CURLOPT_SSL_VERIFYPEER - verify the peer's SSL certificate
#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_VERIFYPEER, long verify);
CURLOPT_SSL_VERIFYPEER(3) curl_easy_setopt options CURLOPT_SSL_VERIFYPEER(3)
NAME
CURLOPT_SSL_VERIFYPEER - verify the peer's SSL certificate
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_VERIFYPEER, long verify);
DESCRIPTION
Pass a long as parameter to enable or disable.
This option determines whether curl verifies the authenticity of the
peer's certificate. A value of 1 means curl verifies; 0 (zero) means it
does not.
When negotiating a TLS or SSL connection, the server sends a certifi-
cate indicating its identity. Curl verifies whether the certificate is
authentic, i.e. that you can trust that the server is who the certifi-
cate says it is. This trust is based on a chain of digital signatures,
rooted in certification authority (CA) certificates you supply. curl
uses a default bundle of CA certificates (the path for that is deter-
mined at build time) and you can specify alternate certificates with
the CURLOPT_CAINFO(3) option or the CURLOPT_CAPATH(3) option.
When CURLOPT_SSL_VERIFYPEER(3) is enabled, and the verification fails
to prove that the certificate is authentic, the connection fails. When
the option is zero, the peer certificate verification succeeds regard-
less.
Authenticating the certificate is not enough to be sure about the
server. You typically also want to ensure that the server is the server
you mean to be talking to. Use CURLOPT_SSL_VERIFYHOST(3) for that. The
check that the host name in the certificate is valid for the host name
you are connecting to is done independently of the CURLOPT_SSL_VERI-
FYPEER(3) option.
WARNING: disabling verification of the certificate allows bad guys to
man-in-the-middle the communication without you knowing it. Disabling
verification makes the communication insecure. Just having encryption
on a transfer is not enough as you cannot be sure that you are communi-
cating with the correct end-point.
NOTE: even when this option is disabled, depending on the used TLS
backend, curl may still load the certificate file specified in CUR-
LOPT_CAINFO(3). curl default settings in some distributions might use
quite a large file as a default setting for CURLOPT_CAINFO(3), so load-
ing the file can be quite expensive, especially when dealing with many
connections. Thus, in some situations, you might want to disable veri-
fication fully to save resources by setting CURLOPT_CAINFO(3) to NULL -
but please also consider the warning above!
DEFAULT
By default, curl assumes a value of 1.
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 certificate check please */
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 1L);
curl_easy_perform(curl);
}
AVAILABILITY
If built TLS enabled.
RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
if not.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | web/curl |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
SEE ALSO
CURLOPT_SSL_VERIFYHOST(3), CURLOPT_PROXY_SSL_VERIFYPEER(3), CUR-
LOPT_PROXY_SSL_VERIFYHOST(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_VERIFYPEER(3)