VB.NET

Stop an SSH Tunnel Listener (StopAccepting)

Demonstrates the Chilkat SshTunnel.StopAccepting method, which stops the local listener so no new client connections are accepted. The only argument (waitForThread) selects whether to wait for the listener thread to exit. Existing forwarded clients remain connected.

Background: The distinction from CloseTunnel is the point: StopAccepting closes only the front door, leaving already-connected clients to finish their transfers undisturbed. That makes it the graceful way to drain a tunnel — stop taking new work, let existing work complete, then close — rather than cutting everyone off at once.

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Dim success As Boolean = False

'  Demonstrates the SshTunnel.StopAccepting method, which stops the local listener so that no new
'  client connections are accepted.  The only argument (waitForThread) selects whether to wait for
'  the listener thread to exit.  Existing forwarded clients remain connected.

Dim tunnel As New Chilkat.SshTunnel

tunnel.DestHostname = "db.internal.example.com"
tunnel.DestPort = 5432

Dim sshPort As Integer = 22
success = tunnel.Connect("ssh.example.com",sshPort)
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
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"

success = tunnel.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


Dim listenPort As Integer = 1080
success = tunnel.BeginAccepting(listenPort)
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


'  ... the tunnel runs for a while ...

'  Stop accepting NEW connections, but leave already-connected clients running.
Dim waitForThread As Boolean = True
success = tunnel.StopAccepting(waitForThread)
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("The listener has stopped; existing clients continue.")

Dim waitForThreadExit As Boolean = True
success = tunnel.CloseTunnel(waitForThreadExit)
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If