telnet-telnet is a process  by which you can configure
router/switch having any physical connection by any means.

let understand it with a example
supose you are working in such comany that have one barnch
in bangalore and 2nd in punee.now you are workin in bangalore
after some time network of pune have some prob.the employ
have coneected you to solve it.then what do you do u donot
go the pune becoz it take time so telnet help you
by the telnet you can troublshoot the network of pune by
seating in the bangalore
so i can say that by telnet u can access the remote network
this is tellnet.


 SSH allows users to log into host systems remotely. Unlike
rlogin or telnet SSH encrypts the login session, making it
impossible for intruders to collect clear-text passwords.

SSH is designed to replace older, less secure terminal
applications used to log into remote systems, such as telnet
or rsh. A related program called scp replaces older programs
designed to copy files between hosts, such as ftp or rcp.
Because these older applications do not encrypt passwords
between the client and the server, you should avoid them
whenever possible. Using secure methods to remotely log into
other systems will decrease the security risks for both your
system and the system you are logging into.
Features of SSH

SSH (or Secure SHell) is a protocol for creating a secure
connection between two systems using a client server
architecture. Under the SSH protocol, the client machine
initiates all connections to a server.

The SSH protocol provides the following safeguards:

    *

      After an initial connection, the client verifies it is
connecting to the same server during subsequent sessions.
    *

      The client transmits its authentication information to
the server, such as a username and password, in an encrypted
format.
    *

      All data sent and received during the connection is
transferred using strong, 128 bit encryption, making
intercepted transmissions extremely difficult to decrypt and
read.
    *

      The client has the ability to use X11 [1] applications
launched from the shell prompt. This technique, called X11
forwarding, provides a secure means to use graphical
applications over a network. 


now how to configured the telnet and how to use it
go to router(config)#line vty 0 4
router(config-line)#login
router(config-line)#password *****

now how to use telnet

step 1 go to cmd mode
step 2 type telnet
microsft telnet> type here open
to (type default gateway ip address of router)
after that
another window open
login name:type the login name
password:
after entering the password
you are able to  telnet process

NOTE-telnet is also known as remote access


thanks
by jitendera sinha.i did done some spelling and
grammatically mistake plz forgave me.it was a long question
and it is possible that there is lots of speel mistake

do you know shridh i used telnet process to hack another
network.but don't do that becoz u r a employ and i am a fresher.