Detailed explanation of how to prevent hotlinking in PHP
This article mainly introduces the method of anti-hotlinking in PHP, and analyzes the related technologies and specific implementation techniques involved in anti-hotlinking in PHP in the form of examples. Friends who need it can refer to it. I hope it can help everyone.
$_SERVER['HTTP_REFERER'] acquisition situation
Note $_SERVER['HTTP_REFERER'] may not always be obtained. It can only be obtained under the following circumstances:
1. The circumstances under which HTTP_REFERER can be obtained are as follows:
1. Use
2 directly. Form submitted with Submit or (POST or GET)
3． Form submitted using Jscript (POST or GET)
2. The following situations cannot be obtained:
1. Link from Favorites
2. Click "Home" or the customized address
3. Use Jscript's location.href or location.replace()
4． Directly enter the address
5 in the browser. <%Response.Redirect%>
6． <%Response.AddHeader%> or Go to
7． Use XML to load the address
strrpos Function explanation:
strrpos - Calculate the position of the last occurrence of the specified string in the target string
Description
int strrpos (string $haystack, string $needle [, int $offset = 0])<br>Returns the last occurrence of needle in string $haystack Numeric location.
| $haystack | Find in this string. |
| $needle | If needle is not a string, it will be converted to an integer and treated as a sequential value of characters. |
Return value
Returns the position where needle exists. If not found, returns FALSE.
Hot link judgment code: asd.php
<?php
//防盗链技术
//先判断是否获取到 $_SERVER['HTTP_REFERER'] 变量
if(isset($_SERVER['HTTP_REFERER'])){
//判断$_SERVER['HTTP_REFERER']是不是以http://localhost/开始的
if(strpos($_SERVER['HTTP_REFERER'],"http://localhost")==0){
echo '<img src="a.png"/>';
}
else{
header("Location:warning.php");//跳转页面到warning.php
//echo $_SERVER["HTTP_REFERER"];
}
}
else {
header("Location:warning.php");
}
?>warning.php
<html> <b>倒链</b> </html>
Anti-theft Chain verification code
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> </head> <body> <a href="http://localhost/wml/asd.php" rel="external nofollow" >验证防盗链</a> </body> </html>
The above is the understanding principle
Generally prevent hot links by configuring the server, such as nginx configuration access
( gif|jpg|jpeg|png|bmp|swf) White list of other files
Detailed configuration can be searched on Baidu
Related recommendations:
Detailed explanation of anti-hotlinking method in PHP
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