CURLOPT_SSLVERSION(3) Library Functions Manual CURLOPT_SSLVERSION(3) 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: SSLv2, SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 and the most recent TLSv1.3. 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 TLSv1.2 since 8.16.0 (unless the TLS library has a stricter rule). CURL_SSLVERSION_TLSv1 TLSv1.0 or later CURL_SSLVERSION_SSLv2 SSLv2 - refused CURL_SSLVERSION_SSLv3 SSLv3 - refused CURL_SSLVERSION_TLSv1_0 TLSv1.0 or later CURL_SSLVERSION_TLSv1_1 TLSv1.1 or later CURL_SSLVERSION_TLSv1_2 TLSv1.2 or later CURL_SSLVERSION_TLSv1_3 TLSv1.3 or later 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. 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 sen- sible default maximum, which was TLSv1.2 up to before 7.61.0 and is TLSv1.3 since then - assuming the TLS library support it. CURL_SSLVERSION_MAX_TLSv1_0 The flag defines maximum supported TLS version as TLSv1.0. CURL_SSLVERSION_MAX_TLSv1_1 The flag defines maximum supported TLS version as TLSv1.1. CURL_SSLVERSION_MAX_TLSv1_2 The flag defines maximum supported TLS version as TLSv1.2. CURL_SSLVERSION_MAX_TLSv1_3 The flag defines maximum supported TLS version as TLSv1.3. DEFAULT CURL_SSLVERSION_DEFAULT PROTOCOLS This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. only All TLS backends support this option. 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 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. SSLv2 and SSLv3 are refused completely since curl 7.77.0 Since 8.10.0 wolfSSL is fully supported. Before 8.10.0 the MAX macros were not supported with wolfSSL and the other macros did not set a minimum, but restricted the TLS version to only the specified one. Rustls support added in 8.10.0. 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). AVAILABILITY Added in curl 7.1 RETURN VALUE 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). SEE ALSO CURLOPT_HTTP_VERSION(3), CURLOPT_IPRESOLVE(3), CURLOPT_PROXY_SSLVERSION(3), CURLOPT_USE_SSL(3) libcurl 2026-08-27 CURLOPT_SSLVERSION(3)
NAME | SYNOPSIS | DESCRIPTION | DEFAULT | PROTOCOLS | EXAMPLE | HISTORY | AVAILABILITY | RETURN VALUE | SEE ALSO
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