Usenet news over TLS — a news server, wrapped in TLS from the first byte.
Port 563 is the implicit-TLS version of NNTP: the client opens the connection, negotiates TLS immediately, and only then starts the normal NNTP conversation of GROUP, ARTICLE, and POST commands. Plain NNTP lives on 119 and can also upgrade in place with the STARTTLS command. RFC 4642 actually discourages the separate-port approach, but 563 stayed in wide use and is what commercial Usenet providers and INN-based servers publish for TLS clients. On a scan it means a news server, which is a narrow and shrinking population.
Fine to expose
A public news service is meant to face the internet and the transport is TLS-encrypted; the exposure to manage is the authentication behind it, not the port.
$ openssl s_client -connect TARGET:563 -quietSeen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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