How to get the router dynamic ip in nodejs

When doing network programming, obtaining the IP address of the router is a common requirement. Whether you are developing web applications or working on network security, it is very important to obtain the dynamic IP address of your router. How to get the router's dynamic IP in Node.js? This article will introduce in detail the method of obtaining the dynamic IP of the router in Node.js.

1. Understand the concept of dynamic IP address

Before understanding how Node.js obtains the dynamic IP of the router, we need to first understand the concept of dynamic IP address. A dynamic IP address refers to an IP address that constantly changes due to changes in network conditions or user needs. That is to say, every time the user restarts or the gateway reconnects to the ISP (Internet Service Provider) service, the IP address assigned by the router There will be changes. A static IP address refers to a resident IP address assigned to a machine and will not change due to changes in network conditions or user needs.

In a LAN, the dynamic IP address of the router is usually automatically assigned by the DHCP server. Therefore, Node.js programming is required to obtain the dynamic IP address of the router.

2. Use Node.js to obtain the router’s dynamic IP address

1. Obtain the router’s public IP address

In Node.js, our common method is to The STUN server sends a request to obtain the router's public IP address. The full name of STUN server is Simple Traversal of UDP through NATs (NAT penetration). It is a network protocol designed to solve the problem of NAT device limitations. It can be parsed by the server to determine the network and other information of the client, and provide information for the client. Provides a common set of network information so that clients can construct UDP packets that traverse the NAT gateway.

The code is as follows:

const stun = require('stun');
const { address } = stun.request('stun.l.google.com:19302');
console.log(address);

In the above code, the stun.request method will send a request to the specified STUN server and return the obtained public IP address of the router. In the console output, you can see the obtained IP address.

2. Obtain the internal IP address of the router

In Node.js, you can use the network interface information API to obtain the internal IP address of the router. The network interface information API mainly contains network interface information, including IP address, subnet mask, etc. We can iterate through these network interfaces, find the network interface connected to the inside of the router, and get its IP address.

The code is as follows:

const os = require('os');
const interfaces = os.networkInterfaces();
let ip = '';
Object.keys(interfaces).forEach(key => {
  interfaces[key].forEach(item => {
    if (item.family === 'IPv4' && !item.internal) {
      ip = item.address;
    }
  });
});
console.log(ip);

In the above code, we obtain all network interface information of this machine by calling the networkInterfaces method of os. Then traverse the network interface information to find the interface connected to the router and obtain the IP address of the interface.

3. Summary

This article mainly introduces the method of Node.js to obtain the router’s dynamic IP address, involving two methods of obtaining the router’s public IP address and intranet IP address. Through the introduction of this article, I hope it can help readers better understand the method of obtaining the IP address of the router, and make it easier to use Node.js programming technology in practical applications.

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