Looking for cisco help

I am a student studying for my CCNA. i am currently in second semster of the four semster class. We have recently started to bang routers, as they call it. i was wondering how to terminate a telnet session into a 2600 series cisco router, i believe its running IOS version 11.3 though i maybe wrong it might be 10.3... i just know for sure its not 12.0... for example if i am aware of a telnet session between my router and another how do i dissconnect the other from my router?

this is kinda weird but whe like to have config wars in the class... kind juvenile but quite fun...

I think this is what you are looking for

Suspend and Terminate Telnet Sessions

Quote:

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To suspend and then disconnect a Telnet session, perform the following steps:

Step 1 Suspend the Telnet session by entering Ctrl-Shift-6 x:

- suspend keystroke -
router#


Step 2 Enter the where EXEC command to check for open sessions:

router# where
Conn Host Address Byte Idle Conn Name
* 1 172.16.1.10 172.16.1.10 0 0 172.16.1.10
2 172.16.1.11 172.16.1.11 0 12 modem2


Step 3 After suspending a session with one modem, you can connect to another modem (then suspend it):

router# telnet modem2
Trying modem2 (172.16.1.11, 2002) ... Open

- suspend keystroke -
router#


Step 4 To disconnect (completely close) a session, issue the disconnect EXEC command:

router# disconnect line 1
Closing connection to 172.16.1.10 [confirm] y
router# disconnect line 2
Closing connection to 172.16.1.11 [confirm] y
router#

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source is here

If you are not on a switched network or you can be on the same hub as your router then you can install a packet sniffer to capture packets to the router on port 23. When you have detected someone attacking your router you could use a tool that crafts packets, (google for them), to send a RST to the IP of the attacker.

If you want to automate the defense use snort, (www.snort.org) with a dynamic rule to send an RST to any station that attempts to connect, (sends a SYN), on port 23.

Then again - you could just turn off Telnet on the exposed port......

wow, that was quick guys thanks alot!

to terminate a telnet session. you can do it in a couple of ways. if you dont want anyone to telnet into your router just do these simple instructions:

router#conf t
router_conf#line vty 0 4
router_conf#no password

this will actually deny any telnet in your router.

if you need anymore help let me know.

wow atomic! thanx i knew that but i completley forgot... are you certified or just intelligent? or both? i love playing with routers and routing but im scared of what the industry is like.... but i cant wait to be able to do this for a living... thanks alot guys

From the sounds of it you are in a lab environment...
You can easily see if anyone is connected via telnet by the 'who' command:

router#who
or
router#show user

This will show all of the active telnet sessions and what vty or line they came in on. You can then kill their session by clearing the line of the session their using.

router#clear line x (where x is the the vty or line number obtained in the who command)

Removing the passwords will disable telnet all together, making the rtr accessible only via the console port. Applying an acl to the vty would add some security but is outside the scope of ccna. I too lived for config wars...

I made a 5 mill allotted for the budget for the network, it isn’t to big especially for 11 schools and I don’t really know what they have to spend so I deemed 5 mill a fair price but we will see what can be done at the data center I will be looking to get a connection. For a base line I have decided to have enough bandwidth for the worst case scenario of each student to have at the same time running 4 video streams of 320x200 video x 15 fps x 20k students x 50% growth I know this is extreme but this is the kind of robustness I deem necessary for a real life test I came up with a bandwidth of 38.4 Gigabytes seems I may have went a little overboard but we will see this is a brainstorm with further input I may be able to come to a compromise or be forced to lol. I was going for a 16 blade server with NAS storage multiplexing at each school site so that is 11 schools. Plus have 5 or 6 blade servers at the data center. I also think I should have RAIC implemented for data integrity. As far as an operating system for the server I would like to implement Linux SE mainly over open BSD because of the support. Also I will try to push for mainly html and java based apps for the thinness of the apps because ill be running a thin client such as either 3comm audery or a more expensive Sun Ray thin client. At the data center I am looking at a 10 Gig internal switch such as foundry or comparable and dual FDDI ring for redundancy this posses the question of say a terroristic disaster takes place and takes out the data center with RAIC I have a way of restoring data but I need to have a redundant path for internet connection. was looking toward satellite or maybe microwave don’t know yet I am just coming up with a rough draft also for security I will have a firewall that can be configured specifically for each school at each site and a main firewall at the data center because say napster comes out with a client that uses pop3 and or http and telnet or something each site will need to have a way to policy their access on a school specific scale I don’t want the robustness of my network eaten by the data center firewall also I will need to have a networked printer in each room I did have the idea of just having a shared printer or 2 on each floor but the fact teachers will have to leave classes unattended isn’t in the best interest.

Ok now I have decided for the backbone connection from internet service provider at the data center to go with one of the Big Iron jet core Gig series switches now I need to decide on what router I want to go with. It would be nice to have matching systems that complement each other u know I don’t want to go overboard on one device and not enough on another. I am going with big iron by foundry because it’s brutal from the data center I am going to have it tie in to 100 meg switches at the schools I am looking to have like 40 to 50 48 port switches with 100 meg ports at each school and routers associated with it to have a uniform system. I was looking at the Cisco 10,000 series routers but may be able to get by with less what do u think also I really should implement Cisco routers and maybe switches at the schools being I am a Cisco guy lol. Input on this would be greatly appreciated thanks

Mishka-

It doesn't seem like the mid-west is that bad. I'm at CA and very close to silicon valley. Our school is so backward on technology it's not even funny! Here are some examples:

1) The CCNA teacher said "All networks must have cables"
2) The network is down at least once every month and the school turns the cheap switches on and off until it works again.
3) The administration REFUSED to assign accounts to each student in order to kick out those who violate rules.
4) We don't HAVE routers to play with ='(

benzenequeen-
wow.. im sorry... i dont know what to say with out laughing.. hehe oh well... im sorry... i guess im lucky when it comes to that... we got a file system sharing thing going on with a huges server in the middle of our campus... the only thing about that is... the only poeple who know who to use are the students that are in the computer classes.... NO ONE ELSE KNOWS HOW TO LOG IN!!! and they installed this proggie called Deepfreeze that freezes the hard drive and anything that is put on it gets deleted next boot up except for what was frozen... all they did was put signs up that said "Dont save on the hard drive" after the frist semester students started to relize what had heppend... so they started using disks... now in the english lab.... 1 out of every 4 floppy drive is broekn or has a metal thing stuck in it froma bad disk... and apprently no one knows what a zip disk is... :)