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This might be a duplicate question but as you can see they didn't get the correct answer.

How to uniquely identify a computer?

Uniquely identify one computer

how would you remembers a computers regardless of ip, "browser" cookies, and browser itself. So It will recognize it once you use it from another browser, or ip address. Any ideas?

UPDATE

I found out that there is a possibility using flash cookies: it seems that it's shared across browsers and clearing the browser cookies does not remove it. my question now is how can I see my flash cookies and know if that is what facebook is doing?

  • Ubiquitous availability (95 percent of visitors will probably have flash)
  • You can store more data per cookie (up to 100 KB)
  • Shared across browsers, so more likely to uniquely identify a machine
  • Clearing the browser cookies does not remove the flash cookies. --Joeri Sebrechts
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Neo
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  • What do you mean, regardless of ip, cookie and browser? I'm sure that if you install a fresh browser you'll net get logged in on facebook. – Nanne Jun 13 '11 at 19:12
  • Possible they are using localstroage. Doubt it since it tracks on other browsers. – ngen Jun 13 '11 at 19:13
  • Regardless of ip, cookie and browser? No. That's how they identify you. Next. – Lightness Races in Orbit Jun 13 '11 at 19:13
  • Are you sure-- have you tested changing IP and cookie simultaneously? If it "sees" any one change, it can update the other known data. AFAIK there isn't a UUID for the machine itself. – zebediah49 Jun 13 '11 at 19:14
  • All i have seen is till today developers store cookies to identify users. If you clear your cache and cookies , facebook will forget you and ask you to re-login. – Johal Jun 13 '11 at 19:17
  • @Nanne obviously you have no idea what I'm talking about, go to your facebook settings and click on security,. It's a new feature, yes if you login from a different browser it will ask for your login credentials but if you set the security settings then in addition to that if it's a new computer it will ask for you to verify the 5 digit number they text to you on the phone, if it's a computer that you've already used and it's a different browser. Or cookies have timedout, or you've cleared it. The user and password will suffice. – Neo Jun 13 '11 at 19:18
  • Have you seen this? https://panopticlick.eff.org/ – GDR Jun 13 '11 at 19:19
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    I know this is a boring duplicate and there is not one real answer, but -5 downvotes is a little over the top. -- You can inspect your Flash cookies here: http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html - Or in ~/.macromedia/..Flash*/#SharedObjects/... somewhere. – mario Jun 13 '11 at 19:22
  • So there was something in common after all, and you're not identifying computers, but plain old cookies but in flash this time? right ;) – Nanne Jun 13 '11 at 19:23
  • @Nanne yeah I didn't think it was identifying computers base on what they look like, of course it had to be cookies or something. It was the concept. It will be good if people could admit to their mistakes, you can start by taking that -1 away. – Neo Jun 13 '11 at 19:31
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    Whining about downvotes and saying stuff like "this is retarded" is probably going to get you more of them, not fewer. – ceejayoz Jun 13 '11 at 19:31
  • @ceejayoz you're right I got carried away as soon as I post the question I got bombarded by negative points. I took that text off. +1 – Neo Jun 13 '11 at 19:33
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    @Neo: I suggest you be a little nicer to people trying to help you. It is definitely related to cookies and I don't think they use flash cookies. I just logged out in Chrome and logged in with Safari (the first time ever) and it asked me to identify the machine. You are saying this should not happen, but it does. They also write in their support that you have to disable "Private browsing" modes to be not asked over and over again: http://www.facebook.com/help/?topic=loginnotifications This is also a strong indicator for cookies. – Felix Kling Jun 13 '11 at 19:42
  • @Felix Kling well people where giving me downvotes because they thought I'm saying you don't need to login from different browser but I was talking about device activation, I was nice to people who were not jumping to conclusions! – Neo Jun 13 '11 at 19:47

2 Answers2

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I suppose a flash cookie is a bit more cross browser and persists.

Joe
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  • yeah if you look at the update that's what I came up with, my new question is to verify it and see it. – Neo Jun 13 '11 at 19:23
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Facebook only remembers based on the cookie in your browser.

The proof to the pudding is if you login and then switch to a different browser, you are not logged in there.

Naftali
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    Ok please login to facebook and go to account settings and then account security and then checkmark the 'Login Approvals When an unrecognized computer or device tries to access my account: Require me to enter a security code sent to my phone' and then login from a different computer then if you still don't know what I'm talking about, come here and I will explain more but I'm sure a 13K rep would. – Neo Jun 13 '11 at 19:22
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    @Neo. that code is probably related to User's IP, nothing to do with the computer – Naftali Jun 13 '11 at 19:23