Tag Archives: GNS3

Configuring Cisco ASA 8.4(2) on GNS3 1.3.13

In one of my previous post (link here) I did a description on how to configure and run an ASAv instance on GNS3 1.4.5. In this post I will describe the steps required to configure and run a Cisco ASA 8.4(2) image on GN3 1.3.13.

Why in this case I insisted to use the previous version suite 1.3.x of GNS3 (1.3.13 at the moment of this writing) instead of the latest available 1.4.x suite ? The answer is because for ASA 8.4(2) to run successful, a QEMU emulator of version 0.11.0 needs to be in place and functional or as it seems, the QEMU 0.11.0 categorically refuse to work in GNS3 1.4.x suite (even it is installed here). Somewhere in forums found that GNS team will no longer offer support for QEMU 0.11.0 in its product. Maybe in one of the future releases but certainly not now …

Someone might ask, why not just use the 2.4.0 version of QEMU present and functional in both GNS3 versions suites ? The truth is that it works, but with a little issue, a very slow speed through device interfaces. In my testings, a simple ASDM image copying can take several hours with a high chance for device crashing. Types and number of NICs, license or whatever else doesn’t change the situation.

So, because of unavailability of QEMU 0.11.0 in GNS3 1.4.x I switched back to 1.3.x version suite. Why then, I didn’t use the 1.3.x suite in my previous article for an ASAv instance configuration ? It is because we needed the VNC console for ASAv initial configuration or that is present only in newer 1.4.x suite.

To conclude: for ASAv you will need GNS3 1.4.x (because of VNC console) and respectively for ASA 8.4(2) you will need the GNS3 1.3.11 (because of QEMU 0.11.0). At least in my testings, this offer me a stable and workable setup.

Note0: do not mix the GNS3 1.3.13 and GNS3 1.4.x on the same machine, simply because they wasn’t designed to work together, configuration that most probably lead to complete nonfunctional setup.

Why bothering also with ASA in addition to ASAv ? Doesn’t ASAv being sufficient ?

Well, the ASAv is a software designed to run in virtual infrastructure and such that, some features are no longer needed here. Take simple, what ASA doing by clustering, in virtual infrastructure with ASAv is accomplished by hypervisor’s High Availability features, multiple contexts are replaced by multiple standalone ASAv instances and so on. To be more precise, that’s the unsupported features that that the official documentation (link here) states: The ASAv does not support the following features: clustering, multiple context mode, active/active failover, EtherChannels, Shared AnyConnect Premium Licenses.

So in case you want to play with ASA clustering or multiple context mode you will need a classic ASA instance running in GNS3. ASAv is good but not always sufficient. Even so, ASAv should be your standard, especially since it is somewhat closer to VIRL style.

What images are needed to run ASA in GNS3 ?

Compared to ASAv where an original qcow (KVM) image was sufficient to configure the device in GNS3, for ASA the original bin image are not sufficient. The truth is that this original image needs to be unpacked, then some files modifications needs to be done and after that repack the content in a way suitable for QEMU. All of this can be done manually or scripted (see GNS3 forums for Cisco Image Unpacker for Windows or repack.v4.sh shell script for Linux) but imho, if you not search for a specific ASA version just do a search on the Internet for ASA 8.4(2) GNS3 files. Other versions should be also be available to. In any case, you should be left with two files: asa-vmlinuz (a Linux kernel) and asa-initrd.gz (a RAM disk file). These are the files used by QEMU in GNS3.

How to configure Cisco ASA 8.4(2) in GNS3 1.3.13 ?

