Routing wrote an article on how to quickly build a pptp-based VPN on vps , but it seems that many people still don’t know what a VPN is, so in this article, I will specifically come to 818 what this VPN is!

Speaking of VPN, we still have to start from the 1990s. At that time, there was no concept of VPN. If companies wanted to access the Internet, they had to buy a dedicated line (we won’t talk about the content of dedicated lines, as long as we know that this thing is called a dedicated line) line, and it is old and expensive). Later, the company opened a branch office. To communicate between the two companies, they had to use the Internet. However, it was not secure enough, so they had to pull a dedicated line to connect by themselves, and the maintenance cost was extremely expensive.

At this time, telecom operators saw business opportunities. They deployed a large number of dedicated lines on their backbone networks specifically for this company’s needs, and then leased them to companies. Compared with setting up a dedicated department to maintain a high-consumption ultra-long dedicated line, renting a dedicated line is really cheap, it saves the overhead of a department, and there is no maintenance cost. How wonderful!

At this time, in order to facilitate the use, a technology such as Frame Relay was also developed for use by companies. At this time, the branches can be connected by a private network, which is “PN” (private network), so that because it is physically connected by its own network cable, the risk of being attacked and intercepted information is greatly reduced, and Ah, and easy to manage (such as domain controllers, some internal resource sharing services, etc.).

However, there are always more situations that are not suitable for renting a dedicated line. For example, in an office, it is too extravagant to pull a dedicated line. At this time, I want to access the company’s internal network. How can this be good? Therefore, VPN technology came into being (virtual private network), and some people call it virtual local area network, that’s the reason.

Having talked about the approximate historical sources, how does a VPN work?

First of all, let’s talk about the structure of VPN. It requires a server and a client to operate. Through a specific protocol, an encrypted pipe is constructed in the Internet, and all data is transmitted to the server through this pipe. The network is sent out, so that the remote client (such as a computer) seems to have joined the local LAN. (The computer has indeed gotten to that place in terms of networking.)

Then understand the role of VPN, you can understand why VPN can be used to surf the Internet scientifically, we only need to find a server in a country that has been scientific or born scientific, and then log in to it. Then, from the perspective of the Internet, your computer “swoops” to that country, Jiangzi, and you can surf the Internet!

Another use of VPN is to play games. For example, some games have IP restrictions on servers in certain countries. Then, through VPN technology, you can obtain a corresponding IP, so that’s OK!

Of course, the application of VPN will definitely not be limited to “science”, we will talk about more about VPN later!