Why do programs or websites think I’m using a new device when I’m not?

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Whenever you use a new device, Google or whatever website/program you’re using will wig out and email you to confirm it’s you. But quite often I have this happen while using my only laptop using software/websites I’ve used dozens of times before. Why is this and how does device identification work? Does it check for new IPs or MAC-addresses or what? And why would it be tricked so often into thinking an old device is new?

In: Technology

Whenever you visit a site and authenticate, it saves a file called a cookie on your computer. When you revisit the site, the browser sends that cookie along. Then the site knows you’re you.

If you clear cookies, the site no longer knows it’s you and needs to authenticate again.

When a website needs/wants to remember that a particular device is tied to a user, it is restricted in what it can do to remember the device.

In order for a website to remember a specific device, it will need to “mark” it somehow. The most common way a website can mark a device is to leave a cookie. A cookie is a small bit of text that a browser allows a website to write and store inside of it. A website can write as many cookies as it needs to. Typically, if a website needs to keep track of a device it will write a unique code that it will associate with your device into the cookie.

If you leave the website and come back to it later, the website can request from the browser all the cookies that it previously recorded. If the browser is able to find and return cookies, the website can check the unique code inside them use that information to determine what to show you (your profile, pictures, settings, etc).

However, cookies are not the only way a website can track you. There’s about 15-20 methods out there. Some of them are well-supported and used frequently, such as HTML5 Local Storage. Other methods are more…ulterior. For instance, a website can force you to download a specific version of image to your cache that has hidden data inside of it. If you visit the website again, the browser will not redownload the image, but instead download the image that it previously saved in the cache. The website can then try to read the hidden values out of the cached image to identify you.

If a website isn’t remembering your device, then you probably do not check “Remember this device” when you log into a site. Or you are clearing your browser history/settings frequently so that any of the “marks” a website is leaving are getting erased.

Basically, when you clear your porn history, everything gets erased. So either stop the porn, or start over every time you delete your pornhub cookies!

IP tracking. if you login with a new IP some apps or servers may flag it as unusual.

can also happen while using cellular data.

as others mentioned there is also cookie tracking.

there are also other things that are checked to varying degrees depending on the place you’re trying to get to. if you are using a browser you don’t usually use it may flag you. changing screen resolution or the size of the window may do it.

there are a lot of things being tracked for any given user on the internet.