How to Install and configure telnet in RHEL / CentOS 5,6

It is recommended to use ssh instead of telnet to connect to a remote system for security purposes. Passwords are transmitted in plain text when you use Telnet. If you still want to use telnet, follow the steps below.

Install telnet

1. In order to turn Telnet on make sure that you have the correct telnet-server and telnet RPMs installed. To verify if you have the telnet packages installed, use the below command.

# rpm -qa | grep telnet
telnet-server-0.17-26.EL3.2
telnet-0.17-26.EL3.2

2. If you do not have the telnet-server or telnet packages installed, you can install them with the RPMs available from your installation media or you can use the yum utility to download and install the package(s). For example:

# yum install telnet-server telnet

Enable telnet

Once you have the packages installed, check the /etc/xinetd.d/telnet file and ensure that disable = yes is changed to read disable = no.

# vi /etc/xinetd.d/telnet
# default: on
# description: The telnet server serves telnet sessions; it uses \\
#       unencrypted username/password pairs for authentication.
service telnet
{
        flags           = REUSE
        socket_type     = stream

        wait            = no
        user            = root
        server          = /usr/sbin/in.telnetd
        log_on_failure  += USERID
        disable         = no
}

2. If the below line is uncommented in /etc/xinetd.conf then add telnet to the file.

# vi /etc/xinetd.conf
enabled = telnet

Turn the telnet server on

1. Turn the Telnet server on using the chkconfig command and then make the service available for immediate use with the service command.

# chkconfig --list telnet
telnet          off

# chkconfig telnet on

# chkconfig --list telnet
telnet          on

The chkconfig command will make the Telnet server available to start the next time the system is rebooted.

2. You will notice that Telnet is part of the xinetd daemon. In order to make the Telnet service available immediately, use service command to restart the xinetd daemon.

# service xinetd restart
Stopping xinetd:                                           [  OK  ]
Starting xinetd:                                           [  OK  ]

Verify

You should now be able to successfully Telnet to the server:

# telnet 192.168.10.10
Trying 192.168.10.10...
Connected to 192.168.10.10
Escape character is '^]'.
[snip]
login: user
Password:
Last login: Sat Nov  2 14:46:57 from 172.168.21.21