linux-ftdp-ssl is the netkit ftp server with
encryption support. ftpd-ssl replaces normal ftpd
using SSL authentication and encryption. It
operates together with normal ftp. It checks if the
other side is also talking SSL, if not it falls back to
normal ftp protocol. Advantages over normal ftp(d)
are that your passwords and the data you send
will not go in cleartext over the line, and nobody
can get it with tcpdump or similar tools.