Check Internet Connectivity - vb.net

Question

I need my application to check for internet connectivity on my user's computer. If there is, an image is displayed and if there isn't, a different image is displayed. Here's the code I used to get this to work:
Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
If NetworkInformation.NetworkInterface.GetIsNetworkAvailable Then
Dim bi1 As New BitmapImage
bi1.BeginInit()
bi1.UriSource = New Uri("Images\greenbar.png", UriKind.Relative)
bi1.EndInit()
Image2.Source = bi1
Else
Dim bi2 As New BitmapImage
bi2.BeginInit()
bi2.UriSource = New Uri("Images\redbar.png", UriKind.Relative)
bi2.EndInit()
Image2.Source = bi2
MessageBox.Show("INTERNET CONNECTION NOT DETECTED")
MessageBox.Show("You must be connected to the internet to use some aspects of this application.")
MessageBox.Show("Please re-establish connection to the Internet and try again, thank you.")
Me.Close()
End If
End Sub
I decided to test this on my own computer by changing my default gateway (thereby making it seem as if I lost connection). But I realized that the code still showed that I was connected. So I'm thinking that it's only checking for connectivity of the interface - which in this case, is my connection to the router (which is true, I was connected to the router).
So, the question: How do I check that the user's PC is actually connected to the internet? I read the article What is the best way to check for Internet connectivity using .NET? but it's in C# and I don't understand that.

Answer 1

You can use this tool to translate C# to VB.NET or vice-versa:
Public Shared Function CheckForInternetConnection() As Boolean
Try
Using client = New WebClient()
Using stream = client.OpenRead("http://www.google.com")
Return True
End Using
End Using
Catch
Return False
End Try
End Function
By the way, the NetworkInterface.GetIsNetworkAvailable method you've used checks whether any network connection is available or not - not Internet Connectivity.
A network connection is considered to be available if any network
interface is marked "up" and is not a loopback or tunnel interface.

Answer 2

Or use this code
If My.Computer.Network.IsAvailable Then
MsgBox("Computer is connected.")
Else
MsgBox("Computer is not connected.")
End If

Answer 3

If My.Computer.Network.Ping("www.Google.com") Then
...
End If

Answer 4

You could use this, which should help you out for VB & C# versions:
Public Function IsConnectionAvailable() As Boolean
' Returns True if connection is available
' Replace www.yoursite.com with a site that
' is guaranteed to be online - perhaps your
' corporate site, or microsoft.com
Dim objUrl As New System.Uri("http://www.google.com/")
' Setup WebRequest
Dim objWebReq As System.Net.WebRequest
objWebReq = System.Net.WebRequest.Create(objUrl)
objWebReq.Proxy = Nothing
Dim objResp As System.Net.WebResponse
Try
' Attempt to get response and return True
objResp = objWebReq.GetResponse
objResp.Close()
objWebReq = Nothing
Return True
Catch ex As Exception
' Error, exit and return False
objResp.Close()
objWebReq = Nothing
Return False
End Try
End Function

Answer 5

Public Function IsConnectionAvailable() As Boolean
' Returns True if connection is available
' Replace www.yoursite.com with a site that
' is guaranteed to be online - perhaps your
' corporate site, or microsoft.com
Dim objUrl As New System.Uri("http://www.yoursite.com/")
' Setup WebRequest
Dim objWebReq As System.Net.WebRequest
objWebReq = System.Net.WebRequest.Create(objUrl)
Dim objResp As System.Net.WebResponse
Try
' Attempt to get response and return True
objResp = objWebReq.GetResponse
objResp.Close()
objWebReq = Nothing
Return True
Catch ex As Exception
' Error, exit and return False
objResp.Close()
objWebReq = Nothing
Return False
End Try
'Here’s how you might use this function in your application:
If IsConnectionAvailable() = True Then
MessageBox.Show("You are online!")
End If

Answer 6

The following will check network connection availability and Internet connection both :
If My.Computer.Network.IsAvailable Then
Try
If My.Computer.Network.Ping("www.Google.com") Then
Infolabel.Text = "Computer is connected to the internet"
Else
Infolabel.Text = "Computer is not connected to the internet"
End If
Catch
End Try
Else
Infolabel.Text = "Computer is not connected to the internet"
End If