Enabling telnet is of great security risk to web server. It should be turned off to avoid further problems. Telnet sends clear text passwords and user names trough logins and therefore it should be disabled on servers and replaced with SSH. TELNET server listens for incoming messages on port 23, and sends outgoing messages to port 23

Follow the steps given below to disable the telnet on server.

a. Login to your server through SSH and su to root.

b. Type pico /etc/xinetd.d/telnet

c. Look for the line: disable = no and replace with disable = yes

d. Now restart the inetd service: /etc/rc.d/init.d/xinetd restart

e. Turn off it through chkconfig as well because it can still start through that.
/sbin/chkconfig telnet off

f. Scan your server to ensure port 23 is closed.
nmap -sT -O localhost
Also run ps -aux | grep telnet and if you find anything other than “grep telnet” as result kill the process.

by hostingcomments.com