NAME

       CURLOPT_SSL_VERIFYHOST - verify the certificate's name against host

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_VERIFYHOST, long verify);

DESCRIPTION

       Pass a long as parameter specifying what to verify.

       This option determines whether libcurl verifies that the server cert is for the server it is known as.

       When negotiating TLS and SSL connections, the server sends a certificate indicating its identity.

       When  CURLOPT_SSL_VERIFYHOST(3)  is  2,  that  certificate must indicate that the server is the server to
       which you meant to connect, or the connection fails. Simply put, it means it has to have the same name in
       the certificate as is in the URL you operate against.

       Curl considers the server the intended one when the Common Name field or a Subject Alternate  Name  field
       in the certificate matches the host name in the URL to which you told Curl to connect.

       When  the  verify  value  is  1,  curl_easy_setopt  will return an error and the option value will not be
       changed.  It was previously (in 7.28.0 and earlier) a debug option of some sorts, but  it  is  no  longer
       supported  due to frequently leading to programmer mistakes. Future versions will stop returning an error
       for 1 and just treat 1 and 2 the same.

       When the verify value is 0, the connection succeeds regardless of the names in the certificate. Use  that
       ability with caution!

       The default value for this option is 2.

       This  option  controls  checking the server's certificate's claimed identity.  The server could be lying.
       To control lying, see CURLOPT_SSL_VERIFYPEER(3).

LIMITATIONS

       DarwinSSL: If verify value is 0, then SNI is also disabled.  SNI  is  a  TLS  extension  that  sends  the
       hostname  to the server. The server may use that information to do such things as sending back a specific
       certificate for the hostname, or forwarding the request to a specific origin server. Some  hostnames  may
       be inaccessible if SNI is not sent.

       NSS:  If  CURLOPT_SSL_VERIFYPEER(3)  is zero, CURLOPT_SSL_VERIFYHOST(3) is also set to zero and cannot be
       overridden.

DEFAULT

       2

PROTOCOLS

       All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

EXAMPLE

       CURL *curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

         /* Set the default value: strict name check please */
         curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 2L);

         curl_easy_perform(curl);
       }

AVAILABILITY

       If built TLS enabled.

RETURN VALUE

       Returns CURLE_OK if TLS is supported, and CURLE_UNKNOWN_OPTION if not.

       If 1 is set as argument, CURLE_BAD_FUNCTION_ARGUMENT is returned.

SEE ALSO

       CURLOPT_SSL_VERIFYPEER(3), CURLOPT_CAINFO(3),

libcurl 7.58.0                                  February 02, 2017                      CURLOPT_SSL_VERIFYHOST(3)