VB.NET Requires Chilkat v11.0.0+

IMAP Use Existing SSH Tunnel

Demonstrates how to connect to an IMAP server using an existing SSH tunnel. This creates a new channel within the SSH tunnel, which can be a TCP or TLS connection, and is connected to a remote IMAP server through port forwarding. VB.NET

Dim success As Boolean = False

'  This example assumes the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim tunnel As New Chilkat.Socket

Dim sshHostname As String = "sftp.example.com"
Dim sshPort As Integer = 22

'  Connect to an SSH server and establish the SSH tunnel:
success = tunnel.SshOpenTunnel(sshHostname,sshPort)
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


'  Authenticate with the SSH server via a login/password
'  or with a public key.  
'  This example demonstrates SSH password authentication.
'  Note: This is not authenticating with the IMAP server, it is
'  for authenticating with the SSH server, which is separate.
success = tunnel.SshAuthenticatePw("mySshLogin","mySshPassword")
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


'  OK, the SSH tunnel is setup.  Now open a channel within the tunnel.
'  Once the channel is obtained, the Socket API may
'  be used exactly the same as usual, except all communications
'  are sent through the channel in the SSH tunnel.
'  Any number of channels may be created from the same SSH tunnel.
'  Multiple channels may coexist at the same time.

Dim imap As New Chilkat.Imap

'  Let the IMAP object also use the SSH tunnel
success = imap.UseSshTunnel(tunnel)
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  Connect to an IMAP server via the already established SSH tunnel.
'  Because the SSH tunnel has been previously setup,
'  this does not establish a direct connection with the IMAP
'  server.  It directs the SSH server to establish the connection.

'  In this example, the IMAP server requires SSL/TLS.  The TLS connection
'  will be enclosed within the SSH tunnel.
imap.Ssl = True
imap.Port = 993
success = imap.Connect("imap.my-imap-server.com")
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  Authenticate with the IMAP server via the SSH tunnel.
success = imap.Login("myLogin","myPassword")
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  Select an IMAP mailbox
success = imap.SelectMailbox("Inbox")
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  How many messages in Inbox?
Dim msgCount As Integer = imap.NumMessages
If (msgCount = 0) Then
    Debug.WriteLine("No messages found.")
    Exit Sub
End If


Dim upperBound As Integer = 10
If (msgCount < upperBound) Then
    upperBound = msgCount
End If


'  Download up to the 1st 10 messages.
Dim email As New Chilkat.Email
Dim i As Integer
Dim bUid As Boolean = False
For i = 1 To upperBound


    success = imap.FetchEmail(False,i,bUid,email)
    If (success = False) Then
        Debug.WriteLine(imap.LastErrorText)
        Exit Sub
    End If


    Debug.WriteLine(email.From)
    Debug.WriteLine(email.Subject)

Next

'  Disconnect from the IMAP server.
'  The SSH tunnel remains open.
success = imap.Disconnect()
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  It is possible to re-use the existing SSH tunnel for the next connection:
success = imap.Connect("imap.my-imap-server2.com")
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  Review the LastErrorText to see that the connection was made via the SSH tunnel:
Debug.WriteLine(imap.LastErrorText)

'  This closes the SSH channel, which is the connection with the IMAP server.
'  It does not close the SSH tunnel
success = imap.Disconnect()
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  Finally, close the SSH tunnel.

'  Note: If other objects are using the same SSH tunnel, the tunnel is not 
'  actually closed.  It is only closed when the last object using the tunnel closes it.

'  At this point, both the imap and tunnel objects have references to the internal
'  SSH tunnel.  We need to close each.

'  This call doesn't actually close the tunnel yet, because the tunnel object still
'  holds an internal reference.
success = imap.SshCloseTunnel()
If (success = False) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


'  This actually closes the SSH tunnel because it's the last object using it.
success = tunnel.SshCloseTunnel()
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("IMAP pre-existing SSH tunnel example completed.")