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 Post subject: Telnet into an instance of GNS3 running on another computer?
PostPosted: Sun Feb 06, 2011 10:14 pm 
Sorry if this has been answered, but I've done some searching and could not find any information.

I have GNS3 running on a desktop PC on my network and I'd like to use my laptop to telnet into the routers. I've tried to do "telnet <gns3.pc.ip.address> <router port>" (for instance, 'telnet 192.168.2.1 2001') but I get a connection refused error. Windows firewall is off on the host PC.

Is this something I can do easily? It seems like if the GNS3 machine is running telnet servers on those ports then I should be able to access them from anywhere on the network but clearly I've missed something or this isn't possible.

Any help is greatly appreciated.




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 Post subject: Re: Telnet into an instance of GNS3 running on another computer?
PostPosted: Mon Feb 07, 2011 7:52 am 
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Joined: Fri Mar 05, 2010 11:33 am
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Location: Australia
You have the right idea - if you have the IPs set up correctly and the firewall is off, there should be no reason why you can't console to the router.

BUT remember the router can only handle one console session - you CAN'T have the console opened on the PC emulating the router AND still telnet to the console from the remote PC. It is one or the other.

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GNS3 WorkBench-a VMware image of Ubuntu with GNS3 and VPCS installed and a collection of exercises/labs


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 Post subject: Re: Telnet into an instance of GNS3 running on another computer?
PostPosted: Mon Feb 07, 2011 1:55 pm 
rednectar wrote:
You have the right idea - if you have the IPs set up correctly and the firewall is off, there should be no reason why you can't console to the router.

BUT remember the router can only handle one console session - you CAN'T have the console opened on the PC emulating the router AND still telnet to the console from the remote PC. It is one or the other.

This may be my issue. I didn't realize they were limited to a single user. I will try again when I get home and if I'm still having problems I'm sure I'll post again! Thanks :)


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 Post subject: Re: Telnet into an instance of GNS3 running on another computer?
PostPosted: Tue Feb 08, 2011 12:51 pm 
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Joined: Fri Mar 05, 2010 11:33 am
Posts: 1494
Location: Australia
Just like a real router you can only have one console. However, a real router also has an Aux port, which works almost the same. Unfortunately there is a bug in Dynamips that prevents us using the Aux port giving a 2nd "console" connection, except for a 7200! There are some moves afoot to update Dynamips for GNS3 (see topic2995.html) which hopefully will fix this for other routers too.

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GNS3 WorkBench-a VMware image of Ubuntu with GNS3 and VPCS installed and a collection of exercises/labs


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 Post subject: Re: Telnet into an instance of GNS3 running on another compu
PostPosted: Thu May 01, 2014 5:55 am 
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Joined: Thu May 01, 2014 5:49 am
Posts: 3
Sorry to hijack your thread.

I am new to networking and my instructor recommended GNS3 as a great way to practice. I was wondering how to do this exact same thing but am a little confused on how to get the Telnet to allow me to access GNS3 running on a separate computer. I have PuTTY installed on both computers but which IP address do I use for the Telnet? Do I use the computers IP (ex. 192.168.1.1) or the the one for the GNS3 Router (ex. 127.0.0.1)?

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Mike

My name is Legion, for we are many. We are the Geth.


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 Post subject: Re: Telnet into an instance of GNS3 running on another compu
PostPosted: Thu May 01, 2014 10:55 am 
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Joined: Sun Sep 16, 2012 9:55 pm
Posts: 541
Location: England
gambyt wrote:
Sorry to hijack your thread.

We'll let you off this time... as a general rule especially with very old threads,it's probably best to start a new thread and reference any threads you've found using a link.

gambyt wrote:
I am new to networking and my instructor recommended GNS3 as a great way to practice.

First off... Welcome! Great to see GNS3 is being recommended as a method to learn!

gambyt wrote:
I was wondering how to do this exact same thing but am a little confused on how to get the Telnet to allow me to access GNS3 running on a separate computer. I have PuTTY installed on both computers but which IP address do I use for the Telnet? Do I use the computers IP (ex. 192.168.1.1) or the the one for the GNS3 Router (ex. 127.0.0.1)?

As you're new to networking, I'd rather not give you the answer straight away... but help you to get there yourself! What I would first suggest is to read up on IPv4 Addressing... in particular reserved addresses (e.g 127.0.0.1) and what they mean.

[1] http://en.wikipedia.org/wiki/Localhost
[2] http://en.wikipedia.org/wiki/IP_address

I hope that helps point you in the right direction! Feel free to ask more questions and we'll do our best to help!

Happy Networking!

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Daniel
Forum Moderator & Debian Package Maintainer for GNS3, Dynamips & VPCS.
Standalone DEB Packages are available from http://gns3.serverb.co.uk - To be updated!


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 Post subject: Re: Telnet into an instance of GNS3 running on another compu
PostPosted: Thu May 01, 2014 11:37 am 
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Joined: Fri Mar 05, 2010 11:33 am
Posts: 1494
Location: Australia
Quote:
Sorry to hijack your thread.


ditto for everything Dan said - and I just did a post on that subject topic9650.html

...but if you want
Quote:
to get the Telnet to allow me to access GNS3 running on a separate computer
then you should make sure the computer running GNS3 has set the IP/host binding: under Preferences <= Dynamips | [Hypervisor Manger] tab to 0.0.0.0

Here is an excerpt from my book GNS3 Network Simulation Guide which gives more detail

Quote:
Accessing a device console remotely
Before you can access the console remotely from another computer, you have to understand how Dynamips gives you access to the console on your local computer.
Dynamips directs the console and AUX physical ports to logical TCP connections. When you start a console session from GNS3, you are actually creating a telnet session to Dynamips, not a serial console connection like on a real router. By default, GNS3 sets the first router to listen on port 2101 (earlier versions used 2000 or 2001 by default) for the console connection, and 2501 for the AUX port. So to set up a console session to the Dynamips simulated router, all you have to do is telnet to your local computer’s relevant TCP port to access the virtual console or AUX router port. You of course already know that the internal IP of your computer is 127.0.0.1 – so in other words you telnet to 127.0.0.1:2101 to get a console session with your first router.
This actually has some implications. For instance, you could access your console by telnetting to port 2101 on your host computer’s IP address from another computer. But there is a catch. Since a bug fix in Dynamips, you have to change the host binding for Dynamips from 127.0.0.1 to 0.0.0.0 to allow this.


Disclaimer: I am the author of GNS3 Network Simulation Guide

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RedNectar
http://rednectar.net
@rednectarchris
GNS3 WorkBench-a VMware image of Ubuntu with GNS3 and VPCS installed and a collection of exercises/labs


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 Post subject: Re: Telnet into an instance of GNS3 running on another compu
PostPosted: Thu May 01, 2014 3:38 pm 
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Joined: Thu May 01, 2014 5:49 am
Posts: 3
Thank you both for the help and again sorry for hijack.



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Mike

My name is Legion, for we are many. We are the Geth.


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