CURLOPT_HTTPPROXYTUNNEL(3)                            curl_easy_setopt options

NAME
       CURLOPT_HTTPPROXYTUNNEL - tunnel through HTTP proxy

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTPPROXYTUNNEL, long
       tunnel);

DESCRIPTION
       Set the tunnel parameter to 1L to make libcurl tunnel all operations
       through the HTTP proxy (set with CURLOPT_PROXY(3)). There is a big
       difference between using a proxy and to tunnel through it.

       Tunneling means that an HTTP CONNECT request is sent to the proxy,
       asking it to connect to a remote host on a specific port number and
       then the traffic is just passed through the proxy. Proxies tend to
       white-list specific port numbers it allows CONNECT requests to and
       often only port 80 and 443 are allowed.

       To suppress proxy CONNECT response headers from user callbacks use
       _SUPPRESS_CONNECT_HEADERS&section=3">CURLOPT_SUPPRESS_CONNECT_HEADERS(3).

       HTTP proxies can generally only speak HTTP (for obvious reasons), which
       makes libcurl convert non-HTTP requests to HTTP when using an HTTP
       proxy without this tunnel option set. For example, asking for an FTP
       URL and specifying an HTTP proxy will make libcurl send an FTP URL in
       an HTTP GET request to the proxy. By instead tunneling through the
       proxy, you avoid that conversion (that rarely works through the proxy
       anyway).

DEFAULT
       0

PROTOCOLS
       All network protocols

EXAMPLE
       CURL *curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/file.txt");
         curl_easy_setopt(curl, CURLOPT_PROXY, "http://127.0.0.1:80");
         curl_easy_setopt(curl, CURLOPT_HTTPPROXYTUNNEL, 1L);
         curl_easy_perform(curl);
       }

AVAILABILITY
       Always

RETURN VALUE
       Returns CURLE_OK

SEE ALSO
       CURLOPT_PROXY(3), CURLOPT_PROXYTYPE(3), CURLOPT_PROXYPORT(3),

libcurl 7.77.0                 November 4, 2020     CURLOPT_HTTPPROXYTUNNEL(3)