CURLOPT_PROXY_SSL_VERIFYHOST - verify the proxy certificate's name against host

Added in curl 7.52.0

2

Pass a long set to 2L as asking curl to verify in the HTTPS proxy's certificate name fields against the proxy name. This option determines whether libcurl verifies that the proxy cert contains the correct name for the name it is known as. When CURLOPT_PROXY_SSL_VERIFYHOST(3) is 2, the proxy certificate must indicate that the server is the proxy to which you meant to connect to, or the connection fails. curl considers the proxy the intended one when the Common Name field or a Subject Alternate Name field in the certificate matches the hostname in the proxy string which you told curl to use. If verify value is set to 1: In 7.28.0 and earlier: treated as a debug option of some sorts, not supported anymore due to frequently leading to programmer mistakes. From 7.28.1 to 7.65.3: setting it to 1 made curl_easy_setopt(3) return an error and leaving the flag untouched. From 7.66.0: treats 1 and 2 the same. When the verify value is 0L, the connection succeeds regardless of the names used in the certificate. Use that ability with caution. See also CURLOPT_PROXY_SSL_VERIFYPEER(3) to verify the digital signature of the proxy certificate.

int main(void) { CURL *curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); /* Set the default value: strict name check please */ curl_easy_setopt(curl, CURLOPT_PROXY_SSL_VERIFYHOST, 2L); curl_easy_perform(curl); } }

CURLOPT_PROXY_SSL_VERIFYHOST - verify the proxy certificate's name against host

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. All TLS backends support this option.

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).

CURLOPT_CAINFO(3), CURLOPT_PROXY_CAINFO(3), CURLOPT_PROXY_SSL_VERIFYPEER(3), CURLOPT_SSL_VERIFYPEER(3) libcurl 2025-06-16 CURLOPT_PROXY_SSL_VERIFYHOST(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSL_VERIFYHOST, long verify);