[c#] Reliable method to get machine's MAC address in C#

I need a way to get a machine's MAC address, regardless of the OS it is running, by using C#.

The application will need to work on XP/Vista/Win7 32bit and 64bit, as well as on those OSs but with a foreign language default. Also, many of the C# commands and OS queries don't work across all the OSs.

Do you have any ideas?

I have been scraping the output of ipconfig /all but this is terribly unreliable as the output format differs on every machine.

Cleaner solution

var macAddr = 
    (
        from nic in NetworkInterface.GetAllNetworkInterfaces()
        where nic.OperationalStatus == OperationalStatus.Up
        select nic.GetPhysicalAddress().ToString()
    ).FirstOrDefault();

Or:

String firstMacAddress = NetworkInterface
    .GetAllNetworkInterfaces()
    .Where( nic => nic.OperationalStatus == OperationalStatus.Up && nic.NetworkInterfaceType != NetworkInterfaceType.Loopback )
    .Select( nic => nic.GetPhysicalAddress().ToString() )
    .FirstOrDefault();

You could go for the NIC ID:

 foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces()) {
     if (nic.OperationalStatus == OperationalStatus.Up){
         if (nic.Id == "yay!")
     }
 }

It's not the MAC address, but it is a unique identifier, if that's what you're looking for.

string mac = "";
foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces())
            {

                if (nic.OperationalStatus == OperationalStatus.Up && (!nic.Description.Contains("Virtual") && !nic.Description.Contains("Pseudo")))
                {
                    if (nic.GetPhysicalAddress().ToString() != "")
                    {
                        mac = nic.GetPhysicalAddress().ToString();
                    }
                }
            }
MessageBox.Show(mac);

WMI is the best solution if the machine you are connecting to is a windows machine, but if you are looking at a linux, mac, or other type of network adapter, then you will need to use something else. Here are some options:

1. Use the DOS command nbtstat -a . Create a process, call this command, parse the output.
2. First Ping the IP to make sure your NIC caches the command in it's ARP table, then use the DOS command arp -a . Parse the output of the process like in option 1.
3. Use a dreaded unmanaged call to sendarp in the iphlpapi.dll

Heres a sample of item #3. This seems to be the best option if WMI isn't a viable solution:

using System.Runtime.InteropServices;
...
[DllImport("iphlpapi.dll", ExactSpelling = true)]
        public static extern int SendARP(int DestIP, int SrcIP, byte[] pMacAddr, ref uint PhyAddrLen);
...
private string GetMacUsingARP(string IPAddr)
{
    IPAddress IP = IPAddress.Parse(IPAddr);
    byte[] macAddr = new byte[6];
    uint macAddrLen = (uint)macAddr.Length;

    if (SendARP((int)IP.Address, 0, macAddr, ref macAddrLen) != 0)
        throw new Exception("ARP command failed");

    string[] str = new string[(int)macAddrLen];
    for (int i = 0; i < macAddrLen; i++)
        str[i] = macAddr[i].ToString("x2");

    return string.Join(":", str);
}

To give credit where it is due, this is the basis for that code: http://www.pinvoke.net/default.aspx/iphlpapi.sendarp#

Try this:

    /// <summary>
    /// returns the first MAC address from where is executed 
    /// </summary>
    /// <param name="flagUpOnly">if sets returns only the nic on Up status</param>
    /// <returns></returns>
    public static string[] getOperationalMacAddresses(Boolean flagUpOnly)
    {
        string[] macAddresses = new string[NetworkInterface.GetAllNetworkInterfaces().Count()];

        int i = 0;
        foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces())
        {
            if (nic.OperationalStatus == OperationalStatus.Up || !flagUpOnly)
            {
                macAddresses[i] += ByteToHex(nic.GetPhysicalAddress().GetAddressBytes());
                //break;
                i++;
            }
        }
        return macAddresses;
    }

foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces())
{
     if (nic.OperationalStatus == OperationalStatus.Up)
     {
            PhysicalAddress Mac = nic.GetPhysicalAddress();
     }
}

let's say I have a TcpConnection using my local ip of 192.168.0.182. Then if I will like to know the mac address of that NIC I will call the meothod as: GetMacAddressUsedByIp("192.168.0.182")

public static string GetMacAddressUsedByIp(string ipAddress)
    {
        var ips = new List<string>();
        string output;

        try
        {
            // Start the child process.
            Process p = new Process();
            // Redirect the output stream of the child process.
            p.StartInfo.UseShellExecute = false;

            p.StartInfo.RedirectStandardOutput = true;
            p.StartInfo.UseShellExecute = false;
            p.StartInfo.CreateNoWindow = true;
            p.StartInfo.FileName = "ipconfig";
            p.StartInfo.Arguments = "/all";
            p.Start();
            // Do not wait for the child process to exit before
            // reading to the end of its redirected stream.
            // p.WaitForExit();
            // Read the output stream first and then wait.
            output = p.StandardOutput.ReadToEnd();
            p.WaitForExit();

