My exploration of Internet sharing

Since the beginning of college, I have always been exploring the question of how to suddenly access the Internet through various client restrictions to achieve Internet sharing with roommates. Internet sharing is not easy for ISPs, so it involves many restrictions and anti-restrictions. In the era of using a vro to access the Internet at the beginning, you can go to the "method" of "change to the same IP address, the same MAC address", to the proxy server, to the Sygate, and then to the NAT address, now, frequently used enable WLAN and use virtual machines to simulate Nat. After many generations of exploration, We have summarized a basic and feasible Internet sharing method. This article will address the limitations of the Internet client, explore solutions one by one, and then introduce my current Internet sharing solution.
When I was impressed with the Internet, I felt that the Internet should be free. To get online, all I had to do was find a network cable and insert it into my computer. Later, I found that some networks are plugged in with a network cable, so they cannot access the Internet! Then the problem arises.
Must the TCP/IP attribute input box be filled with appropriate numbers? I noticed that in the active status of the network connection, only sending, not receiving, and a yellow exclamation point is displayed. This is most likely to happen in the school's data center. The solution is very simple, that is, refer to the IP Address Configuration of the computer that can access the Internet next to it, and then write it to your computer. In essence, it can access the Internet, but it only needs to be changed. I have seen a table for maintaining IP addresses in many machine rooms, offices, and Internet cafes. So far, I still cannot understand it. It is no longer easy to plug in a network cable to access the Internet, why not implement it? I once asked a question (http://www.zhihu.com/question/20971480) on zhihu online, but the answer was not informative. I think the reason why users cannot connect to the Internet without plugging in the network cable is that the network management is unwilling to implement it.
However, these are generally not in the dormitory. the most primitive authentication method in the dormitory is to use a modem for pppoe authentication dial-up Internet access. However, all routers now have the automatic dial-up access function. Therefore, you can use the vro configuration method to flash the internet. The enhanced version of dial-up Internet authentication is to add a "dial-up" software, such as "star speed 』. However, this method is still used for dial-up Internet access, so it still has the account and password for dial-up Internet access. Generally, you only need Baidu's "ADSL Internet account password viewing tool" to learn the real login information, then I went back to the dial-up Internet, so I was still killed in seconds.
Smart ISP knows that the router must stop working to avoid internet sharing. Therefore, the concept of an Internet client is proposed. The client has many functions. In addition to allowing you to access the Internet, it also includes using a different Internet Protocol than ADSL to avoid normal router operation. It also has the client monitoring function, this includes monitoring network interface changes of the client, MAC addresses, and related process information. However, if you leave the client for monitoring, you only need to change the Protocol to avoid the router. Now, using common proxy servers can be easily solved. Here we have to mention two representative software: CCProxy and Sygate. CCProxy is a proxy server software, which has the advantages of easy operation and double-click. The disadvantage is that the software must provide Proxy functions before it can be used. Another drawback is that it has become a target for client monitoring. Sygate is also a software that can easily achieve Internet sharing. It provides a complete TCP/IP function. Roommates can access the Internet without any configuration, however, Sygate cannot run on Windows XP and is now a target for client verification.
It can be seen that the key to achieving shared Internet access is to solve the client authentication problem. Fortunately, there are several ways to solve this problem: 1. Use the client to detect imperfect problems and run some software for Internet sharing; 2. You can find some clients on the Internet.
1. Use the client to detect incomplete problems and run some software that shares the internet. I have noticed that many clients can detect CCProxy servers (such as complaints about detecting proxy software), but Windows ICS services (such as enabling wi-fi) or FY and other emerging software, but the performance is very silent. Therefore, you can directly use these software. This can solve the problem, but there are still some restrictions, such as the Hunan Unicom client srun3000, the same dormitory switch does not provide the LAN function, sometimes it is still unpleasant.
