.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) 1998 - 2015, 2018, Daniel Stenberg, <daniel@haxx.se>, et al. .\" * .\" * This software is licensed as described in the file COPYING, which .\" * you should have received as part of this distribution. The terms .\" * are also available at https://curl.haxx.se/docs/copyright.html. .\" * .\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell .\" * copies of the Software, and permit persons to whom the Software is .\" * furnished to do so, under the terms of the COPYING file. .\" * .\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY .\" * KIND, either express or implied. .\" * .\" ************************************************************************** .\" .TH CURLOPT_SSLVERSION 3 "17 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options" .SH NAME CURLOPT_SSLVERSION \- set preferred TLS/SSL version .SH SYNOPSIS #include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLVERSION, long version); .SH 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, TSL v1.1, TSL v1.2 and the most recent TLS v1.3. Use one of the available defines for this purpose. The available options are: .RS .IP CURL_SSLVERSION_DEFAULT The default acceptable version range. The mimimum acceptable version is by default TLS 1.0 since 7.39.0 (unless the TLS library has a stricter rule). .IP CURL_SSLVERSION_TLSv1 TLS v1.0 or later .IP CURL_SSLVERSION_SSLv2 SSL v2 (but not SSLv3) .IP CURL_SSLVERSION_SSLv3 SSL v3 (but not SSLv2) .IP CURL_SSLVERSION_TLSv1_0 TLS v1.0 or later (Added in 7.34.0) .IP CURL_SSLVERSION_TLSv1_1 TLS v1.1 or later (Added in 7.34.0) .IP CURL_SSLVERSION_TLSv1_2 TLS v1.2 or later (Added in 7.34.0) .IP CURL_SSLVERSION_TLSv1_3 TLS v1.3 or later (Added in 7.52.0) .RE The maximum TLS version can be set by using \fIone\fP of the CURL_SSLVERSION_MAX_ macros below. It is also possible to OR \fIone\fP of the CURL_SSLVERSION_ macros with \fIone\fP of the CURL_SSLVERSION_MAX_ macros. The MAX macros are not supported for SSL backends axTLS or wolfSSL. .RS .IP 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 1.2 up to before 7.61.0 and is TLS 1.3 since then - assuming the TLS library support it. (Added in 7.54.0) .IP CURL_SSLVERSION_MAX_TLSv1_0 The flag defines maximum supported TLS version as TLS v1.0. (Added in 7.54.0) .IP CURL_SSLVERSION_MAX_TLSv1_1 The flag defines maximum supported TLS version as TLS v1.1. (Added in 7.54.0) .IP CURL_SSLVERSION_MAX_TLSv1_2 The flag defines maximum supported TLS version as TLS v1.2. (Added in 7.54.0) .IP CURL_SSLVERSION_MAX_TLSv1_3 The flag defines maximum supported TLS version as TLS v1.3. (Added in 7.54.0) .RE .SH DEFAULT CURL_SSLVERSION_DEFAULT .SH PROTOCOLS All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. .SH EXAMPLE .nf 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, CURL_SSLVERSION_TLSv1); /* Perform the request */ curl_easy_perform(curl); } .fi .SH 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. .SH RETURN VALUE Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. .SH "SEE ALSO" .BR CURLOPT_USE_SSL "(3), " CURLOPT_HTTP_VERSION "(3), " .BR CURLOPT_IPRESOLVE "(3) "