Hello all. I have had some peers ask me for help in getting up and running quickly with GNS3 to help master the PIX/ASA.

Here is my step-by-step on that.

I am installing on the following system:

  • Alienware

  • Windows Vista Home Premium

  • AMD Athlon 64 X2 Dual Core Processor 5600+ 2.80 GHz

  • 4 GB RAM

Notice I am running Vista (sigh). There is a lot of misinformation out there about GNS3 not working with Vista. This is not true, as you will read below.

I head up to and download the WIN32-all-in-one EXE file available from the Download area. I run this EXE and proceed with the install. This is a “spousal” installation, just say YES (next) to everything the install wizard has to ask you. :-)

In order to get ready to run my first emulations, I have created a folder called c:\Cisco Images and I have placed the following images there c3725-advsecurityk9-mz.124-15.T7.bin, pix723.bin, and pix724.bin. I should mention that for all of this I want to be logged in as a Vista Administrator.

I now launch GNS3 and perform the following:

Step 1: In the Setup Wizard dialog click the large 1 button.

Step 2: Click the Dynamips option in the left pane and click the Test button on the Dynamips tab to ensure that Dynamips can be found successfully.

Step 3: Click Pemu in the left pane and in the Defaults PIX settings area, click the button and select your PIX image from your Cisco Images folder. In my case, this results in C:\Cisco Images\pix724.bin.

Step 4: Click the button for Base Flash: and select your base flash image. In my case, this results in C:\Cisco Images\pix723.bin.

Step 5: Click OK in the Preferences dialog.

Step 6: Click the large 2 button.

Step 7: Under the Settings area, click the button and choose your IOS image file from your Cisco Images folder.

Step 8: Choose Save and then Close from the IOS images and hypervisors dialog.

Step 9: Click OK in the Setup Wizard.

Step 10: In GNS3, drag your router model from the Nodes Type pane into the main topology pane. Right-click the router (R0) and choose Start.

Step 11: Right-click the router and choose Idle PC. Click OK in the IDLE PC dialog. Click OK in the next IDLE PC dialog.

Step 12: Drag the PIX firewall from the Nodes Type pane into the main topology pane. Right-click the firewall (FW0) and choose Start. NOTE: If your firewall fails to start with an error 209, it might be a Vista permissions issue. Close everything down. Right-click the file C:\Program Files\GNS3\pemuwrapper.exe and choose Run As Administrator. Then from the Start Menu, right-click GNS3 and choose Run As Administrator. You should be fine now.

Step 13: From the GNS3 toolbar, choose the Add a Link button. Click Manual. Click R0 and choose an interface and then click FW0 and choose an interface.

Step 14: You are now ready to configure your devices and start having some fun! Hover your mouse over a device you want to configure and notice the port number. Use your favorite terminal program (Terra Term, CRT, HyperTerminal) and connect to Localhost and that port number you just found.

Happy Emulating!

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18 Responses to “Using GNS3 to Help Master the PIX/ASA – Basic Setup and the First Emulation”

  1. Ivan Mendonca says:


    In GNS3, can we use most of the Layer 2 commands like private vlan, bridge group and many others. In dynamips I can’t user most of the Layer 2 commands.

  2. To Ivan:

    To practice with switches in GNS3 – you can throw a switch module in on of the 3700 series routers.

    The only problem is that many of the commands are pretty different from the 3550/3560 that is in the lab. I think the best way to go is to use PCs to emulate your routers – and then grab a couple of 3550s as cheap as you can to use in conjunction. Many on this site have done just that! Check out our Dynamips forum.

  3. To JanZ:

    Yes – I heard that as well – apparently – for now it is just the PIX – not the ASA.

  4. JanZ says:

    thanks for this useful post.can we run ASA image through the same process?i heard it is not the case?

  5. Sai says:


    when I console in FW, connection failed. (telnet 4000)
    when I telnet 10525, I got this error “200-At least a module and a command must be specified”
    Please help.

  6. Sai says:

    I Miss out something to describe. I’m using pix634.bin.
    I can console into the routers..

  7. Hello sai…I had to hover my mouse over the device to find the correct port number to use for telnet.

    Also – I have heard that it can be picky about versions of the PIX IOS. If you are sure the device started and you have the correct port number and it is still not working – you might want to try another image.

    Also – you can post your questions in the Dynamips area of and you might have more people that can help. I stopped using Dynamips for the PIX as I am now only studying on the ASA platform.

    Thanks for using our blog site!

  8. Sai says:


    Thanks for your reply. After I change the IOS version pix723.bin , I can manage to emulate.

  9. Wow – thanks for confirming that it is very version picky.

  10. Sikandar says:

    I am installing GNS3 on my system OS Windows Vista Home Premium 32 bit but the step-2 is failing.
    when i click the Test button on the Dynamips tab to ensure that Dynamips can be found successfully it showing this
    Failed to start Dynamips.what would be the possible issue & way out i followed all the above steps.

  11. Koike says:


    It´s a good idea to use BES (Battle Encoder Shirase) to limit the CPU utilization for PEMU and Dynamips as both consumes 100% of utilization and you can limit this utilization to less than 40% with newer CPU´s of 2.8GHz and above.
    Congratulations for this great tutorial!

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  13. Juan says:

    I’m having problem with GNS3 0.6.1 on Vista Ultimate, Can’t open the console (telnet to localhost). I activated the telnet client and tried to use the putty. Some help will appreciate…

  14. ray says:


    I had the same problem. I did the following to fix the issue.

    1. click on Edit
    2. click on Prferences
    3. click on Dynamips
    4. click on the browser button on the far right on the “Executable path:”.
    5. The correct path should look like this “C:\Program Files (x86)\GNS3\Dynamips\dynamips-wxp.exe”
    Well, at least for me.
    6. Then click “test” and it should work.

  15. Ashish says:

    Is anyone Installed ASA on GNS3 new released version (0.7) on WIndow Vista Platform
    Guide me too for the same… So I able to practice ASA labs on it…

  16. [..] A bit unrelated, but I quite simply liked this site post [..]

  17. piyush says:

    I am unable to connect 2 router with one pix firewall.So kinldly provide me configuration or guidance about connectivity with 2 router and one pix .

  18. Hello Dear
    I gone through this post, now i connect firewall and router and both start properly but when i access router through consle so it strats but firewall doesn’t ? Why any reason and solution


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