TELNET is disabled or not installed by default in most UNIX/Linux machines for security reasons. To use TELNET, first, check your remote server to see if TELNET daemon is installed. If it is installed, follow the instructions below to enable the telnet service.
1. First, open /etc/xinetd.d/telnet
and set the disable to no.
disable = no
2. Then, restart xinetd:
Red Hat: /etc/rc.d/init.d/xinetd restart
SUSE: /etc/rc.d/xinetd restart
In most cases, you can choose SSH as an alternative connection method over TELNET. SSH provides much secure connection and adds extra features such as X11 forwarding and tunneling.