DataFlex

SSH Commands to a Cisco Switch

Demonstrates establishing an SSH session with a Cisco switch (or similar device) and sending commands in a device console session. Each command is sent, and its output is read up to the device's next prompt.

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.

Background: Network devices differ from general-purpose servers in that they expose a menu- or prompt-driven console rather than a Unix shell, so exec requests are usually unavailable and driving the interactive console is the only option. That makes prompt matching the synchronization mechanism, and it is why a PTY is appropriate here despite the general advice to avoid one. Retrieving the received text between commands is essential: a prompt left in the buffer would make the next receive return immediately with the wrong output.

Chilkat DataFlex Downloads

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSsh
    Integer iPort
    String sPassword
    Integer iChannelNum
    Boolean iCaseSensitive
    String sCmdOutput
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

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

    //  Demonstrates establishing an SSH session with a Cisco switch (or similar device) and sending
    //  commands in a device console session.
    //  
    //  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.

    Get Create (RefClass(cComChilkatSsh)) To hoSsh
    If (Not(IsComObjectCreated(hoSsh))) Begin
        Send CreateComObject of hoSsh
    End

    Move 22 To iPort
    Get ComConnect Of hoSsh "172.16.16.100" iPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  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.
    Move "mySshPassword" To sPassword

    Get ComAuthenticatePw Of hoSsh "mySshLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Start a shell session.
    Get ComQuickShell Of hoSsh To iChannelNum
    If (iChannelNum < 0) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  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.
    Set ComReadTimeoutMs Of hoSsh To 15000

    Move True To iCaseSensitive

    //  The switch presents a prompt ending in "#".  Reading up to it confirms the session is ready.
    Get ComChannelReceiveUntilMatch Of hoSsh iChannelNum "#" "utf-8" iCaseSensitive To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetReceivedText Of hoSsh iChannelNum "utf-8" To sCmdOutput
    Get ComLastMethodSuccess Of hoSsh To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sCmdOutput

    //  Send a command and read its output up to the next prompt.
    Get ComChannelSendString Of hoSsh iChannelNum "show clock" + (character(10)) "utf-8" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComChannelReceiveUntilMatch Of hoSsh iChannelNum "#" "utf-8" iCaseSensitive To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Retrieving the text also clears the receive buffer, which matters: if the prompt were left
    //  buffered, the next receive would match it immediately and return the wrong output.
    Get ComGetReceivedText Of hoSsh iChannelNum "utf-8" To sCmdOutput
    Get ComLastMethodSuccess Of hoSsh To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sCmdOutput

    //  Additional commands follow the same send / read-to-prompt / retrieve pattern.
    Get ComChannelSendString Of hoSsh iChannelNum "show version" + (character(10)) "utf-8" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComChannelReceiveUntilMatch Of hoSsh iChannelNum "#" "utf-8" iCaseSensitive To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetReceivedText Of hoSsh iChannelNum "utf-8" To sCmdOutput
    Get ComLastMethodSuccess Of hoSsh To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sCmdOutput

    Send ComDisconnect To hoSsh


End_Procedure