I recently starting using a VPN service utilizing OpenVPN. While surfing the internet I noticed some comments in a forum stating that the IPV6 address was able to pass through the VPN. I went to the web page they suggested www.test-ipv6.com and sure enough the IPV6 address was read by the web page while using the VPN. I then recorded the IPV6 address rebooted the computer and the router. The first 3 sets of 4 hexadecimal values of the IPV6 static prefix address remained the same. Privacy addressing implemented in Windows 7 correctly randomized my mac address and prevented its exposure via IPV6.
If an ISP assigns a unique IPV6 static prefix (I assume they will since this is to the advantages of marketers, the ISP and the government) to each account this could be used to track a user to a location. My ISP currently uses a persistent IP address which is tied to the mac address of my modem. I can shut off my modem and turn it back on and the same IP address is assigned. I have had the same IP address for years. I am concerned that an essentially statically assigned IPV6 static header could be used to track persons just as the the IPV4 address is today, with the additional scary attribute of being visible even through a VPN by the destination server. I was able to stop this behavior by shutting off the Teredo tunneling protocol in my Windows 7 machine. Shutting off the protocol in device manager was only temporary since a reboot restored the device. I had to use a registry hack to permanently shut of Teredo and prevent my IPV6 address from being read at www.test-ipv6.com while using the VPN and the OpenVPN software. Hiding your IPV4 address is one of the primary purposes of a VPN. Are people aware their IPV6 address may be used to track them even when using a VPN? Please comment and explain if I am somehow wrong.
i'm not sure if most people are aware of it or not, I Just Untick Internet protocol version 6(TCP/IPV6) in my local area connection and tap driver connection used by Openvpn( or if im useing the client a VPN provides)
Edit, And if You want to change your Mac address so that your isp will assign you a different ip You can use this software, It does work, You just might have to tun off your modem then turn it back on after changing the mac address to get it to register properly. Gives you the option to change it to a random mac address or enter it manually, And also remembers the original incase you want or need to change it back. http://www.technitium.com/tmac/index.html