as far as I know the current (.NET 2.0 and 3.5) version of FtpWebRequest supports Explicit SSL only. Actually, .NET 2.0 does not currently support implicit SSL, only explicit. We will consider adding this for a future release. JonCole – MSFTModerator at MSDN forum post If you need to use both Implict and Explicit TLS/SSL … Read more
Extending the solutions that have been proposed so far, the issue is that implicit FTPS connections need the socket to be ssl wrapped automatically, before we get a chance to call login(). A lot of the subclasses that people are proposing do this in the context of the connect method, we can more generally manage … Read more
Indeed some FTP(S) servers do require that the TLS/SSL session is reused for the data connection. This is a security measure by which the server can verify that the data connection is used by the same client as the control connection. Some references for common FTP servers: vsftpd: https://scarybeastsecurity.blogspot.com/2009/02/vsftpd-210-released.html FileZilla server: https://svn.filezilla-project.org/filezilla?view=revision&revision=6661 ProFTPD: http://www.proftpd.org/docs/contrib/mod_tls.html#TLSOptions (NoSessionReuseRequired … Read more