PHP获取客户端IP地址的方法

PHP获取客户端IP地址的方法。

if ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"]) {
     $ip = $HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"];
} elseif ($HTTP_SERVER_VARS["HTTP_CLIENT_IP"]) {
     $ip = $HTTP_SERVER_VARS["HTTP_CLIENT_IP"];
} elseif ($HTTP_SERVER_VARS["REMOTE_ADDR"]) {
     $ip = $HTTP_SERVER_VARS["REMOTE_ADDR"];
} elseif (getenv("HTTP_X_FORWARDED_FOR")) {
     $ip = getenv("HTTP_X_FORWARDED_FOR");
} elseif (getenv("HTTP_CLIENT_IP")) {
     $ip = getenv("HTTP_CLIENT_IP");
} elseif (getenv("REMOTE_ADDR")) {
     $ip = getenv("REMOTE_ADDR");
} else {
     $ip = "Unknown";
}

echo "IP: ".$ip;