some history: my broadcast,
by Jordan Hubbard (ucbvax!jkh), 2 Apr 1987. It seems the default
configuration for Suns back then was that "everyone" really meant
everyone -- resulting in some fun when Jordan ran rwall (remote
write to all) to the broadcast netgroup. Some good snippets in
retrospect:
Since rwall is an RPC service, and RPC doesn't seem to give a damn who you are as long as you're root (which is trivial to be, on a work- station), I have to wonder what other RPC services are open holes. We've managed to do some interesting, unauthorized, things with the YP service here at Berkeley, I wonder what the implications of this are. ...
(An) alternative (to getting rid of rwall) would be to tighten up all the IMP gateways to forward packets only from trusted hosts. I don't like that at all, from a standpoint of reduced convenience and productivity.
Fast-forward to 15 years later: RPC services are almost all firewalled off due to insecurity, and packet filters on gateways -- ie. firewalls -- are standard kit. The internet has changed a lot since then.