.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) 1998 - 2020, Daniel Stenberg, , 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.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_SSL_OPTIONS 3 "19 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options" .SH NAME CURLOPT_SSL_OPTIONS \- set SSL behavior options .SH SYNOPSIS #include CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_OPTIONS, long bitmask); .SH DESCRIPTION Pass a long with a bitmask to tell libcurl about specific SSL behaviors. Available bits: .IP CURLSSLOPT_ALLOW_BEAST Tells libcurl to not attempt to use any workarounds for a security flaw in the SSL3 and TLS1.0 protocols. If this option isn't used or this bit is set to 0, the SSL layer libcurl uses may use a work-around for this flaw although it might cause interoperability problems with some (older) SSL implementations. WARNING: avoiding this work-around lessens the security, and by setting this option to 1 you ask for exactly that. This option is only supported for Secure Transport, NSS and OpenSSL. .IP CURLSSLOPT_NO_REVOKE Tells libcurl to disable certificate revocation checks for those SSL backends where such behavior is present. This option is only supported for Schannel (the native Windows SSL library), with an exception in the case of Windows' Untrusted Publishers block list which it seems can't be bypassed. (Added in 7.44.0) .IP CURLSSLOPT_NO_PARTIALCHAIN Tells libcurl to not accept "partial" certificate chains, which it otherwise does by default. This option is only supported for OpenSSL and will fail the certificate verification if the chain ends with an intermediate certificate and not with a root cert. (Added in 7.68.0) .IP CURLSSLOPT_REVOKE_BEST_EFFORT Tells libcurl to ignore certificate revocation checks in case of missing or offline distribution points for those SSL backends where such behavior is present. This option is only supported for Schannel (the native Windows SSL library). If combined with \fICURLSSLOPT_NO_REVOKE\fP, the latter takes precedence. (Added in 7.70.0) .IP CURLSSLOPT_NATIVE_CA Tell libcurl to use the operating system's native CA store for certificate verification. Works only on Windows when built to use OpenSSL. This option is experimental and behavior is subject to change. (Added in 7.71.0) .IP CURLSSLOPT_AUTO_CLIENT_CERT Tell libcurl to automatically locate and use a client certificate for authentication, when requested by the server. This option is only supported for Schannel (the native Windows SSL library). Prior to 7.77.0 this was the default behavior in libcurl with Schannel. Since the server can request any certificate that supports client authentication in the OS certificate store it could be a privacy violation and unexpected. (Added in 7.77.0) .SH DEFAULT 0 .SH PROTOCOLS All TLS-based protocols .SH EXAMPLE .nf CURL *curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/"); /* weaken TLS only for use with silly servers */ curl_easy_setopt(curl, CURLOPT_SSL_OPTIONS, CURLSSLOPT_ALLOW_BEAST | CURLSSLOPT_NO_REVOKE); ret = curl_easy_perform(curl); curl_easy_cleanup(curl); } .fi .SH AVAILABILITY Added in 7.25.0 .SH RETURN VALUE Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. .SH "SEE ALSO" .BR CURLOPT_SSLVERSION "(3), " CURLOPT_SSL_CIPHER_LIST "(3), "