---
name: "CURLOPT_PROXY_SSLVERSION"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_PROXY_SSLVERSION"
---

# CURLOPT\_PROXY\_SSLVERSION(3)

preferred HTTPS proxy TLS version

## 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\_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.

- CURL\_SSLVERSION\_MAX\_TLSv1\_0

  The flag defines maximum supported TLS version as TLSv1.0.

- CURL\_SSLVERSION\_MAX\_TLSv1\_1

  The flag defines maximum supported TLS version as TLSv1.1.

- CURL\_SSLVERSION\_MAX\_TLSv1\_2

  The flag defines maximum supported TLS version as TLSv1.2.

- CURL\_SSLVERSION\_MAX\_TLSv1\_3

  The flag defines maximum supported TLS version as TLSv1.3.

## DEFAULT

CURL\_SSLVERSION\_DEFAULT

## PROTOCOLS

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

All TLS backends support this option.

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    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 */
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## HISTORY

**CURL\_SSLVERSION\_**\* macros became *long* types in 8.16.0, prior to this version a *long* cast was necessary when passed to *[curl\_easy\_setopt(3)](/curl_easy_setopt/3.md)*.

## AVAILABILITY

Added in curl 7.52.0

## RETURN VALUE

*[curl\_easy\_setopt(3)](/curl_easy_setopt/3.md)* returns a CURLcode indicating success or error.

CURLE\_OK (0) means everything was OK, non-zero means an error occurred, see *[libcurl-errors(3)](/libcurl-errors/3.md)*.

## SEE ALSO

[**CURLOPT\_HTTP\_VERSION**(3)](/CURLOPT_HTTP_VERSION/3.md), [**CURLOPT\_IPRESOLVE**(3)](/CURLOPT_IPRESOLVE/3.md), [**CURLOPT\_SSLVERSION**(3)](/CURLOPT_SSLVERSION/3.md), [**CURLOPT\_USE\_SSL**(3)](/CURLOPT_USE_SSL/3.md)