No sysadmin in their right mind is going to leave the telnet
port open on any of their machines. There is a reason why it is deactivated
in a default xinetd installation: it is completely unsecure.

All usernames and passwords travel over the line *unencrypted*. Astute use
of a packet sniffer can enable a 3rd party to gain root shell access to your
machine and wreak havoc.

Please, do consider deactivating telnet again and going for ssh instead.
It's secure, all data including usernames and passwords is encrypted before
being sent over the line.