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Open Wireless Link

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Open Wireless Link (OWL) is an open implementation of the Apple Wireless Direct Link (AWDL) ad hoc protocol for Linux and macOS written in C and part of the Open Wireless Link project.

OWL runs in user space and makes use of Linux’s Netlink API for Wi-Fi specific operations such as channel switching and to integrate itself in the Linux networking stack by providing a virtual network interface such that existing IPv6-capable programs can use AWDL without modification.

You can use OWL to in combination with OpenDrop to enable Apple AirDrop functionality on Linux-based systems such as a Raspberry Pi 3.

Disclaimer

OWL is experimental software and is the result of reverse engineering efforts by the Open Wireless Link project. Therefore, it does not support all features of AWDL or might be incompatible with future AWDL versions. OWL is not affiliated with or endorsed by Apple Inc. Use this code at your own risk.

Requirements

Wi-Fi card with active monitor mode. To use OWL, you will need a Wi-Fi card supporting active monitor mode with frame injection. We recommend the Atheros AR9280 chip (IEEE 802.11n) which we used to develop and test this code. Configurations that do not support active monitor mode, i.e., ACK received frames, might suffer from throughput degradation because the sender will re-transmit each frame up to 7 times as per the IEEE 802.11 standard. Have a look at issue #9 if you want to find out whether your card meets the requirements.

No support for virtual machines and WSL. OWL requires direct access to the Wi-Fi card which means that virtualized environments (except with USB or PCIe passthrough) and Windows Subsystem for Linux (WSL, see issue #8), are not supported.

OWL requires libpcap for frame injection and reception, libev for event handling, and libnl (Linux only) for interactions with the system's networking stack which have to be installed on the target system.

On Debian Linux,

sudo apt install libpcap-dev libev-dev libnl-3-dev libnl-genl-3-dev libnl-route-3-dev

On Fedora Linux,

sudo dnf install libpcap-devel libev-devel libnl3-devel

On macOS, you need to add support for tun/tap devices, e.g., via tuntaposx. You can install everything via Homebrew:

brew install libpcap libev
brew cask install tuntap

Build from source

The project is build using CMake. To build the project, simply clone this repository in <OWLDIR> and run

cd <OWLDIR>
git submodule update --init
mkdir build
cd build
cmake ..
make
sudo make install

Use

Simply run

sudo owl -i <WLAN_IFACE>

You can specify a wireless channel using the -c parameter. Available channels are 6, 44 and 149. Note that only some of these channels may be available for use in your country based on your regulatory domain. OWL will warn you if it is unable to use the specified channel, in which case you will only be able to monitor the network. On Linux, you can check which channels are available for use in your country using iw list in Frequencies section. A channel is not available if it is listed as disabled or no IR.

You may increase the log level with -v and -vv and daemonize the program with -D. For other options, have a look at daemon/owl.c. Warning: do not use the -N flag in setups without Nexmon such as this as it will likely cause several problems.

When started, OWL creates a virtual network interface awdl0 with a link-local IPv6 address. Discovered AWDL peers are automatically added (and removed) to (and from) the system's neighbor table. Run ip n to see a list of all current neighbors.

Architecture

The following figure shows the core structure of OWL.

Overview

Code Structure

We provide a coarse structure of the most important components and files to facilitate navigating the code base.

Current Limitations/TODOs

Our Papers

Contact