Golang : Get the IPv4 and IPv6 addresses for a specific network interface

Problem:

You need to find the IP address of a specific network interface on your machine for developing your application. Perhaps your machine has couple of network interfaces and your application needs to use a specific interface for security reason.

How to find the IP address either version 4 or 6?

Solution:

Use net package Interfaces() function. Below is an example of how to use the Interfaces() to find out the available interfaces and then specify a network interface by name to list out the IP addresses.

NOTE : This example will enumerate all the available network interfaces. If you need to specify a particular interface on your machine, first find out the interface name and then plug in the name in net.InterfaceByName("name").

Here you go!

 package main

 import (
 "fmt"
 "net"
 )

 func main() {

 // get available network interfaces for
 // this machine
 interfaces, err := net.Interfaces()

 if err != nil {
 fmt.Print(err)
 return
 }

 for _, i := range interfaces {

 fmt.Printf("Name : %v \n", i.Name)

 byNameInterface, err := net.InterfaceByName(i.Name)

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

 //fmt.Println("Interface by Name : ", byNameInterface)

 addresses, err := byNameInterface.Addrs()

 for k, v := range addresses {

 fmt.Printf("Interface Address #%v : %v\n", k, v.String())
 }
 fmt.Println("------------------------------------")

 }
 }

Sample output on my machine. Your machine result will be different.

Name : lo0

Interface Address #0 : ::1/128

Interface Address #1 : 127.0.0.1/8

Interface Address #2 : fe80::1/64

------------------------------------

Name : gif0

------------------------------------

Name : stf0

------------------------------------

Name : en3

Interface Address #0 : fe80::1aa6:f7ff:fe16:e80b/64

Interface Address #1 : 192.168.1.64/24

------------------------------------

If the network interface has no IP address, usually it means the status is DOWN.

References:

https://www.socketloop.com/tutorials/golang-how-to-detect-a-server-machine-network-interface-capabilities

https://golang.org/pkg/net/#Addr