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when I visit a website, the website gets my ip address.

Does it get any other info, i.e., MAC?

My ISP is TWC.

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3 Answers 3

Packets containing your MAC would not leave your router. Outgoing traffic from your router will have the router's WAN MAC address, and this will change for each hop the packet takes until it's final destination.

Besides IP address, there's a wealth of information sites can get from browser, Java, and Adobe Flash APIs, such as OS version and other attributes. MAC address directly cannot be one of them unless you have a bizarre browser plugin that would collect that info through your browser for some reason.

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Also worth noting that the MAC address can sometimes be extracted from the IPv6 address if you are accessing a website using that –  MikelR Oct 2 '13 at 22:58
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@MikelR I was about to add this as well. In IPv6, the interface identifier, which is transmitted publicly, may be generated based off of the machine's MAC Address. –  root Oct 2 '13 at 23:13
    
@MikelR: related –  grawity Oct 3 '13 at 2:57

Most likely, they don't need your MAC address - chances are your browser's fingerprint is specific enough to identify you, i.e. from all the bits and pieces that can be accessed, a web page can be fairly certain it is you revisiting the same site - or to track you among multiple 'befriended' sites.

You can see how 'unique' you are among 3 million others on this site: https://panopticlick.eff.org/

The system fonts installed on your PC and your browser plugins seem to be good replacement for a MAC address - at least for my PC's.

There is also a related question here: How easy is it to alter a browser fingerprint?


Another site that displays what a website can learn from you if you just load a webpage is http://www.secustudy.com/

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MAC isn't available, other hardware information appears to be. Source: a website blacklisted my Win7 laptop whenever I used it from a certain network. If I opened the same site on a different device (using the same network connection), I had full access. If I took my laptop on the road, I had full access. When I accessed the site using the same laptop and network, but running Linux Mint, I was blacklisted again. The only common factor was my laptop and network connection; ergo my conclusion that the site was able to pull hardware information beyond what Panopticlick can see.

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