Znail

Znail is a network emulator inteded to run on a Raspberry Pi. Equipped with two network interfaces, the Raspberry Pi acts as a network bridge. Znail can then control network traffic passing through the bridge.

With a system under test connected to the network through this bridge, Znail can help you answer question about how that system behaves under various network conditions.

Features

• Emulate packet delay
• Emulate packet loss
• Emulate packet duplication
• Emulate packet reordering
• Emulate packet corruption
• Control packet rate
• Capture network packets
• Emulate a disconnect (by powering down one of its network interfaces)
• Override answers to DNS queries (by redirecting DNS traffic to its internal DNS server)
• Redirect IP traffic from one host to another
• Not apply any of the above for certain hosts using a whitelist

Znail can be managed in one of two ways, using its web interface or its REST API.

Getting Started

The easiest way to get started with Znail is to download a Rasbian image with Znail pre-installed.

The image can then be installed on a Raspberry Pi.

Generating a Custom Image

A virtual machine is used to build the image. Vagrant and the vagrant-scp plugin is required.

To set up the environment on recent Ubuntu systems, run the following commands:

sudo apt update
sudo apt install vagrant
vagrant plugin install vagrant-scp

To generate an image:

make image

The resulting image can be found in the dist/image directory.

Development

The Python environment requires that the pip tool is installed.

To set up the development environment on recent Ubuntu systems, run the following commands:

sudo apt update
sudo apt install python3-pip python3-venv

To build and activate the virtual Python environment:

source ./activate

To automatically format the code:

make format

To run tests and static code analysis:

make check

More information about what targets the build system provides:

make help

Special Thanks

Special thanks to Alice Persson for contributing the Znail logotype.

License

Distributed under the terms of the Apache License 2.0.