Names for headers that can be trusted when using trusted proxies.
The default names are non-standard, but widely used by popular reverse proxies (like Apache mod_proxy or Amazon EC2).
protected static $trustedHeaders = array(
self::HEADER_CLIENT_IP => 'X_FORWARDED_FOR',
self::HEADER_CLIENT_HOST => 'X_FORWARDED_HOST',
self::HEADER_CLIENT_PROTO => 'X_FORWARDED_PROTO',
self::HEADER_CLIENT_PORT => 'X_FORWARDED_PORT',
);