Bitcoin Core Debates Future of CJDNS Support Amid Low Peer Availability

Bitcoin Core contributors are reviewing the viability of the optional CJDNS network transport. Recent observations indicate a very small pool of reliable CJDNS peers, prompting discussion of a warning in a future 32.x release and possible removal in a subsequent 33.x version.

Current peer statistics

One seeder database recorded 25 CJDNS addresses, of which 22 were reachable and only seven passed the strict "good" node criteria. Another tester reported seeing just three to four CJDNS peers despite the client shipping with 11 fixed CJDNS seeds.

Security implications

The limited address set could make CJDNS‑only nodes more vulnerable to eclipse attacks, where an adversary monopolizes a node’s outbound connections. Bitcoin Core normally maintains eight full‑relay outbound slots and two block‑relay‑only slots, and a thin CJDNS pool may fail to fill these slots reliably.

Documentation and usage guidance

Current documentation already advises against operating CJDNS‑only, noting the risk of insufficient outbound peers. Recent updates (CJDNS 22.1 auto‑peering and March 2026 setup documentation) have reduced configuration friction, but the underlying peer pool remains small.

Potential deprecation path

The open issue proposes a warning in a 32.x release followed by optional removal in 33.x, though no implementation branch or pull request has been submitted yet. The change would affect only transport settings (e.g., -cjdnsreachable or -onlynet=cjdns) and not consensus rules.

Outlook

Bitcoin Core continues to support CJDNS, but the debate highlights the trade‑off between network diversity and the practical resilience offered by a transport with a minimal peer base.