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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 authen- tic, 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 certi- fication 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) 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 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_VERIFYPEER(3) option. WARNING: disabling verification of the certificate allows bad guys to man-in-the-middle the communication without you knowing it. Disabling veri- fication makes the communication insecure. Having encryption on a transfer is not enough as you cannot be sure that you are communicating with the correct end-point. When libcurl uses secure protocols it trusts responses and allows for exam- ple HSTS and Alt-Svc information to be stored and used subsequently. Dis- abling certificate verification can make libcurl trust and use such infor- mation 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) { CURLcode result; 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); result = curl_easy_perform(curl); curl_easy_cleanup(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 2026-06-11 CURLOPT_SSL_VERIFYPEER(3)
NAME | SYNOPSIS | DESCRIPTION | DEFAULT | PROTOCOLS | EXAMPLE | AVAILABILITY | RETURN VALUE | SEE ALSO
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