[tor-talk] Find Real IP via ISP.

[Jason Long]

Thus we must not Visit a site with and without Tor in a same time?



On Tuesday, November 22, 2016 5:25 PM, Mirimir <mirimir at riseup.net> wrote:



On 11/22/2016 04:48 AM, Jason Long wrote:
> Hello.
> As "Seth David Schoen" said, Governments can see that users using
> tor but can't see what they are doing. My questions is that if an
> ISP see that an IP address, For example, 100.100.100.1 connected
> to the Tor network and user IP address changed to 200.200.200.1
> then if the user visit a website with Tor then if the websites
> owners show 200.200.200.1 to the ISP then can ISP give
> 100.100.100.1 to the website owner?
> 
> Thank you.

As others have pointed out, ISPs don't know Tor exit IP addresses.
Websites, of course, know Tor exit IP addresses. Because they see them
when users connect. But knowing them doesn't allow them, or even help
them, find users' ISP-assigned IP addresses.

However, let's say that you've used a website without Tor. And let's say
that you have an account. If you subsequently login to that account
using Tor, the website operator could contact your ISP (which it knows
from your prior use without Tor) and ask what you were doing at the time
you logged in. And they would learn that you were using Tor.

Even without an account, cookies could mark you just as well.

Even so, ISPs generally won't provide that sort of information without a
court order. So you would need to attract major attention from the
website, or interested third parties, before you'd be at risk.

There's also the possibility of website fingerprinting. So if you had
used a website without Tor, your ISP could have collected data that
allows them to identify connections to that website. Consider
<http://hubblesite.org/gallery/wallpaper/>. There are many images, and
they tend to load in a particular order. So the network traffic pattern
is relatively unique. Many porn sites, for example, also have distinct
fingerprints.

But generally, if a website has never seen you without Tor, they have no
chance of even tracking you back to your ISP. Let alone getting your
identity from the ISP.
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