### Telnet Server ###

 1. Shell interface on remote system
 2. Binds to TCP:23

Caveat:
 1. Clear-text based application (credentials are transmitted in the clear)
 2. By default, 'root' is NOT permitted access via telnet-server - /etc/securetty

Requirements:
 1. xinetd - installed automatically via yum

Install Telnet Server:
 1. yum -y install telnet-server
 2. nano /etc/xinetd.d/telnet - change 'disable = yes' to 'disable = no'
 3. service xinetd restart - effects changes

Tasks:
 1. Connect to both systems from either system using 'telnet' client
  a. telnet 192.168.75.199 - This will allocate a free pseudo-terminal, if the user authenticates successfully

Note: By default, telnet-server reads and dislplays the contents of: /etc/issue

Note: TCP|UDP ports are 16-bit based: 2**16, OR, 0-65535

Note: ptys are assigned sequentially, by default

 2. Enable 'root' login via telnet
  a. mv /etc/securetty /etc/securetty.disabled

Note: Wherever/whenever possible opt for SSH in place of Telnet Server