What is port mapping and port forwarding, and what are their differences

1、 What is port mapping



Port mapping: Port mapping is the process of mapping a port from an internal network host to a port from an external network host, providing corresponding services. When the user accesses this port of the external IP, the server automatically maps the request to the corresponding machine inside the local area network< Br/>


For example, we have a web server on the internal network, but users on the external network cannot directly access the server. So we can set up a port mapping on the router. As long as external users access port 80 of the router's IP, the router will automatically redirect traffic to port 80 of the internal web server. And there is also a Session on the router, which can accurately send messages to the host requesting users from the external network when the internal server returns data to the router. During this process, the router acts as a reverse proxy, protecting the security of hosts in the internal network< Br/>


2、 What is port forwarding



Port forwarding: Port forwarding, sometimes referred to as tunneling, is a method used by a secure shell (SSH) for network security communication< Br/>


For example, we currently have no direct access to the external network within our internal network. But we can access the external network through NAT on the router. If we currently have 100 hosts on our internal network, then we all communicate with the external network through this public IP of the router. So, when a message on the internet is sent back, how does the router know that the message is for him and the other message is for you? This requires us to bind our IP address to the port of the router. At this point, there will be a table in the router that corresponds to the intranet IP and the router port. When the 10000 port of the router receives a message, it knows to send it to it, and when the 20000 port receives a message, it knows to send it to you. This is port forwarding, which forwards the traffic received by one port to another host< Br/>


3、 The difference between port mapping and port forwarding



For example:



Port forwarding: The focus of forwarding is on& Ldquo; Transfer& Rdquo; Above. The delivery person should hand over all the packages to the security guard at the entrance, who will then distribute them according to the recipients on each package< Br/>


Port mapping: It means installing a cabinet for each person at the entrance, and the delivery person directly puts the package into the corresponding cabinet according to the recipient's name< Br/>


4、 How to use peanut shells for port mapping and achieve external network access to local servers



Mapping enables external network access to local servers. When your internal and external content needs to be accessed by external network users, port mapping can be performed< Br/>


Download peanut shells, register them, and then assign them to a secondary domain name, set up internal and external network ports, or internal network hosts< Br/>


The IP address of the internal network host is the same IP address as your internal network segment. How can I check my internal network IP? Please enter cmd in the win key search boxOpen the command line and enter ipconfig to view the IP segment of the internal network< Br/>


Then set the port mapping function of the router< Br/>


Some routers are directly set up in virtual servers< Br/>


After setting up, restart the router. Of course, if the port is occupied by others, other ports can be used< Br/>


You can access the internal server using the domain name 25c8898k47. zip. vip: 55694< Br/>


5、 The reason why the router has set port mapping in the gateway but cannot be accessed by the external network



1. First, check if the port mapping you set is correctly mapped to the server on your intranet. Whether the IP address of the forwarding rule you set is the IP address of your server< Br/>


2. Unable to access the internal network server, please check if the server is turned on. You can use other computers within the local area network to access your server and confirm if it is turned on and can be successfully accessed< Br/>


3. Please check if you have mapped all the ports required by the server. It is possible that the ports required to access the server have not been fully set, resulting in access failure. You can open& Ldquo; DMZ Host& Rdquo; Let's check if the port is not fully mapped. If the DMZ host is enabled and the server can be accessed normally, it may be due to incomplete port addition< Br/>


4. Is& set on the gateway; Ldquo; Firewall; Rdquo;, Whether to filter the ports for server communication, resulting in access failure< Br/>


5. Local firewall: As the local network is a trusted area, the firewall does not block access to the local network. If the access source address is an external network address (non trusted area address), it may be blocked by the firewall and cannot be accessed< Br/>


6. The service provider will block the corresponding port: connect a computer to the gateway WAN port to simulate the internal and external network environment. If the computer connected to the WAN port can access the internal network server normally, but cannot access it on the Internet, it may be because the server blocks the corresponding port, causing the virtual server to be unable to access it< Br/>


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