Tell HN: Cloudflare is blocking Pale Moon and other non-mainstream browsers

This echoes the user agent checking that was prevalent in past times. Websites would limit features and sometimes refuse to render for the "wrong" browser, even if that browser had the ability to display the website just fine. So browsers started pretending to be other browsers in their user agents. Case in point - my Chrome browser, running on an M3 mac, has the following user agent:

"'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36'"

That means my browser is pretending to be Firefox AND Safari on an Intel chip.

I don't know what features Cloudflare uses to determine what browser you're on, or if perhaps it's sophisticated enough to get past the user agent spoofing, but it's all rather funny and reminiscent just the same.

As a counterpoint, I asked Claude to write a script to fetch Claude usage and expose it as a Prometheus metric. As no public API exists, Claude suggested I grab the request from the Network tab. I copied it as cURL, and attempted to run it, and was denied with a 403 from CF.

I forgot the script open, polling for about 20 minutes, and suddenly it started working.

So even sending all the same headers as Firefox, but with cURL, CF seemed to detect automated access, and then eventually allowed it through anyway after it saw I was only polling once a minute. I found this rather impressive. Are they using subtle timings? Does cURL have an easy-to-spot fingerprint outside of its headers?

Reminded me of this attack, where they can detect when a script is running under "curl | sh" and serve alternate code versus when it is read in the browser: https://news.ycombinator.com/item?id=17636032