How to setup ASA 5520 on GNS3

GNS3 (Graphical Network Simulator) is a fabulous open source software that emulates the routers and other networking hardware. It’s widely used for studying, designing and testing the networks.

Cisco ASA (Adaptive Security Appliance) is a very well-known firewall. It’s also one of the expensive hardwares. Thanks to GNS3, we can now emulate the latest ASA 5520 running ASA 8.4 and learn all about ASA and firewall technology.

The steps are as follows:

Step #1 : Download the ASA 8.4 initrd image and vmlinuz kernel zip file. Unzip it into a folder.

Step #2 : Create a Qemu virtual hard drive. If your GNS3 installation has multiple Qemu programs, choose the latest one. Open the command prompt as administrator and navigate into the GNS3 folder and run,

qemu-img create FLASH <Size>

This creates a virtual hard drive of size 512 MB in the qemu folder.

Step #3 : Start GNS3 and open the Preferences window (Ctl+Shift+P) from the edit menu. Click on Qemu VMs. And New.


Choose Qemu VM type as ASA 8.4(2) and give the VM a name. And click Next.


Select the appropriate Qemu binary, the 64-bit one if you’re system is 64-bit; and leave the default memory 512 MB to the VM.

Next browse and select the ASA initrd image and the Kernel image which you downloaded in step #1. And click Finish.


Step #4 : Advanced Settings

Click on Edit of the ASA-5520 we’ve just created and go to the Advanced settings tab.

ASA_Advanced Settings

Replace the Kernel Command Line and Options settings with the following :

Kernel Command Line : ide_generic.probe_mask=0x01 ide_core.chs=0.0:980,16,32 auto nousb console=ttyS0,9600 bigphysarea=65536 ide1=noprobe no-hltand

Options : -icount auto -hdachs 980,16,32 -vga none -vnc none


Click on the HDD tab and browse and select the FLASH virtual hard drive we created in step #2. And click OK.

ASA_Advanced Settings_FLASH

Step #5 : Verify the working of ASA.

Drag and drop the ASA-5520 from the Devices menu into the work space. Right click on the device and select start from the context menu. Right click on it one more time and select console.

ASA Verification

If everything goes right, you’ll see ASA booting in the console. After few minutes you’ll be presented with the ASA User mode prompt. Enter enable to get into the Privilege mode. The ASA prompts for a password; there’s no password. Hit Enter. Run show version to see the ASA software version (8.4) and the hardware ASA-5520. Enjoy!


About Deepak Devanand

Seeker of knowledge
This entry was posted in ASA, GNS3, Uncategorized and tagged , , , , , . Bookmark the permalink.

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