interfaces.go

package main

import (
	"fmt"
	"net"
)

func main() {
	_, vpn, _ := net.ParseCIDR("172.27.0.0/16")
	ifaces, err := net.Interfaces()
	if err != nil {
		panic(err)
	}
	for _, i := range ifaces {
		addrs, err := i.Addrs()
		if err != nil {
			fmt.Println(err)
			continue
		}
		for _, a := range addrs {
			switch v := a.(type) {
			case *net.IPNet:
				isConnected := vpn.Contains(v.IP)
				fmt.Printf("%v : %v | %v\n", i, v, isConnected)
				if isConnected {
					fmt.Println("CONNECTED!")
				}
			}
		}
	}
}