        }
        catch
        {
            return null;
        }

        // pattern to get all connections
        var pattern = @"(?xis) 
(?<Header>
     (\r|\n) [^\r]+ :  \r\n\r\n
)
(?<content>
    .+? (?= ( (\r\n\r\n)|($)) )
)";

        List<Match> matches = new List<Match>();

        foreach (Match m in Regex.Matches(output, pattern))
            matches.Add(m);

        var connection = matches.Select(m => new
        {
            containsIp = m.Value.Contains(ipAddress),
            containsPhysicalAddress = Regex.Match(m.Value, @"(?ix)Physical \s Address").Success,
            content = m.Value
        }).Where(x => x.containsIp && x.containsPhysicalAddress)
        .Select(m => Regex.Match(m.content, @"(?ix)  Physical \s address [^:]+ : \s* (?<Mac>[^\s]+)").Groups["Mac"].Value).FirstOrDefault();

        return connection;
    }

public static PhysicalAddress GetMacAddress()
{
    var myInterfaceAddress = NetworkInterface.GetAllNetworkInterfaces()
        .Where(n => n.OperationalStatus == OperationalStatus.Up && n.NetworkInterfaceType != NetworkInterfaceType.Loopback)
        .OrderByDescending(n => n.NetworkInterfaceType == NetworkInterfaceType.Ethernet)
        .Select(n => n.GetPhysicalAddress())
        .FirstOrDefault();

    return myInterfaceAddress;
}

The MACAddress property of the Win32_NetworkAdapterConfiguration WMI class can provide you with an adapter's MAC address. (System.Management Namespace)

MACAddress

    Data type: string
    Access type: Read-only

    Media Access Control (MAC) address of the network adapter. A MAC address is assigned by the manufacturer to uniquely identify the network adapter.

    Example: "00:80:C7:8F:6C:96"

If you're not familiar with the WMI API (Windows Management Instrumentation), there's a good overview here for .NET apps.

WMI is available across all version of windows with the .Net runtime.

Here's a code example:

System.Management.ManagementClass mc = default(System.Management.ManagementClass);
ManagementObject mo = default(ManagementObject);
mc = new ManagementClass("Win32_NetworkAdapterConfiguration");

ManagementObjectCollection moc = mc.GetInstances();
    foreach (var mo in moc) {
        if (mo.Item("IPEnabled") == true) {
              Adapter.Items.Add("MAC " + mo.Item("MacAddress").ToString());
         }
     }

Changed blak3r his code a bit. In case you have two adapters with the same speed. Sort by MAC, so you always get the same value.

public string GetMacAddress()
{
    const int MIN_MAC_ADDR_LENGTH = 12;
    string macAddress = string.Empty;
    Dictionary<string, long> macPlusSpeed = new Dictionary<string, long>();
    try
    {
        foreach(NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces())
        {
            System.Diagnostics.Debug.WriteLine("Found MAC Address: " + nic.GetPhysicalAddress() + " Type: " + nic.NetworkInterfaceType);

            string tempMac = nic.GetPhysicalAddress().ToString();

            if(!string.IsNullOrEmpty(tempMac) && tempMac.Length >= MIN_MAC_ADDR_LENGTH)
                macPlusSpeed.Add(tempMac, nic.Speed);
        }

        macAddress = macPlusSpeed.OrderByDescending(row => row.Value).ThenBy(row => row.Key).FirstOrDefault().Key;
    }
    catch{}

    System.Diagnostics.Debug.WriteLine("Fastest MAC address: " + macAddress);

    return macAddress;
}

Here's some C# code which returns the MAC address of the first operational network interface. Assuming the NetworkInterface assembly is implemented in the runtime (i.e. Mono) used on other operating systems then this would work on other operating systems.

New version: returns the NIC with the fastest speed that also has a valid MAC address.

