mod_pubsub_post: Restructure authentication and authorization (BC) This deprecates the default "superuser" actor model and makes the default equivalent to the previous "request.id". A single actor and secret per node is supported because HTTP and WebHooks don't normally include any authorization identity. Allowing authentication bypass when no secret is given should be relatively safe when the actor is unprivileged, as will be unless explicitly configured otherwise.

---
summary: Block s2s connections based on admin blocklists
...

This module uses the blocklists set by admins for blocking s2s
connections.

So if an admin blocks a bare domain using [Blocking Command][xep191]
via [mod\_blocklist][doc:modules:mod_blocklist] then no s2s connections
will be allowed to or from that domain.