.