When you access a webpage, this page is sometimes opened. Sometimes it is normal, and sometimes it is caused by unreasonable Apache configuration.
The normal situation may be that the website administrator does not want to access your IP address segment, so in Apache, access to your IP address segment is limited according to the IP address. it is usually set through Order, deny, and allow, for example:
Order allow, deny <br/> allow from all <br/> deny from x. x
In addition, when we set up a virtual server during development, we will also see the tip of the above: this can usually be caused by directory permissions. if the user running Apache has no permission to read the directory.
In addition, if there is no index. php file in a directory and the Options settings do not allow the index, for example:
Options-Indexes
When you access a directory, the preceding error message is displayed.