Network Scanner

Okay, i have achieved a part of my dreams in coding today. I've always wanted to write nifty little network tools that serve a purpose, today, I have actually written one, well at least the draft of a proof of concept for a larger project. Two key reference that I used to generate the code was: http://www.xtremevbtalk.com/showthread.php?t=321718

1:  Imports System  
2:  Imports SnmpSharpNet  
3:  Public Class Form1  
4:    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click  
5:      'check if keyed fields contain numeric only data,stop if they don't  
6:      If Not IsNumeric(Me.tb_f_o1.Text) Then Exit Sub  
7:      If Not IsNumeric(Me.tb_f_o2.Text) Then Exit Sub  
8:      If Not IsNumeric(Me.tb_f_o3.Text) Then Exit Sub  
9:      If Not IsNumeric(Me.tb_f_o4.Text) Then Exit Sub  
10:      If Not IsNumeric(Me.tb_t_o1.Text) Then Exit Sub  
11:      If Not IsNumeric(Me.tb_t_o2.Text) Then Exit Sub  
12:      If Not IsNumeric(Me.tb_t_o3.Text) Then Exit Sub  
13:      If Not IsNumeric(Me.tb_t_o4.Text) Then Exit Sub  
14:      tb_results.Text += "start" & vbCrLf  
15:      'convert text box values to integers  
16:      Dim a_to As Integer = CInt(Me.tb_t_o1.Text)  
17:      Dim a_from As Integer = CInt(Me.tb_f_o1.Text)  
18:      Dim b_to As Integer = CInt(Me.tb_t_o2.Text)  
19:      Dim b_from As Integer = CInt(Me.tb_f_o2.Text)  
20:      Dim c_to As Integer = CInt(Me.tb_t_o3.Text)  
21:      Dim c_from As Integer = CInt(Me.tb_f_o3.Text)  
22:      Dim d_to As Integer = CInt(Me.tb_t_o4.Text)  
23:      Dim d_from As Integer = CInt(Me.tb_f_o4.Text)  
24:      ' Use Parse() to convert from the integers to an IPAddress.  
25:      Dim fromAddress As System.Net.IPAddress = System.Net.IPAddress.Parse(a_from & "." & b_from & "." & c_from & "." & d_from)  
26:      Dim toAddress As System.Net.IPAddress = System.Net.IPAddress.Parse(a_to & "." & b_to & "." & c_to & "." & d_to)  
27:      ' We need the integral value of the IP. The Address property is deprecated. Use GetAddressBytes() and  
28:      ' convert the bytes to a value. If you are using IPv4, this should be 4 bytes, 32 bits, only Integer is needed.  
29:      Dim currentAddress As System.Net.IPAddress  
30:      Dim addressBytes() As Byte = fromAddress.GetAddressBytes()  
31:      Dim addressValue As Integer = BitConverter.ToInt32(addressBytes, 0)  
32:      Dim toaddressBytes() As Byte = toAddress.GetAddressBytes()  
33:      Dim toaddressValue As Integer = BitConverter.ToInt32(toaddressBytes, 0)  
34:      ' The bytes come out in network order; we don't want to figure out if that's backwards or not. Use this method  
35:      ' to convert to whatever the host machine uses.  
36:      addressValue = System.Net.IPAddress.NetworkToHostOrder(addressValue)  
37:      toaddressValue = System.Net.IPAddress.NetworkToHostOrder(toaddressValue)  
38:      For i = addressValue To toaddressValue  
39:        Dim thei As Integer = i  
40:        Dim theb() As Byte  
41:        ' We're ready to go back to bytes; convert the number back to network order  
42:        thei = System.Net.IPAddress.HostToNetworkOrder(thei)  
43:        ' Turn it back into bytes, create the new IP  
44:        theb = BitConverter.GetBytes(thei)  
45:        currentAddress = New System.Net.IPAddress(theb)  
46:        Dim thehostname As String  
47:        Try  
48:          thehostname = System.Net.Dns.GetHostEntry(currentAddress.ToString).HostName.ToString  
49:        Catch ex As Exception  
50:          thehostname = "Could not detect hostname"  
51:        End Try  
52:        tb_results.Text += " IP: " & currentAddress.ToString & " | Active: " & pinger(currentAddress.ToString) & " | Hostname: " & thehostname & vbCrLf  
53:        My.Application.DoEvents()  
54:      Next  
55:      tb_results.Text += "done" & vbCrLf  
56:    End Sub  
57:    Function pinger(ip As String)  
58:      If My.Computer.Network.Ping(ip) Then  
59:        Return (1)  
60:      Else  
61:        Return (0)  
62:      End If  
63:    End Function