As more and more people are discovering IPv6, there is a tendency to test and play with the technology.  Windows and other OS systems come ready to play out of the box with pre-configured IPv6 Tunnels.  These actions are usually harmless.  For many network administrators, willingness to allow exploration balanced against risk of network threats is something they simply cannot live with.

So, if we are not fully compliant with IPv6 on firewalls and such, how can we disable the default IPv6 capabilities in Windows 7 as well as other OS's?

1. Use netsh to disable all IPv6 interfaces.  This requires you open a Windows Command in 'Run as Administrator'.  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.  Here is how you will disable all IPv6 transition technologies (Teredo, 6to4, and ISATAP):
   1. "netsh interface teredo set state disabled"
   2. "netsh interface ipv6 6to4 set state state=disabled undoonstop=disabled"
   3. "netsh interface ipv6 isatap set state state=disabled"

2. The problem with #1 is that this must be done on every computer, and a savvy user will find articles just like this one and reverse these commands (if they have the Administrative privileges).  So another option is to 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.

3. A third option is to 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.