2. You can find some "shanzhai version" clients on the Internet. For example, there is a zdcclient on shenzhou.com. The "Cottage version" client has many advantages. First, it can detect clients without or without any reason, so it can directly avoid this problem. Then, for some reason, the official Client Version may not provide compatibility guarantee for the latest version of the operating system, and may not be able to run, disconnect the network, or break the card, but may happen from time to time. Community Active, keeping up with the times, and running very powerful. However, the client may not be found or blocked. All in all, the version is awesome, but it is a bit embarrassing.
Looking back and thinking, what is the simplest way to access the network? Of course, there is no authentication. You can access the Internet by plugging in the network cable, or connect to Wi-Fi to access the Internet. Wireless network adapters are common in laptops, so it is not a problem to connect to Wi-Fi (but it is also a problem to show that the above 1 and 2 cannot be achieved ). Plug in the network cable to access the Internet. This is the most ideal way to access the Internet, you need to return to the working principle of Sygate. After analysis, we can find that Sygate is actually a Virtual Interface with two network interfaces. One is used to access the Internet, and the other is used to share the network with other computers, but it is not compatible with systems after Windows XP. Further exploration will find that a service called NAT (Network Address Translation) is actually doing this.
The problem is that two network interfaces are required to connect to the Internet and provide network sharing. However, in real life, basically no one has to assign two NICs to their computers. I have noticed that most virtual machines provide Nat mode for their own virtual machines to access the Internet, and then provide the function to expand n bridging NICs. So there are two solutions: 1, You can expand two bridging NICs on the virtual machine, and then directly run the client on the Virtual Machine to access the Internet and use NAT to provide network sharing. ; 2, The host runs the client network, and then provides the virtual machine with a NAT network interface for the Virtual Machine to access the Internet, and a bridge network interface for Nat shared Internet access. . Among the two methods, 1 has better scalability and can be scaled in parallel; 2 has better usability and does not require network switching between virtual machines/hosts. I have used virtualbox, hyper-V, and VMWare. Only hyper-V Supports bridging. Both virtualbox and VMWare provide Nat. However, I found that on my computer, no matter what system I use, even if I use bridging and are in the same network segment, the host cannot access the virtualbox virtual machine. I don't know why, while the roommate's computer is normal.
Of course, virtual machines use the Windows server system. It is usually very easy to enable the NAT service. It can be solved by Baidu "How to enable Nat in Windows Server 2003/2008/2008 R2/2012, since the entire process is a graphical interface, the installation and configuration process is very simple. It is worth mentioning that it is best to determine which Nic is used to connect to the Internet and which Nic is used for external sharing. A static IP address is required for an external shared network. Generally, 10. x, 172.16.x.x, or 10. x is used.
in this step, you can share the Internet with your roommate, but you still need to configure the IP attribute. The solution is also very simple. You can add a DHCP role to the server to automatically set the IP address for the roommate's computer. Then you can "plug in the network cable and access the Internet. This is why I am puzzled by "using static IP addresses in the school room/Internet cafe/solution room". It is clear that DHCP is very simple.
it is worth mentioning that, by extending two bridging NICs on each virtual machine, you can connect multiple network interfaces in parallel. After a layer of NAT, a single IP address and multiple gateways can share the Internet. The direct result is that the Internet access speed doubles. Last semester, I used three Windows Server 2003 connections to connect to three 4 m connections, enabling a dormitory to achieve 12 M bandwidth. The normal speed of thunder downloading can reach MB per second, the effect is very obvious. But there are also some problems. When there are multiple gateways, the system will only use these network interfaces for redundant backup in case of errors, instead of using multiple gateways in parallel by default. Therefore, the speed of normal Internet access (Webpage Browsing, single-thread download, and youku video viewing) is not optimized, and because all computers use the default gateway, the computer's Internet access speed will not increase or decrease. I have not solved this problem yet, but if you need to explore it, you can start with Google "Multi-nic Server Load balancer" or "multiple network interface NLB.
in the past, Internet sharing was very advanced, but it seems that Internet sharing is common. It seems silly to have tried some methods before. A long time ago, the idea of "plugging in a network cable and surfing the Internet" had been realized. However, as time passes, shared Wi-Fi is used more now. In short, Internet sharing is no longer a problem. If your computer can access the Internet, you have to believe that Internet sharing is always possible.