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CURLOPT_SSL_VERIFYPEER(3) curl_easy_setopt options CURLOPT_SSL_VERIFYPEER(3)
CURLOPT_SSL_VERIFYPEER - verify the peer's SSL certificate
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_VERIFYPEER, long
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
When negotiating a TLS or SSL connection, the server sends a
certificate indicating its identity. Curl verifies whether the
certificate is authentic, i.e. that you can trust that the server is
who the certificate 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 determined at build time) and you can specify alternate
certificates with the CURLOPT_CAINFO(3) option or the CURLOPT_CAPATH(3)
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
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're connecting to is done independently of the
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
communicating 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
CURLOPT_CAINFO(3). curl default settings in some distributions might
use quite a large file as a default setting for CURLOPT_CAINFO(3), so
loading the file can be quite expensive, especially when dealing with
many connections. Thus, in some situations, you might want to disable
verification fully to save resources by setting CURLOPT_CAINFO(3) to
NULL - but please also consider the warning above!
By default, curl assumes a value of 1.
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
CURL *curl = curl_easy_init();
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);
If built TLS enabled.
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
libcurl 7.73.0 June 24, 2018 CURLOPT_SSL_VERIFYPEER(3)