How to Install GNS3 on Ubuntu

The GNS3 network simulator program can be installed on Windows operating systems as well as easily downloaded, installed, and used on Linux-based systems.

How to Install GNS3 on Ubuntu

How to Install GNS3 2.2.18 on Ubuntu 20.10

With the GNS3 (Graphical Network Simulator 3) program, you can create more specific network topologies and run and use these devices virtually with GNS3 on your computer without the need to purchase network products such as Cisco Router and Switch.

We have previously installed the GNS3 network simulator program on the Windows operating system. While installing GNS3 on the Windows platform, we proceed with graphical steps.

On the Ubuntu operating system, applications are usually installed using the terminal. In Linux systems, you must define the repo addresses of a program. And so, sometimes setting up a program can be time-consuming and complicated.

GNS3 is more specific than the Cisco Packet Tracer program, so users prefer this simulator program more.

GNS3 is a constantly updated network simulator program and its most current version is 2.2.18. In our previous articles, we installed on other Linux systems and Windows 10;

How to Set Up and Use GNS3

To install Cisco simulator software on your Linux / Ubuntu 20.10 (Groovy Gorilla) distribution, follow the steps below in order.

   Step 1

Open Terminal by pressing Ctrl + Alt + T keys together on the Ubuntu desktop. To add GNS3 to the Repository, type the following command in Terminal and press Enter.

sudo add-apt-repository ppa:gns3/ppa

Adding the GNS3 Repo Address

   Step 2

To add the repo address of the GNS3 software, enter your system’s root password and then press the Enter key. If you want to cancel this process, as you can see in the terminal, press the Ctrl + C keys together.

Typing the Root Password

   Step 3

To check the current versions of the programs installed on your Linux / Ubuntu system, type the sudo apt-get update command and press Enter.

sudo apt update

Updating the Package List

   Step 4

After checking the versions of installed programs, execute the apt list –upgradable command to see which programs will be upgraded. If you want to continue the update process immediately, execute the sudo apt upgrade command.

As you can see in the image below, some services running in the background block the process during the update. Check the ID numbers of the conflicting services, ie processes, on your system as follows and then execute the sudo kill -9 (Process ID) command on the terminal to terminate this process.

sudo apt upgrade
sudo kill -9

Terminating Conflicting Services

   Step 5

When you apply the sudo apt upgrade command again, if you get the “dpkg was interrupted” error, execute the “sudo dpkg –configure -a” command as stated in the terminal. Then start the update again.

sudo dpkg --configure -a

Fixing Dpkg Error

   Step 6

After applying the necessary commands, press the Y key and then Enter to start updating the applications running on your system.

Confirming Updates for Packages

   Step 7

Update time may vary depending on your Ubuntu distribution and installed applications. After completing this process, execute the command “sudo apt install gns3-server gns3-gui” in the terminal to install the GNS3 simulator software.

sudo apt install gns3-server gns3-gui

Initiating Cisco Simulator Setup

   Step 8

Dependent packages that require the simulator program to work properly on Ubuntu will be installed. Press Y then Enter to confirm the installation of all specified packages in the terminal.

Confirming the Installation of Packages

   Step 9

Don’t forget to check your connection as dependent packages for GNS3 will be downloaded from the Internet. At the last stage of the installation, when the Wireshark program is being installed, when you encounter the Configuring ubridge window, press Enter on the Yes option to allow non-superusers users to run this software.

Non-superusers Permission Settings

   Step 10

Likewise, press Enter on the Yes option to allow non-superusers members to perform packet analysis on the network with the Wireshark program.

Non-superusers Permission Settings

   Step 11

After successfully completing the GNS3 setup, run the program from the applications panel.

Running the Program

   Step 12

After running the GNS3 simulator, a Setup Wizard window will appear. You can close this window or proceed to view and verify localhost settings.

In the Setup Wizard window, select “Run appliances on my local computer” and then click the Next button.

Run appliances on my local computer

   Step 13

Continue without changing the default settings in the local server configuration window. If there is another application in your system that may conflict with GNS3, specify another value in the Port section.

Local Server Configuration

   Step 14

In the local server status window, you can see that the Localhost service is not conflicting with another application and is running smoothly. Continue by clicking Next in the service verification window.

Viewing Local Server Status

   Step 15

The summary window shows you that the GNS3 simulator software is running locally. Click Finish to close this window and go to the next step.

Checking the Information in the Summary Window

   Step 16

Now you need to add a Router IOS image to the Cisco simulator program and test it. To add a new IOS to the program, go to File / Preferences from the menu.

Adding Router IOS Image

   Step 17

Click on the Dynamips / IOS Router tab and then the New button.

Dynamips / IOS Router

   Step 18

In the New IOS Router Template window, click the Browse button to specify the location of the IOS image.

