Use Windows Management Instrumentation (WMI) to get a MAC Address or Hard Drive Serial Number

A MAC address is a unique 48 bit number assigned to each Network Interface Card (NIC) by its manufacturer. The MAC address can be retrieved via VB.NET in a number of different ways. The easiest is to use Windows Management Instrumentation (WMI) which provides access to information about objects managed by Windows. With it you can enumerate all disk drives, network adapters, processes, query all network connections that are up, services that are paused etc.

To retrieve the MAC Address we can create a SQL query to be executed by the System.Management namespace's ManagementObjectSearcher object. To use the ManagementObjectSearcher, you will first need to set a reference, in Solution Explorer, to the System.Management.dll.

The query will select all values (i.e. properties) from the Win32_NetworkAdapterConfiguration WMI provider. By specifying a Where predicate of IPEnabled = True", the query will only return the values for the active network card. This is important since more than one network adapter may exist.

Results of the query run by the ManagementObjectSearcher's Get method are returned as a ManagementObjectCollection. Since our query retrieved all network adapter properties, we can loop through the collection and extract the MAC Address.

Here is the VB.NET code to get the MAC address:

    '
    ' Requires setting a reference to System.Management.dll
    '
    Imports System.Management 

    Try
        Dim strMACAddress as string = ""
        '
        ' Create the query, in SQL syntax, to retrieve the properties from
        ' the active Network Adapter.
        '
        Dim strQuery As String = _
            "SELECT * FROM Win32_NetworkAdapterConfiguration WHERE IPEnabled = True"

        '
        ' Create a ManagementObjectSearcher object passing in the query to run.
        '
        Dim query As ManagementObjectSearcher = New ManagementObjectSearcher(strQuery)

        '
        ' Create a ManagementObjectCollection assigning it the results of the query.
        '
        Dim queryCollection As ManagementObjectCollection = query.Get()

        '
        ' Loop through the results extracting the MAC Address.
        '
        Dim mo As ManagementObject

        For Each mo In queryCollection
            strMACAddress = mo("MacAddress").ToString().Replace(":", "")
            Exit For
        Next

        Return strMACAddress 

    Catch ex As Exception
        Return ""
    End Try

Similarly, you can get a wealth of information about your hard drives using WMI by changing the query to retrieve information from the Win32_PhysicalMedia provider.

    Dim strSN as String = ""
    Dim strQuery As String = "SELECT * FROM Win32_PhysicalMedia"
    Dim query As ManagementObjectSearcher = New ManagementObjectSearcher(strQuery)
    Dim queryCollection As ManagementObjectCollection = query.Get()
    Dim mo As ManagementObject

    For Each mo In queryCollection
        strSN = mo("SerialNumber").ToString()
    Next

This is just a small sample of the power of WMI and the ManagementObjectSearcher class. You can poke around in Google or MSDN to learn how to use it to retrieve tons of other information about your computer.