检测登录用户是否在作为未登记用户之前访问了页面

Question

I was wondering whether it is possible to detect that currently logged user visited the page before but not being logged in.

I was thinking of IP, cookies, browser etc, but IP may be changed easily, delete cookies is a piece of cake, also you can change browser.

After some searching and thinking I came up with idea... it is not possible. Even if it was - it would need a quite big database space to do it and would probably be not to hard to deceive.

Is my conclusion right or you have some ideas?

Answer 1

Your conclusion is right if you want a 100% accurate result. If you dont mind a few misses then you use cookies.

• Cookies
  • If the cookies is there, 100% accurate that he was there
  • If its not there, the cookies could have been deleted or user is using other browser/device
• IP
  • Never an accurate result, as IP's are shared between users (office buildings, wifi hotspots)
• Finger printing (combine all info you have on a user to identify them)
  • Never an accurate result, but better then just IP.