Network C# Tutorial

using System;
using System.Management;
class MainClass
{
    public static void Main()
    {
        ManagementObjectSearcher query = new ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration WHERE IPEnabled = 'TRUE'") ;
        ManagementObjectCollection queryCollection = query.Get();
        foreach( ManagementObject mo in queryCollection )
        {
            string[] defaultgateways = (string[])mo["DefaultIPGateway"];
            foreach(string defaultgateway in defaultgateways)
            {
                Console.WriteLine("Gateway: {0}", defaultgateway);
            }
        }
    }
}
Gateway: 192.168.1.1
Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an ob
ject.
at MainClass.Main()