What do cookies mean on the Internet?

Internet browser's record mark Cookie

Cookies are also called cookies.

Cookies are a technology that allows the website server to store a small amount of data in the client hard disk or memory or read data from the client hard disk. Cookies are very small text files that are put on your hard disk by the Web server when you browse the website. It can record your user ID, password, the pages you visited, the time you stayed and other information. When you come to the website again, the website can read Cookies and get your relevant information, so you can take corresponding actions, such as displaying a welcome slogan on the page, or allowing you to log in directly without entering an ID or password.

In essence, it can be regarded as your ID card. But Cookies can't be executed as code, and they can't spread viruses, and they are your exclusive files and can only be read by the server that provides them. The saved pieces of information are stored in the form of "name-value pair", which is just a named piece of data. A website can only get the information it puts on your computer. It can't get information from other Cookies, nor can it get any other information from your computer.

Most of the contents in Cookies are encrypted, so ordinary users seem to be just meaningless alphanumeric combinations, and only the CGI processor of the server knows their true meaning.

Cookies are text files or data stored in the hard disk of the user's computer transmitted by the website we visit, so their storage location in the hard disk is closely related to the operating system and browser used. In the computer of Windows 9X system, the storage location of cookie file is C: Windows Cookies, and in the computer of Windows NT/2000/XP, the storage location of cookie file is C: \ documents and settings \ user name \ cookies.

Cookies files on the hard disk can be read through a Web browser, and the command format is: user name @ website address [number]. Txt, for example, the file name of a Cookies in the author's computer is ch @163 [1]. Txt, it should be noted that Cookies on the hard disk belong to text files, not programs.

Cookies settings

You can view all Cookies saved in your computer by selecting "Settings/View Files" in the General tab of IE's Tools/Internet Options. These files are usually named in the format of user@domain, where user is your local user name and domain is the domain name of the website you visit. If NetsCape browser is used, it is stored in "C:PROGRAMFILESNETS- CAPEUSERS". Unlike IE, Netscape uses Cookie files to record cookies of all websites.

We can set cookies appropriately: open the Privacy tab in Tools /Internet Options (note that this setting only exists in IE6.0/IE7.0, and other versions of IE can adjust the security level of cookies by clicking the Custom Level button in the Security tab of Tools /Internet Options). Usually, it can be adjusted to the "medium high" or "high" position. Most forum sites need to use Cookie information. If you never go to these places, you can set the security level to "block all Cookies". If you only want to block Cookie from individual websites, you can click the Edit button to add the websites to be blocked to the list. In the Advanced button option, you can set first-party cookies and third-party cookies. The first-party Cookie is the Cookie of the website you are browsing, and the third-party Cookie is the Cookie sent to you by the website you have not browsed. Generally, you should choose "Reject" for third-party Cookie. If you need to save Cookie, you can use ie's Import and Export function, open File/Import and Export and follow the prompts.

Writing and reading Cookies

Cookies collection is a data collection attached to the response object and the request object, which needs to be used before the response or request.

The syntax used to send Cookies to clients is usually:

When a nonexistent cookie set is set, it will be created on the client, and if the cookie already exists, it will be replaced. Because cookies are sent to the client as part of the header information of HTTP transmission, the code that sends cookies to the client is usually placed before the tag of the HTML file sent to the browser.

If users want to read cookies, they must use the cookie collection of the requested object in the following ways:

It should be noted that the browser can exchange data of Cookies with the server only before the server downloads any data to the browser. Once the browser starts to receive the data downloaded from the server, the data exchange of Cookies will stop. To avoid mistakes, respond. Buffer=True should be added in front of programs and browsers.

The application of Cookies

Almost all website designers will use Cookie when designing websites, because they all want to provide a more friendly and humanized browsing environment for users who browse websites, and at the same time, they can collect visitors' information more accurately.

Website visitor number management

Due to the use of proxy server and cache, the only way to help the website accurately count the number of visitors is to establish a unique ID for each visitor. Using Cookie, websites can accomplish the following tasks: measure how many people have visited it; Determine how many visitors are new users (that is, first-time visitors) and how many are old users; Determine how often users visit websites.

Usually, website designers use background databases to achieve the above goals. When a user visits a website for the first time, the website will create a new ID in the database and send it to the user through a Cookie. When the user visits again, the website will add 1 to the counter corresponding to the user ID to obtain the number of visits of the user or judge whether the user is a new user or an old user.

Customize the appearance of web pages according to users' preferences.

Some website designers provide users with the right to change the content, layout and color of web pages, allowing users to input their own information, and then modify some parameters of the website through this information to customize the appearance of web pages.

Realize "shopping basket" and other functions in e-commerce websites.

You can use Cookie to record the user's ID, so that when you put something new into the shopping basket, the website can record it and record your ID in the database of the website. When you "pay the bill", the website can search all your choices in the database through ID, so as to know what is in your shopping basket.

In general, the database of a website can store the content you choose, the pages you visit, the information you fill in the form and so on. Cookie containing your unique ID are stored in your computer.

