Installation de GNS3 sous Windows

Getting started with GNS3 on Windows: step-by-step installation

I. Presentation

In this article fromintroduction to GNS3, we will learn how to install this tool and set up the QEMU based virtual machine. Thereafter, we will see in practice how to use GNS3 through different examples.

But by the way, what is GNS3?

GNS3 is a platform that integrates a set of tools allowing us to simulate a more or less complex network. Indeed, using GNS3, we will be able to simulate a complete network, integrating network equipment such as switches, routers or even UTMs, but also client machines and servers under Linux, Unix or Windows. At first glance, this solution may seem complex to handle, this article aims to dissipate this complexity.

II. How GNS3 works

The principle of operation of GNS3 is written in its name, indeed GNS, which means Graphic Network Semulatorit’s all in Simulator.

To simulate the equipment making up a network, we have the option of going through virtualization and emulation. As a reminder, the difference between emulation and virtualization lies in the fact that emulation will artificially recreate hardware using hardware resources of the machine, while virtualization will use physical hardware, allocating spaces dedicated to each virtualized system.

From this difference, we can deduce that the use of virtualization is more efficient while they are the reasons that would lead us to emulate. Virtualization relies on hardware, so we can only virtualize systems that are compatible with our hardware. Considering this statement, we see the limitation of virtualization which does not allow us to run machines that use another processor architecture than the one present on the machine where GNS3 would be installed. Concretely, this means that we cannot virtualize switches or routers since its equipment is not equipped with x86 or x64 processor unlike the machines where we can install GNS3.

To emulate network equipment, we must therefore go through emulation. Historically, under GNS3, we used Dynamips which is a MISP architecture emulator used in older versions of CISCO routers. Today, the recommendation made by the team in charge of maintaining and developing GNS3 is to use the QEMU emulator, which is a reference in this area and is more flexible since it is not limited to emulating CISCO routers.

We can also import virtual machines in GNS3, we will then have to use a type 2 virtualization system, that is to say VirtualBox, VMWare Workstation or Player, or Hyper-V.

III. Step-by-step installation of GNS3

The installation of GNS3 requires the creation of an account on the GNS3 website. Once the account has been created, we will go to the following address to connect: Site GNS3.

Installation GNS3 - Etape 1

Once identified, we have access to the links to download the executable. We start from the premise that we are in a Windows environment.

When the download is complete, we go to the folder ” Downloads » and we will double-click on the executable that we have just downloaded, this will have the effect of launching the installation wizard.

The first dialog box is a welcome message recommending that you close all open applications. We go to the next step by clicking on the button ” Next “.

In the next step we have access to the user license that we must accept to allow us to continue with the installation. We will click on the button “ I Agree ».

We will add the GNS3 application to the Windows start folder, therefore we will leave the options of this default window and we will click on the ” Next ».

We then need to indicate which components we want to install. We will install the thick client, we also have the option of installing the thin client (web client), we will also recover the virtual machine. Regarding the virtual machine, we will explain this point a little later in this article.

We will then select the location where we want to install the components. For performance reasons, it can be very interesting to install on an SSD hard drive. Once the location has been selected, we can click on the “ Next ».

Since previously we selected ” GNS3 VM it asked us to select the hypervisor that will be used to run the VM. For this article, VMWare Workstation will be used, so it’s ” VMWARE Workstation which will be chosen.

The installation process starts with the download of the virtual machine included.

When the download is complete, a dialog will tell you where the file was downloaded.

When it’s done, we’ll move on to installing WinPCAP. This software integrates libraries allowing to add a low level network layer, it will thus be possible for us to manipulate packets and frames. We will leave the default values, until installation.

Then, we will install NPCAP which allows frame capture. We will also leave the default values.

Then, we go to the installation of Solar-Putty which is a terminal which will allow us to parameterize the equipment of the models carried out with GNS3. Accept the terms of use then click on the ” Accept ».

We will then be asked for an email address to continue.

Once the installation of solar-putty is installed, we will move on, a proposal to install another tool from SolartWinds is proposed, having never needed this tool, we will check “ No “, then we will click on “ Next ».

We have finished with the actual installation of GNS3, we can continue by clicking on the button ” Finish ».

We will not use the configuration wizard, we will click directly on the ” Cancel ».

IV. Configuration de GNS3

The virtual machine we downloaded is a server. This virtual machine runs among others QEMU, it is in this VM that we will install the equipment that will need to be emulated. To import this machine into VMWare Workstation, we will need to decompress the archive that was downloaded during the installation of GNS3.

Note: you must have VMware Player (free) or VMware Workstation (paid) on your computer to follow the rest of this tutorial.

In this archive, we have an OVA, it is a virtual machine delivered as an Appliance (Open Virtual Appliance). As a reminder, an Appliance is a concept that is in fact a virtual machine that integrates everything necessary for the proper functioning of the application. We will find there among others the QEMU emulator, but also Dynamips, Docker, etc.

To use this Appliance, we will need to import this Appliance into VMWare Workstation. For this we can double-click on the OVA file.

This will open the VMWare Import Wizard. We will select ” VMware Workstation » before clicking on the button « OK ».

After naming the virtual machine and its location, we will click on the “ Import ».

After importing it, we can see the configuration of the virtual machine.

The configuration of the appliance is relatively light, indeed, a switch, as we will see later, needs 768 MB of RAM. Since the appliance is configured with 2 GB, we will not be able to run 3 switches. So we will add RAM.

Also, as we mentioned at the beginning of this article, emulation requires CPU resources, so we need to add vCPU.

The number of vCPUs or the number of RAM will depend on your machine, we recommend at least 8 GB of RAM and 4 vCPUs, you will then have to adapt the configuration to your needs in terms of LAB.

To change the configuration of the appliance, we will click on the link ” Edit Virtual Machine Settings ».

Once we have access to the machine configuration, we will add RAM.

Then, after selecting “Processors” we will indicate 2 processors of 2 cores.

We will also modify the network card parameter, we will indicate for “ Network Adapter » the VMnet 1 which is the network « Host-Only ” by default, and the VMnet8 network which is the default NAT network for the interface ” Network Adapter 2 ».

A quick reminder about networks in VMware Workstation, there are 3 types of networks:

  • Host-Only: machines on the same network can communicate with each other, but the machines do not have internet access.
  • NAT : Network Address Translation, uses address translation technology to connect to the Internet. Address translation is done on the physical host. The network is dedicated, can communicate with each other.
  • Bridge : In this type of network, the virtual machines are on the same network as the host machine.

To modify the configuration of the network adapters, after having clicked on the network adapter, we will select the Custom option then in the drop-down list, we will choose “VMnet1” for Network Adapter and for Network Adapter 2 the VMnet 8.

To validate these changes, we must click on the button “ OK ».

Once the virtual machine is finalized, we can configure GNS3 for the use of the appliance. In GNS3, we will pull down the “ Edit » where we will select « Preferences… ».

From the side menu we will select GNS3 VM. In the central part we will activate “ Enable the GNS3 VM » by checking the box, then in « VMware Workstation/ Player (Recommanded) », we will select the GNS3 appliance, we will indicate the number of vCPUs and the amount of RAM that we have assigned to the appliance. To validate its modifications, we can click on the button “ Apply » then on « OK ».

After clicking the button ” OK », the GNS3 virtual machine launches.

Within GNS3, in the right side menu in the ” Servers Summary », we see a green part next to GNS3 VM which allows us to check that the appliance is functional.

Voila, the installation of GNS3 on Windows is complete! See you in a future article to switch to the use of GNS3.

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