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How does SNI-based routing work in Traefik?
Server Name Indication (SNI) is the hostname a TLS client sends during the handshake, before the connection is even decrypted, and Traefik reads it to decide which router and certificate to use for that connection.
This lets a single Traefik instance terminate TLS for multiple domains on the same entrypoint and port, each with its own certificate, by routing purely on the SNI value rather than needing separate IPs or ports per domain.
SNI routing also applies at the TCP router level, where Traefik can pass an entire encrypted connection through to a backend based only on SNI, without terminating TLS itself, which is how it can route non-HTTP TLS traffic like a database connection.
SNI is read by Traefik:
SNI routing at the TCP router level allows Traefik to:
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