How to prohibit reading files in php

In recent years, with the rapid development of the Internet and the popularity of websites, PHP has gradually become an indispensable language in Web development. However, when developing a mature website, you often encounter some security issues that require special attention. Among them, prohibiting PHP from reading files is a very important security issue. This article will explore the specific methods and significance of prohibiting reading files in PHP.

1. Why do you need to prohibit PHP from reading files?

First of all, we need to make it clear that PHP is a powerful server-side language that can easily read any file on the server. However, this feature, if abused, can pose a significant risk to the security of the server. Therefore, PHP needs to be prohibited from reading files to ensure the security of the server.

If PHP can read files on the server at will, anyone can execute some dangerous commands by calling the exec function or system function, such as deleting important files, modifying sensitive data, etc. In this way, the data security of the server will be greatly threatened. In order to protect the security of various files and data on the server, we need to prohibit PHP from reading files.

2. How to prevent PHP from reading files?

Prohibiting PHP from reading files is a relatively tedious task and requires us to do a lot of work to achieve the desired effect. Below we will introduce in detail how to prohibit PHP from reading files from the following aspects:

1. Prohibit PHP from calling the exec function and system function

The exec function and the system function are two commonly used functions in PHP , they can all execute some external programs or commands. In some cases, this functionality is essential. However, in a web server, if anyone can access these functions, then this will cause a big security risk, so these two functions need to be restricted.

There is a disable_functions option in PHP's php.ini configuration file, where we can limit the functions called. If you need to disable the exec and system functions, you can add the following content to disable_functions:

disable_functions = exec,system

In this way, PHP will prohibit calling these two functions.

2. Prohibit PHP from accessing specific directories

Some important files and data are stored on the server, and these files and data are very sensitive. If PHP can freely access these files and directories, it will pose a great threat to the security of the server.

So, we need to set up a web server such as Apache or Nginx to prohibit PHP from accessing specific directories. You can add the following content to the configuration file of the web server:

[Sat Jan 13 18:55:07 2018] [error] [client xxx.xxx.xxx.xxx] File does not exist: /var/ www/html/phpmyadmin/php
[Sat Jan 13 19:15:02 2018] [error] [client xxx.xxx.xxx.xxx] PHP Warning: file_get_contents(/var/www/html/wp
[Sat Jan 13 19:17:27 2018] [error] [client xxx.xxx.xxx.xxx] File does not exist: /var/www/html/test

View Apache and Nginx access logs, We will find that there are many error records similar to the above. Among them, /var/www/html/ is the Web root directory. We can create a new directory, such as /var/www/html/phpdata/, to store our sensitive files and Data. Then, you can prohibit PHP from accessing this directory by configuring a web server such as Apache or Nginx.

3. Prohibit PHP from accessing files

The method to prohibit PHP from accessing files is also very simple, that is Control of file permissions. By setting the read and write permissions of the file, we can prevent PHP from reading the specified file.

We can use the chmod command to set the file permissions to 600 or 700. This way , the owner of the file (usually the administrator) can read or write, but other users cannot read or write. You can use the following command to set permissions:

$ chmod 600 filename
$ chmod 700 dirname

In short, in order to protect the security of the server, we need to prohibit PHP from reading files. We can achieve the same effect by restricting PHP functions, Web server access, file permissions and other methods.

3. Summary

Prohibiting PHP from reading files is an important security measure that can effectively protect the security of the server. We need to always pay attention to security issues when writing Web applications and take a A series of measures to avoid being attacked by hackers. I hope this article can help you and better protect the security of your server.

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