VB.NET

Close the SSH Tunnel

Demonstrates the Chilkat MailMan.SshCloseTunnel method, which closes the SSH tunnel used for SMTP or POP3 communication. This example opens and authenticates a tunnel, performs a mail operation through it, and then closes it.

Background: An SSH tunnel holds an open connection to the SSH server for as long as it is needed, so closing it releases both that connection and the resources on the SSH server. The natural pattern is open → authenticate → do mail work → close. It is the counterpart to SshOpenTunnel, and is separate from closing the mail connections themselves (CloseSmtpConnection / Pop3EndSession), which ride inside the tunnel.

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Dim success As Boolean = False

'  Demonstrates the MailMan.SshCloseTunnel method, which closes the SSH tunnel used for SMTP
'  or POP3 communication.

Dim mailman As New Chilkat.MailMan

'  Configure the POP3 server connection.
mailman.MailHost = "pop.example.com"
mailman.MailPort = 995
mailman.PopSsl = True
mailman.PopUsername = "user@example.com"
mailman.PopPassword = "myPassword"

'  Open and authenticate the SSH tunnel.
success = mailman.SshOpenTunnel("ssh.example.com",22)
If (success = False) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


success = mailman.SshAuthenticatePw("sshUser","sshPassword")
If (success = False) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


'  ... perform mail operations through the tunnel ...
Dim count As Integer = mailman.GetMailboxCount()
If (count < 0) Then
    Debug.WriteLine("Failed to get the mailbox count.")
Else
    Debug.WriteLine("Mailbox count: " & count)
End If


'  Close the SSH tunnel when finished with it.
success = mailman.SshCloseTunnel()
If (success = False) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("SSH tunnel closed.")