Package: wnpp netkit-ftp-ssl is unmaintained/non-existing upstream and the package seems to be unmaintained as well (see related #986997).
The current maintainer of netkit-ftp-ssl, Mats Erik Andersson, is apparently not active anymore. Therefore, this package has been orphaned. Maintaining a package requires time and skills. Please only adopt this package if you will have enough time and attention to work on it. If you want to be the new maintainer, please see https://www.debian.org/devel/wnpp/#howto-o for detailed instructions how to adopt a package properly.