  1. Download the latest version for 1.3.x GNS3 version suite. To do that, go to GNS3 web site – avoid the download button witch will direct you only to GNS3 1.4.x download, instead, click on software  (top bar menu) – on the left, written with small font size, click on To download Version 1.3.13 of GNS3 Click Here (see screenshot below). After, authentication a download for GNS3-1.3.13-all-in-one.exe file should start.

art - configuring Cisco ASA 8.4(2) on GNS3 1.3.13 - download page

  1. Install the 1.3.13 GNS3. No rocket science here, just follow the installation wizard. Setup will install one by one all the components needed: Dynamips, QEMU, GNS3, WinPcap, Wireshark and many others parts.
  2. Initial GNS3 configuration. At this step, I usualy configure some general, non-essential, GNS3 preferences:


    1. General – Local paths – projects/binary images – redirected to a shorted path, e.g. C:\GNS3\projects and respectively C:\GNS3\images
    2. In Topology View change the default label text style to a less accentuated one.
    3. In Miscellaneous – disable the Automatically check for update and Automatically send crash reports options.
  3. Create a new Cisco ASA device by starting New QEMU VM template from Edit – Preferences – QEMU VMs – New menu. Use the following parameters:


    1. Type: ASA 8.4(2)
    2. Name: ASA5520-8.4(2) or any meaningful title you choose
    3. Qemu binary: leave the default qemu.exe (v0.11.0)
    4. RAM: 1024MB or more, 1024 is the minimum
    5. Initial RAM disk (initrd): select RAM disk file, e.g. asa8420-initrd.gz
    6. Kernel image (vmlinuz): select Kernel image file, e.g. asa842-vmlinuz

I will recommend to store original OS images in other folder than that used by GNS3 for image storage. When you specify an image to be used by GNS3 a copy of that original file would be automatically copied to GNS3 binary image folder location.

After device creation, edit VM configuration and add up to 6 network adapters (network section). Leave the rest parameters untouched.

art - configuring Cisco ASA 8.4(2) on GNS3 1.3.13 - ASA device summary settings

art - configuring Cisco ASA 8.4(2) on GNS3 1.3.13 - ASA device general settings    art - configuring Cisco ASA 8.4(2) on GNS3 1.3.13 - ASA device HDD

 art - configuring Cisco ASA 8.4(2) on GNS3 1.3.13 - ASA device network    art - configuring Cisco ASA 8.4(2) on GNS3 1.3.13 - ASA device advanced settings

Note1: The steps above was successfully tested inside a Virtual Machine with Windows Server 2012R2 as a guest OS. The VM was provisioned with 2x vCPU and 8GB RAM and run on an ESXi host. Physical server equipped with Intel Xeon E5320 1.86GHz CPU.

Note2: There is no need for: Expose hardware assisted virtualization to the guest OS …No VT-x needed inside the Virtual Machine.

Use the newly created ASA device template

Now, you can use the newly created ASA device template, just drag the device to the map pane, build the topology and start it. Open console, if everything is ok you should see a typical ASA OS loading progress. After a minute, you will be faced with long awaited Cisco ASA CLI (use empty password for privileged exec mode).

You can use as many Cisco ASA instances in your projects as you want, sure no more than your hardware permit. Every time you instantiate a new Cisco ASA device, a flash disk device is created and mounted automatically for each Cisco ASA instance thus no additional steps for virtual disk creation needed. You can find the qcow virtual disk file (flash.qcow2) associated to your ASA device in project folder/project-files/qemu/dev-uiid/ folder.

Usualy, the first step before using ASA is to put a license key. If you do a simple google search you will find several freely flying license keys. Just use one of them. For me, it turned out to be ok the following activation key: activation-key 0x7212d04a 0xe041d3fe 0x1d22f820 0xea5440e4 0x8231dd9f … which unlike other keys does not hung loading progress for several minutes after activation.

Configuring Cisco ASAv 9.x on GNS3 1.4.x

Recently I went through an interesting experience of Cisco ASA setup in GNS3. I must say it was a real challenge, but finally, not an impossible task. There is a lot of particularities you must take into account, all depending from ASA version to GNS3 release. In this post, I will focus on how to configure an ASAv firewall to run as a QEMU VM in new GNS3 version suite 1.4.x. As of date of this writing I was able to access ASAv image version 9.5(2.204) and the GNS3 1.4.5 setup.

