Made a guest account for a friend to access my machine and restricted him to a very small set of permissions.
That seems to work as expected using ssh, when running
groupsthe correct groups are being shown, both invoked as root and as a user.
su ing also works as expected, guest group is the only one he belongs to.
All of that works when I ssh into my machine from the same machine, as well.
However, if I log in using a virtual terminal on that same machine with his account, and run
id then he's in audio, cdrom, scanner, floppy and all that.
Distribution is Slackware 13.37 (updated to current), if it helps.