---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Long: ech
Arg: <config>
Help: Configure Encrypted Client Hello (ECH) for use with the TLS session
Added: 8.8.0
Category: tls ECH
Protocols: HTTPS
Multi: single
See-also:
  - doh-url
Example:
  - --ech true $URL
---

# `--ech`

Specifies how to do ECH (Encrypted Client Hello).

The values allowed for \<config\> can be:

## "false"
Do not attempt ECH

## "grease"

Send a GREASE ECH extension

## "true"

Attempt ECH if possible, but do not fail if ECH is not attempted.
(The connection fails if ECH is attempted but fails.)

## "hard"

Attempt ECH and fail if that is not possible.
ECH only works with TLS 1.3 and also requires using
DoH or providing an ECHConfigList on the command line.

## "ecl:<b64val>"

A base64 encoded ECHConfigList that is used for ECH.

## "pn:<name>"

A name to use to over-ride the `public_name` field of an ECHConfigList
(only available with OpenSSL TLS support)

## Errors

Most errors cause error
*CURLE_ECH_REQUIRED* (101).