The 1.4.x suite of GNS3 is a relatively new appearing into the scene, and how is typical with new software releases, surely expected to have some bugs and/or incompatibilities. That’s why my first attempts was made in previous software suite of 1.3.x version (actually 1.3.13 version). It was a wrong way, because how I realized soon, for ASAv to be configured, a VNC console should be attached, or in 1.3.13 I didn’t found how to do that (is not excluded that I missed something). As a consequence, I quickly switched to newest GNS3 1.4.5 version. The following text assume a newly setup of GNS3 version 1.4.5 with no additional settings, except maybe only for the default location for project and binary images folder – I prefer to reconfigure these on C:\GNS3\Projects and respectively C:\GNS3\Images.

Cisco ASA virtual appliance (ASAv)

Cisco ASAv is a re-imaged version of Cisco ASA specifically designed to run as a VM on top of some hypervisor. In fact, the same ASA code is running, but in different form factor. There are versions for vSphere, Hyper-V and KVM. Just because GNS3 use QEMU as a VM emulator we will employ the KVM image of ASAv. By the way, ASAv is the image Cisco use in their notable virtual labs VIRL. Not all ASA versions are available in a VM format – I suppose only those starting with 9.x, thereby if you want to try some older versions, e.g. popular ASA 8.4(2), you will need to experience another approach (a new article devoted to this subject should come). It’s worth noting that the ASAv have some limitations compared to classical ASA, in particular you wouldn’t be able to build firewall clusters (failover or A/A), test multiple context mode feature or play with Etherchannel. For this scenarios, I usualy use an 8.4(2) ASA setup – which, by the way should run only in QEMU 0.11.0 which in turn can’t be started in GNS 1.4.x, only in previous suite 1.3.x !!!.

So, before we start we need to obtain somewhat the ASAv image. If you are fortunate enough to have access to Cisco downloads (a service contract associated with your profile is needed) then just go to cisco.com – All downloads – Products – Security – Firewalls – Adaptive Security Appliances (ASA) – Adaptive Security Virtual Appliance (ASAv) and download the qcow2 (KVM) image of ASAv for your preferred version.

configuring Cisco ASAv 9.x on GNS3 1.4.x - download page for Cisco ASAv

In case you do not have access to official Cisco downloads, yet I recommend to try a simple Internet search, good chances are to find somewhere a leaked image (usualy on some China resources). To be honest, I can’t understand why Cisco restrict downloads to this type of software, anyway, next after setup you will need a license key to go over the limitations of unlicensed state of appliance (bandwith limitation to 100kbps). It would be fine if Cisco would allow download and free use of appliance in unlicensed state, respectively for production usage a suitable license should be bought.

Configuring ASAv template on GNS3

A step by step guide follow:

  1. Start new QEMU VM Template wizard with following parameters:

    1. Type: Default
    2. Name: ASAv-8.5(2.204) or any meaningful title
    3. Qemu binary: qemu-system-x86_64w.exe (v2.4.0)
    4. RAM: 2048 MB
    5. Disk Image (hda): C:\GNS3\images\QEMU\asav952-204.qcow2

Note: I will recommend to store original OS images in other folder than that used by GNS3 for image storage. When you specify an image to be used by GNS3 a copy of that original file would be automatically copied to GNS3 binary image folder location.

  1. Edit newly created QEMU Template:

    1. General settings – Symbol :/symbols/asa.svg
    2. General settings – Category: Security Devices
    3. General settings – Console Type: VNC

Note0: in my testing, I tried to change vCPUs from 1 to 4, but nothing more than 1514 Illegal Instruction (core dumped) … error message got in ASAv, hence don’t touch that value, we will set the number of vCPUs in other place for ASAv to be an SMP virtual machine.

Note1: Switching the console to VNC type one it’s like directly connect with a keyboard and a monitor to the virtual machine. Initial ASAv configuration don’t allow access to the serial console port so at least at this stage, the only possible option is VNC. Don’t forget, the ASAv was designed to play in a VM with a full console. Even so, we will configure serial console port to ASAv as well.

