Get real IP address of a visitor

How to get the real IP address of a visitor

<?php
function getRealIpAddr(){
	if (!empty($_SERVER['HTTP_CLIENT_IP'])){
		//check ip from share internet
		$ip = $_SERVER['HTTP_CLIENT_IP'];
	}
	elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])){
		//to check ip is pass from proxy
		$ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
	}
	else{
		$ip = $_SERVER['REMOTE_ADDR'];
	}
	return $ip;
}?>

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