Introduction

We will follow most of the steps in the official Installation guide on GNS3’s website, however during the installation and initial set up of GNS3.
I ran into issues and errors, I will show you all the steps I went through to get GNS3 installed and running.

Installation

The official installation guide for Linux can be found using the link below: https://docs.gns3.com/docs/getting-started/installation/linux/

1. Refresh apt:

sudo apt update

2. Install python and the required emulation & gui packages.
   When following the original guide, “dynamips” is not found.
   So in order to continue with the installation, we will remove it from this step and install it manually in the next step.

sudo apt install python3 python3-pip pipx python3-pyqt5 python3-pyqt5.qtwebsockets python3-pyqt5.qtsvg qemu-kvm qemu-utils libvirt-clients libvirt-daemon-system virtinst  software-properties-common ca-certificates curl gnupg2 

3. We will now install “dynamips”. First we need to download the dynamips package, then install it.

wget http://ftp.us.debian.org/debian/pool/non-free/d/dynamips/dynamips_0.2.14-1_amd64.deb

and then

sudo dpkg -i dynamips_0.2.14-1_amd64.deb

4. Use pipx to install gns3:

pipx install gns3-server

pipx install gns3-gui

We then add the “bin” directory to the “path” for the terminal to be able to find and run GNS3

pipx ensurepath

5. To launch the GUI, we will need to prepare the virtual environment. Inject the GNS server and QT elements:

pipx inject gns3-gui gns3-server PyQt5

6. Close and then reopen your terminal. You can then type “gns3” in the terminal to start it.

gns3

Fixing Issues and Errors

1. The first issue I ran into is that I would get a “libvirt Not Installed / virbr0 Missing” error when trying to add a “cloud” or “NAT” node.
   To fix this issue run the following command:

sudo virsh net-start default

2. The next issue I ran into was GNS3 throwing out a “No VPCS Path” error.
   We will need to do the following steps to fix it.

   2.1 Install the library.

   sudo apt install vpcs
   

   After doing this, GNS3 would complain that there is a “Mismatch in the VPCS versions”. In order to fix this, we now need to build the latest version of VPCS ourselves.

   2.2 First we need to download the source code from Github: https://github.com/GNS3/vpcs/releases

   Once downloaded, extract the “.zip” file and cd into the “src” folder

   cd src
   

   then run the following command to build the VPCS binary

   ./mk.sh
   

   Once it has completed the build. We will remove the old version of VPCS.

   sudo rm /usr/bin/vpcs
   

   Then copy the new version to “/usr/bin/”. So for example:

   sudo cp /home/youtube/Downloads/vpcs-0.8.3/src/vpcs /usr/bin/vpcs
   

That should be all the issues fixed. You can then run GNS3

gns3