我们经常要用数据库记录用户的IP，以下代码可以获取客户端真实的IP：

//获取用户真实IP

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);

}

使用方法如下：

echo getIp();