/// <summary>
/// Finds the MAC address of the NIC with maximum speed.
/// </summary>
/// <returns>The MAC address.</returns>
private string GetMacAddress()
{
    const int MIN_MAC_ADDR_LENGTH = 12;
    string macAddress = string.Empty;
    long maxSpeed = -1;

    foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces())
    {
        log.Debug(
            "Found MAC Address: " + nic.GetPhysicalAddress() +
            " Type: " + nic.NetworkInterfaceType);

        string tempMac = nic.GetPhysicalAddress().ToString();
        if (nic.Speed > maxSpeed &&
            !string.IsNullOrEmpty(tempMac) &&
            tempMac.Length >= MIN_MAC_ADDR_LENGTH)
        {
            log.Debug("New Max Speed = " + nic.Speed + ", MAC: " + tempMac);
            maxSpeed = nic.Speed;
            macAddress = tempMac;
        }
    }

    return macAddress;
}

Original Version: just returns the first one.

/// <summary>
/// Finds the MAC address of the first operation NIC found.
/// </summary>
/// <returns>The MAC address.</returns>
private string GetMacAddress()
{
    string macAddresses = string.Empty;

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

    return macAddresses;
}

The only thing I don't like about this approach is if you have like a Nortel Packet Miniport or some type of VPN connection it has the potential of being chosen. As far as I can tell, there is no way to distinguish an actual physical device's MAC from some type of virtual network interface.

I really like AVee's solution with the lowest IP connection metric! But if a second nic with the same metric is installed, the MAC comparison could fail...

Better you store the description of the interface with the MAC. In later comparisons you can identify the right nic by this string. Here is a sample code:

   public static string GetMacAndDescription()
    {
        ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration where IPEnabled=true");
        IEnumerable<ManagementObject> objects = searcher.Get().Cast<ManagementObject>();
        string mac = (from o in objects orderby o["IPConnectionMetric"] select o["MACAddress"].ToString()).FirstOrDefault();
        string description = (from o in objects orderby o["IPConnectionMetric"] select o["Description"].ToString()).FirstOrDefault();
        return mac + ";" + description;
    }

    public static string GetMacByDescription( string description)
    {
        ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration where IPEnabled=true");
        IEnumerable<ManagementObject> objects = searcher.Get().Cast<ManagementObject>();
        string mac = (from o in objects where o["Description"].ToString() == description select o["MACAddress"].ToString()).FirstOrDefault();
        return mac;
    }

ipconfig.exe is implemented using various DLLs including iphlpapi.dll ... Googling for iphlpapi reveals a corresponding Win32 API documented in MSDN.

We use WMI to get the mac address of the interface with the lowest metric, e.g. the interface windows will prefer to use, like this:

public static string GetMACAddress()
{
    ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration where IPEnabled=true");
    IEnumerable<ManagementObject> objects = searcher.Get().Cast<ManagementObject>();
    string mac = (from o in objects orderby o["IPConnectionMetric"] select o["MACAddress"].ToString()).FirstOrDefault();
    return mac;
}

Or in Silverlight (needs elevated trust):

public static string GetMACAddress()
{
    string mac = null;
    if ((Application.Current.IsRunningOutOfBrowser) && (Application.Current.HasElevatedPermissions) && (AutomationFactory.IsAvailable))
    {
        dynamic sWbemLocator = AutomationFactory.CreateObject("WbemScripting.SWBemLocator");
        dynamic sWbemServices = sWbemLocator.ConnectServer(".");
        sWbemServices.Security_.ImpersonationLevel = 3; //impersonate

        string query = "SELECT * FROM Win32_NetworkAdapterConfiguration where IPEnabled=true";
        dynamic results = sWbemServices.ExecQuery(query);

        int mtu = int.MaxValue;
        foreach (dynamic result in results)
        {
            if (result.IPConnectionMetric < mtu)
            {
                mtu = result.IPConnectionMetric;
                mac = result.MACAddress;
            }
        }
    }
    return mac;
}

IMHO returning first mac address isn't good idea, especially when virtual machines are hosted. Therefore i check send/received bytes sum and select most used connection, that is not perfect, but should be correct 9/10 times.

public string GetDefaultMacAddress()
{
    Dictionary<string, long> macAddresses = new Dictionary<string, long>();
    foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces())
    {
        if (nic.OperationalStatus == OperationalStatus.Up)
            macAddresses[nic.GetPhysicalAddress().ToString()] = nic.GetIPStatistics().BytesSent + nic.GetIPStatistics().BytesReceived;
    }
    long maxValue = 0;
    string mac = "";
    foreach(KeyValuePair<string, long> pair in macAddresses)
    {
        if (pair.Value > maxValue)
        {
            mac = pair.Key;
            maxValue = pair.Value;
        }
    }
    return mac;
}

This method will determine the MAC address of the Network Interface used to connect to the specified url and port.

