获取IP地址

 
function get_client_ip(){ //获得pppoe拨号上来的ipaddress
   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);

}