How to set or get the NetworkAddress key from the registry

Question

I want to read and modify the registry key value of my NetworkAddress. Its path in the registry is:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class{4D36E972-E325-11CE-BFC1-08002BE10318}\0011

Inside that path there is a key named NetworkAddress. How do I read and modify this key?

Here is what I have tried:

 RegistryKey myKey = Registry.LocalMachine.OpenSubKey(@"HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}\0011",true);
       MessageBox.Show((string) myKey.GetValue("NetworkAddress"));
       myKey.SetValue("NetworkAddress", "002408B2A2D2", RegistryValueKind.String);

I have tried this code and it is giving me this exception: Object reference not set to an instance of an object. How do I solve this issue? Please help me and thank you.

Answer 1

You are getting the exception because the factory method couldn't find the sub key at the specified location and returned null.

Despite your sub key address being perfectly valid, because you are using Registry.LocalMachine.OpenSubKey you are essentially specifying HKEY_LOCAL_MACHINE in the sub key address twice. The solution is to change your sub-key path to:

SYSTEM\ControlSet001\Control\Class{4D36E972-E325-11CE-BFC1-08002BE10318}\0011

You may also want to consider a more robust approach:

using (RegistryKey myKey =
    Registry.LocalMachine.OpenSubKey(
        @"SYSTEM\ControlSet001\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}\0011", true))
{
    if (myKey != null)
    {
        Console.WriteLine((string) myKey.GetValue("NetworkAddress"));
        myKey.SetValue("NetworkAddress", "002408B2A2D2", RegistryValueKind.String);
    }
}

Answer 2

C# is quite a rich language, so this is a lot easier to do without the registry

using System.Net.NetworkInformation;

var local = NetworkInterface.GetAllNetworkInterfaces().Where(i => i.Name == "Local Area Connection").FirstOrDefault();
var stringAddress = local.GetIPProperties().UnicastAddresses[0].Address.ToString();
var ipAddress = IPAddress.Parse(address);