VB.NET

Set the FTP TLS Version and Ciphers

Demonstrates the TLS negotiation properties SslProtocol and SslAllowedCiphers, and reads back the negotiated TlsVersion and TlsCipherSuite after connecting.

Background: SslProtocol sets the allowed (or minimum) TLS version — default lets Chilkat negotiate the best available, while a value like TLS 1.2 or higher enforces a floor for policy compliance. SslAllowedCiphers narrows the offered cipher suites, which most applications should leave at the secure defaults. The read-only TlsVersion and TlsCipherSuite report what was actually agreed, useful for logging and audits.

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VB.NET

Dim success As Boolean = False

Dim ftp As New Chilkat.Ftp2

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

ftp.AuthTls = True

'  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"

'  Require at least TLS 1.2.  Accepted values include "default", "TLS 1.3", "TLS 1.2",
'  "TLS 1.2 or higher", and so on.  "default" lets Chilkat negotiate the best available.
ftp.SslProtocol = "TLS 1.2 or higher"

'  Optionally restrict the cipher suites offered.  Leave empty to use Chilkat's secure defaults.
ftp.SslAllowedCiphers = "TLS_AES_256_GCM_SHA384,TLS_CHACHA20_POLY1305_SHA256"

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


'  After connecting, read back what was actually negotiated.
Debug.WriteLine("Negotiated TLS version: " & ftp.TlsVersion)
Debug.WriteLine("Negotiated cipher suite: " & ftp.TlsCipherSuite)

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