Introducing Ephemeral IDs: a new tool for fraud detection

In the early days of the Internet, a single IP address was a reliable indicator of a single user. However, today’s Internet is more complex. Shared IP addresses are now common, with users connecting via mobile IP address pools, VPNs, or behind CGNAT (Carrier Grade Network Address Translation). This makes relying on IP addresses alone a weak method to combat modern threats like automated attacks and fraudulent activity. Additionally, many Internet users have no option but to use an IP address which they don’t have sole control over, and as such, should not be penalized for that.

At Cloudflare, we are solving this complexity with Turnstile, our CAPTCHA alternative. And now, we’re taking the next step in advancing security with Ephemeral IDs, a new feature that generates a unique short-lived ID, without relying on any network-level information.

When a website visitor interacts with Turnstile, we now calculate an Ephemeral ID that can link behavior to a specific client instead of an IP address. This means that even when attackers rotate through large pools of IP addresses, we can still identify and block malicious actions. For example, in attacks like credential stuffing or account signups, where fraudsters attempt to disguise Continue reading