The question sat open since July because nobody knew what closing would cost. It is
now measured: zero. No destinations, no remote users, no rooms with outside
participation, across four months of operation - while the federation API answers
HTTP 200 from the public internet, since the well-known delegation routes federation
over 443 and port 8448 being shut changes nothing.
So the trade is not reach against safety but an unused capability against Synapse's
largest remote-facing surface. Recommended B, an empty federation_domain_whitelist:
one line, versioned, reversible in minutes, and honest about what it does not do -
the endpoints keep answering, so the server becomes unengaged rather than invisible.
Decision remains sorb's.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Thore CimbalandClaude Opus 5
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