Solved

Reverse Telnet -how does this work

Posted on 2001-09-16
5
795 Views
Last Modified: 2008-02-01
Can someone give me a run down on how to set up a reverse telnet scenario between a Cisco router and 2 attached switches.
0
Comment
Question by:Silas
5 Comments
 
LVL 8

Accepted Solution

by:
scraig84 earned 20 total points
ID: 6487452
I don't know how much info you were looking for, but it is pretty simple.  First off, you need to have a router with async ports.  Attach the async ports to the switches' console ports and configure the lines in the IOS config with something similar to:

line 110 111
 no exec
 disconnect-character 81
 transport input telnet

Last you telnet to the Cisco router, using the line # plus 2000 as the port.  Following the example above, if I was trying to go to the switch on line 110 and an IP address on the Cisco router is 1.2.3.4, I would type the following to get to the switch:

telnet 1.2.3.4 2110

One thing to remember when doing reverse telnet is to exit the exec session before terminating the telnet session.  If you don't, you may wind up leaving the switch in enbable mode.

The following link may help as well:
http://www.cisco.com/warp/public/793/access_dial/comm_server.html

Hope that gets you started.
0
 
LVL 1

Expert Comment

by:Chriskohn
ID: 6488275
Here is a link from Cisco that may help you
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/dial_c/dcrtelnt.htm   Hope this helps, Worker
0
 

Author Comment

by:Silas
ID: 6497254
line vty 0 4 makes sense to me, but line 110?  What exactly does that refer to?
0
 
LVL 8

Expert Comment

by:scraig84
ID: 6497297
It is a physical line, such as an asynch port.  If you add an async card to your router, you need to configure the physical aspects of these lines with the line command.  A vty line is a telnet line allowing inbound telnet connections.  When you reverse telnet, you are initiating a telnet session over a vty line to the router, and it is then initiating a physical connection over a physical line that was specified with the port used in the telnet command.

After you have added an async card, when you do a "show line", you will see the available TTY lines that it has associated with the async ports.  If you do a show line on any router, you will at least see the line numbers associated with the console port, and additionally you will see lines for an aux port and any vty lines you have created.

Hope that helps.
0
 
LVL 2

Expert Comment

by:irp
ID: 6524181
If you do not have async ports (from NM-16A, NM-4A/S, WIC-2A/S) etc. you can use the AUX port (1700 series upwards), which appears as different line numbers on different platforms. This obviously only gives you one port though.
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

In the world of WAN, QoS is a pretty important topic for most, if not all, networks. Some WAN technologies have QoS mechanisms built in, but others, such as some L2 WAN's, don't have QoS control in the provider cloud.
Quality of Service (QoS) options are nearly endless when it comes to networks today. This article is merely one example of how it can be handled in a hub-n-spoke design using a 3-tier configuration.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

809 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question