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

Solution 1:

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();

Solution 2:

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.

Solution 3:

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());
         }
     }