Clean up IPv6

[alrik]

Hi,

I'm not sure if this is the intended behavior of uT or not. I have native IPv6 from my ISP. So I get several global v6 addresses, including 2 autoconfigured addresses on my LAN, in addition to a Teredo client address. The two autoconfiguration addresses include a "permanent" one that has a static component and a temporary (RFC 4941) one that Windows usually assigns as per privacy extensions.

What I'm seeing uTorrent do is use all 3 addresses to talk to peers. What I want it to do is only use the temporary (RFC 4941) address. (Unless of course you don't have a temporary address available.) That address is the default one. Your browser and other v6-capable apps always use it. Using the "permanent" address (or whatever the right name is) is a privacy concern because the 64-bit extension does not change and you can in principle be tracked by it.

In addition, uTorrent should not use your Teredo address if you have a native IPv6 interface. That means your source address in outgoing IPv6 packets and the destination address in incoming IPv6 packets should always be a native one, rather than the 2001::/32 Teredo client address. In other words, it should only use the Teredo interface as a relay, not as a client. Windows automatically routes IPv6 traffic from other interfaces through Teredo if you're communicating with a Teredo host. This is why simply disabling Teredo is not an ideal option.

I don't think the problem is that uT binds specifically to those addresses. The problem seems to be that it announces those addresses to trackers and/or DHT. The reason is that I only see the undesirable addresses/interfaces being used for incoming connections. uT's outgoing IPv6 connections all seem to use the default RFC 4941 address (as desired). So don't simply advertise every IPv6 address uT can get its hands on.

Also, I see uTorrent attempt to connect to clients on fe80:: link-local addresses. I'm not sure if it's uTorrent that's reporting those addresses to trackers or other clients, but if it is, it should obviously not do that.

[Kitsoran]

It's left to Windows to choose the interface, if ut communicates on it then that will get out. I think the best option for you would be to set the interface metrics such that the privacy aware address is preferred over the others. Not sure how that would work, I don't have native IPv6 to dick with. If it's like any connection though then you can change it from the network adapter properties. netsh interface ipv6 show interfaces will show you the interfaces and the current metrics. Perhaps that will show something interesting.

Can the permanent one be disabled?

[alrik]

Thanks for your feedback, Kitsoran. I've played around with netsh/ipv6 and it looks like the individual addresses do not have metrics. Only interfaces do. And both the permanent (let's call it non-temporary) and the temporary address are on the same interface. But I don't think the metrics or preferences are the issue here.

The issue is that uTorrent collects all these addresses from your system and sends them over to the trackers and/or DHT so that other peers can connect to them. How do I know this? My router's connection stats show it. It shows connections being attempted to my non-temporary address, but are not being replied to (which is a good thing). uTorrent should only report one address per interface and that address should be the temporary/privacy-enabled one. Or it should at least have an option for it.

I don't think the non-temporary addresses can be disabled. But it's probably not a good idea even if it could. You still need a way to reach your host that doesn't change every few hours...