Specific Network Interface IPv4 Availability - No Connectivity, Local, Internet

Question

How to determine the connection status of a specific NetworkInterface ?

  NetworkInterface[] nets = NetworkInterface.GetAllNetworkInterfaces(); foreach (var n in nets) { // TODO: determine connectivity status of each network interface // ( mainly interested in IPv4 connectivity ) } 

• This question is not about a general Internet connection and as such using GetIsNetworkAvailable() not a solution
• OperationalStatus.Up can be used to filter some inactive network interfaces, but not all - OperationalStatus.Up goes to some interfaces that show "No network access" for IPv4 and IPv6
• I also know how to get IPv4 UnicastAddresses , but then what / is it useful?
• I could not find anything in these WMI sections

i.e. retrieval for each interface status as Internet, local, limited or not

Answer 1

I think that in the Microsoft dialog box that you show above, the information obtained by encoding using the network location API is used.

http://msdn.microsoft.com/en-us/library/ee264321%28v=VS.85%29.aspx

Answer 2

As mentioned above, you need to use the Network List Manager as described there

To do this, first add a link to it, as shown in the screenshot below. Right-click on your project in your Visual Studio solution. Choose Add> Link .... Go to "COM" and find the entry "Network List 1.0 Library" using the search field.

This will create an Interop DLL for this COM interface in your binary output folder. This DLL is called Interop.NETWORKLIST.dll.

In your Solution Explorer, you can right-click on the NETWORKLIST link you just added and select “View in Object Explorer” to check the interfaces available to you.

Here you can implement the Network Manager class, as shown below, to subscribe to connection change events.

 using System; using System.Runtime.InteropServices.ComTypes; using System.Diagnostics; using NETWORKLIST; namespace SharpDisplayManager { public class NetworkManager: INetworkListManagerEvents, IDisposable { public delegate void OnConnectivityChangedDelegate(NetworkManager aNetworkManager, NLM_CONNECTIVITY aConnectivity); public event OnConnectivityChangedDelegate OnConnectivityChanged; private int iCookie = 0; private IConnectionPoint iConnectionPoint; private INetworkListManager iNetworkListManager; public NetworkManager() { iNetworkListManager = new NetworkListManager(); ConnectToNetworkListManagerEvents(); } public void Dispose() { //Not sure why this is not working form here //Possibly because something is doing automatically before we get there //DisconnectFromNetworkListManagerEvents(); } public INetworkListManager NetworkListManager { get { return iNetworkListManager; } } public void ConnectivityChanged(NLM_CONNECTIVITY newConnectivity) { //Fire our event OnConnectivityChanged(this, newConnectivity); } public void ConnectToNetworkListManagerEvents() { Debug.WriteLine("Subscribing to INetworkListManagerEvents"); IConnectionPointContainer icpc = (IConnectionPointContainer)iNetworkListManager; //similar event subscription can be used for INetworkEvents and INetworkConnectionEvents Guid tempGuid = typeof(INetworkListManagerEvents).GUID; icpc.FindConnectionPoint(ref tempGuid, out iConnectionPoint); iConnectionPoint.Advise(this, out iCookie); } public void DisconnectFromNetworkListManagerEvents() { Debug.WriteLine("Un-subscribing to INetworkListManagerEvents"); iConnectionPoint.Unadvise(iCookie); } } } 

You can create your network manager as follows:

 iNetworkManager = new NetworkManager(); iNetworkManager.OnConnectivityChanged += OnConnectivityChanged; 

After receiving connection change events, you can check the IsConnectedToInternet and IsConnected attributes, as shown below:

  public void OnConnectivityChanged(NetworkManager aNetwork, NLM_CONNECTIVITY newConnectivity) { //Update network status UpdateNetworkStatus(); } /// <summary> /// Update our Network Status /// </summary> private void UpdateNetworkStatus() { //TODO: Test the following functions to get network and Internet status //iNetworkManager.NetworkListManager.IsConnectedToInternet //iNetworkManager.NetworkListManager.IsConnected } 

Here is a related question: INetworkConnectionEvents Supports what?