Read MAC Address from network adapter in .NET

Question

I\'d like to be able to read the mac address from the first active network adapter using VB.net or C# (using .NET 3.5 SP1) for a winform application

Answer 1

from http://www.dotnetjunkies.com/WebLog/jkirwan/archive/2004/02/10/6943.aspx

  Dim mc As System.Management.ManagementClass
  Dim mo As ManagementObject
  mc = New ManagementClass("Win32_NetworkAdapterConfiguration")
  Dim moc As ManagementObjectCollection = mc.GetInstances()
  For Each mo In moc
     If mo.Item("IPEnabled") = True Then
        ListBox1.Items.Add("MAC address " & mo.Item("MacAddress").ToString())
     End If
  Next

I am sure you'll have no trouble porting this code to C# if you need to

Answer 2

using Linq..

using System.Net.NetworkInformation;
..

NetworkInterface nic =
    NetworkInterface.GetAllNetworkInterfaces()
    .Where(n => n.OperationalStatus == OperationalStatus.Up).FirstOrDefault();

if (nic != null)
    return nic.GetPhysicalAddress().ToString();

Answer 3

Since .Net 2.0 there's been a NetworkInterface class in the System.Net.NetworkInformation namespace that will give you this information. Try this:

        foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces())
        {
            if (nic.OperationalStatus == OperationalStatus.Up)
            {
                Console.WriteLine(nic.GetPhysicalAddress().ToString());
                break;
            }
        }

Answer 4

You need to DllImport GetAdaptersInfo -- here's some C# code

http://www.codeguru.com/cpp/i-n/network/networkinformation/comments.php/c5451/?thread=60212

Answer 5

For anyone using the more limited Compact Framework (.NET v2.0 CF) the following code works on both Windows CE 5.0 and CE 6.0 (reading just the adaptor name, but search for "typedef struct _IP_ADAPTER_INFO" on MSDN to get the full definition of the structure returned):

private const int MAX_ADAPTER_NAME_LENGTH = 256;
[DllImport ("iphlpapi.dll", SetLastError = true)]
private static extern int GetAdaptersInfo(byte[] abyAdaptor, ref int nSize);

// ...
private static string m_szAdaptorName = "DM9CE1";

// ...
private void GetNetworkAdaptorName()
{
    // The initial call is to determine the size of the memory required. This will fail
    // with the error code "111" which is defined by MSDN to be "ERROR_BUFFER_OVERFLOW".
    // The structure size should be 640 bytes per adaptor.
    int nSize = 0;
    int nReturn = GetAdaptersInfo(null, ref nSize);

    // Allocate memory and get data
    byte[] abyAdapatorInfo = new byte[nSize];
    nReturn = GetAdaptersInfo(abyAdapatorInfo, ref nSize);
    if (nReturn == 0)
    {
        // Find the start and end bytes of the name in the returned structure
        int nStartNamePos = 8;
        int nEndNamePos = 8;
        while ((abyAdapatorInfo[nEndNamePos] != 0) &&
                    ((nEndNamePos - nStartNamePos) < MAX_ADAPTER_NAME_LENGTH))
        {
            // Another character in the name
            nEndNamePos++;
        }

        // Convert the name from a byte array into a string
        m_szAdaptorName = Encoding.UTF8.GetString(
            abyAdapatorInfo, nStartNamePos, (nEndNamePos - nStartNamePos));
    }
    else
    {
        // Failed? Use a hard-coded network adaptor name.
        m_szAdaptorName = "DM9CE1";
    }
}

Answer 6

Here's a class to do that:

