Chabot College

CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY

Chabot CollegeChabot College

ELEC 99.08ELEC 99.08telnet


telnettelnet

• Uses services of Layers 7 - 1


telnettelnet• Functions:

– Tests layers 7 - 1– Remote access over the network to virtual terminal console of router.

Useful for remote administration.


telnettelnet• Listener:

– by default, hosts “listen” on port 23– telnet listener called “daemon” on unix, “service” on NT– Cisco routers listen for telnet on port 23– telnet login should be controlled with password.


telnettelnet• When you telnet to a remote router, your screen shows

the remote router’s prompt:

hayward# telnet fremonttrying 10.2.0.1…open

User access verificationPassword:fremont>

hayward fremont


telnettelnet• When you exit your telnet session on a remote router, you

return to the previous router’s prompt:

hayward# telnet fremonttrying 10.2.0.1…open

User access verificationPassword:fremont> exithayward#

hayward fremont


telnet - out & backtelnet - out & back• As you telnet from ‘hayward’ to other routers, you can

return to your “home” router each time:

hayward oakland sanfranciso



telnet to oakland

telnet to sanfranciso

home router

exit oakland


telnet - daisy chaintelnet - daisy chain• As you telnet from router to router, you can “daisy chain”

your sessions:



telnet to oakland


home router


telnet - daisy chaintelnet - daisy chain• As you you exit, you will return one hop at a time along

the chain:



telnet to oakland


home router


exit oakland


exit sanfrancisco


IOS telnet CommandsIOS telnet Commands

• To telnet to another router, use any of these:

hayward# telnet 10.0.2.1hayward# connect 10.0.2.1hayward# 10.0.2.1

hayward 10.0.2.1


IOS telnet CommandsIOS telnet Commands• You may also use host names, but only if

– DNS services are running and enabled, or– your router has an IP host table in its config

hayward# telnet fremonthayward# connect fremonthayward# fremont

hayward fremont (10.0.2.1)


IOS telnet CommandsIOS telnet Commands• To exit your telnet session and return to the previous

router’s prompt, use any of these:

fremont> exithayward#

hayward fremont

fremont> logouthayward#


telnet - exittelnet - exit• Be sure to exit your telnet session when done!• Don’t just close your hyperterm session and leave yourself connected to the remote router. If you don’t exit, the VTY

port you were using will remain busy and unusuable by other students. • Remember, there are only 5 VTY ports!

fremont> exithayward#


telnet practice - Router e_SIMtelnet practice - Router e_SIMTry it now with Router e-SIM:

– Start Router e-SIM

– Give all your routers a configuration:

• click SHOW DONE

• in the row of SET buttons at the bottom, click A, B, C, D, E

• click HIDE DONE

– Login - Password - cisco

Limitations: Router e-SIM understands only these commands:

– telnet xxx.xxx.xxx.xxx (IP Address)

– exit


telnet practice - Router e_SIMtelnet practice - Router e_SIM• Try these, in order:

Lab_A> telnet 201.100.11.2Lab_B> exitLab_A> telnet 199.6.13.2Lab_C> exitLab_A> telnet 210.93.105.2Lab_E> exit

Lab_A> telnet 201.100.11.2Lab_B> telnet 199.6.13.2Lab_C> telnet 204.204.7.2Lab_D> telnet 210.93.105.2Lab_E> exitLab_D> exitLab_C> exitLab_B> exitLab_A>

Out & back

Daisy chain

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