Get MAC Address in C# from IP Address/Hostname

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I was hoping to find something to get MAC address of a machine given its IP address or hostname. There could be multiple ways to do the same. But I thought I'll give the "nbtstat" a chance. nbtstat is a command in windows which gets you the details about protocol statistics and current TCP/IP connections using NBT (NetBIOS over TCP/IP). Here is a small program in C# which does the exact same thing: (If you want just the exe, let me know via a comment here and I'll send you the executable.)

    1 // No copyrights(c). Use as you wish!

    2 

    3 using System;

    4 using System.Diagnostics;

    5 using System.Net;

    6 using System.Net.NetworkInformation;

    7 using System.Runtime.InteropServices;

    8 using System.Text;

    9 

   10 namespace Yours.Truly

   11 {

   12     // *************************************************************************

   13     /// <summary>

   14     /// A class to get the MAC address from IP address. The same class can be

   15     /// modified a little to get the MAC address from the specified hostname.

   16     /// </summary>

   17     public class GetMacAddressFromIPAddress

   18     {

   19         /// <summary> Ping timeout (in ms) </summary>

   20         private const int PING_TIMEOUT = 1000;

   21 

   22         // *********************************************************************

   23         /// <summary>

   24         /// Initializes a new instance of <see cref="GetMacAddressFromIPAddress"/>.

   25         /// </summary>

   26         public GetMacAddressFromIPAddress()

   27         {

   28         }

   29 

   30         // *********************************************************************

   31         /// <summary>

   32         /// Gets the MAC address from specified <paramref name="IPAddress"/>

   33         /// using nbtstat in hyphen (-) separated format.

   34         /// </summary>

   35         /// <remarks>

   36         /// <para>

   37         /// The same class can be modified to accept hostname and then resolve

   38         /// the hostname to Ip address to get the MAC address or just pass "-a"

   39         /// argument to "nbtstat" to get the mac address from hostname. If you

   40         /// want to find the MAC address from only the IP address change the

   41         /// switch to "-A".

   42         /// </para>

   43         /// <para>

   44         /// The current program can resolve both hostname as well as IP address

   45         /// to MAC address. The "-a" argument can actually accept both IP address

   46         /// as well as hostname.

   47         /// </para>

   48         /// </remarks>

   49         /// <param name="ipAddress">The IP address or hostname for the machine

   50         /// for which the MAC address is desired.</param>

   51         /// <returns>A string containing the MAC address if MAC address could be

   52         /// found.An empty or null string otherwise.</returns>

   53         private string GetMacAddress(string ipAddress)

   54         {

   55             string macAddress = string.Empty;

   56 

   57             if (!IsHostAccessible(ipAddress)) return null;

   58             try

   59             {

   60                 ProcessStartInfo processStartInfo = new ProcessStartInfo();

   61                 Process process = new Process();

   62                 processStartInfo.FileName = "nbtstat";

   63                 processStartInfo.RedirectStandardInput = false;

   64                 processStartInfo.RedirectStandardOutput = true;

   65                 processStartInfo.Arguments = "-a " + ipAddress;

   66                 processStartInfo.UseShellExecute = false;

   67                 process = Process.Start(processStartInfo);

   68 

   69                 int Counter = -1;

   70 

   71                 while (Counter <= -1)

   72                 {

   73                     // Look for the words "mac address" in the output.

   74                     // The output usually looks likes this:

   75 

   76                     // Local Area Connection:

   77                     //Node IpAddress: [13.15.111.222] Scope Id: []

   78 

   79                     //           NetBIOS Remote Machine Name Table

   80 

   81                     //       Name               Type        Status

   82                     //    --------------------------------------------

   83                     //    SAMGLS0790W    <00>  UNIQUE      Registered

   84                     //    SAMPLS0790W    <20>  UNIQUE      Registered

   85                     //    NA            <00>  GROUP       Registered

   86 

   87                     //    MAC Address = 00-21-70-2B-A5-43

   88 

   89                     Counter =

   90                         macAddress.Trim().ToLower().IndexOf("mac address", 0);

   91                     if (Counter > -1)

   92                     {

   93                         break;

   94                     }

   95                     macAddress = process.StandardOutput.ReadLine();

   96                 }

   97                 process.WaitForExit();

   98                 macAddress = macAddress.Trim();

