CURLOPT_SSL_VERIFYPEER(3) Library Functions Manual 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 certificate
indicating its identity. curl verifies whether the certificate is au-
thentic, 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 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 signed by a CA, the connection fails.
When this option is disabled (set to zero), the CA certificates are not
loaded and the peer certificate verification is simply skipped.
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 hostname
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 communicat-
ing with the correct end-point.
When libcurl uses secure protocols it trusts responses and allows for
example HSTS and Alt-Svc information to be stored and used subsequently.
Disabling certificate verification can make libcurl trust and use such
information from malicious servers.
DEFAULT
1 - enabled
PROTOCOLS
This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS,
POP3S, SMTPS etc.
All TLS backends support this option.
EXAMPLE
int main(void)
{
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
Added in curl 7.4.2
RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
CURLINFO_CAINFO(3), CURLINFO_CAPATH(3), CURLOPT_CAINFO(3), CUR-
LOPT_PROXY_SSL_VERIFYHOST(3), CURLOPT_PROXY_SSL_VERIFYPEER(3), CUR-
LOPT_SSL_VERIFYHOST(3)
libcurl 2026-07-12 CURLOPT_SSL_VERIFYPEER(3)
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