All the answers here are not capable of achieving this goal.

I wrote this answer years ago (in 2014). So I decided to give it a little "face lift". Please look at the updates section

    /// <summary>
    /// Get the MAC of the Netowrk Interface used to connect to the specified url.
    /// </summary>
    /// <param name="allowedURL">URL to connect to.</param>
    /// <param name="port">The port to use. Default is 80.</param>
    /// <returns></returns>
    private static PhysicalAddress GetCurrentMAC(string allowedURL, int port = 80)
    {
        //create tcp client
        var client = new TcpClient();

        //start connection
        client.Client.Connect(new IPEndPoint(Dns.GetHostAddresses(allowedURL)[0], port));

        //wai while connection is established
        while(!client.Connected)
        {
            Thread.Sleep(500);
        }

        //get the ip address from the connected endpoint
        var ipAddress = ((IPEndPoint)client.Client.LocalEndPoint).Address;

        //if the ip is ipv4 mapped to ipv6 then convert to ipv4
        if(ipAddress.IsIPv4MappedToIPv6)
            ipAddress = ipAddress.MapToIPv4();        

        Debug.WriteLine(ipAddress);

        //disconnect the client and free the socket
        client.Client.Disconnect(false);
        
        //this will dispose the client and close the connection if needed
        client.Close();

        var allNetworkInterfaces = NetworkInterface.GetAllNetworkInterfaces();

        //return early if no network interfaces found
        if(!(allNetworkInterfaces?.Length > 0))
            return null;

        foreach(var networkInterface in allNetworkInterfaces)
        {
            //get the unicast address of the network interface
            var unicastAddresses = networkInterface.GetIPProperties().UnicastAddresses;
           
            //skip if no unicast address found
            if(!(unicastAddresses?.Count > 0))
                continue;

            //compare the unicast addresses to see 
            //if any match the ip address used to connect over the network
            for(var i = 0; i < unicastAddresses.Count; i++)
            {
                var unicastAddress = unicastAddresses[i];

                //this is unlikely but if it is null just skip
                if(unicastAddress.Address == null)
                    continue;
                
                var ipAddressToCompare = unicastAddress.Address;

                Debug.WriteLine(ipAddressToCompare);

                //if the ip is ipv4 mapped to ipv6 then convert to ipv4
                if(ipAddressToCompare.IsIPv4MappedToIPv6)
                    ipAddressToCompare = ipAddressToCompare.MapToIPv4();

                Debug.WriteLine(ipAddressToCompare);

                //skip if the ip does not match
                if(!ipAddressToCompare.Equals(ipAddress))
                    continue;

                //return the mac address if the ip matches
                return networkInterface.GetPhysicalAddress();
            }
              
        }

        //not found so return null
        return null;
    }

To call it you need to pass a URL to connect to like this:

var mac = GetCurrentMAC("www.google.com");

You can also specify a port number. If not specified default is 80.

UPDATES:

2020

• Added comments to explain the code.
• Corrected to be used with newer operating systems that use IPV4 mapped to IPV6 ( like windows 10 ).
• Reduced nesting.
• Upgraded the code use "var".

Really hate to dig up this old post but I feel the question deserves another answer specific to windows 8-10.

Using NetworkInformation from the Windows.Networking.Connectivity namespace, you can get the Id of the network adapter windows is using. Then you can get the interface MAC Address from the previously mentioned GetAllNetworkInterfaces().

This will not work in Windows Store Apps as NetworkInterface in System.Net.NetworkInformation does not expose GetAllNetworkInterfaces.

string GetMacAddress()
{
    var connectionProfile = NetworkInformation.GetInternetConnectionProfile();
    if (connectionProfile == null) return "";

    var inUseId = connectionProfile.NetworkAdapter.NetworkAdapterId.ToString("B").ToUpperInvariant();
    if(string.IsNullOrWhiteSpace(inUseId)) return "";

    var mac = NetworkInterface.GetAllNetworkInterfaces()
        .Where(n => inUseId == n.Id)
        .Select(n => n.GetPhysicalAddress().GetAddressBytes().Select(b=>b.ToString("X2")))
        .Select(macBytes => string.Join(" ", macBytes))
        .FirstOrDefault();

    return mac;
}