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Case study

OWL: an open Apple Wireless Direct Link implementation

Reimplements Apple Wireless Direct Link (AWDL), the proprietary Wi-Fi ad hoc protocol Apple devices use for peer-to-peer links such as AirDrop, as a user-space C daemon for Linux and macOS; the README calls it the result of reverse engineering by the Open Wireless Link project at TU Darmstadt's SEEMOO lab. OWL runs the master election, synchronises availability windows and the channel sequence, parses and crafts AWDL action and data frames, and provides an awdl0 virtual interface with a link-local IPv6 address, so unmodified IPv6 programs such as SEEMOO's OpenDrop AirDrop client can reach Apple devices. The authors describe the recovered protocol in a MobiCom 2018 paper.

Targets
Protocol
Category
Independent reconstruction cases
Relationship
Independent reconstruction project
Sources reviewed

Requirements & limits

  • Archived; the README calls OWL experimental and no longer maintained, says it does not support all AWDL features and may be incompatible with later AWDL versions, and states no affiliation with or endorsement by Apple. The last code change is a January 2022 buffer-overread fix; the 2026-08-17 and 2026-10-12 commits only replaced links to the former owlink website, which the README says is no longer associated with the project. There are no tags or releases.
  • Needs a Wi-Fi card with active monitor mode and frame injection, used directly: the authors developed and tested with an Atheros AR9280, and virtual machines without USB or PCIe passthrough and WSL are not supported. OWL runs with sudo on one wireless interface, which it then uses only for AWDL, so no access-point connection can run alongside it; channels 6, 44 and 149 are available subject to the local regulatory domain, and OWL can only monitor when it cannot use the chosen channel.
  • Builds with CMake 3.5+ and a C compiler against libpcap, libev and, on Linux, libnl; on macOS it uses CoreWLAN and needs a tun/tap driver such as tuntaposx. googletest and the radiotap library are git submodules. The workflow on ubuntu-latest and macos-latest builds the code and runs the googletest suite for frame-buffer parsing, election, peers and synchronisation; interoperation with Apple devices is the authors' report.
  • Nothing from Apple is needed to build it, and the repository holds only source code, tests, build files and an architecture diagram; using it requires nearby Apple devices with AWDL. README lists known gaps: static election metric and counter values, a channel sequence fixed at start-up because adapting it would need a better understanding of Apple's implementation, and no concurrent AP connection. It also cites the group's MobiCom 2018 protocol paper and demo and a USENIX Security 2019 security analysis of AWDL.
  • GPL-3.0 (COPYING); AWDL and AirDrop remain Apple's proprietary technology. Nothing was built or run with Wi-Fi hardware or Apple devices in this review; the reviewed sources establish no AI or REA use.

About this entry

The description was reviewed against primary sources. This does not establish runtime testing, security auditing or verified compatibility.

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Primary sources

  1. README.md GitHub · seemoo-lab/owl · Revision 0ee3263
  2. CMakeLists.txt GitHub · seemoo-lab/owl · Revision 0ee3263
  3. .gitmodules GitHub · seemoo-lab/owl · Revision 0ee3263
  4. daemon/owl.c GitHub · seemoo-lab/owl · Revision 0ee3263
  5. src/frame.h GitHub · seemoo-lab/owl · Revision 0ee3263
  6. tests GitHub · seemoo-lab/owl · Revision 0ee3263
  7. .github/workflows/test.yml GitHub · seemoo-lab/owl · Revision 0ee3263
  8. COPYING GitHub · seemoo-lab/owl · Revision 0ee3263
  9. https://doi.org/10.1145/3241539.3241566

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