  1. Network – Adapters: 6x (default e1000 type)
  2. Advanced Settings – Additional settings – Options: -cpu Haswell -smp 4,sockets=4,cores=1,threads=1

Note0: I successful used this string for all my Intel CPU. The microarchitecture (Haswell, Nehalem and so on) seems to no matter – successfully ran on different CPU generation with no problems. For AMD CPUs, community recommend to use (haven’t tested): -cpu Opteron_G5 -smp 4,sockets=4,cores=1,threads=1

Note1: the default option’s value: –nographic, should be cleared. This will be guarantee an automatic VNC console opening (for non-linked mode VM operation).

  1. (Optional) Activate CPU throttling – Percentage of CPU allowed: 80%
  2. Advanced Settings – uncheck: Use as a linked base VM.

configuring Cisco ASAv 9.x on GNS3 1.4.x - qemu ASAv template - summary

configuring Cisco ASAv 9.x on GNS3 1.4.x - qemu ASAv template - general settings    configuring Cisco ASAv 9.x on GNS3 1.4.x - qemu ASAv template - hdd

configuring Cisco ASAv 9.x on GNS3 1.4.x - qemu ASAv template - network    configuring Cisco ASAv 9.x on GNS3 1.4.x - qemu ASAv template - advanced settings

I think I will provide some additional inputs about the setting named: Use as a linked base VM. By default, QEMU VMs works as a linked VM which means that every time you create a new QEMU VM (in our case ASAv) in your project, a linked virtual disk is created to the original qcow2 image. All the modifications are thus recorded in that new file but yet unmodified block are read from original image. Through this, we can create hundreds of new QEMU VMs without needing to clone the virtual disk (that’s the similar to the technology used in VDI). Given the fact that during the life of an ASAv VM, disk modifications are really very few, results that the disk overhead created by each new ASAv are truly negligible. If you disable linked VM mode (uncheck the: Use as a linked base VM) the QEMU VM will interact directly with original qcow2 virtual disk (all writes will be recorded here). As a consequence a single QEMU VMs from this template can be started (just try to drag and drop a second ASAv to workspace and you will see an error message).

Why then we intentionally disabled linked base VM mode? First off, we need this only during ASAv template making and after this we will switch back to linked mode. Our interest is to do a series of configuration changes (first boot, serial console, ASDM image upload) in the original image file which we want to keep in all new ASAv instances created from this template.

Surely, the same results can be achieved by making the template in linked mode (linked qcow2 virtual disk) and then committing all the changes to the original qcow2 image via qemu-img.exe tool, but, I think it is harder. Just disabling and then re-enabling the VM’s linked mode settings seems to be much easier … the choice is yours.

To check the virtual disk that is mounted to QEMU VM just drag a new ASAv to an empty project, right click ASAv device – and choose show in file manager. An explorer window to qcow2 image opens – with linked mode disabled this would be the template image asav952-204.qcow2 located in binary image folder, whereas for linked mode this would be a qcow2 image (somewhere in project’s folder) linked to the original template – base virtual disk image. Also, additionaly you can check what qcow2 images are involved via Windows resource monitor – CPU – Associated Handles – filter by QEMU string.

  1. Drag a new instance of ASAv 9.5(2.204) to the working space on an empty project in GNS3. No topology are needed to continue, just single, unconnected ASAv device.
  2. Power-ON newly instantiated ASAv device (right-click – start) and immediately open the console (right-click – console).  In opened VNC terminal a loading progress (Linux) can pe observed.
  3. On Boot Loader phase choose the option: bootflash:/asa952-204-smp-k8.bin with no configuration load (anyway no configuration yet exists).

