DataFlex

Connect an SSH Tunnel Through a Jump Host

Demonstrates the Chilkat SshTunnel.ConnectThroughSsh method, which connects to an SSH 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 SSH hostname and port.

Background: This chains the tunnel through a "jump host" (bastion): the application reaches a gateway server, then tunnels onward to an SSH server that is only accessible from inside the network. Each hop authenticates separately with its own credentials. The result is a normal SshTunnel — still requiring its own authentication and BeginAccepting — whose transport is routed through the first connection.

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Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Variant vSshJump
    Handle hoSshJump
    Integer iSshPort
    String sPassword
    Handle hoTunnel
    Boolean iWaitForThreadExit
    String sTemp1

    Move False To iSuccess

    //  Demonstrates the SshTunnel.ConnectThroughSsh method, which connects to an SSH 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 SSH 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 iSshPort
    Get ComConnect Of hoSshJump "jump.example.com" iSshPort 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

    //  Set up the tunnel and connect to the target SSH server through the jump host.
    Get Create (RefClass(cComChilkatSshTunnel)) To hoTunnel
    If (Not(IsComObjectCreated(hoTunnel))) Begin
        Send CreateComObject of hoTunnel
    End
    Set ComDestHostname Of hoTunnel To "db.internal.example.com"
    Set ComDestPort Of hoTunnel To 5432

    Get pvComObject of hoSshJump to vSshJump
    Get ComConnectThroughSsh Of hoTunnel vSshJump "ssh.internal.example.com" iSshPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Authenticate to the target SSH server (its own credentials).
    Get ComAuthenticatePw Of hoTunnel "mySshLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  After authenticating, call BeginAccepting to start listening for local connections to forward.

    Move True To iWaitForThreadExit
    Get ComCloseTunnel Of hoTunnel iWaitForThreadExit To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Send ComDisconnect To hoSshJump


End_Procedure