Section: curl_easy_setopt options (3)
Updated: November 04, 2020
CURLOPT_PROXY - set proxy to use
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY, char *proxy);
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 Proxy. Default when no scheme or proxy type is specified.
HTTPS Proxy. (Added in 7.52.0 for OpenSSL, GnuTLS and NSS)
SOCKS4a Proxy. Proxy resolves URL hostname.
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 don't work unless you
tunnel through the HTTP proxy. Such tunneling is activated with
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.
The application does not have to keep the string around after setting this
libcurl respects the proxy environment variables named http_proxy
etc. If set, libcurl will use the specified
proxy for that URL scheme. So for a "FTP://" URL, the ftp_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
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!
All except file://.
Note that some protocols don't do very well over proxy.
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/file.txt");
curl_easy_setopt(curl, CURLOPT_PROXY, "http://proxy:80");
Since 7.14.1 the proxy environment variable names can include the protocol
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
Returns CURLE_OK if proxies are supported, CURLE_UNKNOWN_OPTION if not, or
CURLE_OUT_OF_MEMORY if there was insufficient heap space.