---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_PROXY_SSLVERSION
Section: 3
Source: libcurl
See-also:
  - CURLOPT_HTTP_VERSION (3)
  - CURLOPT_IPRESOLVE (3)
  - CURLOPT_SSLVERSION (3)
  - CURLOPT_USE_SSL (3)
---

# NAME

CURLOPT_PROXY_SSLVERSION - preferred HTTPS proxy TLS version

# SYNOPSIS

~~~c
#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_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

All

# EXAMPLE

~~~c
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 7.52.0

# RETURN VALUE

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