What is Telnet and How to Telnet into a Router

What is Telnet

Working: Telnet is used to manage network devices at the command level. Unlike SSH which provides a secure connection, Telnet does not, and it simply provides a basic unsecured connection. It allows you to connect the remote computers over a TCP/IP network (such as the Internet). To make a connection to a telnet server or remote host use telnet client software on your computer. After establishing the connection with the remote host your client becomes a virtual terminal, allowing you to communicate with the remote host from your computer.

Many lower-level network devices support Telnet because it required no additional processing as compared to SSH. Caution the login credentials will be transmitted in the clear when connecting to a device using Telnet over a public network. It uses TCP/23 Port and also it is an application layer protocol.

Note: For login into the remote host, which requires you have an account on that system.

How to Telnet into a Router

How to Telnet into a Router

Configuring the Router R1 Serial Interface

Router> enable

Router# configure terminal

Enter configuration commands, one per line. End with CNTL / Z.

Router (config) # hostname R1

R1 (config) # interface serial 0/1//0

R1 (config-if) # ip address 192.168.1.1 255.255.255.0

R1 (config-if) # encapsulation ppp

R1 (config-if) # clock rate 64000

R1 (config-if) # keepalive 10

R1 (config-if) #no shutdown

R1 (config-if) #end

Configuring the Router R1 Interface FastEthernet

R1# configure terminal

R1 (config) #int fa0/0

R1 (config-if) #ip add 192.168.2.100 255.255.255.0

R1 (config-if) #no sh

R1 (config-if) #

Interface Status up

R1 (config-if) #exit

R1 (config) #int fa0/1

R1 (config-if) #ip add 192.168.3.100 255.255.255.0

R1 (config-if) #no sh

R1 (config-if) #

Interface Status up

R1 (config-if) #

R1#

Configuring the Router R2 Serial Interface

Router> enable

Router# configure terminal

Enter configuration commands, one per line. End with CNTL / Z.

Router (config) # hostname R2

R2 (config) # interface serial 0/1//0

R2 (config-if) # ip address 192.168.4.1 255.255.255.0

R2 (config-if) # encapsulation ppp

R2 (config-if) # keepalive 10

R2 (config-if) #no shutdown

R2 (config-if) #

Interface Status up

R2 (config-if) #end

R2#

Configuring the Router R2 Interface FastEthernet

R2# configure terminal

R2 (config) #int fa0/0

R2 (config-if) #ip add 192.168.5.100 255.255.255.0

R2 (config-if) #no sh

R2 (config-if) #

Interface Status up

R2 (config-if) #exit

R2 (config) #int fa0/1

R2 (config-if) #ip add 192.168.6.100 255.255.255.0

R2 (config-if) #no sh

R2 (config-if) #

Interface Status up

R2 (config-if) #end

R2 #

Ping Verification on Router R1 to R2

R1 # ping 192.168.4.1

Successful Ping Verification

R1#

R1# telnet 192.168.4.1

Trying 192.168.4.1 ...Open

[Connection to 192.168.4.1 closed by foreign host]

R1#

Note: Skip the word telnet and give only IP Address and press ENTER the result will be the same.

R1#192.168.4.1

Trying 192.168.4.1 ...Open

[Connection to 192.168.4.1 closed by foreign host]

R1#

Configure Enable and Line Passwords on Router R2

R2 (config) # line vty 0?

<0-15>

R2 (config) # line vty 0 4

R2 (config-line) # password Networking123

R2 (config-line) #login

R2 (config-line) #exit

R2 (config) #enable password Ithome

Telnet Verification on Router R1 to R2

R1#telnet 192.168.4.1

Trying 192.168.4.1 ...Open

User Access Verification

Password:

R2>en

Password:

R2#

Note: For security reasons, while typing passwords in Cisco, it won’t show the passwords. To move forward the password should be entered correctly otherwise you will not move forward.

R1#192.168.4.1

Trying 192.168.4.1 ...Open

User Access Verification

Password:

R2>en

Password:

R2#

Note: Now you have complete access to Router 2 and you can configure many commands as you want. Typing the Command LOGOUT or EXIT at Privileged EXEC Mode or Enable Mode one can terminate the session. If you want to go back on the Router R1 without breaking the session simply press Ctrl+shift+6 key combinations, Release it, and from the Keyboard press the X key.

R2#

(Press Ctrl+shift+6 key combinations, release it, and from the Keyboard press the X key).

R1#sh sessions

Telnet Session

R1#

Note:The above output shows that there is only 1 suspended session with host 192.168.4.1. Asterisk (*) next connection to 1 indicates that session 1 was one’s last session, and by pressing the ENTER twice one can return to one’s last session. By typing the connection number and pressing the ENTER key twice one can also return to any session.

R1# resume 1

[Resuming connection 1 to 192.168.4.1 ...]

R2#

R1# 1

[Resuming connection 1 to 192.168.4.1 ...]

R2#

Note: one can disconnect the session by issuing a command disconnect.

R1# disconnect 1

Closing connection to 192.168.4.1 [confirm]

R1#

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