CONNECT

Establishes a tunnel to the server identified by the request target.

Use CONNECT for proxy tunneling, such as establishing a TLS tunnel through an HTTP proxy. It is neither safe nor idempotent.

httpmethodsproxytunnel

Reference (http)

CONNECT origin.example.com:443 HTTP/1.1
Host: proxy.example.com

Use CONNECT for proxy tunneling, such as establishing a TLS tunnel through an HTTP proxy. It is neither safe nor idempotent.

Common mistakes

Exposing CONNECT through an origin server or proxy without strict authorization and destination controls.

Registry reference: rfc9110

Sources