Class: WP_HTTP_Proxy  - X-Ref

Core class used to implement HTTP API proxy support.

There are caveats to proxy support. It requires that defines be made in the wp-config.php file to
enable proxy support. There are also a few filters that plugins can hook into for some of the
constants.

Please note that only BASIC authentication is supported by most transports.
cURL MAY support more methods (such as NTLM authentication) depending on your environment.

The constants are as follows:
<ol>
<li>WP_PROXY_HOST - Enable proxy support and host for connecting.</li>
<li>WP_PROXY_PORT - Proxy port for connection. No default, must be defined.</li>
<li>WP_PROXY_USERNAME - Proxy username, if it requires authentication.</li>
<li>WP_PROXY_PASSWORD - Proxy password, if it requires authentication.</li>
<li>WP_PROXY_BYPASS_HOSTS - Will prevent the hosts in this list from going through the proxy.
You do not need to have localhost and the site host in this list, because they will not be passed
through the proxy. The list should be presented in a comma separated list, wildcards using * are supported. Example: *.wordpress.org</li>
</ol>

An example can be as seen below.

define('WP_PROXY_HOST', '192.168.84.101');
define('WP_PROXY_PORT', '8080');
define('WP_PROXY_BYPASS_HOSTS', 'localhost, www.example.com, *.wordpress.org');