CURLOPT_SSLVERSION3

Usage

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLVERSION, long version);

Overview

Pass a long as parameter to control which version range of SSL/TLS versions to use.

The SSL and TLS versions have typically developed from the most insecure version to be more and more secure in this order through history: SSL v2, SSLv3, TLS v1.0, TLS v1.1, TLS v1.2 and the most recent TLS v1.3.

Use one of the available defines for this purpose. The available options are:

CURL_SSLVERSION_DEFAULT

The default acceptable version range. The minimum acceptable version is by default TLS v1.0 since 7.39.0 (unless the TLS library has a stricter rule).

CURL_SSLVERSION_TLSv1

TLS v1.0 or later

CURL_SSLVERSION_SSLv2

SSL v2 - refused

CURL_SSLVERSION_SSLv3

SSL v3 - refused

CURL_SSLVERSION_TLSv1_0

TLS v1.0 or later (Added in 7.34.0)

CURL_SSLVERSION_TLSv1_1

TLS v1.1 or later (Added in 7.34.0)

CURL_SSLVERSION_TLSv1_2

TLS v1.2 or later (Added in 7.34.0)

CURL_SSLVERSION_TLSv1_3

TLS v1.3 or later (Added in 7.52.0)

The maximum TLS version can be set by using one of the CURL_SSLVERSION_MAX_ macros below. It is also possible to OR one of the CURL_SSLVERSION_ macros with one of the CURL_SSLVERSION_MAX_ macros. The MAX macros are not supported for WolfSSL.

CURL_SSLVERSION_MAX_DEFAULT

The flag defines the maximum supported TLS version by libcurl, or the default value from the SSL library is used. libcurl uses a sensible default maximum, which was TLS v1.2 up to before 7.61.0 and is TLS v1.3 since then - assuming the TLS library support it. (Added in 7.54.0)

CURL_SSLVERSION_MAX_TLSv1_0

The flag defines maximum supported TLS version as TLS v1.0. (Added in 7.54.0)

CURL_SSLVERSION_MAX_TLSv1_1

The flag defines maximum supported TLS version as TLS v1.1. (Added in 7.54.0)

CURL_SSLVERSION_MAX_TLSv1_2

The flag defines maximum supported TLS version as TLS v1.2. (Added in 7.54.0)

CURL_SSLVERSION_MAX_TLSv1_3

The flag defines maximum supported TLS version as TLS v1.3. (Added in 7.54.0)

In versions of curl prior to 7.54 the CURL_SSLVERSION_TLS options were documented to allow only the specified TLS version, but behavior was inconsistent depending on the TLS library.

Default

CURL_SSLVERSION_DEFAULT

Protocols

All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

Examples

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    /* ask libcurl to use TLS version 1.0 or later */
    curl_easy_setopt(curl, CURLOPT_SSLVERSION, (long)CURL_SSLVERSION_TLSv1);
    /* Perform the request */
    curl_easy_perform(curl);
  }
}

Return value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.