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace MacAddress
{
    class MacAddress
    {
        byte[] _address;

        public MacAddress(byte[] b)
        {
            if (b == null)
                throw new ArgumentNullException("b");
            if (b.Length != 8)
                throw new ArgumentOutOfRangeException("b");
            _address = new byte[b.Length];
            Array.Copy(b, _address, b.Length);
        }

        public byte[] Address { get { return _address; } }

        public override string ToString()
        {
            return Address[0].ToString("X2", System.Globalization.CultureInfo.InvariantCulture) + ":" +
                    Address[1].ToString("X2", System.Globalization.CultureInfo.InvariantCulture) + ":" +
                    Address[2].ToString("X2", System.Globalization.CultureInfo.InvariantCulture) + ":" +
                    Address[3].ToString("X2", System.Globalization.CultureInfo.InvariantCulture) + ":" +
                    Address[4].ToString("X2", System.Globalization.CultureInfo.InvariantCulture) + ":" +
                    Address[5].ToString("X2", System.Globalization.CultureInfo.InvariantCulture);
        }

        public static List<MacAddress> GetMacAddresses()
        {
            int size = 0;
            // this chunk of code teases out the first adapter info
            int r = GetAdaptersInfo(null, ref size);
            if ((r != IPConfigConst.ERROR_SUCCESS) && (r != IPConfigConst.ERROR_BUFFER_OVERFLOW))
            {
                return null;
            }
            Byte[] buffer = new Byte[size];
            r = GetAdaptersInfo(buffer, ref size);
            if (r != IPConfigConst.ERROR_SUCCESS)
            {
                return null;
            }
            AdapterInfo Adapter = new AdapterInfo();
            ByteArray_To_IPAdapterInfo(ref Adapter, buffer, Marshal.SizeOf(Adapter));

            List<MacAddress> addresses = new List<MacAddress>();
            do
            {
                addresses.Add(new MacAddress(Adapter.Address));
                IntPtr p = Adapter.NextPointer;
                if (p != IntPtr.Zero)
                {
                    IntPtr_To_IPAdapterInfo(ref Adapter, p, Marshal.SizeOf(Adapter));
                }
                else
                {
                    break;
                }
            } while (true);
            return addresses;
        }

        // glue definitions into windows
        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        private struct IPAddrString
        {
            public IntPtr NextPointer;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 4 * 4)]
            public String IPAddressString;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 4 * 4)]
            public String IPMaskString;
            public int Context;
        }

        private class IPConfigConst
        {
            public const int MAX_ADAPTER_DESCRIPTION_LENGTH = 128;
            public const int MAX_ADAPTER_NAME_LENGTH = 256;
            public const int MAX_ADAPTER_ADDRESS_LENGTH = 8;
            public const int ERROR_BUFFER_OVERFLOW = 111;
            public const int ERROR_SUCCESS = 0;
        }

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        private struct AdapterInfo
        {
            public IntPtr NextPointer;
            public int ComboIndex;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = IPConfigConst.MAX_ADAPTER_NAME_LENGTH + 4)]
            public string AdapterName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = IPConfigConst.MAX_ADAPTER_DESCRIPTION_LENGTH + 4)]
            public string Description;
            public int AddressLength;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = IPConfigConst.MAX_ADAPTER_ADDRESS_LENGTH)]
            public Byte[] Address;
            public int Index;
            public int Type;
            public int DhcpEnabled;
            public IntPtr CurrentIPAddress;
            public IPAddrString IPAddressList;
            public IPAddrString GatewayList;
            public IPAddrString DhcpServer;
            public Boolean HaveWins;
            public IPAddrString PrimaryWinsServer;
            public IPAddrString SecondaryWinsServer;
            public int LeaseObtained;
            public int LeaseExpires;
        }
        [DllImport("Iphlpapi.dll", CharSet = CharSet.Auto)]
        private static extern int GetAdaptersInfo(Byte[] PAdapterInfoBuffer, ref int size);
        [DllImport("Kernel32.dll", EntryPoint = "CopyMemory")]
        private static extern void ByteArray_To_IPAdapterInfo(ref AdapterInfo dst, Byte[] src, int size);
        [DllImport("Kernel32.dll", EntryPoint = "CopyMemory")]
        private static extern void IntPtr_To_IPAdapterInfo(ref AdapterInfo dst, IntPtr src, int size);
    }
}

And here's some test code:

        List<MacAddress> addresses = MacAddress.GetMacAddresses();
        foreach (MacAddress address in addresses)
        {
            Console.WriteLine(address);
        }

I'm sure the ToString method could be better, but it does the job.