Long Dan said: "I want to use this language to make a small game" "Game? Brother Long wants to make a game by himself? Unlikely, right? Ge Jiawei said in surprise. Actually, it's no wonder that Ge Jiawei was surprised. Because, as a general rule, it takes at least a team of dozens of people to make a game, and it can only be completed by working together. Even if it is dozens of people, it will take at least half a year to complete a game.

"I'm the editor-in-chief, you assist me, I believe there is no problem. What dozens of people can do, the two of us can still complete, this is the benefit of this programming language I invented, I will give this language program a name, just call it 'Dan language', because I Long Dan invented it, it will be popular in China in the future" Long Dan said to Ge Jiawei with confidence. When Xiaoge heard this, he was also excited, and said: "Since Brother Long is confident, then what am I afraid of, our brother did it."

The two of them worked for three months without sleeping or eating, and finally the compilation was completed. This game developed by Long Dan is not actually called a game, it should be said to be an intelligent program. It appears in the face of a pet, after the customer downloads the client, a pet appears on the computer desktop, and the form of the pet is varied, it can be a puppy or a kitten, or a beautiful woman and a handsome guy, depending on the customer's hobbies.

After the customer downloads, whether it is a pet or a character, they are all low-level and young, and only with continuous training and feeding can they gradually grow up. Whatever you teach it, it will be, and it is a program that evolves itself.

The design of the dragon pill is like this: the lowest level of the beginner stage is free to download, and you can find and cultivate, which takes a long time. If you want to shorten the time, you have to download the advanced stage of the program, but it costs money.

After the program was completed, Long Dan and Ge Jiawei did repeated tests, and the test results were very satisfactory. Long Dan asked Ge Jiawei to take out 2 million as a promotion fee and put it on major download websites for players to download for free. A month later, the number of downloads exceeded 1 million, and the number of VIP members who purchased the premium stage reached 100,000. Long Dan divided the VIP into several stages, the price ranged from 100 yuan to 500 yuan, and in the third month, the number of online users reached 1 million, the number of VIPs reached more than 200,000, and the income of Long Dan in three months reached more than 60 million.

Seeing the rising numbers on the books, Ge Jiawei simply smiled crookedly, sighing that Long Dan was a god, and he earned more than 60 million yuan with a small program with a three-month system. Long Dan said with a smile: "This is the beginning, what is it now, there will be better things for you to see in the future", "There are better ones?" How much does that cost? Ge Jiawei opened his mouth wide in surprise, and he was able to stuff several steamed buns.

Due to the rapid increase in the business volume of Longdan's network company, it required a large amount of server capacity to serve customers. Long Dan asked Ge Jiawei to contact the computer room of the communication company, rented an entire computer room, and used matrix servers to adapt to the bandwidth needs of gamers, but because the technology of the communication company is not so advanced, the firewall technology is still so bad, and the computer room of the communication company is often attacked by hackers. This has cost the players of Longdan's intelligent game.

Long Dan reached an agreement with the communication company, and Long Dan used the "Dan language" to design a powerful firewall program, and maintain and upgrade, and the price paid by the communication company is to reduce the cost of bandwidth for the Long Dan network company, since then, complement each other, since then, the communication company's computer room has never been broken by hackers, and Long Dan has also greatly reduced expenses. The telecommunications company only charged a small fee to Longdan Network Company for a symbolic fee. This incident gave Long Dan a great inspiration, and Long Dan thought about it for a long time and prepared to develop a firewall program that is unique in the world.

