B4X

Continue SSH Tunnel Keyboard-Interactive Authentication

Demonstrates the Chilkat SshTunnel.ContinueKeyboardAuth method, which submits a response to a keyboard-interactive prompt. The only argument is the response text; for a request with multiple prompts, an XML response is supplied instead. It returns XML indicating the next prompt or the final result.

Background: This is the second half of the exchange started by StartKeyboardAuth. A server may issue several rounds of prompts, so a robust client loops: submit answers, read the returned XML, and continue until it sees success or failure. On success, BeginAccepting still must be called before the tunnel forwards traffic.

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Dim success As Boolean = False

'  Demonstrates the SshTunnel.ContinueKeyboardAuth method, which submits a response to a
'  keyboard-interactive prompt.  The only argument is the response.  For multiple prompts, an XML
'  response is supplied instead.

Dim tunnel As ChilkatSshTunnel
tunnel.Initialize("tunnel")

'  The tunnel forwards accepted local connections to this destination through the SSH server.
tunnel.DestHostname = "db.internal.example.com"
tunnel.DestPort = 5432

'  Connect to the SSH server.  This performs the TCP/proxy connection and SSH handshake, but
'  does not authenticate yet.
Dim sshPort As Int = 22
success = tunnel.Connect("ssh.example.com", sshPort)
If success = False Then
    Log(tunnel.LastErrorText)
    Return
End If


'  Begin keyboard-interactive authentication to receive the server's prompt(s).
Dim infoRequestXml As String = tunnel.StartKeyboardAuth("mySshLogin")
If tunnel.LastMethodSuccess = False Then
    Log(tunnel.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 = "mySshPassword"

'  Submit the response (typically the password).  The returned XML indicates the next prompt or
'  the final result.
Dim result As String = tunnel.ContinueKeyboardAuth(password)
If tunnel.LastMethodSuccess = False Then
    Log(tunnel.LastErrorText)
    Return
End If

Log(result)

Dim waitForThreadExit As Boolean = True
success = tunnel.CloseTunnel(waitForThreadExit)
If success = False Then
    Log(tunnel.LastErrorText)
    Return
End If