Remote User IP Detection in PHP

This function returns the IP of the Remote machine.

function getip()
{

if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"),
"unknown"))

$ip = getenv("HTTP_CLIENT_IP");

else if (getenv("HTTP_X_FORWARDED_FOR") &&
strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))

$ip = getenv("HTTP_X_FORWARDED_FOR");

else if (getenv("REMOTE_ADDR") &&
strcasecmp(getenv("REMOTE_ADDR"), "unknown"))

$ip = getenv("REMOTE_ADDR");

else if (isset($_SERVER['REMOTE_ADDR']) &&
$_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))

$ip = $_SERVER['REMOTE_ADDR'];

else

$ip = "unknown";
return($ip);
}