CURLOPT_PROXY_SSLVERSION(3) Library Functions ManualCURLOPT_PROXY_SSLVERSION(3)
NAME
CURLOPT_PROXY_SSLVERSION - preferred HTTPS proxy TLS version
SYNOPSIS
#include <curl/curl.h>
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_SSLVER-
SION_MAX_ macros below. It is also possible to OR one of the CURL_SS-
LVERSION_ 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 in-
consistent 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, (long)CURL_SSLVERSION_TLSv1);
/* Perform the request */
curl_easy_perform(curl);
}
}
AVAILABILITY
Added in curl 7.52.0
RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
CURLOPT_HTTP_VERSION(3), CURLOPT_IPRESOLVE(3), CURLOPT_SSLVERSION(3),
CURLOPT_USE_SSL(3)
libcurl 2026-07-12 CURLOPT_PROXY_SSLVERSION(3)
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