dtcm

Calendar Manager came from Sun's DeskSet and went into CDE as dtcm. The idea was that a calendar should be a service rather than a file in a home directory: the daemon rpc.cmsd on each machine held its users' calendars and answered queries over ONC RPC. That let you browse colleagues' calendars, see when they were busy and book a meeting that appeared in everyone's view, long before Exchange made that the norm. The command-line tools dtcm_insert, dtcm_lookup and dtcm_delete did the same from scripts, and an invitation could travel as a dtmail attachment and be filed via ToolTalk.

The price was that every workstation ran an RPC service as root, listening to the whole network. In 1999 CERT warned of a buffer overflow in rpc.cmsd that yielded a root shell on Solaris, HP-UX and AIX, and a large share of university Unix machines sat exposed for weeks. The calendar became a textbook case of what happened when 1980s workgroup thinking met the internet. The program survives in the open-sourced CDE code, daemon included, for anyone wishing to relive both the meeting culture and the threat model.