Presentation on Telnet & SSH

Guided By Ms. Preeti Jha Ms. Deepika Jain

Presented By Vinod Gour

Contents:-What is TELNET & SSH ?Why use TELNET & SSH ?Initial recruitment for configuration.Difference B/W TELNET & SSH. Configuration •For Ubuntu•For Window Troubleshooting. References

TELNET:-TELNET is an abbreviation for Terminal Network. It is the standard TCP/IP protocol for virtual terminal service, it proposed by ISO. TELNET enables the establishment of a connection to a remote system in such a way so that the remote system appears to an local system .

Telnet was developed in 1969 beginning with RFC 15Telnet is stateful protocols  like FTP.

In stateful protocol the client connects to the server, conducts a series of operations via that connection, and then disconnects, But in A stateless protocol server that treats each request as an independent transaction that is unrelated to any previous request.

Telnet is general-purpose client-server application program

TELNET (TErminal NETwork) is a general purpose client-server program that lets user access any application on a remote computer. It establishes a connection to a remote system, such that the local terminal appears to be a terminal at the remote system. We can do two type of log in through “TELNET Protocol” . 1. Local Log-in. 2. Remote Log-in.

Telnet use NVT Character Set

NVT stands for network virtual terminal .A network virtual terminal is responsible for basic terminal and provides a standard .It defines how data and commands are send across the network.It allows interoperability between telnet and a variety of heterogeneous components. 

SSHAnother popular remote login application program is Secure Shell (SSH). SSH, like TELNET, uses TCP as the underlying transport protocol.

Secure Shell (SSH) is a cryptographic  network protocol for secure data communication because SSH is more secure and provides more services than TELNET.

 It was designed as a replacement for Telnet and other insecure remote shell protocols such as the Berkeley rsh  and rexec  protocols

OpenSSH is the implementation of the SSH protocol. Basically in a short way of saying it, ssh is the proprietary software and openssh is the free open source version of ssh.

Why use Telnet & SSH

• TELNET & SSH is most often used to establish connections from a certain computer to a remote machine over a network, to execute commands and transfer file between them.

• Some time we are in the out side of the home or office and we have to perform some operation on the our computer which are placed on the home or office in this situation we can use the services of TELNET & SSH

Difference b/w Telnet & SSH

Telnet

• RFC 15 (1969)

• port 23

• Transmit in plain text

• Pure Text Interface

SSH

• RFC 4250(1995)

• port 22

• Public key encryption

• GUI possible and

other features

Configuration(Ubuntu)

Initial requirement for Configuration

• Our System should be updated.

• Synaptic Package Manager.

• Internet Connection.

• telnet , telnetd , openssh-client , openssh-server packages .

• Putty software & Mobassh-server.

• IP address , Username & password of remote machine.

Telnet Server Installation

First we run the update command on terminal.

Command- Sudo apt-get update

• Then Install telnet server to make our machine a remote server

for remote login.

Command- sudo apt-get install telnetd

telnetd -- DARPA TELNET protocol server

• sudo - execute a command as another user

• The apt-get command is a powerful command-line tool used

to work with Ubuntu's  Advanced Packaging Tool (APT)

performing such functions as installation of new software

packages, upgrade of existing software packages, updating of

the package list index, and even upgrading the entire Ubuntu

system.

Telnet Client Installation

• Install telnet client to make our machine a client for accessing

remote server.

Command - sudo apt-get install telnet

Connection to remote machine

Syntax:- telnet IPAddress Port No

PortNo - It is optional but well known port no. is

23 for telnet.

Ipaddress - remote machine Ipaddress

We will use logout command to close the connection.

• Then server ask for username and password After enter the

username and password we can login to remote host.

Operation perform on server’s file

We can see that welcome file exist on desktop.

• And now we can see that after execute rm command welcome file not

exist on server side

Server installation :-Command:- sudo apt-get install openssh-server

SSH(ubuntu)

Client Installation :-Command :- sudo apt-get install openssh-client

Connection Establishment

Command:- ssh username@ipaddress • This command run on the client side and username and

ipaddress of remote machine

GUI connection by SSH

• Go to the places on the menu bar and click on the “connect to

the server” then appear a dialog box. In this dialog box we

select the service type ssh and enter the server address , port

no. and username of the remote machine and click on the

connect button .

After the click on the connect button new dialog box appear for ask the

password like –

• After enter the password appear the new window for access server’s

file like-

Configuration(Windows)

Telnet configuration:-

• follow the following path.

• Path :- Control Panel\All Control Panel Items

\Programs and Features.

• Click on the turn windows features on or off and mark the

telnet client & telnet server checkbox in new appears dialog

box.

Connection Establishment

• Open the command prompt.

• Execute the following command-

telnet remotemachine ipaddress portno

SSH configuration

• First download & install the Mobassh Server on the remote

machine(Server side).

• Second download & install the putty software on the client

machine.

• Run the Mobassh server.

• Then client side run the putty software .

• Enter the ipaddress of remote machine and choose the

connection type.

• After that click on the open button.

After click on the open button new window appear and ask

for username and password like-

After the enter the user name and password server welcome page appear

and we can access any file of the remote computer.

Troubleshooting

1. When we install the package first time after installation the

ubuntu then some kind of problem occur like-

Unable to locate package package -name

• Solution – execute the sudo apt-get update command

2. If Internet Connection is lost during running process of update

command in ubuntu 11.04 and after we want again execute the

update command then some kind of error occur like-

Solution- remove the lock file by rm command

Command – sudo rm var/lib/apt/lists/lock

• Some time error occur during connection establishment to

remote machine through SSH like-

• Solution- Delete the known _host file by rm command

• Command- rm –f /home/username/.ssh/known_host

References

• http://www.slideshare.net/xtephan/network-telnet-ssh-5740946

• http://www.putty.org/

• http://mobassh.mobatek.net/

• http://www.zimmertech.com/tutorials/web-design/38/

webdesignbasics_ssh-telnet-basics.php

• http://medusa.sdsu.edu/network/CS576/Lectures/ch19_TELNET.pdf

• http://www.wikipedia.com/

Any Query ?