CURLOPT_PR...VERIFYPEER(3)

🎀 NAME 🎀

CURLOPT_PROXY_SSL_VERIFYPEER — verify the proxy's SSL certificate 💅

Hey bestie, you found the CURLOPT_PROXY_SSL_VERIFYPEER(3) page in the Library Functions Manual — the header shows the truncated CURLOPT_PR...VERIFYPEER(3) (terminal-core 💅), but the full name is right above ✨.

✨ SYNOPSIS ✨

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSL_VERIFYPEER,
                          long verify);

💖 DESCRIPTION 💖

Okay so this option is the proxy's vibe check for its SSL certificate. You pass a long as the parameter, set to 1L to turn verification on or 0L to turn it off. Periodt.

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) — the one used for ordinary HTTPS servers. Sibling energy, same security brain 💅.

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. No cap, that chain is the whole plot 🔥.

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. Like, zero means it just shrugs and lets it through 😭.

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. Two separate checks, two separate main characters 👑

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. This is not a cute lil shortcut; it is a security no-no 💀.

🌸 DEFAULT 🌸

1 — verification is on by default, bestie ✨

🦋 PROTOCOLS 🦋

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

All TLS backends support this option. Every one of them, slay 💅.

🎀 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)

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Sign-off time, bestie: this page is from libcurl, dated 2026-10-12, and its footer label is CURLOPT_PR...VERIFYPEER(3) 💖🫶