99 lines
3.0 KiB
Markdown
99 lines
3.0 KiB
Markdown
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---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Title: CURLOPT_SSL_VERIFYPEER
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Section: 3
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Source: libcurl
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See-also:
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- CURLINFO_CAINFO (3)
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- CURLINFO_CAPATH (3)
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- CURLOPT_CAINFO (3)
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- CURLOPT_PROXY_SSL_VERIFYHOST (3)
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- CURLOPT_PROXY_SSL_VERIFYPEER (3)
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- CURLOPT_SSL_VERIFYHOST (3)
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---
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# NAME
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CURLOPT_SSL_VERIFYPEER - verify the peer's SSL certificate
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_VERIFYPEER, long verify);
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~~~
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# DESCRIPTION
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Pass a long as parameter to enable or disable.
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This option determines whether curl verifies the authenticity of the peer's
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certificate. A value of 1 means curl verifies; 0 (zero) means it does not.
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When negotiating a TLS or SSL connection, the server sends a certificate
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indicating its identity. Curl verifies whether the certificate is authentic,
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i.e. that you can trust that the server is who the certificate says it is.
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This trust is based on a chain of digital signatures, rooted in certification
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authority (CA) certificates you supply. curl uses a default bundle of CA
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certificates (the path for that is determined at build time) and you can
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specify alternate certificates with the CURLOPT_CAINFO(3) option or the
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CURLOPT_CAPATH(3) option.
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When CURLOPT_SSL_VERIFYPEER(3) is enabled, and the verification fails to
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prove that the certificate is signed by a CA, the connection fails.
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When this option is disabled (set to zero), the CA certificates are not loaded
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and the peer certificate verification is simply skipped.
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Authenticating the certificate is not enough to be sure about the server. You
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typically also want to ensure that the server is the server you mean to be
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talking to. Use CURLOPT_SSL_VERIFYHOST(3) for that. The check that the host
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name in the certificate is valid for the hostname you are connecting to is
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done independently of the CURLOPT_SSL_VERIFYPEER(3) option.
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WARNING: disabling verification of the certificate allows bad guys to
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man-in-the-middle the communication without you knowing it. Disabling
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verification makes the communication insecure. Just having encryption on a
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transfer is not enough as you cannot be sure that you are communicating with
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the correct end-point.
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When libcurl uses secure protocols it trusts responses and allows for example
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HSTS and Alt-Svc information to be stored and used subsequently. Disabling
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certificate verification can make libcurl trust and use such information from
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malicious servers.
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# DEFAULT
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1 - enabled
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# PROTOCOLS
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All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
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# EXAMPLE
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~~~c
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int main(void)
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{
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CURL *curl = curl_easy_init();
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if(curl) {
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curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
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/* Set the default value: strict certificate check please */
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curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 1L);
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curl_easy_perform(curl);
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}
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}
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~~~
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# AVAILABILITY
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If built TLS enabled.
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# RETURN VALUE
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Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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