Problem description:

What is a proxy server?

Analysis:

What is an agent?

What is an agent? This is an agent. Ordinary Internet access is a typical client-server structure: users use client programs on computers, such as browsers, to make requests, and remote WWW server programs respond to requests and provide corresponding data. The proxy is located between the client and the server. For the server, the proxy is the client, the proxy request and the server response. For the client, the proxy is the server, which accepts the client's request and transmits the data uploaded by the server to the client. Its role is very similar to that of an agent service provider in real life. So the Chinese name of Proxy Server is proxy server.

Working mechanism of proxy server

The working mechanism of proxy server is very similar to the proxy often mentioned in our life. Suppose your own machine is machine A, the data you want to obtain is provided by server B, and the proxy server is C, then the specific connection process is like this.

First, machine A needs data from machine B. A directly establishes a connection with machine C. After receiving the data request from machine A, machine C establishes a connection with machine B, downloads the data requested by machine A locally, and then sends the data to machine A to complete the agent task.

The proxy server has four functions:

First, improve the access speed. Because the data requested by the customer is stored in the hard disk of the proxy server, the next time this customer or other customers request the data of the same destination site, it will be directly read from the hard disk of the proxy server, and the hard disk of the proxy server plays a caching role. When many customers visit popular websites, the advantages of proxy server are more obvious.

Second, the proxy can act as a firewall. Because all users who use the proxy server must access the remote site through the proxy server, you can set corresponding restrictions on the proxy server to filter or filter out some information. This is the most commonly used method for LAN network management to limit the access range of LAN users, and it is also the reason why LAN users can't browse some websites. If dial-up users use a proxy server, they must also abide by the access restrictions of the proxy server unless you don't use this proxy server.

Third, visit some websites that cannot be accessed directly through proxy servers. There are many open proxy servers on the Internet. When the access rights of customers are restricted, but the access rights of these proxy servers are not restricted, it is possible for customers to access the target website through proxy servers. Most domestic colleges and universities use the education network, and they can't go abroad, but they can surf the Internet through proxy servers, which is also the reason why proxy servers are hot in colleges and universities.

Fourth, security has been improved. No matter in the chat room or browsing the website, the destination website can only know that you are from the proxy server, but your real IP cannot be detected, which improves the safety of users.

Settings of proxy server:

To set up a proxy server, you must first know the address and port number of the proxy server, and then fill in the corresponding address and port number in the proxy server setting column of IE or NC. Suppose we have a Proxy server with an address of proxy and a port number of 3000. The configuration method in IE is to use the Inter option/connection/proxy server in the view menu, and then check the check box in front of the Inter option through proxy server to fill in the proxy server address in the address bar. For example, if the proxy server address is proxy in this example, fill in the port number 3000 in the port box, click the Apply button at the bottom, and then click OK to complete the setting. The next time you use IE, users will find that no matter what website you browse, IE always connects to the proxy server first. If you use NC, the setting is a little more complicated. Use the Preferences menu item under the Edit menu, and then select Agent under Advanced. At this point, select the second person in the proxy option on the right to configure the proxy, and then click the View … button on the right to open the proxy server configuration interface. Fill in the corresponding contents in the column of proxy server address and port number, click OK to return to the parameter setting window, and then click OK to complete the proxy server setting. When customers browse the web again, they will automatically send an application to the proxy server you set up and get the data. When browsing websites, both IE and NC can clearly see the process of connecting to the proxy server before connecting to the target website in the browser status bar.

However, don't confuse proxy servers with routers. The proxy server is a service software built on the application layer, while the router is a network device or computer, which works in the IP layer and forwards the data after reaching the IP layer. Generally speaking, the proxy server works on a computer equipped with a modem and a network card. Different proxy server software provides different services, generally providing common services such as www and FTP. In the intranet, each guest must have an independent IP address, and use the port number of the proxy server to point to the IP address and service of the proxy server IP configured in the "Control Panel-Internal Items" of the guest. After the proxy server is started, it will use Winsock.dll to open the designated service port and wait for the guest's request. Your proxy server can work when the modem of the proxy server dials the Internet. When you send a connection request in IE, your client will send the packet directly to the proxy server. When the server captures this IP packet, it must first analyze what it is. If it is an HTTP request, the proxy server will send an HTTP request to your ISP. After receiving the response, the proxy server will forward the IP packet to the intranet, and your passenger plane will get the IP packet. In addition, your proxy server can also serve as a good firewall. Please refer to the readme file of your proxy server for specific operations.

When you visit the Web server of the Internet, do you know how many personal information will be leaked to others? In the process of accessing the Internet, the web browser will at least send more than 20 personal messages to the web server without your knowledge. If these personal information are transmitted to well-known websites or web servers of large enterprises, there will be no big problem. If you send it to a Web server that doesn't even know who opened the website, it will be deeply disturbing. In jargon, the information that a web browser sends to a web server is an "environment variable". Its main contents include: (1) IP address (REMOTE_A DDR) and host name (remote _ host) assigned to the computer; (2)2) The serial number of the port used by the web browser (remote _ port); (3) The product name of the web browser (http _ user _ agent); (4) The webpage address of the recently visited website (HTTP_REFERER), etc.

Although the above items do not contain personal information such as e-mail address and name, the IP address and host name in (1) are really difficult to reassure in terms of security, but what methods can be taken to hide your IP address?

Solving this problem is actually very simple. You only need to access the Web server through the proxy server. The role of the proxy server is that it can accept all kinds of terminal access requests to the Web server. In the enterprise network, the proxy server is set in the part where the company's local area network and the Internet are interconnected. When dialing up the Internet, you can use the proxy server provided by the Internet provider.