CURLOPT_PROXY_SSLVERSION(3) Library Functions Manual NAME CURLOPT_PROXY_SSLVERSION - preferred HTTPS proxy TLS version SYNOPSIS #include CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSLVERSION, long version); DESCRIPTION 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. DEFAULT CURL_SSLVERSION_DEFAULT PROTOCOLS This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. All TLS backends support this option. EXAMPLE 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); } } AVAILABILITY Added in curl 7.52.0 RETURN VALUE Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. SEE ALSO CURLOPT_HTTP_VERSION(3), CURLOPT_IPRESOLVE(3), CURLOPT_SSLVERSION(3), CURLOPT_USE_SSL(3) libcurl 2024-12-11 CURLOPT_PROXY_SSLVERSION(3)