One, for the PHP page completely inaccessible situation
1. Verify that PHP is a problem or a server such as IIS
Judging method, a static file is placed in the directory and the browser is used to determine if the static file can be accessed. If you can access it, it's a PHP problem.
If this is a problem with IIS, there are two common cases in which a decision is telnet.
Linux Telnet is actually more useful because the default is to turn on Echo. Instead of windows, you need set localecho, otherwise you won't see the text you entered
1.1 Firewall Forbidden 80 port
After entering Telnet, enter the command, open domain 80
Example: Open www.baidu.com 80
If you can connect, a black screen will appear, waiting for the input
Indicates that a connection that cannot be opened to a host fails on port 80, which means that the port is unreachable. Possible reasons are: The DNS server does not have this domain name (with nslookup), the remote host does not open or prohibit connection (with Ping and other commands), and here, the firewall does not open 80 port.
1.2 Permissions on the target directory on the server are not set correctly
In this case, you will generally be prompted to log in to the dialog box, not to display the page
1.3 Other issues
Assuming that the host to be accessed is www.baidu.com, then check with the following command:
> Telnet www.baidu.com 80
Will come out a black screen, this time fast, because the server may not wait for you to enter, he is expecting a quick input. (You can play in Notepad first, and then paste it in), direct telnet may not localecho, may need to blind hit
Instruction example, do not enter the characters in parentheses:
get/http/1.1 (carriage return)
Host:www.baidu.com (carriage return)
Enter
Note that there are two carriage returns after the host row.
This is a request to impersonate the browser to the target host with Telnet.
Note that the content of the reply header has very rich information, such as 200, indicating that the request was successful. 500 indicates an internal server error, and so on, the specific information can be seen related documents.
1.4 A little background knowledge
The above steps involve the browser initiating the request process, which may be helpful under the introduction:
1, you enter the domain name in the browser's address bar, and press ENTER.
2, the browser requests the DNS server to convert the domain name to an IP address--note that this step is also not related to your Web server (IIS or Apache).
3. The browser requests a connection to your Web server-the equivalent of our Telnet 80 port. Of course, if you specify a port number, he will connect to the ports you specify. But the default port is 80, this is the RFC specified HTTP port, HTTPS port is 443, the process is more complex, there is the process of key exchange and encryption, so there is no way to do trouble shooting this way, it is recommended that at this stage to fix the HTTP first.
4, established a connection, the server waits for the browser to send the request header, the browser sends the request header. The request header ends with a blank line.
5. The request header format is as follows:
Method "Space" request path (does not include domain name, such as/a.html or/) "Space" protocol
HOST: The requested domain name
For example:
get/index.php http/1.1 (carriage return)
Host:www.baidu.com (carriage return)
Enter
The request header may have additional information, such as the submitted information, but for us, this is enough.
method, commonly used is get and post, the General Request Web page with get, submit information with post.
6. The server processes and returns data, including header and Web page body.
http/1.1 OK
This line begins with the protocol, as well as the error code (or success code), which is interpreted by the error code.
There may be a lot of information useful for a browser, but for us it is necessary to know the code and error code interpretation.
In the information body, there may be many other things, such as a detailed explanation of the information. When PHP error reports are turned on, they are also reported in the header.
2, confirm PHP extension load.
2.1ISAPI expansion
For ISAPI extensions, under the configuration of the home directory:
Find PHP:
If not, add it.
2.2 For the FastCGI method
Another way to load is fastcgi, this method needs to determine whether it is fastcgi engine problem or PHP problem, the method is to skip the fastcgi, directly loaded with CGI Php.exe.
Second, the PHP page section can access the situation
The simple way to judge whether this is the case is to create a new PHP file and enter the following:
Note that case and space must be correct. The normal situation is to output a Phpinfo page, as shown in:
This page is very useful.
1, Judge php file load correctness
Confirm that the loaded Configuration file is loaded with php.ini files that you want him to load. It is possible to modify the file error.
2, judge whether the extension of MySQL load
Most of the time this may be the case, that is, the page white screen, but obviously, the page is half loaded. For example, the tittle section has been shown, including sites such as Supersite, Discuz, and so on, which is likely to happen.
Judging method is very simple, the page search MySQL, if not the following content is not loaded
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