HOW TO INSTALL SSH SERVICE ON REDHAT ?

Secure shell (SSH) can be used to provide similar functionality as telnet, but it is much more secure. Telnet is consider insecure mainly because it sendsusername and password information in clear text. Therefore, telnet should be replaced with SSH.

How to install TELNET services on Linux?

Telnet is a Terminal emulation protocol that allows remote access to a system. Telnet can also refer to software which can be used by a client to remotely connect to and configure operating systems and network devices

TELNET uses TCP port 23 by default