> NFS ran in plaintext and used the sender’s IP address for authentication
and it still does
replies(2):
and it still does
Back when I was a summer intern at Sun in 1987, it was common knowledge among the engineers at Sun that NFS stood for "No File Security", and the rpc mount protocol would trust the client to tell the server its host name, which the server would look up in /etc/exports to decide how much to trust it.
So if you know that Scott McNealy's workstation's name was "doober" (which it was), and it gave permission to a server named "mama", then on any workstation you could type:
% hostname mama; mount doober:/usr /mnt; hostname `hostname`
And you'd have Scott McNealy's /usr file system mounted.
This also worked over the internet!
(Not that this is of any consequence....) :-)
For those who aren't familiar with this, up until the mid-1990s or so, Sun let individual engineers name their own workstations. In fact many regarded this as a privilege. Each workstation ran its own copy of sendmail, so one's email address was login@hostname. People came up with all kinds of clever login/hostname combinations, such as what Don mentioned, eat@joes.
My all time favorite was Rich Burridge's, whose workstation was named "stard". Since his login was richb, his email address was...
richb@stard