How to modify IP address using Golang programming language

Golang is a strongly typed, compiled language that is widely used in containers, cloud computing, microservices and other fields. When using Golang for network programming, modifying the IP address is one of the common operations. This article will introduce how to modify the IP address using the Golang programming language.

1. Get the current IP address

Before starting to modify the IP, we need to get the current IP address of the machine. It is very convenient to obtain the local IP address using Golang. The "net" package in the Golang standard library provides the function of obtaining the local IP address. The following is a simple program for obtaining the IP address of the local machine:

package main

import (
    "fmt"
    "net"
)

func main() {
    addrs, err := net.InterfaceAddrs()
    if err != nil {
        fmt.Println(err)
    }

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

In the above code, we first call the InterfaceAddrs() function in the net package to obtain all the network interfaces of the local machine, and then use The for loop loops through all interfaces and finds the IP addresses within them. If the IP address is not a loopback address, print it out.

2. Modify IP address

After obtaining the IP address of the machine, the next step is how to modify the IP address. In Golang, to modify the IP address, you need to use the "netlink" sub-package in the "net" package. Use the netlink package to create, delete, and modify network connections, devices, addresses, etc. The following is a program to modify IP:

package main

import (
    "fmt"
    "net"
    "os/exec"
)

func main() {
    ip := "192.168.31.222"
    mask := "255.255.255.0"
    iface := "eth0"

    cmd := exec.Command("ip", "addr", "flush", "dev", iface)
    err := cmd.Run()
    if err != nil {
        fmt.Println(err)
    }

    link, err := netlink.LinkByName(iface)
    if err != nil {
        fmt.Println(err)
    }

    addr, err := netlink.ParseAddr(fmt.Sprintf("%s/%s", ip, mask))
    if err != nil {
        fmt.Println(err)
    }

    err = netlink.AddrAdd(link, addr)
    if err != nil {
        fmt.Println(err)
    }

    err = netlink.LinkSetUp(link)
    if err != nil {
        fmt.Println(err)
    }
}

In the above code, we first define three variables ip, mask and iface, which respectively represent the IP address, subnet mask and network interface name that need to be modified. . Then use the ip addr flush command to clear all addresses on the eth0 network card. If the clearing operation is successful, proceed to the next step, otherwise the program will terminate here. Then use the LinkByName() function in the netlink package to find the network card named eth0. Next, define an address addr, and parse the IP address and subnet mask into an address structure through the ParseAddr() function in the netlink package. Next, call the AddrAdd() function in the netlink package to add the new address to the eth0 network card. Finally, call the LinkSetUp() function in the netlink package to activate the eth0 network card. This completes the modification of the IP address.

It should be noted that the above program needs to be run using sudo and needs to be run in a Linux environment.

Conclusion

This article introduces how to use the Golang programming language to modify the IP address. We first obtain the IP address of the local machine through the "net" package, and then use the "netlink" sub-package to modify the IP address. Network programming is one of Golang's strengths. By studying this article, you can have a deeper understanding of the related knowledge of network programming in Golang.

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