C# - Find Through Which Network Device User Is Connected To Internet?

Using the code below i will get all network interfaces wich are enabled and functional on the machine.

Private netIntrfc As NetworkInterface() = NetworkInterface.GetAllNetworkInterfaces()
For i As Integer = 0 To netIntrfc.Length - 1
If netIntrfc(i).OperationalStatus = OperationalStatus.Up Then

[code]....

But my problem is how to get the default one, the one(ethernet adapter) through wich user is connected to internet?I need to change some settings of default(through wich user is connected to internet) adapter. settings i change through registry so i could sample add same settings for each network interface but that could cause problems and makes no point then?

EDITED:for now i have done like code below, so if this can help someone other...

Dim u As UdpClient = New UdpClient(System.Net.Dns.GetHostName, 1)
Dim localAddr As IPAddress = CType(u.Client.LocalEndPoint, IPEndPoint).Address
Private netIntrfc As NetworkInterface() = NetworkInterface.GetAllNetworkInterfaces()

[code]....