Telnet is a very old communication protocol, it is not secure because the password authentication is transmitted in
clear text. SSH is a secure protocol and is the replacement for telnet. Red Hat recommends that you use SSH to
connect to the server, which is why Telnet is disabled by default. This is why the administrator account root is
not allowed to connect using Telnet by default. However you can also allow the root account to connect via telnet
by editing a file, it is recommended that you use su to logon as root.
Check to see if the correct telnet-server and telnet RPMs installed:
# rpm -qa | grep telnet
telnet-server-0.17-39.el5
telnet-0.17-39.el5
If the telnet-server or telnet packages is not installed, then it can be installed with the RPMs available on the
installation media or use the up2date utility along with your RHN subscription to download and install the
package(s). For example:
# up2date telnet-server telnet
You can also download the telnet rpm from website other than redhat and then use the command rpm -i
telnet-0.17-017-39.el5.rpm to install.
Once you have the telnet package is installed, edit the /etc/xinetd.d/telnet file and change the disable = yes to
read disable = no. See the example below.
{
flags = REUSE
socket_type = stream
wait = no
user = root
server = /usr/sbin/in.telnetd
log_on_failure += USERID
disable = no
}
Turn the Telnet server on using the chkconfig command and then make the service available for immediate use with
the service command. You will need to restart the xinetd service. If xinetd is not already started then the
restart command will start it.
# chkconfig telnet on
# chkconfig xinetd on
# chkconfig –list telnet
telnet on
# service xinetd restart
Stopping xinetd: [ OK ]
Starting xinetd: [ OK ]
The chkconfig command will make the Telnet server available to start the next time the system is rebooted, it will
also start the xinetd service. Telnet is part of the xinetd service.