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Comment by ers35

8 years ago

I used Censys to search for the IPv4 addresses of servers serving matching TLS certificates: https://censys.io/ipv4?q=443.https.tls.certificate.parsed.na...

Couldn't someone DDoS'ing a site use this to get around Cloudflare "protection?"

Uh, asking for a friend.

  • Yes. One can identify the IP address of the origin server behind a reverse proxy if the server responds to direct requests in a way that identifies itself. See: https://cloudpiercer.org/

    Two steps towards obscuring the origin server include requiring that the HTTP Host header is set and only responding to Cloudflare IP ranges: https://www.cloudflare.com/ips/