Popular articles, port ing principle, public network, Intranet, NAT

Port ing principle

To connect a computer on the Intranet to the Internet, port ing is required.
Port ing is divided into dynamic and static
Dynamic port ing:
A computer in the Intranet will send packets to the NAT gateway to access xinlang. the packet header includes the IP address, port, and local IP address and port of the other party (I .e. xinlang network, the NAT gateway will replace the local IP address and port with its own public IP address and an unused port, and write down the ing relationship for future packet forwarding. Then, send the data to Sina. Upon receiving the data, Sina responds and sends the data to the unused port of the NAT Gateway. Then, the NAT Gateway forwards the data to the computer on the Intranet, implement communication between the Intranet and the Internet. when the connection is closed, the NAT Gateway releases the port allocated to the connection so that future connections can continue to be used.
Dynamic port ing is actually the way NAT Gateway works.

Static port ing: a fixed port is opened on the NAT gateway, and the data received by the port is set to which IP address and port to forward to the Intranet, whether or not there is a connection, this ing will always exist. Allows the Internet to access a computer on the Intranet.

A nat gateway can be a vswitch, router, or computer.

Now many articles about port ing are very misleading. Many people do not know how to use the port ing software on their own computers. In fact, port ing is done on the gateway !!! The gateway is rarely a computer, and most people cannot control the gateway, so the software for port ing is useless. (In this case, I want to emphasize that I used to do this .)
If Port ing is enabled, it is equivalent to opening all the faucets, so that the pipeline will withstand the maximum bandwidth pressure. For some early terminal devices (such as gateways) with poor quality, it is easy to strike when the workload is too high.
Either upgrade the device or limit the Network workload
Refreshing the latest firmware may also be a solution
I had this problem when I first opened ADSL (I lost my connection in 20 minutes ).
The solution was later --- cat switched to the bridge mode, and added a Broadband Router (more than 150) as the gateway, so there was no such worry.
The continuous online time even reaches one week, that is, no one is disconnected in the middle of the night and can be automatically redeployed.

We recommend that you use a vro instead of a cat to perform the routing function. The cat tries its best to work in the PPPOE bridging mode, and the maximum number of connections is 200.

What Is intranet, Intranet TrueHost, Internet, and NAT?
Internet and Intranet are two Internet access methods.

Intranet access mode: the IP address obtained by the computer accessing the Internet is the reserved IP address on Inetnet. The reserved IP address can be in the following three forms:
10. x
172.16.x.x to 172.31.x.x
192.168.x.x
Computers on the intranet use the NAT (Network Address Translation) Protocol to access the Internet through a public gateway. Computers on the Intranet can send connection requests to other computers on the Internet, but other computers on the Internet cannot send connection requests to computers on the Intranet.

Internet Access Mode: the IP address obtained by the computer on the Internet is a non-reserved IP address on Inetnet. Computers on the Internet and other computers on the Internet can access each other at will.

NAT (Network Address Translator) is a Network Address translation that converts Intranet IP addresses and public IP addresses, and converts a large number of Intranet IP addresses into one or a small number of public IP addresses, reduce the usage of public IP addresses. The most typical application of NAT is: In a LAN, you only need a computer to connect to the Internet, you can use NAT to share the Internet connection, so that other computers in the LAN can also access the Internet. Using the NAT protocol, computers in the LAN can access computers on the Internet, but computers on the Internet cannot access computers in the LAN.

In Windows, software such as Internet Connection Sharing, sygate, winroute, and natd in unix/linux use the NAT protocol to share Internet connections.

Almost all Internet access methods provided by Internet service providers are based on the NAT protocol.

How to detect Internet and Intranet
Enter the URL:
Http://www.linkwan.com/gb/broadmeter/SpeedAuto/

Global Network Speed Measurement and IP address query. You can click a site such as Xiamen to start speed measurement.

Query Result

Test Results

Your computer (not logged on) (IP: 222.47.12.198, from Fuzhou City, Fujian province>)
10:12:22 connection
Heping network technology-Xiamen station (Xiamen, Fujian, China)
Speed
579.71 Kbps (72.46 KB/second)

If the IP address is the same as the red IP address, it means that you are on the Internet. If it is different, it means that you have connected to the Internet through the gateway, that is, you are on the Intranet.
(You can also obtain the local IP address from the global statistics of BC)

Note:

1. If the proxy server is set in your browser, clear the proxy server settings, refresh the page, and check again.

2. Although some schools or large government agencies allocate public IP addresses to users, schools or organizations will close out-of-school access requests to the school for security purposes. Although these users have a public IP address, they still need an intranet dynamic domain name to create a website. If you access the Internet through the campus network or the network of an organization and find that you have a public IP address, please debug the website on the local machine and open the firewall, ask a friend on the Internet to visit your website through an IP address. If the access is available, it is the public network; if the access is not available, it is the Intranet.

3. If you use an ADSL shared device/router with port ing to access the Internet, or use a computer with a public IP address, and you have permission to set port ing for the gateway computer, although this situation belongs to the Intranet, it can also be set as a public network.