I having gotten a Free Pascal version (Linux so far) written that works as an external program. Not really a door.

Its working for Linux so far, and allows you to drop to shell (command line).

Anyone interested in testing?

--- Mystic BBS v1.12 A42 2019/02/01 (Linux/64)
* Origin: The ByteXchange BBS | bbs.thebytexchange.com (10:102/1)