In this guide I’ll walk you through the steps required to install GNS3 on Ubuntu 20.04 (Focal Fossa). GNS3 network emulator is an open source tool used to simulate, configure, test and troubleshoot virtual and real networks. For Students preparing for Networking Certifications, this tool is key for acing the exam. This includes but not limited to Cisco Certifications- CCNA, CCNP, CCIE, Juniper certifications, Aruba, HPE and many other vendors.

GNS3 tool can be installed on Windows, macOS and on Linux. The Virtualization for instances used in inter-connection includes VirtualBox, VMware and Docker. With all available tools you’ll be able to simulate complex network scenarios and sent packets through as if you’re working on actual appliances.

GNS3 Features

  • Fully free and Open Source – No monthly or yearly license fees
  • There is no limit on the number of devices supported – CPU and RAM hardware is your only limitation
  • GNS3 supports all VIRL images (IOSv, IOSvL2, IOS-XRv, CSR1000v, NX-OSv, ASAv)
  • GNS3 can run with or without hypervisors in multi-vendor environments
  • It has support for multiple switching options (ESW16 Etherswitch, IOU/IOL Layer 2 images, VIRL IOSvL2)
  • GNS3 supports both free and paid hypervisors – Virtualbox, VMware Workstation, VMware Player, ESXi, Fusion
  • GNS3 has native support for Linux without the need for need for additional virtualization software

Install GNS3 on Ubuntu 20.04 (Focal Fossa)

Installation of GNS3 on Ubuntu 20.04 (Focal Fossa) is done from a PPA repository. We will initiate the installation by adding the repository, do system update, then installing required packages on Ubuntu Linux.

Step 1: Add GNS3 PPA repository

Run the following commands to add the GNS3 repository:

sudo add-apt-repository ppa:gns3/ppa

Input your user password and Press [ENTER] to continue:

[sudo] password for jkmutai: 
 PPA for GNS3 and Supporting Packages. Please see for more details
 More info:
Press [ENTER] to continue or Ctrl-c to cancel adding it.
Hit:1 focal InRelease
Hit:2 focal-updates InRelease              
Hit:3 focal-security InRelease               
Hit:4 focal-backports InRelease            
Hit:5 focal InRelease                 
Reading package lists... Done

Step 2: Install GNS3 GUI & GNS3 Server on Ubuntu 20.04

Once the repository has been added, installation of GNS3 packages on Ubuntu 20.04 can be performed.

sudo apt update                                
sudo apt install gns3-server gns3-gui

A number of packages will be installed in your system, press the y key to accept installation:

The following packages will be upgraded:
  libnss-systemd libpam-systemd libsystemd0 systemd systemd-sysv
6 upgraded, 124 newly installed, 0 to remove and 112 not upgraded.
Need to get 101 MB of archives.
After this operation, 465 MB of additional disk space will be used.
Do you want to continue? [Y/n] y

Allow non-root users to use wireshark:

install gns3 ubuntu 01

Allow them to capture packets as well.

install gns3 ubuntu 02

Step 3: Install IOU Support (Optional)

IOU (IOS over Unix) is an internal Cisco tool for simulating the ASICs in Cisco Switches. This enables you to play with Layer 2 switching in your LABS.

Install GNS3 IOU package to unlock this feature:

sudo dpkg --add-architecture i386
sudo apt update
sudo apt install gns3-iou

Accept installation prompt:

The following packages will be upgraded:
1 upgraded, 10 newly installed, 0 to remove and 111 not upgraded.
Need to get 8,575 kB of archives.
After this operation, 34.2 MB of additional disk space will be used.
Do you want to continue? [Y/n] y

Step 4: Docker Support (Optional)

If you plan on using Docker Engine in your networking stack, you’ll need to install the runtime.

To Install Docker CE, use our guide below:

Install Docker CE on Ubuntu

After installing Docker and IOU, add your user to the following groups:

for i in ubridge libvirt kvm wireshark docker; do
  sudo usermod -aG $i $USER

Step 5: Launch GNS3 on Ubuntu 20.04

Now that GNS3 is installed on Ubuntu 20.04, you can launch it from the terminal or from Desktop launcher.

$ gns3

On the first page, select “Run the appliances on my computer”

install gns3 ubuntu 03

On the second page, confirm local server configuration location.

install gns3 ubuntu 04

Confirm that the connection is successful.

install gns3 ubuntu 05

Complete GNS3 setup on Ubuntu 20.04 Linux.

install gns3 ubuntu 06

To be able to capture GNS3 packets for analysis, you need Wireshark.

Networking courses to sharpen your skills.

You can install it using our guide in the link below.

How to install Wireshark on Ubuntu

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