How to get IP addresses of all devices in local network?

I have a lot of devices in one local network. How can I get ip addresses of all these devices?

@MartinSeptim
Try This:

using UnityEngine;
    using System.Net;
    using System.Net.Sockets;
        public string LocalIPAddress()
             {
                 IPHostEntry host;
                 string localIP = "";
                 host = Dns.GetHostEntry(Dns.GetHostName());
                 foreach (IPAddress ip in host.AddressList)
                 {
                     if (ip.AddressFamily == AddressFamily.InterNetwork)
                     {
                         localIP = ip.ToString();
                         break;
                     }
                 }
                 return localIP;
             }

I need this: Unity - Manual: Network Discovery