FTPS Tutorial

Imports Rebex.Net
Imports Rebex.Security.Certificates

' Create an instance of the Ftp class.
Dim ftp As New Ftp()

' Connect securely using explicit SSL.
ftp.Connect(hostname, SslMode.Explicit)

' Connection is protected now, we can log in safely.
ftp.Login(username, password)

' Specifies whether protection of transferred data is required.
' Default value of this property is "true", so this is not required.
ftp.SecureTransfers = True

Dim ftp As New Ftp()

' Connect to the server with no protection.
ftp.Connect(hostname, 21)

' Upgrade connection to SSL.
' This method also accepts an argument to specify SSL parameters.
ftp.Secure()

' Connection is protected now, we can log in safely.
ftp.Login(username, password)

Dim ftp As New Ftp()

' Connect securely using implicit SSL.
ftp.Connect(hostname, SslMode.Implicit)

' Connection is protected now, we can log in safely.
ftp.Login(username, password)

Dim ftp As New Ftp()

' Connect securely using explicit SSL and a custom port.
ftp.Connect(hostname, port, SslMode.Explicit)

' The Cipher property contains a lot of
' information about the current cipher
Dim cipher As TlsCipher = ftp.TlsSocket.Cipher
Console.WriteLine("Protocol: {0}", cipher.Protocol)
Console.WriteLine("Cipher: {0}", cipher.CipherAlgorithm)
Console.WriteLine("Key exchange: {0}", cipher.KeyExchangeAlgorithm)
Console.WriteLine("MAC algorithm: {0}", cipher.MacAlgorithm)
Console.WriteLine("All together: {0}", cipher)

' ServerCertificate property provides access
' to server certificate chain. The first certificate in the chain
' is the server's certificate.
Dim serverCert As CertificateChain = ftp.TlsSocket.ServerCertificate
Console.WriteLine("Subject: {0}", serverCert(0).GetSubject())
Console.WriteLine("Issuer: {0}", serverCert(0).GetIssuer())

' Specify desired arguments via Ftp's Settings property

' Only use suites that are currently considered secure.
ftp.Settings.SslAllowedSuites = TlsCipherSuite.Secure
' Allow both SSL 3.0 and TLS 1.0 protocols to be used.
ftp.Settings.SslAllowedVersions = TlsVersion.SSL30 Or TlsVersion.TLS10
' You can also specify the common name of
' the FTP server if it differs from its hostname.
ftp.Settings.SslServerName = hostname

' Connect securely using explicit SSL.
ftp.Connect(hostname, SslMode.Explicit)

' Connection is protected now, we can log in safely.
ftp.Login(username, password)

' Only use the specified cipher suites.
ftp.Settings.SslAllowedSuites =
 TlsCipherSuite.DHE_DSS_WITH_AES_256_CBC_SHA Or
 TlsCipherSuite.DHE_DSS_WITH_AES_128_CBC_SHA

' A custom certificate verification handler.
Private Sub ftp_ValidatingCertificate(sender As Object, e As SslCertificateValidationEventArgs)
    ' Use the built-in validation method to validate the chain.
    ' It is up to you to use another validation method if needed.
    Dim res As ValidationResult = e.CertificateChain.Validate(e.ServerName, 0)

    ' Accept the certificate if the chain is valid.
    If res.Valid Then
        e.Accept()
    End If

    ' If the chain is not valid, let's display the certificate
    ' information and validation status to the user and let
    ' him decide what to do.

    Dim cert As Certificate = e.CertificateChain(0)
    Dim shouldAccept As Boolean = SomeCustomDialog(cert, res.Status)

    If shouldAccept Then
        e.Accept()
    Else
        e.Reject()
    End If
End Sub

Dim ftp As New Ftp()

' Set the certificate request handler to
' CertificateRequestHandler.StoreSearch.
ftp.Settings.SslClientCertificateRequestHandler = CertificateRequestHandler.StoreSearch

' Connect securely using explicit SSL.
ftp.Connect(hostname, SslMode.Explicit)

' Connection is protected now, we can log in safely.
' Some servers may not require login if the client
' successfully authenticated itself using a certificate
' known to the server - there is no need to call the Login
' method in these cases.
ftp.Login(username, password)

Dim ftp As New Ftp()

' Load a certificate chain from a .PFX/.P12 file
' that contains a certificate and its private key.
Dim certificateChain As CertificateChain = certificateChain.LoadPfx(pfxCertPath, pfxPassword)

' Assing a certificate request handler based on
' the chain loaded from the PFX file.
ftp.Settings.SslClientCertificateRequestHandler = CertificateRequestHandler.CreateRequestHandler(certificateChain)

' Connect securely using explicit SSL.
ftp.Connect(hostname, SslMode.Explicit)

' Connection is protected now, we can log in safely.
' Some servers may not require login if the client
' successfully authenticated itself using a certificate
' known to the server - there is no need to call the Login
' method in these cases.
ftp.Login(username, password)

' A custom certificate request handler class.
' Implements ICertificateRequestHandler interface.
Public Class CustomRequestHandler
    Implements ICertificateRequestHandler

    ' This method gets called during the SSL handshake
    ' process if the server requests the client's certificate.
    Public Overloads Function Request( _
     ByVal socket As TlsSocket, _
     ByVal issuers() As DistinguishedName) _
     As CertificateChain _
     Implements ICertificateRequestHandler.Request

        ' Load the certificate with a private key from a PFX file.
        Dim path As String = "myCertificate.pfx"
        Dim cert As Certificate = Certificate.LoadPfx(path, "password")

        ' We actually need a certificate chain, so let's build one.
        Dim chain As CertificateChain = CertificateChain.BuildFrom(cert)
        Return chain
    End Function
End Class