VB.NET

FTP over Implicit TLS (Ssl, AuthSsl, AutoFix)

Demonstrates the SSL/TLS connection-mode properties Ssl, AuthSsl, and AutoFix. Setting Ssl true selects implicit FTPS, in which TLS begins immediately after the TCP connection on port 990.

Background: FTP has two ways to add TLS: implicit (this example) starts encrypted from the first byte on a dedicated port, 990; explicit (via AuthTls) connects in the clear on port 21 and issues AUTH TLS to upgrade. Explicit is the modern standard; implicit persists mainly for legacy servers. AuthSsl is an obsolete AUTH SSL variant to avoid. AutoFix, on by default, infers the mode from the port — disable it when you set these properties explicitly so it does not override your choice.

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Dim success As Boolean = False

Dim ftp As New Chilkat.Ftp2

ftp.Hostname = "ftp.example.com"
ftp.Username = "myFtpLogin"

'  Normally you would not hard-code the password in source.  You should instead obtain it
'  from an interactive prompt, environment variable, or a secrets vault.
ftp.Password = "myPassword"

'  Ssl = True selects IMPLICIT FTPS: TLS begins immediately after the TCP connection, before
'  the greeting.  Port 990 is conventional for implicit FTPS.  Ssl takes priority over AuthTls
'  and AuthSsl.
ftp.Ssl = True
ftp.Port = 990

'  AuthSsl selects the legacy AUTH SSL command and is very uncommon -- use AuthTls (explicit
'  FTPS) for modern servers instead.  Left False here.
ftp.AuthSsl = False

'  AutoFix (default True) automatically adjusts Ssl/AuthTls/AuthSsl based solely on the Port
'  (21 or 990).  Disable it when setting these properties explicitly, as here.
ftp.AutoFix = False

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


Debug.WriteLine("Connected using implicit FTPS.")

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