>>>>> "Ethan" == Ethan Benson <[EMAIL PROTECTED]> writes:
Ethan> On Tue, Oct 17, 2000 at 01:56:16PM +1100, Brian May wrote:
>> Wrong - shutdown.allow has no affect for ctrl+alt+del. You can
>> press this even if you are not logged in.
Ethan> Wrong, the existance of /etc/shutdown.allow means that a
Ethan> listed user must be logged in on any of the console tty's
Ethan> for control-alt-delete to work. it does not require a
Ethan> login per se, but someone [listed in shutdown.allow] does
Ethan> have to be logged in for it to work. that is what the -a
Ethan> switch does, man shutdown.
Ethan> if NOBODY is logged into the console and shutdown.allow
Ethan> exists control-alt-delete is disabled. i use this to
Ethan> disable user directed shutdown one a machine i administer
Ethan> remotely. (so they don't kill it while im working)
I stand corrected. A case of misleading documentation:
-a Use /etc/shutdown.allow.
would suggest that it only checks the current user (ie root, as root
started init, which started the shutdown process. However, later on
it says:
shutdown can be called from init(8) when the magic keys
CTRL-ALT-DEL are pressed, by creating an appropriate entry
in /etc/inittab. This means that everyone who has physical
access to the console keyboard can shut the system down.
To prevent this, shutdown can check to see if an autho
rized user is logged in on one of the virtual consoles. If
shutdown is called with the -a argument (add this to the
invocation of shutdown in /etc/inittab), it checks to see
if the file /etc/shutdown.allow is present. It then com
pares the login names in that file with the list of people
that are logged in on a virtual console (from
/var/run/utmp). Only if one of those authorized users or
root is logged in, it will proceed. Otherwise it will
write the message.
It looks like (to me) that making shutdown setuid root means anybody
can shutdown the computer, from any location, as /etc/shutdown.allow
is only checked when -a is passed. Am I wrong?
If I am wrong, then the documentation should be corrected for this
special case.
--
Brian May <[EMAIL PROTECTED]>
