(Visual Basic 6.0) 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.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

' Starting in v9.5.0.49, all Chilkat classes can be unlocked at once at the beginning of a program
' by calling UnlockBundle.  It requires a Bundle unlock code.
Dim chilkatGlob As New ChilkatGlobal
Dim success As Long
success = chilkatGlob.UnlockBundle("Anything for 30-day trial.")
If (success <> 1) Then
    Debug.Print chilkatGlob.LastErrorText
    Exit Sub
End If

Dim tunnel As New ChilkatSocket

Dim success As Long

Dim sshHostname As String
sshHostname = "www.my-ssh-server.com"
Dim sshPort As Long
sshPort = 22

' Connect to an SSH server and establish the SSH tunnel:
success = tunnel.SshOpenTunnel(sshHostname,sshPort)
If (success <> 1) Then
    Debug.Print 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 <> 1) Then
    Debug.Print 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 ChilkatImap

' Let the IMAP object also use the SSH tunnel
success = imap.UseSshTunnel(tunnel)
If (success <> 1) Then
    Debug.Print 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 = 1
imap.Port = 993
success = imap.Connect("imap.my-imap-server.com")
If (success <> 1) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' Authenticate with the IMAP server via the SSH tunnel.
success = imap.Login("myLogin","myPassword")
If (success <> 1) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' Select an IMAP mailbox
success = imap.SelectMailbox("Inbox")
If (success <> 1) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

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

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

' Download up to the 1st 10 messages.
Dim i As Long
Dim bUid As Long
bUid = 0
For i = 1 To upperBound

    Dim email As ChilkatEmail
    Set email = imap.FetchSingle(i,bUid)
    If (imap.LastMethodSuccess = 0) Then
        Debug.Print imap.LastErrorText
        Exit Sub

    Else
        Debug.Print email.From
        Debug.Print email.Subject
        Debug.Print "----"

    End If

Next

' Disconnect from the IMAP server.
' The SSH tunnel remains open.
success = imap.Disconnect()
If (success <> 1) Then
    Debug.Print 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 <> 1) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' Review the LastErrorText to see that the connection was made via the SSH tunnel:
Debug.Print 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 <> 1) Then
    Debug.Print 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 <> 1) Then
    Debug.Print 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 <> 1) Then
    Debug.Print tunnel.LastErrorText
    Exit Sub
End If

Debug.Print "IMAP pre-existing SSH tunnel example completed."