Shortcomings of biscuits

Although Cookie is widely used, it can achieve some functions that other technologies can't. However, there are also some imperfections, which bring inconvenience to the application.

Many people use a computer.

Any computer used in public or many computers used in office or home will be used by more than two people at the same time. In this way, when you use it to shop in the online supermarket, the online supermarket or website will leave a Cookie on this machine, and someone may try to use your account to shop in the future, which brings the possibility of insecurity. Of course, on some computers that use multi-user operating systems (such as Windows NT or UNIX), this will not be a problem. Because under the multi-user operating system, Cookie of different accounts are placed in different places.

When deleting Cookies

If your browser doesn't work properly, you can delete all temporary Internet files on your computer. However, once you do this, you will lose all the cookies. When you visit the website again, the website will think you are a new user and assign you a new user ID and a new Cookie. In this way, the proportion of new and old users in the website statistics will be biased, and it is difficult for you to restore the parameter selection saved in the past.

When a person uses more than one computer

Some people often use more than one computer in one day. For example, there is a computer in the office, a computer at home and a laptop for mobile office. Unless the website uses special technology to solve this problem, you will have three different Cookies files on these three machines, and any website you visit on these three machines will treat you as three different users.

Prevent cookies from leaking

Want to know whether the website you visited has Cookies written in your hard disk or memory? You only need to follow the following steps to understand and control the Cookies information of the website you are visiting.

Step 1 Click Tools Internet Options in the IE window to open the Internet Options Settings window;

Step 2 Click the "Security" tab in the "Internet Options" setting window, and then click the "Custom Level" button to enter the "Security Settings" window;

Step 3 Find the "Cookies" setting item in the "Security Settings" window. There are two sub-options under the "cookie" setting, in which "Allow cookies to be stored on your computer" refers to the cookie file stored on the hard disk of the user's computer; "Allow the use of each conversation cookie (no storage)" refers to the cookie information stored in the memory of the user's computer. Cookie files stored in hard disk are permanent, while cookie information stored in memory is temporary. If you want IE to send a prompt when all Cookies from the website are about to be received, you can select the "Prompt" item in the above two sub-options. Of course, you can also select "Enable" to allow IE to accept all Cookies information (this is also the default option for IE); If "Prohibit" is selected, the website is not allowed to store cookies on your computer, and the website cannot read cookies already on your computer.

IE6.0 provides more reliable personal privacy and security protection measures, allowing users to control how much information the browser sends. A privacy tab has been added to the Internet Options window (Figure 1), so that users can directly set the privacy level when browsing, and control the Cookies used by other websites on the computer as needed. If the website we are browsing uses Cookie, a yellow exclamation mark will appear in the browser status bar. Double-click to open the privacy report dialog box, where users can view specific privacy policies, or you can directly click the "Settings" button to adjust the security privacy level in the above "Privacy" tab.

In the "General" tab, the "Delete cookie" button (Figure 2) is added, which is convenient for users to directly clear the cookies of this machine. In addition, some options to further improve security (such as clearing temporary Internet files when closing the browser) have been added in the Advanced tab of Tool Options. In fact, how to better protect personal privacy and security is the key technology in Microsoft's next generation products. " NET "strategic software. Now IE6.0 has tried to take the first step.

In addition, because Cookies are not all stored in the computer in the form of files, some information is stored in memory. For example, when you browse a website, the web server will automatically generate cookies in memory, and when you close IE browser, it will automatically delete cookies. Then the above two methods don't work, and we need to use Registry Editor to modify the system settings. It should be noted that please make a backup before modifying the registry, so that you can recover smoothly after problems occur.

Run Regedit and find the following key values: HKEY _ local _ machine \ software \ Microsoft \ Windows \ current version \ Internet \ Set the Scachespecial path cookie, which is the key value of the cookie in memory. Delete the key value. At this time, no matter what form cookies exist, we don't have to be afraid anymore. (Note: The new version of Windows may no longer be located in this registry directory)

Finally, it is necessary to explain that putting an end to Cookies can enhance the information security of computers, but it also has some shortcomings. For example, on some web pages that need Cookies support, there will be some inexplicable errors. A typical example is that you can't use the free email address of some websites in the future.

Cookie cheating

By analyzing the format of Cookie, we know that the last two items are its URL path and domain name, and the server relies on these two parameters to identify cookies. Under normal circumstances, when we want to browse a website, the URL we enter is its domain name, which needs to be converted into an IP address through the domain name management system DNS before we can connect. If we can make some settings on DNS and map the IP address of the target domain name to other websites, we can illegally access the Cookie of the target website.

Cookie cheating is actually very simple. For example, in the installation directory under Win9X, there is a file named hosts.sam. When you open it as text, you will see the following format:

127.0.0. 1 local host

After setting, the localization of domain name resolution can be realized, just add IP and domain name to the file according to the above format and save it as hosts. Hosts file can actually be regarded as a local DNS system, which can be responsible for resolving domain names into IP addresses. Its priority is higher than DNS server, and its concrete implementation is a part of TCP/IP protocol.