VB.Net – Check Network Availability

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How do we check to see that a specific network is available, in Visual Basic .NET?

Solution

To see if any network is available you can use the VB.Net My namespace:

My.Computer.Network.IsAvailable

To see if you can use an available network to get to a specific server, you can use:

My.Computer.Network.Ping(host name or IP address, or a System.Uri)

DNS Test

Another solution was to test with DNS. This way you can test for specific names inside xxx network to tell if you are inside/outside. The nested try statements shows this concept:

Imports System.Net

Module Networker

Dim Online_Status As Boolean = vbFalse
Dim InsideJoeNetwork As Boolean = vbFalse
Dim CurrentJoeIPAddress As New IPHostEntry

Public ReadOnly Property GetOnlineStatus() As String
    Get
        Return Online_Status
    End Get
End Property

Public ReadOnly Property InsideJoeNet() As String
    Get
        Return InsideJoeNetwork
    End Get
End Property

Sub Initialize()
    Set_Online_Status()
End Sub

Public Sub Set_Online_Status()

    If My.Computer.Network.IsAvailable Then
        Try
            Dim DNSTest As IPHostEntry = Dns.GetHostEntry("google.com")
            If DNSTest.AddressList.Length > 0 Then
                Online_Status = True
                Detect_Joe_Network()
            Else : Online_Status = False
            End If

        Catch ex As System.Net.Sockets.SocketException
            Online_Status = False
        End Try
    End If
End Sub

Public Sub Detect_Joe_Network()

    If Online_Status = True Then
        Dim JoeIP As IPHostEntry = New IPHostEntry()

        Try
            JoeIP = Dns.GetHostEntry("laptop")
            If JoeIP.AddressList.Length > 0 Then
                InsideJoeNetwork = True
                CurrentJoeIPAddress = JoeIP
                'MessageBox.Show(JoeIP.HostName.ToString(), "JoeIP", MessageBoxButtons.OK, MessageBoxIcon.Information)
            End If
        Catch ex As Sockets.SocketException

            Try
                JoeIP = Dns.GetHostEntry("laptop.exampledomain.com")
                If JoeIP.AddressList.Length > 0 Then
                    InsideJoeNetwork = False
                    CurrentJoeIPAddress = JoeIP
                    ' MessageBox.Show(JoeIP.HostName.ToString(), "JoeIP", MessageBoxButtons.OK, MessageBoxIcon.Information)
                End If
            Catch ey As Sockets.SocketException
            End Try
        End Try

    End If
End Sub

End Module