Functions and setting methods of "forwarding rules" on TP-LINK Broadband Router

Now TP-LINK home Broadband Router because of the cheap price, performance also go, market share is quite high, TP-LINK home router has a function: "forwarding rules ", A considerable number of people still do not know its purpose. Next, let's talk about it briefly.

We know that all networked hosts on the internet need a unique IP address. The IP addresses used now belong to IPv4 and IPv4 addresses are classified into several categories, as long as we know that IPv4 faces the depletion of available IP addresses, the common 192.168.x.x addresses in the LAN are all private IP addresses.

192.168.x.x, a private IP address, cannot communicate directly with a public IP address, one of our commonly used vro functions is to convert a private IP address into a public IP address that can communicate with hosts on other Internet, provided that the vro has a public IP address. The Wan port on the router refers to the wide area network port, which is used to connect to the public network, and the LAN port is used for the internal LAN.

The working principle of a home router is roughly like this: You can use the WAN port to call pppoe to obtain a public IP address, the PC in the LAN obtains the LAN private IP address from the router through DHCP or the PC in the LAN manually specifies the private IP address of 192.168.x.x. When the PC in the LAN has a request to access the public network, the vro converts the access requests of the PC in the LAN into the access requests of its own public IP address to access other hosts on the Internet. After the other party returns the requested data, then, return the response data to the PC in the LAN. The PC in the LAN obtains the required data and completes an access.

The above is a basically complete communication process, but careful people will find that this access request was initiated by the PC in the LAN behind the router, what if other hosts on the internet want to access the PC in the LAN after the router? You must know that the PC in this lan does not have a public IP address. Only this vro has a public IP address.

Therefore, most routers have such a function: Port ing or port forwarding. On the Home Router of the TP-LINK, this function is called "forwarding rule", this function is to complete other hosts on the Internet to access the router after the PC in the LAN.

What should I do if I want to complete port ing or "forwarding rules" on a vro?
First, you need to know what services to complete and the TCP or UDP ports required to complete this service. For example, the web service requires port 80 by default, and the FTP service requires port 20 and port 21 by default.
Second, you need to know the private IP address of the PC in the LAN. If there are two PCs in the LAN, A and B, the IP address of a is 192.168.0.2, And the IP address of B is 192.168.0.3, host a wants to provide web services and has installed corresponding web service programs such as IIS, Apache, machine B wants to provide FTP services and has installed corresponding service programs such as IIS, Serv-U, and g6ftp. These services can only be provided to other machines in the LAN, but cannot be accessed by other hosts on the Internet.
Third, set port ing on the router ("forwarding rules" on the TP-LINK router), add an 80 service port, select the IP address 192.168.0.2 (that is, machine A in the above example ), because the Web Service uses the TCP protocol, select "TCP" in the protocol section, and then enable ". Then, add Port 20 and port 21, the IP address is 192.168.0.3 (host B in the preceding example). TCP is also selected for all protocols. You must also check "enable". Note that the configured FTP service can only be connected in Port mode, other settings are required to use PASV mode.
After saving the configurations, You need to restart the vro.

After the preceding settings, other hosts on the internet can access the machines in the LAN after the router. In this example, only the web service and FTP service are set, to provide other services, you only need to make corresponding settings.