telnetd binary package in Ubuntu Xenial s390x

 The in.telnetd program is a server which supports the DARPA telnet interactive
 communication protocol.
 .
 This legacy server should in general be abandoned in favour of a contemporary
 ssh-server, as this implementation only is able to process password and user
 name in clear text. Other variants, like telnetd-ssl and a selection of
 Kerberized TELNET servers, are able to improve on this by providing secure
 forms of authentication and encryption.

Source package