   99             }

  100             catch (Exception e)

  101             {

  102                 // Something unexpected happened? Inform the user

  103                 // The possibilities are:

  104                 // 1.That the machine is not on the network currently

  105                 // 2. The IP address/hostname supplied are not on the same network

  106                 // 3. The host was not found on the same subnet or could not be

  107                 //    resolved

  108                 Console.WriteLine("Failed because:" + e.ToString());

  109             }

  110 

  111             return macAddress;

  112         }

  113 

  114         #region Getting MAC from ARP

  115 

  116         [DllImport("iphlpapi.dll", ExactSpelling = true)]

  117         static extern int SendARP(int DestIP, int SrcIP, byte[] pMacAddr,

  118             ref uint PhyAddrLen);

  119 

  120         // *********************************************************************

  121         /// <summary>

  122         /// Gets the MAC address from ARP table in colon (:) separated format.

  123         /// </summary>

  124         /// <param name="hostNameOrAddress">Host name or IP address of the

  125         /// remote host for which MAC address is desired.</param>

  126         /// <returns>A string containing MAC address; null if MAC address could

  127         /// not be found.</returns>

  128         private string GetMACAddressFromARP(string hostNameOrAddress)

  129         {

  130             if (!IsHostAccessible(hostNameOrAddress)) return null;

  131 

  132             IPHostEntry hostEntry = Dns.GetHostEntry(hostNameOrAddress);

  133             if (hostEntry.AddressList.Length == 0)

  134                 return null;

  135 

  136             byte[] macAddr = new byte[6];

  137             uint macAddrLen = (uint) macAddr.Length;

  138             if (SendARP((int) hostEntry.AddressList[0].Address, 0, macAddr,

  139                 ref macAddrLen) != 0)

  140                 return null;

  141 

  142             StringBuilder macAddressString = new StringBuilder();

  143             for (int i = 0; i < macAddr.Length; i++)

  144             {

  145                 if (macAddressString.Length > 0)

  146                     macAddressString.Append(":");

  147 

  148                 macAddressString.AppendFormat("{0:x2}", macAddr[i]);

  149             }

  150 

  151             return macAddressString.ToString();

  152         } // end GetMACAddressFromARP

  153 

  154         #endregion Getting MAC from ARP

  155 

  156         // *********************************************************************

  157         /// <summary>

  158         /// Checks to see if the host specified by

  159         /// <paramref name="hostNameOrAddress"/> is currently accessible.

  160         /// </summary>

  161         /// <param name="hostNameOrAddress">Host name or IP address of the

  162         /// remote host for which MAC address is desired.</param>

  163         /// <returns><see langword="true" /> if the host is currently accessible;

  164         /// <see langword="false"/> otherwise.</returns>

  165         private static bool IsHostAccessible(string hostNameOrAddress)

  166         {

  167             Ping ping = new Ping();

  168             PingReply reply = ping.Send(hostNameOrAddress, PING_TIMEOUT);

  169             return reply.Status == IPStatus.Success;

  170         }

  171 

  172         // *********************************************************************

  173         /// <summary>

  174         /// The netry point for the application.

  175         /// </summary>

  176         /// <param name="args">An array of command line arguments.</param>

  177         [STAThread]

  178         static void Main(string[] args)

  179         {

  180             bool macRequired = true;

  181             while (macRequired)

  182             {

  183                 Console.WriteLine("Enter the IP address for which mac address is " +

  184                                 "required:(Enter exit to quit the program.)");

  185                 string ipAddress = Console.ReadLine();

  186                 StringComparer cp = StringComparer.OrdinalIgnoreCase;

  187                 if (cp.Compare(ipAddress, "Exit") == 0) break;

  188 

  189                 GetMacAddressFromIPAddress getMacAddress =

  190                     new GetMacAddressFromIPAddress();

  191 

  192                 Console.WriteLine("Please wait while I try to find the MAC address...");

  193                 // You may also use the ARP table. Call GetMACAddressFromARP here

  194                 string MacAddress = getMacAddress.GetMacAddress(ipAddress);

  195 

  196                 Console.WriteLine(MacAddress);

  197             } // end while

  198         }

  199 

  200     } // end class GetMacAddressFromIPAddress

  201 

  202 } // end namespace Yours.Truly