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using Telnet to get information from a Router using .net

Posted on 2009-07-16
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Last Modified: 2012-05-07
Hello Experts,
         I am trying to get a stream of data from a router. If I use the commands on the command line they work fine. I am trying to get it to work in vb.net with no avail.  In the code pasted below I loop until I get a response for username and password which seems to work.  When I send the commands (system ,shell, top) I will get the response back "Username:telnet" or sometimes "password...".

Thanks in Advance
Bill
Dim myIPAddress As String = "192.168.1.1"
        Dim localAdd As System.Net.IPAddress = IPAddress.Parse(myIPAddress)
        Dim sock As TcpClient
        Dim s As String
        Dim n As Integer
 
        Try
            sock = New TcpClient()
            sock.Connect(myIPAddress, 23)
 
            Dim b As Boolean = sock.Connected
 
            Dim ns As NetworkStream = sock.GetStream
            Dim sr As New StreamReader(ns)
            Dim result As String
 
            Dim sw As New StreamWriter(ns)
           
            Dim b1 As Boolean
 
            Do Until n = 2
                If Not b1 Then
                    sw.WriteLine("telnet")
                    sw.Flush()
                End If
 
                result = sr.ReadLine
 
                If InStr(result, "Username") Then
                    sw.WriteLine("USERNAME")
                    sw.Flush()
                    b1 = True
                    n += 1
                End If
 
                If InStr(result, "Password") Then
                    sw.WriteLine("PASSWORD")
                    sw.Flush()
                    b1 = True
                    n += 1
                End If
 
            Loop
 
 
            sw.WriteLine("system")
            sw.Flush()
            result = sr.ReadLine
 
            sw.WriteLine("shell")
            sw.Flush()
            result = sr.ReadLine
 
            sw.WriteLine("top")
            sw.Flush()
            result = sr.ReadLine
 
            s = result
 
        Catch ex As Exception
            MessageBox.Show("Error " & ex.Message)
        Finally
            sock.Close()
        End Try

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Question by:bill_home
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4 Comments
 
LVL 28

Expert Comment

by:Jan Springer
ID: 24878098
If you don't get an answer to this question, you may want to consider 'rancid' to get the configuration data and changes or write something in perl using the expect module.
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Author Comment

by:bill_home
ID: 24878575
What is rancid?  I noticed that questions of this type are left un-answered all over the web.
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LVL 28

Expert Comment

by:Jan Springer
ID: 24878637
rancid is a tool that is used to monitor a device's configuration.

http://www.shrubbery.net/rancid/
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Accepted Solution

by:
bill_home earned 0 total points
ID: 24897321
I found out how to get around this, it was all about hand-shaking with tcpip I will put the solution here if anyone needs it.. kind of a kludge but it worked

 Dim sReadline As String = ""
        Dim passflag As Boolean
        Dim adminflag As Boolean

        Do
            sw.WriteLine("")
            result = sr.ReadLine
            sReadline = Mid(result, 1, 4)
        Loop Until sReadline = "User" Or sReadline = "Pass"

        Do
            If sReadline = "User" Or adminflag Then
                If ns.CanRead And ns.CanWrite Then
                    passflag = False
                    adminflag = True
                    sw.WriteLine("username")
                    result = sr.ReadLine
                    sReadline = Mid(result, 1, 4)
                End If
            End If


            If sReadline = "Pass" Or passflag Then
                If ns.CanRead And ns.CanWrite Then
                    passflag = True
                    adminflag = False
                    sw.WriteLine("password")
                    result = sr.ReadLine
                    sReadline = Mid(result, 1, 4)
                End If
            End If
        Loop Until sReadline = "Wire"

        Do
            sw.WriteLine("system")
            result = sr.ReadLine
            sReadline = Mid(result, 1, 7)
        Loop Until sReadline = "system>"

        Do
            sw.WriteLine("shell")
            result = sr.ReadLine
            sReadline = Mid(result, 1, 4)
        Loop Until sReadline = "Temp"

        Do
            sw.WriteLine("top")
            result = sr.ReadLine
            sReadline = Mid(result, 1, 80)
            If InStr(sReadline, "Mem", CompareMethod.Binary) > 0 Then
                MessageBox.Show(sReadline) 'mem load
                result = sr.ReadLine
                sReadline = Mid(result, 1, 80) 'blank line
                MessageBox.Show(sReadline)
                result = sr.ReadLine
                sReadline = Mid(result, 1, 80)  'cpu load
                MessageBox.Show(sReadline)
            End If
        Loop ' loop value on form for the amount of times to loop
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