今天网上有人问我php中如何禁用ip访问，通过测试发现如下的代码不错，原理也比较简单

禁止单个IP
<?php
//加IP访问限制
if(getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) {
$userip = getenv('HTTP_CLIENT_IP');
} elseif(getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), 'unknown')) {
$userip = getenv('HTTP_X_FORWARDED_FOR');
} elseif(getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), 'unknown')) {
$userip = getenv('REMOTE_ADDR');
} elseif(isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], 'unknown')) {
$userip = $_SERVER['REMOTE_ADDR'];
}
$banned_ip = array (
"127.0.0.1",
"203.0.0.1",
"56.12.50.65",
"192.168.1.88"
);
if (in_array($userip,$banned_ip))
{
die ("Your IP is block to connect !");
}
echo "脚本之家测试";
?>
禁止IP段

 
<?php 
//加IP访问限制 
if(getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) { 
$userip = getenv('HTTP_CLIENT_IP'); 
} elseif(getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), 'unknown')) { 
$userip = getenv('HTTP_X_FORWARDED_FOR'); 
} elseif(getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), 'unknown')) { 
$userip = getenv('REMOTE_ADDR'); 
} elseif(isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], 'unknown')) { 
$userip = $_SERVER['REMOTE_ADDR']; 
} 
$ban_range_low=ip2long("217.0.0.0"); //ip段上 
$ban_range_up=ip2long("217.255.255.255");//ip段尾 
$ip=ip2long($userip]); 
if ($ip>$ban_range_low && $ip<$ban_range_up) 
{ 
print "Banned"; 
exit(); 
} 
?>