It’s probably documented somewhere but from wp-includes/class-http.php
Adds Proxy support to the WordPress HTTP API.
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:
- WP_PROXY_HOST – Enable proxy support and host for connecting.
- WP_PROXY_PORT – Proxy port for connection. No default, must be defined.
- WP_PROXY_USERNAME – Proxy username, if it requires authentication.
- WP_PROXY_PASSWORD – Proxy password, if it requires authentication.
- 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 blog host in this list, because they will not be passed through the proxy. The list should be presented in a comma separated list, wildcards usingare supported, eg. *.www.remarpro.com
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, *.www.remarpro.com');