What is a proxy server (Proxy)

First, what is a proxy server? A proxy server (Proxy) is a server between a browser and a web server. When you browse the Internet through a proxy server, the browser does not directly retrieve the web page from the web server but sends a request to the proxy server. The server retrieves the information needed by the browser and sends it to your browser. Moreover, most proxy servers have a buffering function that constantly stores newly fetched data on its native storage. If the data requested by the browser already exists on its local storage and is up to date, then it By not retrieving data from the web server and directly transferring the data on the memory to the user's browser, the browsing speed and efficiency can be significantly improved. Proxy Server (Proxy Server) is an important security function provided by the Internet link-level gateway. Its work is mainly in the Open System Interconnection (OSI) type of dialogue layer. The main functions are: 1. Connecting the Internet and the Intranet Firewall: Because all users on the intranet access the Internet through the proxy server, they only map to an IP address. Therefore, the outside world cannot directly access the intranet. At the same time, IP address filtering can be set to limit the access rights of the internal network to the outside. To be on the safe side, firewalls are built in many places, and using a proxy can break through the firewall's limitations. Similarly, proxy can also be used to restrict the blocking of IP addresses and prohibit users from accessing certain web pages. For example, most domestic promos are forbidden to access VOA (voa com not voa org, the latter is an American volunteer!), once the attempt is made, there will be a forbidden word as a warning. For example, if you want a playboy from the newsstand, you may not only get it, but you will also be taught a lesson. It’s really @#$%^&&*).... This restriction is artificial, and the different store's blockade of the address is different. So if you can't do it, you can try another one. (For example, the blockade of geocities in the previous period) 2. Saving IP overhead: As mentioned above, all users occupy only one IP address externally, so it is not necessary to rent too many IP addresses, which reduces the maintenance cost of the network. Of course, there are also disadvantages. For example, many cyber hackers use this method to hide their real IP addresses and escape surveillance. 3, improve access speed: usually the proxy server is set a large hard disk buffer (may be up to a few GB or more), when there is outside information, it is also saved to the buffer, when other users When the same information is accessed again, the information is directly taken out from the buffer and transmitted to the user to improve the access speed. Second, who set up a proxy server? The main ergonomic server is the ISP and some companies, enterprises and units with intranets. The ISP sets up the proxy server in order to reduce the data traffic and improve the browsing speed of the user. It allows its users to access the WWW network through the proxy server, so that for a considerable part of the data that is frequently repeatedly accessed, the proxy server can directly transmit to the proxy server. Users do not need to download repeatedly; there are intranet units, they may rent a dedicated line or dial-up Internet, but only this machine can access the Internet, then install a proxy server software on it, so other machines on the intranet It is also possible to go online through this proxy server. 3. Who uses a proxy server? The most direct users are of course the poor people in the education network and the technology network whose IP is restricted and cannot access foreign resources. They can search for foreign resources through the proxy server by searching for the proxy servers on ChinaNet that do not have permission restrictions. . The second largest user group of proxy servers is 169 users. They can only switch inside the 169 network. They must access the Internet through proxy servers that span 169 and ChinaNet. (This is what we need most, 嘻嘻 … …) In addition, some 163 users or users of the Education Technology Network who can directly access foreign countries also search for and use the proxy server for some need (such as hidden identity). Fourth, what is a free proxy server? When searching for a proxy server address using a software such as a proxy hunter, a similar message such as "To password" and "Free" will appear in the verification status bar. If you set the proxy address of "Password" to a proxy server, when you visit the web page, a dialog box will pop up asking for "Username" and "Username" and "Password". This means that this proxy server is not free to use, you need to register with him to get the username and password to use. Of course, if you are a password cracker (hacker!), then go ahead! If you are lucky, the following "username/password" may be used: <;user/passwd”,“demo/demo”,“guest/guest”,“temp/temp”,“share /share” (sometimes add a number after the password, like guest2, etc.). If you set the address of “Free” as a proxy server, you will find that you are not required to enter a password when accessing the webpage. This is “free proxy server”. Why is there a FREE? 1. It is a system vulnerability. Once it is discovered by the network management, it will be blocked. 2. It is a kind network administrator and other people who have the opportunity to approach the host. The machine is set as a proxy server. 3. It is a real good-hearted person, that is, to be yourself. The machine acts as a free agent for the benefit of the majority of colleagues. This is really worthy of admiration! However, the closure was also the fastest. 4, ISPs in order to improve the impact, free of charge for a period of time, generally very short. V. About the speed of the proxy server Using the proxy hunter 2.8 and below to search for the authentication proxy address, there will be something like "Free 3 seconds", "Free 15 seconds", and 3 seconds and 15 seconds here means The response time of the proxy server, the shorter the time, the faster the proxy server is, and the better it is used! In the agent hunter version 3.0 or lower, the verification time column is changed to "time characteristic", and the display is similar to this: " 0.9