CURLOPT_PROXY_SSLVERSION - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSLVERSION,
                          long version);

Pass a long as parameter to control which version of SSL/TLS to attempt to use when connecting to an HTTPS proxy.

Use one of the available defines for this purpose. The available options are:

CURL_SSLVERSION_DEFAULT

The default action. This attempts to figure out the remote SSL protocol version.

CURL_SSLVERSION_TLSv1

TLSv1.x

CURL_SSLVERSION_TLSv1_0

TLSv1.0

CURL_SSLVERSION_TLSv1_1

TLSv1.1

CURL_SSLVERSION_TLSv1_2

TLSv1.2

CURL_SSLVERSION_TLSv1_3

TLSv1.3

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 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)

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.

CURL_SSLVERSION_DEFAULT

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

All TLS backends support this option.

int main(void)
{
  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);
  }
}

Added in curl 7.52.0

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

CURLOPT_HTTP_VERSION(3), CURLOPT_IPRESOLVE(3), CURLOPT_SSLVERSION(3), CURLOPT_USE_SSL(3)

curl_easy_setopt(3), CURLOPT_PROXY_SSL_CIPHER_LIST(3), CURLOPT_PROXY_SSL_OPTIONS(3), CURLOPT_PROXY_TLS13_CIPHERS(3), CURLOPT_SSLVERSION(3), CURLOPT_TLS13_CIPHERS(3), CURLOPT_USE_SSL(3), libcurl-symbols(3).