Shulou(Shulou.com)06/01 Report--

This article mainly introduces "how to install and configure Telent services under the CentOS system". In the daily operation, I believe that many people have doubts about how to install and configure Telent services under the CentOS system. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the doubts about "how to install and configure Telent services under the CentOS system". Next, please follow the editor to study!

The purpose of Telnet

Telnet is the standard protocol and main way of Internet remote login service. Originally developed by ARPANET, it is now mainly used for Internet sessions. Its basic function is to allow users to log in to the remote host system.

Telnet allows us to sit in front of our own computers and log in to another remote computer through the Internet network, either in the next room or on the other side of the world. When logging on to the remote computer, the local computer is equivalent to a terminal of the remote computer. We can use our own computer to directly manipulate the remote computer and enjoy the same operation rights as the local terminal of the remote computer.

The main purpose of Telnet is to use information resources that the local computer does not have on the remote computer. If the main purpose of the remote computer is to transfer files between the local computer and the remote computer, then using FTP will be faster and more efficient.

Interactive process

When we log in to the remote computer system using Telnet, we actually start two programs: one is the Telnet client program, which runs on the local host, and the other is the Telnet server program, which runs on the remote computer to be logged in.

The Telnet client on the local host mainly performs the following functions:

Establish a TCP connection to the remote server.

Receives locally entered characters from the keyboard.

Change the input string to a standard format and send it to the remote server.

Receives output information from a remote server.

Display this information on the local host screen.

The "service" program of the remote host is often nicknamed "wizard". It usually waits quietly on the remote host and becomes active as soon as it receives a request from the local host and performs the following functions:

Notify the local host that the remote host is ready.

Wait for the local host to enter a command.

Respond to commands from the local host (such as displaying directory contents, or executing a program, etc.).

Send the results of the execution of the command back to the local computer for display.

Re-wait for commands from the local host.

In Internet, many services adopt such a client / server structure. For users, it is usually all they need to know about the client program.

Installation and use of Telnet

Yum install telnet

Yum installation is simple and fast.

The code is as follows:

Yum install telnet-server

Configure telnet

Telnet is put in xinetd, and change disable to yes, as follows:

The code is as follows:

# vim / 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 # changed from yes to no

}

If you need to use root to log in using telnet, add pts/0, pts1 and so on, otherwise skip this step

The code is as follows:

# cat / etc/securetty | grep pts

Pts/0

Pts/1

Pts/2

Pts/3

Start telnet

The code is as follows:

# service xinetd start

Starting xinetd: [OK]

Confirm whether to start or not

The code is as follows:

# netstat-lnt | grep: 23

Tcp 0 0:: 23: * LISTEN

Create a normal user

If you already have a user, you can skip this step.

The code is as follows:

# useradd ttlsa # create a user

# passwd ttlsa # change password

Changing password for user ttlsa.

New password:

Retype new password:

Passwd: all authentication tokens updated successfully.

Telnet connection testing

Log in using root

The code is as follows:

CentOS release 6.5 (Final)

Kernel 3.15.4-x86_64-linode45 on an x86_64

Login: root

Password:

Last login: Thu Feb 12 08:37:11 from 58.246.52.46

[root@li220-237] #

Ordinary user login

The code is as follows:

CentOS release 6.5 (Final)

Kernel 3.15.4-x86_64-linode45 on an x86_64

Login: ttlsa

Password:

$w

08:41:05 up 199 days, 21:57, 2 users, load average: 0.00, 0.01, 0.05

USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT

Ttlsa pts/1 51.241.12.49 08:40 1.00s 0.00s 0.00s w

Root pts/0 51.241.12.49 08:27 1:37 0.01s 0.01s-bash

At this point, the study on "how to install and configure Telent services under the CentOS system" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.