(VB.NET) POP3 SSH Tunneling (Port Forwarding)

Demonstrates how to connect to a POP3 server through an SSH tunnel. Reads a POP3 mailbox and display the FROM and SUBJECT header fields of each email.

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

' The mailman object is used for receiving (POP3) 
' and sending (SMTP) email.
Dim mailman As New Chilkat.MailMan


' The SSH hostname may be a hostname or an 
' IP address, such as "192.168.1.108".
' The port is typically 22 (the standard port for SSH).
Dim sshHostname As String = "www.my-ssh-server.com"
Dim sshPort As Integer = 22

' Connect to an SSH server and establish the SSH tunnel:
Dim success As Boolean = mailman.SshOpenTunnel(sshHostname,sshPort)
If (success <> True) Then
    Debug.WriteLine(mailman.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 POP3 server, it is
' for authenticating with the SSH server, which is separate.
success = mailman.SshAuthenticatePw("ssh_login","ssh_password")
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


' OK, the SSH tunnel is setup.  The mailman may
' be used exactly the same as usual, except all communications
' are now sent through the SSH tunnel.

' The SSH tunnel may be kept open for any number of 
' POP3 connections.  

' Set the POP3 server's hostname
mailman.MailHost = "mail.my-pop3-server.com"

' Set the POP3 settings for your POP3 server:
mailman.PopUsername = "pop3_login"
mailman.PopPassword = "pop3_password"
mailman.MailPort = 995
mailman.PopSsl = True

' Connect to the POP3 server through the already-established SSH tunnel:
success = mailman.Pop3BeginSession()
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


' A visual inspection of the LastErrorText after
' a successful POP3 connection will confirm the SSH tunneling.
' Note: If the POP3 connection uses SSL/TLS, then the SSL/TLS 
' secure channel will be wrapped within the SSH tunnel.
Debug.WriteLine(mailman.LastErrorText)

' How many messages are in the POP3 inbox?
Dim numToDownload As Integer = mailman.GetMailboxCount()
If (numToDownload > 5) Then
    numToDownload = 5
End If

If (numToDownload = 0) Then
    Exit Sub
End If


' Download a max of 5 messages
Dim i As Integer
Dim email As Chilkat.Email
For i = 1 To numToDownload
    email = mailman.FetchByMsgnum(i)
    If (mailman.LastMethodSuccess = False) Then
        Debug.WriteLine(mailman.LastErrorText)
        Exit Sub
    End If

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

Next


' Close the connection with the POP3 server, leaving the SSH tunnel open for subsequent POP3 connections.
success = mailman.Pop3EndSession()
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


' Try connecting to a different POP3 server through the same aleady setup SSH tunnel:
' Set the POP3 server's hostname
mailman.MailHost = "mail.my-pop3-server2.com"

' Set the POP3 settings for your POP3 server:
mailman.PopUsername = "pop3_login2"
mailman.PopPassword = "pop3_password2"
mailman.MailPort = 110
mailman.PopSsl = False

success = mailman.Pop3BeginSession()
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


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

success = mailman.Pop3EndSession()
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


' Close the SSH tunnel.
success = mailman.SshCloseTunnel()
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If