Question

i have a simple question but im not able to implement it cuz of lack of experience on C#.

when i open cmd and type arp -a command, it shows me all interfaces and ip addresses are routing.

so, my aim is to implement above process in C# and get ip, mac etc…
could somebody help me out on this trick? i would greatly appreciate. thanks

Answer 1

Chris Pietschmann wrote a blog post on what you’re looking for.

It mimics the “arp -a” command.

IPInfo Class:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net;

/// <summary>
/// This class allows you to retrieve the IP Address and Host Name for a specific machine on the local network when you only know it's MAC Address.
/// </summary>
public class IPInfo
{
    public IPInfo(string macAddress, string ipAddress)
    {
        this.MacAddress = macAddress;
        this.IPAddress = ipAddress;
    }

    public string MacAddress { get; private set; }
    public string IPAddress { get; private set; }

    private string _HostName = string.Empty;
    public string HostName
    {
        get
        {
            if (string.IsNullOrEmpty(this._HostName))
            {
                try
                {
                    // Retrieve the "Host Name" for this IP Address. This is the "Name" of the machine.
                    this._HostName = Dns.GetHostEntry(this.IPAddress).HostName;
                }
                catch
                {
                    this._HostName = string.Empty;
                }
            }
            return this._HostName;
        }
    }


    #region "Static Methods"

    /// <summary>
    /// Retrieves the IPInfo for the machine on the local network with the specified MAC Address.
    /// </summary>
    /// <param name="macAddress">The MAC Address of the IPInfo to retrieve.</param>
    /// <returns></returns>
    public static IPInfo GetIPInfo(string macAddress)
    {
        var ipinfo = (from ip in IPInfo.GetIPInfo()
                  where ip.MacAddress.ToLowerInvariant() == macAddress.ToLowerInvariant()
                  select ip).FirstOrDefault();

        return ipinfo;
    }

    /// <summary>
    /// Retrieves the IPInfo for All machines on the local network.
    /// </summary>
    /// <returns></returns>
    public static List<IPInfo> GetIPInfo()
    {
        try
        {
            var list = new List<IPInfo>();

            foreach (var arp in GetARPResult().Split(new char[] { '\n', '\r' }))
            {
                // Parse out all the MAC / IP Address combinations
                if (!string.IsNullOrEmpty(arp))
                {
                    var pieces = (from piece in arp.Split(new char[] { ' ', '\t' })
                                  where !string.IsNullOrEmpty(piece)
                                  select piece).ToArray();
                    if (pieces.Length == 3)
                    {
                        list.Add(new IPInfo(pieces[1], pieces[0]));
                    }
                }
            }

            // Return list of IPInfo objects containing MAC / IP Address combinations
            return list;
        }
        catch(Exception ex)
        {
            throw new Exception("IPInfo: Error Parsing 'arp -a' results", ex);
        }
    }

    /// <summary>
    /// This runs the "arp" utility in Windows to retrieve all the MAC / IP Address entries.
    /// </summary>
    /// <returns></returns>
    private static string GetARPResult()
    {
        Process p = null;
        string output = string.Empty;

        try
        {
            p = Process.Start(new ProcessStartInfo("arp", "-a")
            {
                CreateNoWindow = true,
                UseShellExecute = false,
                RedirectStandardOutput = true
            });

            output = p.StandardOutput.ReadToEnd();

            p.Close();
        }
        catch(Exception ex)
        {
            throw new Exception("IPInfo: Error Retrieving 'arp -a' Results", ex);
        }
        finally
        {
            if (p != null)
            {
                p.Close();
            }
        }

        return output;
    }

    #endregion
}