Question

first question here!

I have written and borrowed code to form a IP Address and MAC address finder console application. It send Asynchrous Ping request, and for every IP Address it finds it does and ARP request to find the MAC address.

How can I configure this to work with a different submask than /24 (255.255.255.0) to find IP Address’s?

This is NOT for a botnet. It is for my friend who is a network technician.

using System;
using System.Diagnostics;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;

namespace FindIpAndMacPro
{
    internal class Program
    {
        private static CountdownEvent _countdown;
        private static int _upCount;
        private static readonly object LockObj = new object();

        private static void Main()
        {
            _countdown = new CountdownEvent(1);
            var sw = new Stopwatch();
            sw.Start();
            Console.Write("Skriv in IP-Adress");
            string ipBase = Console.ReadLine();

            for (int i = 0; i < 255; i++)
            {
                string ip = ipBase + "." + i;
                //Console.WriteLine(ip);
                var p = new Ping();
                p.PingCompleted += PPingCompleted;
                _countdown.AddCount();
                p.SendAsync(ip, 100, ip);
            }

            _countdown.Signal();
            _countdown.Wait();
            sw.Stop();
            new TimeSpan(sw.ElapsedTicks);
            Console.WriteLine("Took {0} milliseconds. {1} hosts active.", sw.ElapsedMilliseconds, _upCount);
            Console.WriteLine("External IP (whatismyip.com): {0}", GetExternalIp());
            Console.ReadLine();
        }

        private static void PPingCompleted (object sender, PingCompletedEventArgs e)
        {
            var ip = (string) e.UserState;
            if (e.Reply != null && e.Reply.Status == IPStatus.Success)
            {

                {
                    string name;
                    string macAddress = "";

                    try
                    {
                        IPHostEntry hostEntry = Dns.GetHostEntry(ip);
                        name = hostEntry.HostName;
                        macAddress = GetMac(ip);
                    }
                    catch (SocketException)
                    {
                        name = "?";
                    }
                    Console.WriteLine("{0} | {1} ({2}) is up: ({3} ms)", ip, macAddress, name, e.Reply.RoundtripTime);
                }
                lock (LockObj)
                {
                    _upCount++;
                }
            }
            else if (e.Reply == null)
            {
                Console.WriteLine("Pinging {0} failed. (Null Reply object?)", ip);
            }
            _countdown.Signal();
        }

        [DllImport ("iphlpapi.dll")]
        public static extern int SendARP (int destIp, int srcIp, [Out] byte[] pMacAddr, ref int phyAddrLen);

        private static string GetMac (String ip)
        {
            IPAddress addr = IPAddress.Parse(ip);
            var mac = new byte[6];
            int len = mac.Length;
            SendARP(ConvertIpToInt32(addr), 0, mac, ref len);
            return BitConverter.ToString(mac, 0, len);
        }

        private static Int32 ConvertIpToInt32 (IPAddress apAddress)
        {
            byte[] bytes = apAddress.GetAddressBytes();
            return BitConverter.ToInt32(bytes, 0);
        }

        private static string GetExternalIp()
        {
            const string whatIsMyIp = "http://automation.whatismyip.com/n09230945.asp";
            var wc = new WebClient();
            var utf8 = new UTF8Encoding();
            string requestHtml = "";
            try
            {
                requestHtml = utf8.GetString(wc.DownloadData(whatIsMyIp));
            }
            catch (WebException we)
            {
                Console.WriteLine(we.ToString());
            }

            return requestHtml;
        }
    }
}

Answer 1

first of all you had to calculate the network from subnetmask.if your subnetmask is 255.255.248.0 then you can easly calculate by subtracting the subnetmask from 255. example: 192.168.32.0/21 (255.255.248.0)

 255.255.255.255
-255.255.248.0
 ---------------
  0 . 0 . 7 . 255

the network range is from 192.168.32.0 to 192.168.39.255 (32 + 7)
every 0 is your ipBase here 192.168. the rest is done with for loops. so for all possible networks you need up to 4 for loops. one for every octet of an ip address.
maybe you can use an existing class for calculating subnets but i don’t know such a class