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This article will explain in detail how to use ASP and SQL Server to build a web firewall. The editor thinks it is very practical, so I share it with you as a reference. I hope you can get something after reading this article.

ASP is the middle layer of client / server structure on Web. Although it is written in script language (JavaScript,VBScript, etc.), the program code runs on the server, and only the dynamic HTML file output by ASP can be seen on the client side, ASP still has some loopholes, and the source code of ASP program can be seen by certain means. At this time, through the combination of ASP and SQL Server, we can design a simple, efficient and reliable application.

The main purpose of setting up a firewall for a web page is to provide different services to different visitors according to the content of the web page. Using JavaScript or VBScript, we can easily do this. However, the source code of the web page can be seen in the customer browser, and visitors can view the user authentication method used, which is only a superficial firewall.

The following is a brief introduction to its establishment process.

First, establish Login

Set up the visitor's Login and Password on SQL Server.

Second, create the database DSN on the network server

Use the ODBC data Source Manager in the Control Panel to create the ODBC data resource name of a database, DSN, so that you can later connect to a specific database by using the database DSN.

The ODBC data Source Manager provides three kinds of DSN, namely, user DSN, system DSN, and file DSN. Where user DSN saves the corresponding configuration information in the registry of Windows, but only allows login users who create the DSN to use it. The system DSN also saves the relevant configuration information in the system registry, but unlike the user DSN, the system DSN allows all users who log in to the server to use.

Unlike the above two kinds of database DSN, the file DSN saves the specific configuration information in a specific file on the hard disk. The file DSN is available to all users who log in to the server and provides access to the database DSN even if no user is logged in. In addition, because the file DSN is saved in the hard disk file, it can be easily copied to other machines. In this way, users can directly use the DSN created on other machines without making any changes to the system registry.

In the above three kinds of database DSN, users are advised to choose system DSN or file DSN. If users prefer the portability of file DSN, they can obtain higher security by setting file access rights under the NT system.

To create a new DSN, the user first selects add, and then in the pop-up window, select the type of database to which the user will establish a connection and select the "SQL Server" item in the list. If the user is creating a file DSN, click the next button and enter the file name and save path of the file DSN to be created in the dialog box that follows. If the user is building a system DSN, click the finish button.

After selecting the database, the user needs to set up the database DSN. The user needs to select the specific server that provides the database service, set the login user name and password, and the database to which the user will connect.

III. Program design

The next thing to implement is the function of a simple page firewall. This page restricts access only to users of the intranet (assuming that the IP address of the intranet is from 10.61.96? To 10.65.97? If the access is made by a user outside the unit, the access user name and password are required. Here you use the ServerVariables property of the request object, which is used to get the value of the environment variable.

The program source code (firewall.asp) is as follows:

< html > < head > < meta http-equiv= "Content-Type" content= "text/html Charset=gb_2312-80 "> < meta name=" GENERATOR "content=" Microsoft FrontPage Express 2.0 "> < title > firewall.asp < / title > < / head > < body background=" # 800080 "> <% 'use Request.ServerVariables (" REMOTE_ADDR ") to get the IP address and save it in the variable remoteip remoteip=Request.ServerVariables (" REMOTE_ADDR ") stip=cstr (remoteip) gets the value of the third segment of the IP address and stores it in stip for item1 to 2 stip=right (stip,len (stip)-instr (1) Stip, ".") Next stip=left (stip,instr (1 recording stip, ".")-1)'IP address validity test and password verification, including two aspects: if the IP address matches, it is verified. If the IP address does not match, verify that the user name and password entered are correct if (left (remoteip,5) < > "10.61" or stip < "96" or stip > "97") then username=request.form ("T1") password=request.form ("T2") Set fs = CreateObject ("Scripting.FileSystemObject") Set thisfile = fs.OpenTextFile ("dsn.txt") db loc=thisfile.readline thisfile.close cnstr=db_loc&& "uid=" & & username&& " "& &" pid= "& & password on error resume next set cn=server.createobject (" adodb.connection ") cn.open cnstr if err=3709 then% > < p > < font color=" # FF0000 "> Sorry, user: <% = username% > does not have access Or the password is incorrect! < BR > < / font > < / p > < form method= "POST" > < p align= "center" > username: < input type= "text" name= "T1" size= "20" > password: < input type= "password" name= "T2" size= "20" > < input type= "submit" value= "submit" name= "B1" > < input type= "reset" value= "all rewrite" name= "B2" > < / p > < / form > < end if cn.close set cn=nothing% > < else > Congratulations You have passed the verification and can use the resources of this site directly! <% end if% > < / body > < / html >

Modify the information above, such as IP address, and the program will be ready to run.

Of course, the above is just a firewall function in a page. If a site has more than one page, you can set a session variable to flag the user, which can be judged in the following pages.

This is the end of the article on "how to use ASP and SQL Server to build a web firewall". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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