Teredo opening multiple ports on a local router

Question

While I was opening some ports on my ADSL router (a Sagem Livebox 1.1) I'd noticed that there were perhaps >100 registered UDP entries on random port numbers, all titled "Teredo". All evidence points to a VAIO laptop running Windows 7 that must be setting these ports automatically via WLAN. The computer in question is an office PC that doesn't use any particular network applications except a browser and Skype.

My other computer (running mainly Vista) and using a larger suite of applications has exactly 1 Teredo port registered on the router. What could be causing this behaviour? Is it some quirk caused by some Sony bloatware updater? I wouldn't want to end up with 65536 open ports on my firewall!

Solution

Teredo was created by Microsoft as a solution for ipv6 readiness on existing ipv4 only networks. With Teredo enabled, you may communicate with ipv6 networks through your existing ipv4 connection.

By design, Teredo has to set up separate or unique connections for each 'conversation' over the network. This can be multiple connections per service per instance. So I do not think there is much to worry about, if I am understanding the question correct.

You can disable Teredo under your network adapter properties. Just uncheck the checkbox in the list. It is quite likely that disabling this will not affect anything. But then you may scratch your head several months later, wondering why you cannot access someipv6onlydomain.com, and then simply enable it again.

Comments

[Thomas K.]

I've noticed someone didn't like me using the word mainly when referring to the Vista system. I said precisely mainly because it's a dual boot machine that occasionally boots into Ubuntu instead, but not on a daily basis.