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  1. HTTP (Hypertext Transfer Protocol)
  1. HTTP Headers
  1. ALPN
    1. Overview table
    2. Syntax
    3. Examples

ALPN

Used by user agents to specify response media types that are acceptable. The list of valid values are described in the TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs IANA registry.

ALPN is short for Application-Layer Protocol Negotiation and its original use in TLS is described in RFC 7301.

Overview table

Name
ALPN
Description
Specifies the protocols to initiate a CONNECT tunnel with.
Direction
Request
Specification
RFC 7639: The ALPN HTTP Header Field

Features:

Syntax

ALPN            = 1#protocol-id
protocol-id     = token ; percent-encoded ALPN protocol identifier

Examples

CONNECT www.example.com HTTP/1.1
Host: www.example.com
ALPN: h2, http%2F1.1