A firewall is a combination of software and hardware devices that is constructed on the interface between the internal network and the external network, and between the private network and the public network. It is a combination of computer hardware and software, so that a security gateway (SecurityGateway) is established between the Internet and the intranet, so as to protect the intranet from the intrusion of illegal users, the firewall is mainly composed of four parts: service access rules, authentication tools, packet filtering and application gateways, and the firewall is a software or hardware located between the computer and the network it is connected to. All network traffic and packets flowing in and out of the computer pass through this firewall. In the network, the so-called "firewall" refers to a method of separating the intranet from the public access network (such as the Internet), which is actually an isolation technology. A firewall is a kind of access control that is implemented when two networks communicate, which allows people and numbers you "agree" to enter your network, and at the same time keeps out people and numbers you "disagree" with, preventing hackers in the network from visiting your network to the greatest extent. In other words, if you don't have a firewall, people inside the company can't access the Internet, and people on the Internet can't communicate with people inside the company.

Firewalls are divided into network-layer firewalls and application-layer firewalls: network-layer firewalls can be regarded as IP packet filters that operate on the underlying TCP/IP protocol stack. We can enumerate packets that only allow packets that meet certain rules to pass through the firewall, and prohibit the rest from traversing the firewall (except for viruses, which do not prevent viruses from entering). These rules can usually be defined or modified by the administrator, although some firewall devices may only be able to apply built-in rules. We can also take a more permissive approach to firewall rules and let packets go if they don't meet any of the "negative rules". Most of today's operating systems and network devices have built-in firewall functions. Newer firewalls can use a variety of packet attributes to filter, such as source IP address, source port number, destination IP address or port number, and service type (e.g., WWW or FTP). It can also be filtered by attributes such as protocol, TTL value, domain name or network segment of the source. The application layer firewall operates on the "application layer" of the TCP/IP stack, which is the number of streams generated when you use the browser or when you use FTP. An application-layer firewall can block all packets in and out of an application and block other packets. Theoretically, this type of firewall can completely block the flow of data from the outside into the protected machine. Firewalls can prevent the rapid spread of computer bugs or Trojan horses by monitoring all packets and finding irregularities. However, in terms of implementation, this approach is cumbersome and cumbersome, so most firewalls don't consider designing it this way.

Firewalls often appear in two types of icons on the web. One kind of icon is very figurative, really like a wall. The other type of icon is visualized from the filtering mechanism of the firewall, with a diode icon in the icon. As we know about the diode, it has unidirectional conductivity, which vividly illustrates that the firewall has unidirectional conductivity. This may seem like a contradiction to the current firewall filtering mechanism, but it fully reflects the original design idea of the firewall, and at the same time, it also reflects the filtering mechanism of the current firewall on a considerable extent. Because the original design idea of fire protection was to always trust the internal network and never trust the external network, the original firewall only filtered the incoming traffic from the outside, and did not restrict the communication sent by the internal network users. Of course, the current firewall has changed the filtering mechanism, not only to filter the communication connections sent by the external network, but also to filter some connection requests and packets sent by internal network users, but the firewall still only needs to filter the communication that conforms to the security policy, which can also be said to have "one-way traffic". The original meaning of firewall refers to the ancient construction and use of wooden houses, in order to prevent the occurrence and spread of fire, people piled up solid stones around the house as a barrier, this kind of protective structure is called "firewall". In fact, it is the "door" that works together with the firewall. If there is no door, how can the people in the rooms communicate, and how can the people in these rooms get in? How do these people flee the scene when a fire breaks out? This door is equivalent to the "security policy" of the firewall we are talking about here, so the firewall we are talking about here is not actually a solid wall, but a wall with some small holes. These orifices are reserved for those that are allowed to be communicated, and a filtering mechanism is installed in these orifices, which is referred to as "one-way conductivity" described above. What we usually call a network firewall is borrowed from the metaphor of the firewall that was actually used for fire protection in ancient times, and it refers to a defense system that is isolated between the local network and the external network. Fire protection can isolate the internal LAN from the Internet or other external networks, restrict network access and protect the internal network.

Long Dan has designed the firewall software of "Dan language", which is a firewall in the true sense. He jumped out of the design ideas of all current firewalls and stepped into a new era of the meaning of network firewalls.