VB.NET

Upgrade an FTP Control Channel to TLS (ConvertToTls)

Demonstrates the Chilkat Ftp2.ConvertToTls method, which upgrades an already-connected clear FTP control channel to explicit TLS. It takes no arguments and is used with a manually staged connection created by ConnectOnly while Ssl is disabled.

Background: This exposes the explicit-FTPS AUTH TLS upgrade as a discrete step for the rare case where you need to do something on the clear connection first — inspect the greeting, apply a workaround — before securing it. In the normal case you simply set AuthTls and let Connect perform the upgrade automatically; this manual path exists for staged control.

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Dim success As Boolean = False

'  Demonstrates the Ftp2.ConvertToTls method, which upgrades an already-connected clear FTP control
'  channel to explicit TLS.  It takes no arguments.  It is used with a manually staged connection
'  created by ConnectOnly while Ssl is disabled.

Dim ftp As New Chilkat.Ftp2

ftp.Hostname = "ftp.example.com"
ftp.Port = 21

'  Connect in clear text first (Ssl is false).
success = ftp.ConnectOnly()
If (success = False) Then
    Debug.WriteLine(ftp.LastErrorText)
    Exit Sub
End If


'  Upgrade the control channel to explicit TLS (AUTH TLS).
success = ftp.ConvertToTls()
If (success = False) Then
    Debug.WriteLine(ftp.LastErrorText)
    Exit Sub
End If


'  Now authenticate over the encrypted control channel.
ftp.Username = "myFtpLogin"
ftp.Password = "myPassword"
success = ftp.LoginAfterConnectOnly()
If (success = False) Then
    Debug.WriteLine(ftp.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("Control channel upgraded to TLS and logged in.")

success = ftp.Disconnect()
If (success = False) Then
    Debug.WriteLine(ftp.LastErrorText)
    Exit Sub
End If