Pass a value 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 (but not SSLv3)
#CURL_SSLVERSION_SSLv3-
SSL v3 (but not SSLv2)
#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 get 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 will use 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)