Bagaimana untuk melaksanakan larangan akses dalam php

<?php 
/加IP访问限制 
if(getenv(&#39;HTTP_CLIENT_IP&#39;) && strcasecmp(getenv(&#39;HTTP_CLIENT_IP&#39;), &#39;unknown&#39;)) { 
$userip = getenv(&#39;HTTP_CLIENT_IP&#39;); 
} elseif(getenv(&#39;HTTP_X_FORWARDED_FOR&#39;) && strcasecmp(getenv(&#39;HTTP_X_FORWARDED_FOR&#39;), &#39;unknown&#39;)) { 
$userip = getenv(&#39;HTTP_X_FORWARDED_FOR&#39;); 
} elseif(getenv(&#39;REMOTE_ADDR&#39;) && strcasecmp(getenv(&#39;REMOTE_ADDR&#39;), &#39;unknown&#39;)) { 
$userip = getenv(&#39;REMOTE_ADDR&#39;); 
} elseif(isset($_SERVER[&#39;REMOTE_ADDR&#39;]) && $_SERVER[&#39;REMOTE_ADDR&#39;] && strcasecmp($_SERVER[&#39;REMOTE_ADDR&#39;], &#39;unknown&#39;)) { 
$userip = $_SERVER[&#39;REMOTE_ADDR&#39;]; 
} 
//限制ip 
if ($userip==&#39;192.168.1.88&#39;){ 
header("location:http://t.qq.com/wb631992791");//被禁止后跳转到微博
exit; 
} 
//限制ip段 
$ip_arr = explode(&#39;.&#39;, $userip); 
#限制的ip段，假设是192.168.*.* 
if (!(($ip_arr[0] == &#39;192&#39; && $ip_arr[1]==&#39;168&#39;) )){ 
header("location:http://t.qq.com/wb631992791");//被禁止后跳转到微博
exit; 
}else{ 
header("location:http://afish.cnblogs.com");//正常IP则直接访问小鱼阁首页 
exit; 
} 
?>