$ sudo apt-get update
$ sudo apt-get install inetutils-telnetd 

inetutils-telnetd is installed in your system.

Make ensure the inetutils-telnetd package were installed using the commands given below,

$ sudo dpkg-query -l | grep inetutils-telnetd *

You will get with inetutils-telnetd package name, version, architecture and description in a table

inetutils-telnetd package basic information: