Standard
TLS extension carrying the target domain in plaintext, described by the IETF as perhaps the most sensitive unencrypted information in TLS 1.3.
A single-file Python agent taps the interface with the same filter tcpdump prints for tcp, and it reconstructs method, path, status and p95 latency for HTTP/1.x while gRPC inside TLS stays an opaque byte count.
Reality
A developer dumped the ClientHello that openssl sends and found the requested hostname in plain ASCII inside the server_name extension. A listener holding no private key read it back off the wire, TLS 1.3 included.
Reality
Google's Encrypted Client Hello rollout, wrapped in GREASE decoys so protected sessions look like everything else, removes the plaintext domain that SNI-based logging keys on. Jigsaw reports near-zero interference even in Russia and China.
Perspective Coverage
4 publishersReality
Google's ECH support hides the destination domain from anything watching the TLS handshake, but only when the app's networking library and the site's CDN both cooperate, so the breakage arrives unevenly.
Reality
RFC 9849 encrypts the ClientHello, so the domain field that SNI allowlists and passive TLS logs depend on stops appearing on the wire. In return, operators inherit a key rotation duty; the spec sets no fixed interval.
Reality