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CURLOPT_SSL_OPTIONS(3)	    Library Functions Manual	  CURLOPT_SSL_OPTIONS(3)

NAME
     CURLOPT_SSL_OPTIONS - SSL behavior options

SYNOPSIS
     #include <curl/curl.h>

     CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_OPTIONS, long bitmask);

DESCRIPTION
     Pass  a  long  with a bitmask to tell libcurl about specific SSL behaviors.
     Available bits:

     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 is not 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 set-
	    ting  this option to 1 you ask for exactly that. This option is only
	    supported for Secure Transport and OpenSSL.

     CURLSSLOPT_NO_REVOKE
	    Tells libcurl to disable certificate revocation checks for those SSL
	    backends where such behavior is present. This option  is  only  sup-
	    ported for Schannel (the native Windows SSL library), with an excep-
	    tion  in  the case of Windows' Untrusted Publishers block list which
	    it seems cannot be bypassed.

     CURLSSLOPT_NO_PARTIALCHAIN
	    Tells libcurl to not accept "partial" certificate chains,  which  it
	    otherwise does by default. This option fails the certificate verifi-
	    cation  if	the  chain ends with an intermediate certificate and not
	    with a root cert.

	    Works with OpenSSL and its forks (LibreSSL, BoringSSL, etc).  (Added
	    in 7.68.0)

	    Works with Schannel if the user specified certificates to verify the
	    peer.  (Added in 8.15.0)

     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 CURLSSLOPT_NO_RE-
	    VOKE, the latter takes precedence. (Added in 7.70.0)

     CURLSSLOPT_NATIVE_CA
	    Tell  libcurl to use the operating system's native CA store for cer-
	    tificate verification. This option is independent of other	CA  cer-
	    tificate  locations  set  at run time or build time. Those locations
	    are searched in addition to the native CA store.

	    Works with wolfSSL on Windows, Linux (Debian,  Ubuntu,  Gentoo,  Fe-
	    dora,  RHEL),  macOS,  Android and iOS (added in 8.3.0); with GnuTLS
	    (added in 8.5.0) and with OpenSSL  and  its  forks	(LibreSSL,  Bor-
	    ingSSL, etc) on Windows (Added in 7.71.0).

	    This  works with Rustls on Windows, macOS, Android and iOS. On Linux
	    it is equivalent to using the Mozilla CA  certificate  bundle.  When
	    used  with Rustls _only_ the native CA store is consulted, not other
	    locations set at run time or build time. (Added in 8.13.0)

     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 vi-
	    olation and unexpected.  (Added in 7.77.0)

     CURLSSLOPT_EARLYDATA
	    Tell  libcurl  to try sending application data as TLS1.3 early data.
	    This option is supported for GnuTLS, wolfSSL,  quictls  and  OpenSSL
	    (but  not BoringSSL or AWS-LC). It works on TCP and QUIC connections
	    using ngtcp2.  This option works on a best effort  basis,  in  cases
	    when  it  was  not possible to send early data the request is resent
	    normally post-handshake.  This option does not work when using QUIC.
	    (Added in 8.11.0 for GnuTLS and  8.13.0  for  wolfSSL,  quictls  and
	    OpenSSL)

DEFAULT
     0

PROTOCOLS
     This  functionality  affects  all	TLS based protocols: HTTPS, FTPS, IMAPS,
     POP3S, SMTPS etc.

     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/");
	 /* weaken TLS only for use with silly servers */
	 curl_easy_setopt(curl, CURLOPT_SSL_OPTIONS,
			  CURLSSLOPT_ALLOW_BEAST | CURLSSLOPT_NO_REVOKE);
	 result = curl_easy_perform(curl);
	 curl_easy_cleanup(curl);
       }
     }

HISTORY
     CURLSSLOPT_* macros became long types in 8.15.0, prior to	this  version  a
     long cast was necessary when passed to curl_easy_setopt(3).

AVAILABILITY
     Added in curl 7.25.0

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_PROXY_SSL_OPTIONS(3),     CURLOPT_SSLVERSION(3),	 CURLOPT_SSL_CI-
     PHER_LIST(3)

libcurl 			   2026-06-11		  CURLOPT_SSL_OPTIONS(3)

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