Provided by: libcurl4-doc_7.68.0-1ubuntu2.25_all bug

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 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 (but not SSLv3)

              CURL_SSLVERSION_SSLv3
                     SSL v3 (but not SSLv2)

              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 will use 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.

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_PROXY_SSLVERSION(3), CURLOPT_IPRESOLVE(3)