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using Telnet to get information from a Router using .net

Posted on 2009-07-16
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701 Views
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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