How authenticated origin pulls work
When visitors request content from your domain, Cloudflare first attempts to serve content from the cache. Failing that, Cloudflare sends a request — or an
origin pull — back to your origin web server to get the content.
Authenticated origin pulls make sure that all of these
origin pulls come from Cloudflare. Put another way, authenticated origin pulls ensure that any HTTPS requests outside of Cloudflare will not receive a response from your origin.
Cloudflare enforces authenticated origin pulls by adding an extra layer of TLS client certificate authentication when connecting between Cloudflare and the origin web server.
Standard TLS handshake
TLS handshake with authenticated origin pulls