SSH to a Cisco Switch - Processing "More" Responses

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Demonstrates connecting to a Cisco switch, entering privileged mode with the ena command, and running a command whose response is paged. Each page ends with --More-- and requires a SPACE character to request the next page.

Note: QuickShell allocates a PTY, which is what a network device console expects. The device presents an interactive prompt, and each command's output is read up to the next prompt.

Dim success As Boolean
success = False

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  Demonstrates connecting to a Cisco switch, entering privileged mode, and running a command
//  whose response is paged -- each page ends with "--More--" and requires a SPACE character to
//  request the next page.

Dim ssh As New Chilkat.Ssh

Dim port As Int32
port = 22
success = ssh.Connect("172.16.16.100",port)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
Dim password As String
password = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

Dim channelNum As Int32
channelNum = ssh.QuickShell()
If (channelNum < 0) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

//  IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
//  which means no limit -- without it, this call waits forever if the received data never
//  contains a match.
ssh.ReadTimeoutMs = 15000

Dim caseSensitive As Boolean
caseSensitive = True

//  In unprivileged mode the switch prompt ends with ">".
success = ssh.ChannelReceiveUntilMatch(channelNum,">","utf-8",caseSensitive)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

Dim received As String
received = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

System.DebugLog(received)

//  Send "ena" to enter privileged mode.  Cisco devices expect a bare CR to terminate a command.
success = ssh.ChannelSendString(channelNum,"ena" + EndOfLine.Macintosh,"utf-8")
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

success = ssh.ChannelReceiveUntilMatch(channelNum,"Password:","utf-8",caseSensitive)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

received = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

System.DebugLog(received)

//  The enable password is separate from the login password, and likewise should come from a
//  secure source rather than being hard-coded.
Dim enablePassword As String
enablePassword = "myEnablePassword"
success = ssh.ChannelSendString(channelNum,enablePassword,"utf-8")
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

success = ssh.ChannelSendString(channelNum,EndOfLine.Macintosh,"utf-8")
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

//  In privileged mode the prompt ends with "#" instead of ">".
success = ssh.ChannelReceiveUntilMatch(channelNum,"#","utf-8",caseSensitive)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

received = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

System.DebugLog(received)

//  Run a command whose output is delivered a page at a time.
success = ssh.ChannelSendString(channelNum,"show running-config" + EndOfLine.Macintosh,"utf-8")
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

//  Each read ends either at the device prompt (output complete) or at "--More--" (another page
//  is waiting).  Match the full prompt rather than a bare "#", because "#" also appears inside
//  configuration text and would match too early.
Dim saMatch As New Chilkat.StringArray
success = saMatch.Append("MySwitchName#")
success = saMatch.Append("--More--")

Dim sbReceived As New Chilkat.StringBuilder
Dim moreComing As Boolean
moreComing = True

While moreComing
    success = ssh.ChannelReceiveUntilMatchN(channelNum,saMatch,"utf-8",caseSensitive)
    If (success = False) Then
        System.DebugLog(ssh.LastErrorText)
        Return
    End If

    sbReceived.Clear 
    Dim pageText As String
    pageText = ssh.GetReceivedText(channelNum,"utf-8")
    If (ssh.LastMethodSuccess = False) Then
        System.DebugLog(ssh.LastErrorText)
        Return
    End If

    success = sbReceived.Append(pageText)
    System.DebugLog(pageText)

    //  If this page ended with "--More--", send a SPACE to request the next page.
    moreComing = sbReceived.Contains("--More--",caseSensitive)
    If (moreComing) Then
        success = ssh.ChannelSendString(channelNum," ","utf-8")
        If (success = False) Then
            System.DebugLog(ssh.LastErrorText)
            Return
        End If

    End If

Wend

ssh.Disconnect