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)

libcurl 7.58.0                                  January 10, 2018                           CURLOPT_SSLVERSION(3)