---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_HTTPAUTH
Section: 3
Source: libcurl
Protocol:
  - HTTP
See-also:
  - CURLOPT_PASSWORD (3)
  - CURLOPT_PROXYAUTH (3)
  - CURLOPT_USERNAME (3)
Added-in: 7.10.6
---

# NAME

CURLOPT_HTTPAUTH - HTTP server authentication methods to try

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTPAUTH, long bitmask);
~~~

# DESCRIPTION

Pass a long as parameter, which is set to a bitmask, to tell libcurl which
authentication method(s) you want it to use speaking to the remote server.

The available bits are listed below. If more than one bit is set, libcurl
first queries the host to see which authentication methods it supports and
then picks the best one you allow it to use. For some methods, this induces an
extra network round-trip. Set the actual name and password with the
CURLOPT_USERPWD(3) option or with the CURLOPT_USERNAME(3) and the
CURLOPT_PASSWORD(3) options.

For authentication with a proxy, see CURLOPT_PROXYAUTH(3).

## CURLAUTH_BASIC

HTTP Basic authentication. This is the default choice, and the only method
that is in wide-spread use and supported virtually everywhere. This sends
the username and password over the network in plain text, easily captured by
others.

## CURLAUTH_DIGEST

HTTP Digest authentication. Digest authentication is defined in RFC 2617 and
is a more secure way to do authentication over public networks than the
regular old-fashioned Basic method.

## CURLAUTH_DIGEST_IE

The IE-specific Digest authentication behavior is no longer supported.
This bit is kept for compatibility and is treated as CURLAUTH_DIGEST.

## CURLAUTH_BEARER

HTTP Bearer token authentication, used primarily in OAuth 2.0 protocol.

You can set the Bearer token to use with CURLOPT_XOAUTH2_BEARER(3).

## CURLAUTH_NEGOTIATE

HTTP Negotiate (SPNEGO) authentication. Negotiate authentication is defined
in RFC 4559 and is the most secure way to perform authentication over HTTP.

You need to build libcurl with a suitable GSS-API library or SSPI on Windows
for this to work.

## CURLAUTH_NTLM

HTTP NTLM authentication. A proprietary protocol invented and used by
Microsoft. It uses a challenge-response and hash concept similar to Digest, to
prevent the password from being eavesdropped.

NTLM uses weak cryptographic algorithms and is not considered secure.

## CURLAUTH_NTLM_WB

Support for this is removed since libcurl 8.8.0.

NTLM delegating to winbind helper. Authentication is performed by a separate
binary application that is executed when needed. The name of the application
is specified at compile time but is typically **/usr/bin/ntlm_auth**.

Note that libcurl forks when necessary to run the winbind application and kill
it when complete, calling **waitpid()** to await its exit when done. On POSIX
operating systems, killing the process causes a SIGCHLD signal to be raised
(regardless of whether CURLOPT_NOSIGNAL(3) is set), which must be handled
intelligently by the application. In particular, the application must not
unconditionally call wait() in its SIGCHLD signal handler to avoid being
subject to a race condition. This behavior is subject to change in future
versions of libcurl.

## CURLAUTH_ANY

This is a convenience macro that sets all bits and thus makes libcurl pick any
it finds suitable. libcurl automatically selects the one it finds most secure.

## CURLAUTH_ANYSAFE

This is a convenience macro that sets all bits except Basic and thus makes
libcurl pick any it finds suitable. libcurl automatically selects the one it
finds most secure.

## CURLAUTH_ONLY

This is a meta symbol. OR this value together with a single specific auth
value to force libcurl to probe for unrestricted auth and if not, only that
single auth algorithm is acceptable.

## CURLAUTH_AWS_SIGV4

provides AWS V4 signature authentication on HTTPS header
see CURLOPT_AWS_SIGV4(3).

## CURLAUTH_HTTPSIG

provides RFC 9421 HTTP Message Signatures on outgoing requests,
see CURLOPT_HTTPSIG_ALGORITHM(3).

# DEFAULT

CURLAUTH_BASIC

# %PROTOCOLS%

# EXAMPLE

~~~c
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    /* allow whatever auth the server speaks */
    curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
    curl_easy_setopt(curl, CURLOPT_USERPWD, "james:bond");
    result = curl_easy_perform(curl);
  }
}
~~~

# HISTORY

CURLAUTH_DIGEST_IE was added in 7.19.3

CURLAUTH_ONLY was added in 7.21.3

CURLAUTH_NTLM_WB was added in 7.22.0

**CURLAUTH_*** macros became `long` types in 7.26.0, prior to this version
a `long` cast was necessary when passed to curl_easy_setopt(3).

CURLAUTH_BEARER was added in 7.61.0

CURLAUTH_AWS_SIGV4 was added in 7.74.0

CURLAUTH_DIGEST_IE does nothing since 8.21.0

CURLAUTH_HTTPSIG was added in 8.22.0

# %AVAILABILITY%

# RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
libcurl-errors(3).
