What is linux port forwarding

In Linux, port forwarding refers to using Nginx to monitor the port. When an HTTP request arrives, it matches the HOST and other information of the HTTP request with its configuration file and forwards it to the corresponding application; port forwarding can be used Access the domain name without adding a port.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What is linux port forwarding

What is port forwarding

When we build a data and a download application on the server, the data application starts port 8001, download The application started port 8002. At this time, if we can pass

localhost:8001    //资料
localhost:8002    //下载

, but when we usually access the application, we hope to access the domain name without adding a port, that is, both applications are accessed through port 80. But we know that a port on the server can only be used by one program. What should we do at this time? A common method is to use Nginx for port forwarding. The implementation principle of Nginx is: use Nginx to monitor port 80. When an HTTP request arrives, it will match the HOST and other information of the HTTP request with its configuration file and forward it to the corresponding application. For example, when a user visits linux.linuxmi.com, Nginx knows from the configuration file that this is an HTTP request for a data application, so it forwards the request to the application on port 8001 for processing. When a user visits m.linuxmi.com, Nginx knows from the configuration file that this is an HTTP request to download an application, so it forwards this request to the application on port 8002 for processing. A simple Nginx configuration file (part) is as follows:

#配置负载均衡池
#Demo1负载均衡池
upstream linux_pool{undefined
server 127.0.0.1:8001;
}
#Demo2负载均衡池
upstream m_pool{undefined
server 127.0.0.1:8002;
}
#Demo1端口转发
server {undefined
listen      80;
server_name  linux.linuxidc.com;
access_log logs/linux.log;
error_log logs/linux.error;
#将所有请求转发给demo_pool池的应用处理
location / {undefined
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://linux_pool;
}
}
#Demo2端口转发
server {undefined
listen      80;
server_name  m.linuxidc.com;
access_log logs/m.log;
error_log logs/m.error;
#将所有请求转发给demo_pool池的应用处理
location / {undefined
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://m_pool;
}
}

The above configuration is implemented:

1. When the domain name visited by the user is: http://linux.linuxidc .com, we automatically forward its request to the Tomcat application with port number 8001 for processing.

2. When the domain name visited by the user is: http://m.linuxidc.com, we automatically forward the request to the Tomcat application with port number 8002 for processing.

The above technical implementation is port forwarding. Port forwarding refers to the software uniformly monitoring a certain port on a certain domain name (usually port 80). When the domain name and port of the access server meet the requirements, it will be forwarded to the designated Tomcat server for processing according to the configuration. Our commonly used Nginx also has port forwarding function.

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