Provided by: libcurl4-doc_7.55.1-1ubuntu2_all bug

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),