New IOS Router Template

   Step 19

Select the “c7200-adventerprisek9-mz.152-4.M7.bin” file that you downloaded to your desktop or my documents location and click the Open button to add the IOS image.

Selecting IOS Image

   Step 20

Answer Yes to the question of Would you like to decompress this IOS image and continue.

Extracting IOS File

   Step 21

After selecting the Router 7200 image, click Next.

Router 7200

   Step 22

In the Name and Platform window, you can change the name of the device you added and configure the platform type. Leave the settings here as default and click Next.

Name and Platform

   Step 23

In the Memory window, you can increase or decrease the memory of the Router device you will run. If you have a high-performance desktop or laptop computer, you can increase the memory a little more.

Memory Configuration of the Router

   Step 24

In the Network Adapters window, you can add FastEthernet, GigabitEthernet, or Serial Interface to the slots of the Router, or you can only use the C7200-IO-FE (FastEthernet) network card by default.

Adding a Network Card to the Router

   Step 25

In the Idle-PC window, click the Idle-PC Finder button to automatically set a value to prevent the Router or Switch network devices from using your computer’s processor 100%.

Idle-PC Value Determination

   Step 26

If you get the following error while specifying the idle-PC value, just click OK and continue adding IOS without specifying a value.

Error: Could not send Dynamips command 'vm get_status "AUTOIDLEPC"' to localhost:54121: Connection lost, process running: False

NOTE: The error mentioned above is due to the GNS3 software’s Dynamips incompatibility on Ubuntu 64-Bit.

Error: Could not send Dynamips command 'vm get_status "AUTOIDLEPC"' to localhost:54121: Connection lost, process running: False

   Step 27

Close the IOS add window.

Closing the Window

   Step 28

Now click on File / New Blank Project to create a new project or press CTRL + N keys together for a faster process.

Creating a New Project

   Step 29

Determine the file names you can remember for the network projects you will create. If you create new projects for testing purposes, you can delete them later and create free space on your computer’s disk.

Configuring Project Name and Location

   Step 30

When you want to run the Router you added, you may get the following error this time. As we mentioned above, these errors are caused by the Ubuntu Dynamips error. We did not encounter such errors in older distributions, but we shared the solution with you without waiting for new versions to fix this error in new versions.

Dynamips hypervisor process has stopped, return code: -11
C7200 'Ghost': generic_nvram_extract_config: Unknown error -61605

Dynamips hypervisor process has stopped, return code: -11 C7200 'Ghost': generic_nvram_extract_config: Unknown error -61605

   Step 31

To resolve the Ubuntu Dynamips error, open the terminal on the desktop or any other location, and then execute the command “sudo dpkg –add-architecture i386” to enable 32 Bit architecture on your system.

sudo dpkg --add-architecture i386

Enabling 32-Bit Architecture

   Step 32

After enabling the 32 Bit architecture, execute the command “sudo apt install libc6-dev-i386” in the terminal and press the Y key and then Enter to confirm the installation of the additional packages.

sudo apt install libc6-dev-i386

Installing the Libc6-dev-i386 Package

   Step 33

Likewise, run “sudo apt install libelf-dev:i386 libpcap0.8-dev:i386” to install additional packages to fix the Dynamips error.

sudo apt install libelf-dev:i386 libpcap0.8-dev:i386

Installing Libelf-dev:i386 and Libpcap0.8-dev:i386 Packages

   Step 34

After installing the dependent packages required by the 32 Bit architecture for GNS3, you need to download and install the i386 package to ensure Dynamips can run smoothly. To download and install the Dynamips i386 package, execute the commands below.

sudo dpkg -i dynamips_0.2.21-1~eoan1_i386.deb

NOTE: In the new version of Ubuntu, we have fixed a common error in the simulator program commonly used by users preparing for Cisco exams. It took two business days to fix this error. Please do not imitate our content and do not hesitate to cite it as a source.

Downloading and Installing Dynamips 32-Bit Version

   Step 35

After completing the Dynamips 32 Bit setup, open GNS3 again and create a new project and add the Router you added to the workspace and run it.

Running and Checking the Router

   Step 36

As you can see in the Topology Summary section, the Router started working without any problems.

Reviewing the Topology Summary Tab

   Step 37

Double click on the router to open the CLI prompt and execute a simple command “show version” to test it.

Router CLI Command Prompt


Installing Older Versions

YouTube Video

   Final Word

In this article, we have examined how to run GNS3 on Linux / Ubuntu step by step. And finally, we have added a Cisco IOS image for using Cisco Router or Switch on Ubuntu. Thanks for following us!

   Related Articles

How to Install GNS3 on macOS
How to Configure RIP
How to Configure RIP Version 2
How to Configure EIGRP
How to Configure OSPF


  1. Avatar for Loliverouge Loliverouge 26 February 2021

    Just thank you !

    • Avatar for Tolga Bagci Tolga Bagci 26 February 2021

      You’re welcome, thanks for your comment!


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