Server Name Indication
lastmod 2019-02-12created 2019-02-121 edits
Server Name Indication (SNI) is an extension to TLS, a computer networking protocol. During the handshake, the client sends the server the hostname it is trying to connect to. This allows a server with the same IP address and TCP port number to use multiple certificates, so multiple HTTPS websites (any service running over TLS) can be operated on the same IP without all sites using the same certificate. Conceptually it is the same as HTTP/1.1 name-based virtual hosting (en:virtual hosting), but it was designed for HTTPS. A problem is that the requested hostname is not encrypted, so someone can eavesdrop on which site a user is using.