Package: wnppftp is unmaintained/non-existing upstream and the package seems to be unmaintained as well (see related #986997). It should be removed in favour of tnftp (fully command-line compatible) and tnftp should provide a package transition. Whoever wants to use the netkit source can still install ftp-ssl.
If noone wants to adopt the package, I am going to file a RM bug in a month to enable implementing that transition.