configuring Cisco ASAv 9.x on GNS3 1.4.x - bootloader

  1. In the meantime, it would be interesting to do some analyzing in Resource Monitor. First, to confirm the SMP nature of started QEMU VM look at the number of threads/CPU associated with qemu-system-x86_64w.exe process (CPU – Processes) – should be more than 4x thread/CPU in use, and second, to confirm the non-Linked mode of operation for the ASAv VM do a search in Associated Handles for a qemu key (CPU-Associated Handles) – in non-Linked mode, the VM should interact directly with the original qcow2 image: asav952-204.qcow2 (a screen is inserted below).

screen resource monitor - qemu treads plus handler not linked mode - 2

At the command prompt the number of vCPU can be checked by the show cpu usage commmad:

ciscoasa# sh cpu usage
CPU utilization for 5 seconds = 1%; 1 minute: 1%; 5 minutes: 0%

Virtual platform CPU resources
Number of vCPUs              :     4
Number of allowed vCPUs      :     0
vCPU Status                  :  Noncompliant: Over-provisioned

  1. If you carefully track the booting progress you will see that the appliance will discover that it starts for the first time (Initial bootup detected …) and for the system variables to be applied an automatic reboot will come.  So first time booting will end up with an automatic reboot. On the second boot, also choose the option with no configuration load in Bootloader Dialog. First and second time booting could take some time to progress so be patient and wait them to complete – sometimes it may seem that the appliance hung, try to wait several minutes before doing a forced powering off.
  2. If everything goes smoothly, after the second boot, you should reach the traditional Cisco command line prompter (empty password for privileged mode). At this stage, we will enable the serial console for the appliance. By default, the ASAv works only with traditional VM console (monitor/keyboard directly connected to x86 hardware) and additional steps needed to enable console via serial ports. More about that you can read here ASAv Quick Start Guide, 9.5, section Configure a Network Serial Console Port.

For serial console to be on, a file named use_ttyS0 should exist in root of disk0. It doesn’t matter the content, just to be present. The simplest mode to create such a file is to make a copy of an existing file – the documentation suggest to clone from coredump.cfg file, like shown below:

ciscoasa(config)# cd coredumpinfo

ciscoasa(config)# copy coredump.cfg disk0:/use_ttyS0

  1. Theoretically, here, we can do also some additional configurations, one that we want to keep in all the ASAv instances derived from this template. For example, we can copy here the ASDM image to disk0 to not be bothered with that in the future. Anyway, I will skip this step.
  2. Reload de appliance (type reload in privileged mode). You will see that the command prompt can’t anymore be accessed via de VNC console. I mean, the console will open, but, at one moment the interaction will be handover to the serial console and no more activity going to be possible by VNC. The last message recorded in VNC confirm that: Lina to use serial port /dev/ttyS0 for console IO.

configuring Cisco ASAv 9.x on GNS3 1.4.x - qemu ASAv template - console handover

  1. Now, after all the modifications to the ASAv image, we can switch the template back to his original Linked mode of operation. Also, we will switch the console settings to telnet type. Do the configuration changes in template settings, not in ASAv instance. The ASAv device from our temporary project can be safety removed, it has already done his job.

Using newly created ASAv template

To use the newly created ASAv template, just drag the template icon to the workspace, do your connections and power-on the device. You can use multiple ASAv devices running simultaneous with no problem, on my PC (i7-4970s CPU with12GB RAM) I ran five concurrent instances, all started ok and became usable shortly (less than 1 min).

Just because we don’t mention –nographic in template’s Advanced Settings – Additional Settings the VNC console will automatically open every time you start the device. If you close that window, the appliance will power-off automatically. The VNC console don’t interfere with serial console which you can open via context menu. If you add the -nographic option, the VM will start silent without a VNC console. Anyway, my preference is to leave the VNC console to open automatically, at least for the begging, just to have an additional visibility of the process.

After you load the ASAv device, you will periodically be announced by a missing license warning message: Warning: ASAv platform license state is Unlicensed … It is because the appliance don’t have a license key applied and it works in unlicensed state. As mentioned above, for lab and test scenarios, an unlicensed state are more than sufficient. In this state, you will get all the ASAv features but at the same time be limited to 100 Kbps interface bandwith.

