CURLOPT\_PROXY\_SSLVERSION(3) Library Functions Manual CURLOPT\_PROXY\_SSLVERSION(3)

# [NAME](#NAME)

CURLOPT\_PROXY\_SSLVERSION - preferred HTTPS proxy TLS version

# [SYNOPSIS](#SYNOPSIS)

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSLVERSION,


                          long version);
```

# [DESCRIPTION](#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](#CURL_SSLVERSION_DEFAULT)

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

[CURL\_SSLVERSION\_TLSv1](#CURL_SSLVERSION_TLSv1)

TLSv1.x

[CURL\_SSLVERSION\_TLSv1\_0](#CURL_SSLVERSION_TLSv1_0)

TLSv1.0

[CURL\_SSLVERSION\_TLSv1\_1](#CURL_SSLVERSION_TLSv1_1)

TLSv1.1

[CURL\_SSLVERSION\_TLSv1\_2](#CURL_SSLVERSION_TLSv1_2)

TLSv1.2

[CURL\_SSLVERSION\_TLSv1\_3](#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](#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](#CURL_SSLVERSION_MAX_TLSv1_0)

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

[CURL\_SSLVERSION\_MAX\_TLSv1\_1](#CURL_SSLVERSION_MAX_TLSv1_1)

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

[CURL\_SSLVERSION\_MAX\_TLSv1\_2](#CURL_SSLVERSION_MAX_TLSv1_2)

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

[CURL\_SSLVERSION\_MAX\_TLSv1\_3](#CURL_SSLVERSION_MAX_TLSv1_3)

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

# [DEFAULT](#DEFAULT)

CURL\_SSLVERSION\_DEFAULT

# [PROTOCOLS](#PROTOCOLS)

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

All TLS backends support this option.

# [EXAMPLE](#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](#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)*](/man/os/curl/curl_easy_setopt.3).

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.52.0

# [RETURN VALUE](#RETURN_VALUE)

[*curl\_easy\_setopt(3)*](/man/os/curl/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)*](/man/os/curl/libcurl-errors.3).

# [SEE ALSO](#SEE_ALSO)

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

2026-10-22 libcurl

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Document: CURLOPT_PROXY_SSLVERSION(3) from curl 8.23.0-r2 (Chainguard OS)
Source: https://github.com/curl/curl.git