telnet-ssl binary package in Ubuntu Xenial s390x

 The telnet command is used for interactive communication with another host
 using the TELNET protocol.
 .
 SSL telnet replaces normal telnet using SSL authentication and
 encryption. It interoperates with normal telnetd in both directions.
 It checks if the other side is also talking SSL, if not it falls back
 to normal telnet protocol.
 .
 Advantages over normal telnet: Your passwords and the data you send
 will not go in cleartext over the line. Nobody can get it with
 tcpdump or similar tools. With SSLtelnet you can also connect to
 https-server like https://www.mozilla.org. Just do
 'telnet -z ssl www.mozilla.org 443'

Source package