How to Deny users Telnet or FTP access.

vi /etc/inetd.conf

Comment the line starts with Telnet or
FTP. Save the file and exit.

Stop and start the inetd daemon now by
following commands:

/etc/rc2.d/S72inetsvc stop

/etc/rc2.d/S72inetsvc start

(Your flavor may be /etc/init.d)

or
send a hang-up (HUP) signal to the inetd process to force it to reread the configuration file:

# pkill -HUP inetd

From now on, no one can telnet or FTP to your
server from outside network.