Should i be worried about Teredo in my router a back door
I use the school computer, which I bought from school, administered by the IT-department. I opened a port to my computer when I stumbled upon this:
It points to my computer IP. (I have a static IP to my router.) The contract says the IT-department isn't allowed to enter our computers via a backdoor, but I already caught them with a hidden administrator account that they explained that was there just in case I lost my password. (But I suppose they could change it without that backdoor because the school uses domain user accounts.) It would be no problem for them to install anything on our computers without us necessarily noticing...
Is this another back door, or what could it be used for? There isn't any other teredo UPnP entries to another of the computers (wirelessly connected) here on the router.
There is nothing you need to be worried about. It looks as if Teredo is a IPv6 tunneling technology. According to a Wikipedia article it allows for IPv6 connectivity by tunneling IPv6 packets through your router encapsulated in IPv4/UDP datagrams (so you can still talk IPv6 even though your router doesn't). Teredo and UPnP
UPnP is good to ensure good connectivity. In fact, it’s a feature of UPnP to allow all applications that are uPnP compliant to open ports directly on network devices without notice, warning or notification.
For users who don’t want automatic UPnP manipulation behavior of other programs can disable UPnP on the networked devices.