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Randomizing your useragent is the worst idea ever. Your fingerprint won't conform to the features that are expected. I won't go into too much detail here, on p
by lawl 9y ago
Randomizing your useragent is the worst idea ever.
Your fingerprint won't conform to the features that are expected. I won't go into too much detail here, on purpose. But e.g. if you claim to be Firefox while using chrome, that's completely detectable, server side, even without javascript.
If you have javascript it's of course even easier to just check if your browser supports the features it should according to its user agent.
Edit: Btw. I have actually reversed some fingerprinting JS code in the wild, and yes, they do check if you lie about your useragent.
- Balgair 9y agoThis is HN, you can go into as much detail as you please.
- Feniks 9y agoFunny, I thought we had web standards? Guess nobody gives a shit anymore. Your site shouldn't even have to ask for the useragent.
- lawl 9y agoHTML5 is a living standard, so naturally different browser versions will have different features implemented. Also, there's the thing where you can conform to a spec but it's still possible to tell a difference in implementation by observing certain things. For example the non cryptographically secure random number generators in chrome and firefox used to be different algorithms. So if you seed the RNG with a number and call it, you used to get different results for firefox and chrome and you could tell if their user agent is lieing. (actually it was a bit more complicated than that, you can't seed Math.random in JS, but you get the point) This isn't about sites needing that info to work correctly. This is what sites do for fingerprinting.