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:

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.

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)