Dim prx() As String
prx = System.IO.File.ReadAllLines(IO.Path.Combine(Application.StartupPath, _
  "proxy.txt"))
Me.ListBox1.Items.AddRange(prx)

 Private Shared Function OnlineCheck(ByVal proxy As String) As Boolean
        Try
            Dim wr As Net.HttpWebRequest = CType(Net.HttpWebRequest.Create( _
              "http://www.google.com"), Net.HttpWebRequest)
            wr.Timeout = 3000
            wr.Proxy = New Net.WebProxy(proxy)
            Dim resp As Net.HttpWebResponse = CType(wr.GetResponse,  _
              Net.HttpWebResponse)
            Return resp.StatusCode = Net.HttpStatusCode.OK
        Catch ex As Exception
            Return False
        End Try
    End Function