I am trying to create a telnet client that will connect to several of my network devices on campus and change settings on the devices. So far I can connect with the code below, but I can't seem to get the correct return data from the device. Sometimes I get about 100 bytes and other times I get 3000 bytes. I even put a thread sleep but that still give me different return data from different devices. I know I am going to have to use an asynccallback but I just don't know how to do that. Any help would be great. I have also tried to use networkstream.d ataavailable but this still is sporatic data.
<%@ Page Language="VB" debug="true"%>
<%@ Import Namespace = "System.Web " %>
<%@ Import Namespace = "System" %>
<%@ Import Namespace = "System.Net.Soc kets" %>
<%@ Import NameSpace="Syst em.Threading" %>
<%@ import Namespace="Syst em.Data" %>
<%@ import Namespace="Syst em.Data.SqlClie nt" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dt d">
<script runat="server">
Dim tcpClient As New System.Net.Sock ets.TcpClient
Dim networkStream As NetworkStream
Dim numBytesRead As Integer
Dim returndata As String
Dim bytes(tcpClient .ReceiveBufferS ize) As Byte
Dim sendBytes As [Byte]()
Sub Page_Load(ByVal Source As Object, ByVal E As EventArgs)
tcpClient.Conne ct("10.6.8.0", 23)
networkStream = tcpClient.GetSt ream()
numBytesRead = networkStream.R ead(bytes, 0, tcpClient.Recei veBufferSize)
Send_Receive(vb Cr, "Ctrl-Y", 0)
Send_Receive(Co ntrolKeyPressed ("Y"), "Enter Password:", 0)
Send_Receive("m ypasswordis123" & vbCr, "Setup", 0)
Send_Receive("c ", "#", 0)
Response.Write( "<BR><BR>" & returndata)
Send_Receive("s how mac-address-table vid 20 address 000b.db6e.8208" & vbCr, "#", 1000)
Response.Write( "<BR><BR>" & returndata)
Send_Receive("l ogout" & vbCr, "Setup", 0)
sendBytes = Encoding.ASCII. GetBytes("l")
networkStream.W rite(sendBytes, 0, sendBytes.Lengt h)
'If networkStream.C anRead Then
' Response.Write( "loop 1")
' Dim myReadBuffer(50 00) As Byte
' Dim myCompleteMessa ge As StringBuilder = New StringBuilder()
' Dim numberOfBytesRe ad As Integer = 0
' ' Incoming message may be larger than the buffer size.
' Do
' numberOfBytesRe ad = networkStream.R ead(bytes, 0, 1)
' myCompleteMessa ge.AppendFormat ("{0}", Encoding.ASCII. GetString(bytes , 0, 5000))
' Loop While networkStream.D ataAvailable
' Thread.Sleep(10 0)
' ' Print out the received message to the console.
' Response.Write( ("You received the following message : " + myCompleteMessa ge.ToString()))
'Else
' Response.Write( "Sorry. You cannot read from this NetworkStream." )
'End If
tcpClient.Close ()
networkStream.C lose()
End Sub
' This function sends the Ctrl key to the telnet server
Function ControlKeyPress ed(ByVal character)
ControlKeyPress ed = Chr(Asc(charact er) - 64)
End Function
' This function sends data to the telnet server and waits for data to be returned from the telnet server.
Function Send_Receive(By Val Sending As String, ByVal Finding As String, ByVal Pause As Integer)
sendBytes = Encoding.ASCII. GetBytes(Sendin g)
networkStream.W rite(sendBytes, 0, sendBytes.Lengt h)
' Pause let the returned data buffer complete.
Thread.Sleep(Pa use)
Do
numBytesRead = networkStream.R ead(bytes, 0, tcpClient.Recei veBufferSize)
returndata = Encoding.ASCII. GetString(bytes , 0, numBytesRead)
bytes.Clear(byt es, 0, bytes.Length)
Loop While InStr(returndat a, Finding) = 0
Return returndata
End Function
</script>
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