DataFlex

Connect to an SFTP Server Through a Jump Host

Demonstrates the Chilkat SFtp.ConnectThroughSsh method, which connects to an SFTP server through an already connected and authenticated Ssh object. The first argument is the jump-host Ssh object, and the second and third are the destination hostname and port.

Background: This is the "jump host" (bastion) pattern: the application connects to a reachable gateway, then tunnels onward to an SFTP server that is only accessible from inside the network. Each hop authenticates separately with its own credentials. The result is a normal SFtp object — still requiring its own authentication and InitializeSftp — that happens to be routed through the first connection.

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Variant vSshJump
    Handle hoSshJump
    Integer iPort
    String sPassword
    Handle hoSftp
    String sTemp1

    Move False To iSuccess

    //  Demonstrates the SFtp.ConnectThroughSsh method, which connects to an SFTP server through an
    //  already connected and authenticated Ssh object (a jump host).  The 1st argument is the Ssh
    //  object, and the 2nd and 3rd are the destination hostname and port.

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

    //  Connect and authenticate to the jump host first.
    Move 22 To iPort
    Get ComConnect Of hoSshJump "jump.example.com" iPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSshJump 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 hoSshJump "myJumpLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSshJump To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Connect to the SFTP server through the jump host.
    Get Create (RefClass(cComChilkatSFtp)) To hoSftp
    If (Not(IsComObjectCreated(hoSftp))) Begin
        Send CreateComObject of hoSftp
    End
    Get pvComObject of hoSshJump to vSshJump
    Get ComConnectThroughSsh Of hoSftp vSshJump "sftp.internal.example.com" iPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Authenticate to the SFTP server (its own credentials), then initialize SFTP.
    Get ComAuthenticatePw Of hoSftp "mySshLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComInitializeSftp Of hoSftp To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Connected to the SFTP server through the jump host."

    Send ComDisconnect To hoSftp
    Send ComDisconnect To hoSshJump


End_Procedure