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)