php 获取客户端IP

if ($_SERVER["HTTP_X_FORWARDED_FOR"]) {
    if ($_SERVER["HTTP_CLIENT_IP"]) {
     $proxy = $_SERVER["HTTP_CLIENT_IP"];
   } else {
     $proxy = $_SERVER["REMOTE_ADDR"];
   }
   $ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
 } else {
   if ($_SERVER["HTTP_CLIENT_IP"]) {
     $ip = $_SERVER["HTTP_CLIENT_IP"];
   } else {
     $ip = $_SERVER["REMOTE_ADDR"];
   }
 }

 echo "Your IP $ip<BR>\n";
 if (isset($proxy)) {
   echo "Your proxy IP is $proxy<BR>\n";
 }