How to distinguish between Ethernet and WiFi IP Addresses using VB.NET

Question

I am trying to develop a generic VB.NET based application that will return me the Ethernet IP Address of the local machine. I have referred to several questions discussed here for getting the IP Address of the machine and found a few good suggestions.

The problem I am facing is, when I run this application, it returns me the IP Address of both WiFi and Ethernet. When I run this application on somebody else's machine, I unable to tell which IP Address belongs to which interface. I am interested in Ethernet IP Address only.

Any suggestions ??

Here is the function that returns the list of IP Addresses.

Function getIP() As String

    Dim ips As System.Net.IPHostEntry = System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName)

    For Each ip In ips.AddressList
        If (ip.AddressFamily = System.Net.Sockets.AddressFamily.InterNetwork) Then
            MessageBox.Show(ip.ToString)
            Return ip.ToString
        End If
    Next
    Return Nothing

End Function

Answer 1

Rather than getting IP addresses via an IPHostEntry, you can enumerate through the network adapters, then get the IP addresses from each adapter.

A NetworkInterface provides its type via the NetworkInterfaceType property. For ethernet adapters, this returns Ethernet. For a wireless adapter, the documentation doesn't specify, but it returned Wireless80211 for me.

Sample code:

Imports System.Net.NetworkInformation


Public Class Sample

    Function GetIP() As String
        Dim networkInterfaces() As NetworkInterface


        networkInterfaces = NetworkInterface.GetAllNetworkInterfaces()

        For Each networkInterface In networkInterfaces
            If networkInterface.NetworkInterfaceType = NetworkInterfaceType.Ethernet Then
                For Each address In networkInterface.GetIPProperties().UnicastAddresses
                    If address.Address.AddressFamily = Net.Sockets.AddressFamily.InterNetwork Then
                        Return address.Address.ToString()
                    End If
                Next address
            End If
        Next networkInterface

        Return Nothing
    End Function

End Class

Or, if you want a slightly more concise version, you could use LINQ (equivalent to the code above):

Function GetIP() As String
    Return (
        From networkInterface In networkInterface.GetAllNetworkInterfaces()
        Where networkInterface.NetworkInterfaceType = NetworkInterfaceType.Ethernet
        From address In networkInterface.GetIPProperties().UnicastAddresses
        Where address.Address.AddressFamily = Net.Sockets.AddressFamily.InterNetwork
        Select ip = address.Address.ToString()
    ).FirstOrDefault()
End Function