I found this name when I was configuring Windows firewall. Somehow, it was persistent and even when I unchecked it to disable it, it repeatedly returned. A brief Internet search told me that it's a tunneling software on IPV6, which makes me anxious since I haven't intentionally installed any tunneling software and my knowledge about IPV6 is limited. All I know is detailed than conventional IPV4. I guess it is probably installed through Windows Update (The machine in question is XPSP2 fully patched. but I am not sure). My wild guess is that it might be related with Microsoft collecting the data with Vista and that they are doing the same thing with updated XP. Reading this article, I disabled Teredo through command prompt but I am not sure if I fended off unnecessary security risk or increased the risk. Advice anyone?