How to change the ip address in golang

Golang is a high-performance, concurrency-supported programming language that provides many easy-to-use network programming libraries. If you want to modify the IP address, Golang provides some APIs and tools to make the operation easier. In this article, we will introduce how to modify IP address using Golang.

1. Get local IP address

Getting local IP address in Golang is very simple. We can use the function interface in the net library to obtain the local IP address. The following is a sample code to obtain the local IP address:

    addrs, err := net.InterfaceAddrs()
    if err != nil {
        fmt.Println("Error:", err)
    }
    for _, addr := range addrs {
        if ipnet, ok := addr.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
            if ipnet.IP.To4() != nil {
                fmt.Println("Local IP: ", ipnet.IP.String())
            }
        }
    }

In this code snippet, we use the function interface net.InterfaceAddrs() in the net library to obtain the local IP address. This function returns an array storing IP addresses. Use a loop to traverse the IP address array, filter out IP addresses that are not IPv4 addresses and are not loopback addresses, and finally print out the local IP address.

2. Modify the local IP address

To modify the local IP address, we need to use the netlink library. Netlink is a protocol family used for inter-process communication in the Linux kernel. It is mainly used for communication between the kernel and user space programs. The Netlink library provides a set of functions and structures that allow us to manage and control network interfaces more easily.

The following is a sample code for using the netlink library to change the local IP address:

    link, err := netlink.LinkByName("eth0")
    if err != nil {
        panic(err)
    }

    addr, err := netlink.ParseAddr("192.168.0.2/24")
    if err != nil {
        panic(err)
    }

    if err := netlink.AddrAdd(link, addr); err != nil {
        panic(err)
    }

In this code snippet, we first use the LinkByName function to obtain the network interface information named "eth0". Next, we use the ParseAddr function to parse out the new IP address, and then use the AddrAdd function to add the new IP address to the given network interface.

3. Verify whether the local IP address has changed

After we modify the local IP address, we can run the code again to check whether the change was successful. Using the same method as the code to get the local IP address, we can check if the local IP address has changed to the new IP address we specified. The final code example is as follows:

package main

import (
    "fmt"
    "github.com/vishvananda/netlink"
    "net"
)

func main() {

    addrs, err := net.InterfaceAddrs()
    if err != nil {
        fmt.Println("Error:", err)
    }
    for _, addr := range addrs {
        if ipnet, ok := addr.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
            if ipnet.IP.To4() != nil {
                fmt.Println("Local IP: ", ipnet.IP.String())
            }
        }
    }

    link, err := netlink.LinkByName("eth0")
    if err != nil {
        panic(err)
    }

    addr, err := netlink.ParseAddr("192.168.0.2/24")
    if err != nil {
        panic(err)
    }

    if err := netlink.AddrAdd(link, addr); err != nil {
        panic(err)
    }

    addrs, err = net.InterfaceAddrs()
    if err != nil {
        fmt.Println("Error:", err)
    }
    for _, addr := range addrs {
        if ipnet, ok := addr.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
            if ipnet.IP.To4() != nil {
                fmt.Println("Local IP: ", ipnet.IP.String())
            }
        }
    }
}

This code snippet prints out two local IP addresses. The first is the original local IP address, and the second is the new local IP address printed after modifying the local IP address. In this way, we can check whether the local IP address was successfully modified.

Summary

In this article, we introduced how to use Golang to modify the local IP address. We first demonstrated how to obtain a local IP address, and then introduced how to use the netlink library to modify the local IP address. Finally, we showed how to check whether the local IP address has been changed successfully. Hope this article will be helpful to you.

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