GNS3 is a really great project for emulating networking devices. Since I’m exploring more security related topics lately I wanted to use Kali Linux more.

While a dedicated VM might be good for a long term lab where you use one Kali install as your main machine, Docker is very good to quickly spin up nodes and test stuff.


GNS3 desktop and GNS3 server (on a VM) is a requirement.

Create a custom Dockerfile

You don’t have to be that familiar with Docker, it’s just a few lines where you modify the apt command to your preferences.

Example 1: kali-linux-core

kali-rolling docker image comes with the bare minimum. You can’t even ping. This is why we have to install the packages we need.

# import latest image from kali linux rolling
FROM kalilinux/kali-rolling:latest
# makes so that apt doesn't ask for user input
ENV DEBIAN_FRONTEND=noninteractive
# install required tools and remove lists
RUN apt update && apt install -y kali-linux-core && rm -rf /var/lib/apt/lists/*

You can see here in the last line we install kali-linux-core with apt

This installs just the core packages with base functionality. You can append packages from there.

Example 2: custom packages (recommendation)

I’d probably go with something like this:

# import latest image from kali linux rolling
FROM kalilinux/kali-rolling:latest
# makes so that apt doesn't ask for user input
ENV DEBIAN_FRONTEND=noninteractive
# install required tools and remove lists
RUN apt update && apt install -y kali-linux-core nmap iputils-ping iproute2 tree htop locate && rm -rf /var/lib/apt/lists/*

You can see that I added packages like nmap, iproute2 and locate.

Example 3: kali-linux-headless or other metapackages

You can find a list of metapackages here

The one that might be interesting is kali-linux-headless. This comes with a lot of tools out of the box but requires a huge download.

Also remember that image size affects the resources of your GNS3 server later. In my test the kali-linux-core image was 385MB and the kali-linux-headless image was 8.26GB.

Create docker image locally

Log into GNS3 via ssh. If you haven’t changed anything: user and password is gns3

Go to your home directory


Create a directory for your Dockerfile

mkdir mydocker

Create your dockerfile with your favorite editor like vimor nano

The following command builds the image. You can change b-27p-de and kali-core to a name you like.

docker build -t b-27p-de/kali-core . --network=host

The following message is normal and doesn’t affect the build process:

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

You should see something like this when it’s successful

Successfully built b4ac31922c27

Successfully tagged b-27p-de/kali-core:latest

Check for new image

docker image list

shows more information like the size of your newly created image.

Create template

Back to GNS3 GUI, click on New template

Manually create a new template

Docker -> Docker containers -> New

Then your image should already be visible in the Image list dropdown.

give it a name you like. I used kali-rolling in this example

Network adapters

You usually want to have more than 1 adapter for network testing.

Start command

leave blank

Console type



Add environment variables of your liking. You can leave this blank.

Edit template

Change template symbol (optional)

Now the template exists but we want to fine tune it a little bit.

If you’re like me, you probably want a nice icon for your kali template. Use a custom symbol to add a svg image. It gets uploaded to the server, so anyone using the GNS3 server will see it.

define persistent directories

You can now define directories that you want to be persistent in the template.



What you put in here depends on your default use case. Because this is Docker and no virtual machine, you should keep this to a minimum.

If you need an image with other apt packages you can create one with a modified Dockerfile.

Anything outside of those directories will be lost after the container restarts.

Network settings

Connect to the internet

Drag your newly created template in one of your projects. Connect it to the internet with one of the ports (easiest is NAT like in this example). I’m using port eth0

Configure network settings

right click on kali image -> configure and then Network configuration

If you’re using NAT comment in eth0 setting like in the following example so that it’s able to receive a DHCP address.

# This is a sample network config, please uncomment lines to configure the network

# Uncomment this line to load custom interface files
# source /etc/network/interfaces.d/*

# Static config for eth0
#auto eth0
#iface eth0 inet static
#	address
#	netmask
#	gateway
#	up echo nameserver > /etc/resolv.conf

# DHCP config for eth0
auto eth0
iface eth0 inet dhcp
#	hostname kali-rolling-3

# Static config for eth1
auto eth1
iface eth1 inet static
	metric 500
#	up echo nameserver > /etc/resolv.conf

# DHCP config for eth1
#auto eth1
#iface eth1 inet dhcp
#	hostname kali-rolling-3

You also see the configuration for the second interface here. This one we want to use to interact with our GNS3 lab environment.

Make sure to add a high metric there, so that the default route to the internet is always eth0

Finished 🥳

We can now use our kali docker image to spin up nodes pretty fast and have fun with our lab.