CURLOPT_SSLVERSION(3)

NAME
CURLOPT_SSLVERSION - set preferred TLS/SSL version

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

DESCRIPTION
Pass a long as parameter to control which version of SSL/TLS to attempt to use. Use one of the available defines for this purpose. The available options are:

    CURL_SSLVERSION_DEFAULT
        The default action. This will attempt to figure out the remote SSL protocol version.

    CURL_SSLVERSION_TLSv1
        TLSv1.x

    CURL_SSLVERSION_SSLv2
        SSLv2

    CURL_SSLVERSION_SSLv3
        SSLv3

    CURL_SSLVERSION_TLSv1_0
        TLSv1.0 (Added in 7.34.0)

    CURL_SSLVERSION_TLSv1_1
        TLSv1.1 (Added in 7.34.0)

    CURL_SSLVERSION_TLSv1_2
        TLSv1.2 (Added in 7.34.0)

    CURL_SSLVERSION_TLSv1_3
        TLSv1.3 (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 SSL backends axTLS or wolfSSL.

    CURL_SSLVERSION_MAX_DEFAULT
        The flag defines the maximum supported TLS version as TLSv1.2, or the default value from the SSL library. (Added in 7.54.0)

    CURL_SSLVERSION_MAX_TLSv1_0
        The flag defines maximum supported TLS version as TLSv1.0. (Added in 7.54.0)

    CURL_SSLVERSION_MAX_TLSv1_1
        The flag defines maximum supported TLS version as TLSv1.1. (Added in 7.54.0)

    CURL_SSLVERSION_MAX_TLSv1_2
        The flag defines maximum supported TLS version as TLSv1.2. (Added in 7.54.0)

    CURL_SSLVERSION_MAX_TLSv1_3
        The flag defines maximum supported TLS version as TLSv1.3. (Added in 7.54.0)

DEFAULT
CURL_SSLVERSION_DEFAULT

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

EXAMPLE
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, CURL_SSLVERSION_TLSv1);
  /* Perform the request */
  curl_easy_perform(curl);
}

AVAILABILITY
SSLv2 is disabled by default since 7.18.1. Other SSL versions availability may vary depending on which backend libcurl has been built to use. SSLv3 is disabled by default since 7.39.0.

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

SEE ALSO
CURLOPT_USE_SSL(3), CURLOPT_HTTP_VERSION(3), CURLOPT_IPRESOLVE(3)