Comment by john01dav
9 hours ago
I don't know how much impact this has in practice, but you do not need to scan the entirety of the ipv6 address space because you can just look at the IPs that are registered to known ISPs/ASs.
9 hours ago
I don't know how much impact this has in practice, but you do not need to scan the entirety of the ipv6 address space because you can just look at the IPs that are registered to known ISPs/ASs.
You're gonna need to scan 2^64 addresses once you've located the IPv6 network assigned to my connection before you find my phone. 2^56 if you don't get lucky guessing the network prefix it happens to be on at that moment.
Assuming a scan with a minimum 4 byte ICMP packet, that's about 73786 petabytes of network traffic for that /64. You'll need to shove it down the pipe within a day because IPv6 privacy extensions means the IPv6 address used changes after 24 hours. With only 1gbps fiber, I don't think the deanonimysation is the problem at that kind of traffic level.
I'm also not sure how much it helps, but a friend and I were just talking about how big the numbers get today.
My ISP provides my house a /56 allocation. There are 4,722,366,482,869,645,213,696 addresses. I should have enough for a couple of years, at least.
I guess you could scan it. The IPs for most devices are chosen randomly within a /64 subnet, or they're based on MAC address, but they're not sequential by any means. A /64 is still 18,446,744,073,709,551,616 possible IPs.
Unfortunately I think one of the problems with v6 is people are just unable to apply intuition to numbers this big. The minimum number of /64s an ISP will have is around 4 billion. They generally give subscribers a /56 which is 256 /64s. It's all simple power-of-2 arithmetic. Computer people used to get how big 2^64 is.
I agree. Writing out the whole number was intentional.
How many digits is that? Woah, I can barely count the commas!
Most of the time it's going to be a /64, so even if you know the prefix you're still never going to guess a random address. But a lot of older clients will use a deterministic address based on their MAC, searching the space of MACs for known sbcs would be a lot more tractable.