PureBasic

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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IncludeFile "CkSsh.pb"
IncludeFile "CkSFtp.pb"

Procedure ChilkatExample()

    success.i = 0

    ;  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.

    sshJump.i = CkSsh::ckCreate()
    If sshJump.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  Connect and authenticate to the jump host first.
    port.i = 22
    success = CkSsh::ckConnect(sshJump,"jump.example.com",port)
    If success = 0
        Debug CkSsh::ckLastErrorText(sshJump)
        CkSsh::ckDispose(sshJump)
        ProcedureReturn
    EndIf

    ;  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.
    password.s = "mySshPassword"

    success = CkSsh::ckAuthenticatePw(sshJump,"myJumpLogin",password)
    If success = 0
        Debug CkSsh::ckLastErrorText(sshJump)
        CkSsh::ckDispose(sshJump)
        ProcedureReturn
    EndIf

    ;  Connect to the SFTP server through the jump host.
    sftp.i = CkSFtp::ckCreate()
    If sftp.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkSFtp::ckConnectThroughSsh(sftp,sshJump,"sftp.internal.example.com",port)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSsh::ckDispose(sshJump)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    ;  Authenticate to the SFTP server (its own credentials), then initialize SFTP.
    success = CkSFtp::ckAuthenticatePw(sftp,"mySshLogin",password)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSsh::ckDispose(sshJump)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    success = CkSFtp::ckInitializeSftp(sftp)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSsh::ckDispose(sshJump)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

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

    CkSFtp::ckDisconnect(sftp)
    CkSsh::ckDisconnect(sshJump)


    CkSsh::ckDispose(sshJump)
    CkSFtp::ckDispose(sftp)


    ProcedureReturn
EndProcedure