HI !

I am new so i am study CCNP security . I have already CCNP R&S and CCNA Wireless and Security

I hope i got to learn a lot here on this site. I dont know if it is impropret to ask a GNS3 question .

I am building av site-to-site tunnel for study but i dont get the cli in superputty to toggle and sometimes to start.

anyone that knows?

Hi Oskar,

Are you trying this on routers or an ASA in GNS3? Does it work if you use another program like putty, xshell or securecrt?


Hi Rene

Can you please give me a list of the best cisco IOS images for gns3, I downloaded few of them but I have all time some kind of problem, like cannot save configuration, they do not want start and similar, if you can please type here list of the best and the most stable version of them.


Hi Boris,

I always used this image:


It supports most of the commands and is stable, any newer version like T11, T12, T13 or T14 should also work.


Hi Rene,

I recently joined your website to prepare for my CCNP Route exam. I also downloaded GNS3, but now I want to know the legal way to get Cisco IOS images to run in my GNS3. Appreciate if you can help me with this.



HI Rene

I am a new member and working for a Service provider. I would like to know GNS3 can support for the Labs for CCIE-SP track



Hi Sam,

In the CP track you’ll need IOS XE/XR routers. I think you are better off trying Cisco’s VIRL for this.


Hi Tooryalai,

This is a “grey” area…the official statement from Cisco is that you are only allowed to run Cisco IOS on Cisco hardware, not on emulators. They kinda turn a blind eye to GNS3/dynamips though.

I guess the closest thing to make it “legal” is to buy the hardware, grab the IOS image from it and run it in GNS3. There’s only two problems:

  • Most used hardware is used for labs so there's a big chance it doesn't come up with the original IOS image. Most people download the latest advanced enterprise IOS image they can find and put it on their flashcards.
  • Not all IOS images work well in GNS3.

Personally I use Cisco’s VIRL nowadays. It’s legal, has support for IOS, L2 IOS, IOS XE/XR and the ASA.



I have a questions that’s been bothering me, how can I toggle through port switches on the Layer 3 switches in GNS3? for example the “switched” ports of Fa1/0 -> Fa1/15. This is killing me lol. I just need to connect fast1/0 to my router1 ans fast1/2 to my router2.



Hello Fabian,

Hmm I’m not exactly sure what you mean :slight_smile: Do you mean how you can change the interface numbers? This can be done by changing the slot modules on the router, that’s what affects the port numbers/interfaces.