CURLOPT_PROXY_SSL_VERIFYPEER(3) Library Functions Manual
NAME
CURLOPT_PROXY_SSL_VERIFYPEER - verify the proxy's SSL certificate
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSL_VERIFYPEER,
long verify);
DESCRIPTION
Pass a long as parameter set to 1L to enable or 0L to disable.
This option tells curl to verify the authenticity of the HTTPS proxy's
certificate. A value of 1 means curl verifies; 0 (zero) means it does
not.
This is the proxy version of CURLOPT_SSL_VERIFYPEER(3) that is used for
ordinary HTTPS servers.
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_PROXY_CAINFO(3) option or the
CURLOPT_PROXY_CAPATH(3) option.
When CURLOPT_PROXY_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
regardless.
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_PROXY_SSL_VERIFYHOST(3) for
that. The check that the hostname in the certificate is valid for the
hostname you are connecting to is done independently of the
CURLOPT_PROXY_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
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.
DEFAULT
1
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_PROXY_SSL_VERIFYPEER, 1L);
curl_easy_perform(curl);
}
}
AVAILABILITY
Added in curl 7.52.0
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
CURLOPT_PROXY_SSL_VERIFYHOST(3), CURLOPT_SSL_VERIFYHOST(3),
CURLOPT_SSL_VERIFYPEER(3)
libcurl 2025-02-08 CURLOPT_PROXY_SSL_VERIFYPEER(3)
curl 8.12.0 - Generated Tue Feb 18 14:18:27 CST 2025