Ubuntu Manpage: CURLOPT_PROXY

NAME

       CURLOPT_PROXY - proxy to use

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY, char *proxy);

DESCRIPTION

Set the proxy to use for the upcoming request. The parameter should be a char * to a null-
terminated string holding the host name or dotted numerical IP address. A numerical IPv6
address must be written within [brackets].

To specify port number in this string, append :[port] to the end of the host name. The
proxy's port number may optionally be specified with the separate option
CURLOPT_PROXYPORT(3). If not specified, libcurl will default to using port 1080 for
proxies.

The proxy string may be prefixed with [scheme]:// to specify which kind of proxy is used.

http://
HTTP Proxy. Default when no scheme or proxy type is specified.

https://
HTTPS Proxy. (Added in 7.52.0 for OpenSSL, GnuTLS and NSS)

socks4://
SOCKS4 Proxy.

socks4a://
SOCKS4a Proxy. Proxy resolves URL hostname.

socks5://
SOCKS5 Proxy.

socks5h://
SOCKS5 Proxy. Proxy resolves URL hostname.

Without a scheme prefix, CURLOPT_PROXYTYPE(3) can be used to specify which kind of proxy
the string identifies.

When you tell the library to use an HTTP proxy, libcurl will transparently convert
operations to HTTP even if you specify an FTP URL etc. This may have an impact on what
other features of the library you can use, such as CURLOPT_QUOTE(3) and similar FTP
specifics that do not work unless you tunnel through the HTTP proxy. Such tunneling is
activated with CURLOPT_HTTPPROXYTUNNEL(3).

Setting the proxy string to "" (an empty string) will explicitly disable the use of a
proxy, even if there is an environment variable set for it.

A proxy host string can also include protocol scheme (http://) and embedded user +
password.

Unix domain sockets are supported for socks proxies since 7.84.0. Set localhost for the
host part. e.g. socks5h://localhost/path/to/socket.sock

The application does not have to keep the string around after setting this option.

Environment variables

       libcurl respects the proxy environment variables named http_proxy,  ftp_proxy,  sftp_proxy
       etc.  If  set, libcurl will use the specified proxy for that URL scheme. So for a "FTP://"
       URL, the ftp_proxy is considered. all_proxy is used if no protocol specific proxy was set.

       If  no_proxy  (or  NO_PROXY)  is  set,  it  is  the  exact  equivalent  of   setting   the
       CURLOPT_NOPROXY(3) option.

       The CURLOPT_PROXY(3) and CURLOPT_NOPROXY(3) options override environment variables.

DEFAULT

       Default is NULL, meaning no proxy is used.

       When  you  set  a  host name to use, do not assume that there's any particular single port
       number used widely for proxies. Specify it!

PROTOCOLS

       All except file://. Note that some protocols do not work well over proxy.

EXAMPLE

       CURL *curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/file.txt");
         curl_easy_setopt(curl, CURLOPT_PROXY, "http://proxy:80");
         curl_easy_perform(curl);
       }

AVAILABILITY

       Since 7.14.1 the proxy environment variable names can include the protocol scheme.

       Since 7.21.7 the proxy string supports the socks protocols as "schemes".

       Since 7.50.2, unsupported schemes in proxy strings cause libcurl to return error.

RETURN VALUE

       Returns  CURLE_OK  if   proxies   are   supported,   CURLE_UNKNOWN_OPTION   if   not,   or
       CURLE_OUT_OF_MEMORY if there was insufficient heap space.