Telnet in RHEL5

First check whether telnet-server rpm in installed,
# rpm -q telnet-server
telnet-server-0.17-38.el5
If it is installed, then edit
# vi /etc/xinet.d/telnet change the line disable= yes to disable = no
Then # service xinetd restart
Now We can able to telnet connection of linux system.
Note : It works for the system which is not protected with IPtables and Selinux
If you have iptables enabled. then please follow as below,
Make a rule to allow telnet from external clients
# iptables -I INPUT -p tcp --dport 23 -j ACCEPT
# service iptables save
# service iptables restart
Just give following command and make sure that rule is saved.
# iptables -L
This rule is to allow request coming to port number 23 i.e. telnet connections from any client.