CURLOPT_SSL_VERIFYHOST - verify the certificate's name against host
#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_VERIFYHOST, long verify);
CURLOPT_SSL_VERIFYHOST(3) curl_easy_setopt options CURLOPT_SSL_VERIFYHOST(3)
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 certifi-
cate 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.
If verify value is set to 1:
In 7.28.0 and earlier: treated as a debug option of some sorts, not
supported anymore due to frequently leading to programmer mistakes.
From 7.28.1 to 7.65.3: setting it to 1 made curl_easy_setopt() return
an error and leaving the flag untouched.
From 7.66.0: treats 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 iden-
tity. The server could be lying. To control lying, see CUR-
LOPT_SSL_VERIFYPEER(3).
LIMITATIONS
Secure Transport: 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.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | web/curl |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
SEE ALSO
CURLOPT_SSL_VERIFYPEER(3), CURLOPT_CAINFO(3),
NOTES
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from https://curl.se/down-
load/curl-7.83.1.tar.bz2.
Further information about this software can be found on the open source
community website at http://curl.haxx.se/.
libcurl 7.83.1 November 26, 2021 CURLOPT_SSL_VERIFYHOST(3)