ASmap

ASmap maps IP address ranges to the autonomous systems that announce them and feeds that data into Bitcoin Core. Core can use an ASmap file to spread peers across independent network operators instead of relying only on IP-based bucketing. That makes eclipse attacks harder.

The public ASmap project ties together the research, tooling, and operational work behind this feature. Its main tool, Kartograf, builds IP-to-AS maps from public routing data and preserves the intermediate artifacts needed for review and reproduction. The current workflow draws from RPKI, IRR databases, and RouteViews.

Why fund it?

Peer diversity is part of Bitcoin's security model. Bitcoin Core has accepted user-provided ASmap files since v0.20.0, so better map generation feeds directly into the software node operators already run.

OpenSats funded ASmap in the seventh wave of Bitcoin grants in September 2024. That grant focused on improving ASmap generation, strengthening data sources, and making the tooling faster and easier to use.

What's next?

The public roadmap is straightforward: improve Kartograf, coordinate more collaborative map-generation runs, and make high-quality ASmap files easier to publish and verify. The bitcoin-core/asmap-data repository already acts as a public place to share encoded files for Bitcoin Core, and the broader integration work is tracked in the main Bitcoin Core issue.