Convert an IPv4 to a 6to4 Address

Well, I’m still trying to work out how to get a 6to4 tunnel going on my home internet connection but I think I am slowly piecing things together.

It seems you need to use the anycast address of 192.88.99.1 which is where IPv6 traffic will be forwarded over IPv4 but you need to covert your IPv4 address into an IPv6 address so it is able to be routed back to you via 192.88.99.1.

So how do you calculate it?

The easy way is to use the calculator at Grox – just choose IPv4 to 6to4 Address in the drop down list and put in your public IP address (it should be in yellow at the top of the page). Copy and paste it in and click the Calculate button to get your converted IPv6 address.

Otherwise, you can manually convert your IP address from decimal to hexadecimal and construct your IPv6 address that way. You can use the calculator application in Windows in Programmer mode for this purpose, just make sure you type in your numbers in decimcal mode and then select the option for Hex after each number entry.

For example:

  • For an IP address of 9.10.11.12 (WW.XX.YY.ZZ) your IPv6 address becomes 2002:WWXX:YYZZ::
  • 9.10.11.12 becomes 090a:0b0c (or just 90a:b0c as you can drop the leading zero),
  • This creates an IPv6 address of 2002:090a:0b0c:: or 2002:90a:b0c::

I’m sure I will work this out slowly but surely and once I do I will share this with everyone.

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