---
name: "CURLOPT_SSLVERSION"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_SSLVERSION"
---

# CURLOPT\_SSLVERSION(3)

preferred TLS/SSL version

## NAME

CURLOPT\_SSLVERSION - preferred TLS/SSL version

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLVERSION, long version);
```

## DESCRIPTION

Pass a long as parameter to control which version range of SSL/TLS versions to use.

The SSL and TLS versions have typically developed from the most insecure version to be more and more secure in this order through history: SSL v2, SSLv3, TLS v1.0, TLS v1.1, TLS v1.2 and the most recent TLS v1.3.

Use one of the available defines for this purpose. The available options are:

- CURL\_SSLVERSION\_DEFAULT

  The default acceptable version range. The minimum acceptable version is by default TLS v1.0 since 7.39.0 (unless the TLS library has a stricter rule).

- CURL\_SSLVERSION\_TLSv1

  TLS v1.0 or later

- CURL\_SSLVERSION\_SSLv2

  SSL v2 - refused

- CURL\_SSLVERSION\_SSLv3

  SSL v3 - refused

- CURL\_SSLVERSION\_TLSv1\_0

  TLS v1.0 or later (Added in 7.34.0)

- CURL\_SSLVERSION\_TLSv1\_1

  TLS v1.1 or later (Added in 7.34.0)

- CURL\_SSLVERSION\_TLSv1\_2

  TLS v1.2 or later (Added in 7.34.0)

- CURL\_SSLVERSION\_TLSv1\_3

  TLS v1.3 or later (Added in 7.52.0)

  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 by libcurl, or the default value from the SSL library is used. libcurl uses a sensible default maximum, which was TLS v1.2 up to before 7.61.0 and is TLS v1.3 since then - assuming the TLS library support it. (Added in 7.54.0)

- CURL\_SSLVERSION\_MAX\_TLSv1\_0

  The flag defines maximum supported TLS version as TLS v1.0. (Added in 7.54.0)

- CURL\_SSLVERSION\_MAX\_TLSv1\_1

  The flag defines maximum supported TLS version as TLS v1.1. (Added in 7.54.0)

- CURL\_SSLVERSION\_MAX\_TLSv1\_2

  The flag defines maximum supported TLS version as TLS v1.2. (Added in 7.54.0)

- CURL\_SSLVERSION\_MAX\_TLSv1\_3

  The flag defines maximum supported TLS version as TLS v1.3. (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 TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

## 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

SSLv2 and SSLv3 are refused completely since curl 7.77.0

SSLv2 is disabled by default since 7.18.1. Other SSL versions availability may vary depending on which backend libcurl has been built to use.

SSLv3 is disabled by default since 7.39.0.

## RETURN VALUE

Returns CURLE\_OK if the option is supported, and CURLE\_UNKNOWN\_OPTION if not.

## SEE ALSO

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