It is interesting to see what virtual disks files are involved for an ASAv device started from our completed template. Beacause the template was configured as a Linked Mode VM, a linked virtual disk plus the base disk should be used, a fact confirmet by the screen below: 

configuring Cisco ASAv 9.x on GNS3 1.4.x - qemu ASAv template - linked mode virtual disks

To complete the story,  bellow I insterted a screencast for the process described above (youtube link). Enjoy.

GNS3 – doesn’t work ping through the cloud on VM

First of all I would like to mention that all actions published here have as scope educational purpose. A lot of people who are trying to use GNS3 for testing/lab purpose meet the problem with connection to Internet through cloud.

My problem was: I couldn't ping from router in gns3 any external host. I meet this problem several times on different Operating Systems with different versions of GNS3. I researched on Internet for the solution many times and every time gave up in front of the problem. This is why I decided to write this article. It could be useful for someone in the same situation.

Let's begin with topology:

  1. I decided to install GNS3 on the Linux Ubuntu 14.04. Big Thanks to people who wrote this article http://www.computingforgeeks.com/2014/12/best-way-to-install-gns3-version-12-in.html and special thanks for those who wrote installation script.
  2. One of the most important things is that I decided to install GNS3 on VM using as hypervisor ESXi. Below you can see the topology. So I selected VM1 for this purpose.
  3. I connected ESXi host to the Cisco's switch using two cables. Cable connected to the G0/1 interface was set to trunk. Cable on G0/2 wasn't used (we will use it for debug purpose later).
  4. My VM1 has two interfaces. One is for remote management and the second for testing purpose.
  5. From VM1 I could ping from VLAN 10 interface User PC.


Let's move to GNS3 and create topology:

I am not going explain how to create topology and connect to the cloud you could easy find how to do it on internet. I will just publish screen from my topology:

VMware_GNS3_topologyAfter topology creation I was configured Interface Fa0/0 to get ip address via DHCP:

R1(config)#int fa0/0
R1(config-if)#ip add dhcp
R1(config-if)#no sh
*Mar  1 00:03:35.071: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up
*Mar  1 00:03:36.071: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
*Mar  1 00:03:48.367: %DHCP-6-ADDRESS_ASSIGN: Interface FastEthernet0/0 assigned DHCP address, mask, hostname R1

Ok I have confirmation that packets are going through cloud. Everything is good. Next test is to ping CR2 interface ip address:

R1(config-if)#do ping

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:
Success rate is 0 percent (0/5)

 Hmm.. Maybe ICMP packets were suppressed. Let's try to send ping from VM – ping test passed. So we have the situation when some packets could reach GNS3 and some others couldn't. Let's try to find where is the exactly the problem. Packets could be stuck on VM or somewhere in the network. We are connected to the Cisco switch and we have option to configure SPAN or port mirroring in order to check out suppositions. Let's do it.

C2960(config)#monitor session 1 source interface gigabitEthernet 0/1 both

C2960(config)#monitor session 1 destination interface GigabitEthernet 0/2

Please keep in mind that Gi0/2 interface couldn't send legacy user traffic after this configuration. In our case this is not a problem because I don't use this interface. On the VM2 I run Wireshark application and from R1 in GNS run again ping command. In the wireshark I see that packets leave VM and return back to the host. So problem seems to be somewhere on the VM. It could be SElinux or iptables.

Let's try another thing. Let's check how is set vmnic0 interface for VLAN10 in security tab. For this go the vSphere Client -> Configuration -> Networking -> Properties -> Double-click on your VLAN -> Press Security tab. I had the following configuration:

VMware_GNS3_errorLet's try to change promiscuous mode from Reject to Accept and repeat test again. The results:

R1(config-if)#do ping

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/20/44 ms

Here was my problem. Promiscuous mode allows vSwitch to forward all frames including those which are not directed to VM. Router in GNS3 acts as virtual interface inside of VM. From security purpose VMware block frames which are addressed to VM.

I hope that this article could be useful for you.