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CURLOPT_SSLVERSION - set preferred TLS/SSL version

CURLOPT_SSLVERSION(3) curl_easy_setopt options CURLOPT_SSLVERSION(3)

NAME

CURLOPT_SSLVERSION - set 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 of SSL/TLS to attempt to use.
 
Use one of the available defines for this purpose. The available options are:
CURL_SSLVERSION_DEFAULT
The default action. This will attempt to figure out the remote SSL protocol version.
CURL_SSLVERSION_TLSv1
TLSv1.x
CURL_SSLVERSION_SSLv2
SSLv2
CURL_SSLVERSION_SSLv3
SSLv3
CURL_SSLVERSION_TLSv1_0
TLSv1.0 (Added in 7.34.0)
CURL_SSLVERSION_TLSv1_1
TLSv1.1 (Added in 7.34.0)
CURL_SSLVERSION_TLSv1_2
TLSv1.2 (Added in 7.34.0)
CURL_SSLVERSION_TLSv1_3
TLSv1.3 (Added in 7.52.0)
CURL_SSLVERSION_MAX_DEFAULT
The flag defines the maximum supported TLS version as TLSv1.2, or the default value from the SSL library. Only the NSS library currently allows one to get the maximum supported TLS version. (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)

DEFAULT

CURL_SSLVERSION_DEFAULT

PROTOCOLS

All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

EXAMPLE

CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
/* ask libcurl to use TLS version 1.1 or later */ curl_easy_setopt(curl, CURLOPT_SSLVERSION, CURL_SSLVERSION_TLSv1_1 | CURL_SSLVERSION_MAX_DEFAULT);
/* Perform the request */ curl_easy_perform(curl); }

AVAILABILITY

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_USE_SSL(3), CURLOPT_HTTP_VERSION(3), CURLOPT_IPRESOLVE(3)
August 12, 2017 libcurl 7.55.1